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Prirodna vlakna sve su češća zamjena za do tada tradicionalne vrste ojačala u izradi kompozitnih materijala. Ekologija i kružno gospodarstvo utjecali su na porast biljnih vlakana u tehnologijama proizvodnje zbog njihovih mehaničkih svojstava, recikličnosti, maloga utjecaja na okoliš, male emisije CO2 i širenja privrede na zabačene dijelove svijeta u kojima se ljudi još uvijek bave agrokulturom. Sama prirodna vlakna nemaju dovoljno dobra mehanička svojstva za primjenu u svim područjima strojarstva te se hibridizacijom miješaju sa staklenim vlaknima kako bi se utjecalo na njegov porast. Cilj ovoga rada bio je ispitati utjecaj hibridizacije lanenih vlakana staklenima u epoksidnoj matrici i uvidjeti utjecaj vode na mehaničko ponašanje takvih materijala. Voda je najmanje utjecala na mehanička svojstva kompozita koji su samo od staklenih vlakana ili su vlakna s vanjske strane materijala te su takva svojstva zamjetljiva i na mehaničkim svojstvima. Uzorcima koji su bili u vodi smanjio se modul, a rastezna su i savojna čvrstoća jedino porasle kod materijala sa SSSSSS i SLLLLS konfiguracijom. Natural fibers are an increasingly common substitute for previously traditional types of reinforced composite materials. Ecology and the circular economy have influenced the growth of plant fibers in production technologies due to their mechanical properties, recyclability, low impact on the environment, low CO2 emissions and the expansion of the economy to remote parts of the world where people still engage in agriculture. Natural fibers alone do not have good enough mechanical properties for application in all areas of mechanical engineering, so they are mixed with glass fibers through hybridization in order to influence its growth. The aim of this work was to examine the influence of the hybridization of flax fibers with glass in an epoxy matrix and to see the influence of water on the mechanical behavior of such materials. Water had the least effect on composites that are only made of glass fibers or the fibers are on the outside of the material, and such properties are also noticeable in the mechanical properties. The modulus of the samples that were in water decreased, while the tensile and flexural strength only increased in materials with SSSSSS and SLLLLS configuration due to better fiber adhesion and their protection against water penetration.

Hibridni kompoziti su materijali koji sadrže dvije ili više vrste vlakana kao ojačanje. Izrađeno je pet vrsta hibridnih kompozitnih materijala od epoksidne smole kao matrice te kombinacije tkanina od staklenih i od lanenih vlakana kao ojačanja, ukupno šest slojeva, od čega su dva staklena. Svaki kompozitni materijal ima različit način slaganja vlakana, odnosno negdje su staklena vlakna u vanjskim slojevima, dok su drugdje lanena. Kombinacija slaganja vlakana je sljedeća: SLLLLS, LLSSLL, LSLLSL, SSSSSS, LLLLLL pri čemu S označava sloj staklenih vlakana, a L sloj lanenih vlakana. Ispitana su goriva svojstva kompozitnih materijala u ovisnosti o rasporedu slaganja vlakana. Izmjerena je i tvrdoća svakog pojedinog materijala te je proveden Martens postupak ispitivanja postojanosti oblika materijala pri povišenim temperaturama. Rezultati pokazuju kako svi ispitani materijali spadaju u klasu K2 otpornosti na gorenje. Također, kompozit izrađen od šest slojeva lanenih vlakana se pokazao najboljim pri ispitivanju otpornosti na gorenje, dok je kompozit ojačan staklom najbrže gorio. Od hibrida kompozit LSLLSL se najlošije ponaša pri gorenju, dok ima najvišu tvrdoću i temperaturu postojanosti oblika. Hybrid composites are materials that contain two or more types of fibers as reinforcement. Five types of hybrid composite materials were made using epoxy resin as the matrix and a combination of glass and flax fibers as reinforcement, totaling six layers, two of which are glass. Each composite material has a different fiber arrangement, with glass fibers in the outer layers in some cases, while flax fibers are used elsewhere. The fiber stacking combinations are as follows: SLLLLS, LLSSLL, LSLLSL, SSSSSS, LLLLLL, where S denotes a layer of glass fibers and L denotes a layer of flax fibers. The fuel properties of the composite materials were tested depending on the fiber stacking arrangement. The hardness of each individual material was measured, and the Martens procedure was used to test the shape stability of the materials at elevated temperatures. The results show that all tested materials fall into the K2 class of fire resistance. Additionally, the composite made of six layers of flax fibers performed the best in terms of fire resistance, while the glass-reinforced composite burned the fastest. Among the hybrids, the LSLLSL composite exhibited the poorest performance in terms of burning, but it had the highest hardness and shape stability temperature.

With the development of the automotive industry, a large amount of waste rubber is produced every year. The application and development of recycled rubber concrete (RRC) can effectively reduce ‘black pollution’ caused by waste rubber. However, the addition of recycled rubber particles can lead to a decrease in the compressive behavior of concrete. Previous research has demonstrated that by preventing crack growth, fiber addition can increase the strength and ductility of concrete. In this work, a total of 28 RRC mixes are designed, and the compressive behavior of RRC reinforced by steel fibers (SFs) and glass fibers (GFs) is investigated. The workability of fresh RRC can be negatively impacted by an increase in both fiber contents, with the GF content having a more notable effect. With the addition of fibers, the maximum increase rates for the compressive strength, elastic modulus, strain at peak stress, and compressive toughness were 27%, 8%, 45%, and 152%, respectively. A constitutive model is concurrently put forward to forecast the stress–strain curves of RRC with various fiber contents. These findings indicate that the maximum improvement in compressive behavior is achieved when the GF content was 0.4% and the SF content was 1.2%. The proposed constitutive model can be used to predict the stress–strain curve of hybrid fiber-reinforced recycled rubber concrete (HFRRRC).

Composite materials with carbon and glass fibers in an epoxy matrix are widely used systems due to their excellent mechanical parameters, and machining is a standard finishing operation in their manufacture. Previous studies focused exclusively on the characteristics of the fibers released into the air. This work aimed to analyze the nature of the material waste that remains on the work surface after machining. The dust on the work surface is made up of fibers and a polymer matrix, and due to its dimensions and chemical stability, it is a potentially dangerous inhalable material currently treated as regular waste. The smallest sizes of destroyed carbon fibers were generated during drilling and grinding (0.1 μm), and the smallest glass fiber particles were generated during milling (0.05 μm). Due to their nature, carbon fibers break by a tough fracture, and glass fibers by a brittle fracture. In both cases, the rupture of the fibers was perpendicular to or at an angle to the longitudinal axis of the fibers. The average lengths of destroyed carbon fibers from the tested processes ranged from 15 to 20 µm and 30 to 60 µm for glass fibers.

This experimental study investigated how defects, in particular fiber misalignment, affect the mechanical behavior of glass fiber composites (GFRP) under compressive loading. GFRP cross-plies with three different types of fiber misalignment, namely a fold, a wave, and an in-plane undulation, were fabricated using the resin transfer molding process. The compressive tests were performed at four different temperatures, in order to investigate the role of a change in the matrix properties on the strength of the composite. The experiments showed that the defects, especially at lower temperatures, had a significant impact on the mechanical properties of the composite, exceeding the proportion of the defects inside the composite. With increasing temperature, the damage mechanism changed from fiber-dominated to matrix-dominated and, in doing so, decreased the significance of fiber misalignment for the mechanical behavior.

V nalogi obravnavamo vpliv tehnologije 3D tiskanja termoplastičnih kompozitov, ojačanih z dolgimi enosmernimi steklenimi vlakni na natezno in upogibno trdnost, ter primerjamo rezultate, dobljene z eksperimentalnim testiranjem in numeričnim simuliranjem. V prvem delu naloge smo analizirali materialne lastnosti osnovnega materiala in vlaken. Določili smo materialne parametre in izračunali elastične parametre za popis ortotropnih lastnosti ojačitvenih vlaken s semiempiričnim Chamijevim modelom. Zatem smo določili geometrijo testnih preizkušancev, kjer smo opazovali vpliv tiskane smeri, in geometrijo kompozitnih preizkušancev, pri katerih smo upoštevali izmenično in zgoščeno razporeditev ojačitev po prerezu. Nastale natisnjene preizkušance smo obremenjevali na nateg in upogib ter opazovali njihov odziv. Dobljene rezultate smo primerjali z rezultati numeričnih simulacij, kjer smo vrednotili ojačitve z metodo membran, metodo nosilcev in metodo kompozitne postavitve. S primerjavo rezultatov smo ugotovili, da ima tehnologija 3D tiskanja velik vpliv na končno trdnost kompozita, kjer zaradi šibkega stika med matrico in vlaknom prihaja do razslojevanja. We investigate the impact of 3D printing technology of thermoplastic composites reinforced with long unidirectional glass fibers on the tensile and bending strength, where we compare the results obtained by experimental testing and numerical simulation. In the first part of the assignment, we analysed the material properties of the base material and fibers. We determined the material parameters and calculated the elastic parameters for orthotropic properties of the reinforcing fibers using the semi-empirical Chamis model. After that, we determined the geometry of the test specimens, where we observed the influence of the printed direction, and the geometry of the composite specimens, where we considered the alternating and condensed distribution of reinforcements across the cross-section. The resulting printed test pieces were subjected to tension and bending, and their response was observed. The obtained results were compared with the results of numerical simulations, where reinforcements were evaluated using the membrane method, the beam method and the composite layout method. By comparing the results, we found that the 3D printing technology has a great influence on the final strength of the composite, where delamination occurs due to the weak contact between the matrix and the fiber.

The problem of lack of sustainability for public garden furniture in special weather conditions such as heat and rain, and the damage of these furniture as a result of continuous use and exposure to stress, pressure and land. The research aimed to provide local qualities of overlapping materials suitable to serve as furniture for public parks and by using filler materials reinforced with banana and glass fibers. Hybrid composite materials based on polymeric materials were prepared by manual epoxy casting supported by banana fibers in the form of filaments and glass fibers.Four samples were produced:• The first sample: 50 grams banana fibers bristles, 100 grams glass fibers, 1 kg epoxies.• The second sample: 50 grams banana fibers bristles, 200 grams glass fibers, 1 kg epoxies.• The third sample: 100 grams fiberglass (1) woven layer, 1 kg epoxy.• Fourth sample: 200 grams of fiberglass (2) woven layer, 1 kg epoxy.• The fourth sample is the ideal sample, due to its high tensile strength; high elongation, very high tensile stress and high pressure resistance although it is one of the highest samples in terms of weight loss and ground resistance. They are very suitable qualities for making garden and garden furniture, which allows for a higher use life and resistance to use conditions, and not affected by conditions of weather conditions .• As for the first sample, it is an economic sample. It appears to us in the case of wanting to obtain the lowest cost of raw materials, high tensile strength, high elongation, relatively high flexural stress, with high pressure stress and very little weight loss. It is a very ideal economic sample .• As it becomes clear the important economic aspect in producing this type of furniture in a simple way and in a pure Egyptian style, as the material of banana fibers and glass fibers was used instead of burning them. Also, glass fibers are used for reinforcement, which gives a large part of the continuity of the furniture with some maintenance

U ovom su radu izrađena dva različita polimerna kompozita na bazi epoksidne smole ojačanih staklenim i lanenim vlaknima. Analizirana savojna i međuslojna svojstva kompozita prema normama HRN EN ISO 14125 : 1998 i HRN EN ISO 14130 : 1997. Ispitivanjima su istražene vrijednosti prividne međuslojne smične čvrstoće, savojnog modula elastičnosti, savojne čvrstoće te deformacije prilikom loma. Dobiveni rezultati uspoređeni su sa zahtjevima Hrvatskog registra brodova (HRB) za kompozite ojačane staklenim vlaknima. Istraživanje je pokazalo kako je kompozit epoksidna smola / staklena vlakna postigao najbolje rezultate i zadovoljio sva svojstva, kao i kompozit epoksidna smola / staklo i vlakna, sa malo lošijim rezultatima. Ova smo dva kompozita usporedili sa biokompozitom epoksidna smola / lan, iz prijašnjeg istraživanja, te pomoću te usporedbe uočili promjenu svojstava dodavanjem staklenih vlakana. Uočeno je da većinu svojstava biokompozit nije zadovoljio, za razliku od staklima ojačanih kompozita. Time je zaključeno je da, iako kompoziti ojačani biorazgradivim vlaknima pokazuju zadovoljavajuća svojstva u određenim primjenama, u nekim je primjenama zbog opterećenja neizbježna upotreba dodavanja staklenih vlakana. In this paper, two different poliymer composites based on epoxy resin and reinforced with glass and linen fibers were made. Flexural and interlaminar properties were analyzed according to HRN EN ISO 14125 : 1998 and HRN EN ISO 14130 : 1997. The tests investigated the values of apparent interlaminar shear strength, flexular modulus of elasticity, flexural strength and deformation at break. The obtained results were compared with the requirements of the Croatian Register of Shipping (CRS) for glass fibers reinforced composites. Research has shown that composite epoxy resin / glass fiber achieved the best results and satisfied all properties, as well as composite epoxy resin / glass and fiber, with slightly worse results. . We compared these two composites with biocomposite epoxy resin / flax, from a previous research, and using this comparison we noticed a change in properties by adding glass fibers. It was observed that most of the properties of the biocomposite were not satisfied, unlike the glass reinforced composites. This concluded that, although composites reinforced with biodegradable fibers exhibit satisfactory properties in certain applications, in some applications, due to the load, the use of glass fiber addition is unavoidable

Kompoziti ojačani staklenim vlaknima hibridizirani su lanenim. Provedena je analiza rasteznih svojstava i svojstva gorivosti u ovisnosti o vrsti i slaganju ojačala. Za potrebe ispitivanja mehaničkih svojstava postupkom potlačnog ulijevanja dobivene su dvije vrste kompozita: prvi kompozit sastoji se od četiri sloja vlakana sa staklenim vlaknima u vanjskom sloju i lanenim u sredini. Drugi kompozit sastoji se samo od četiri sloja staklenih vlakana. Kompoziti su povezani epoksidnom smolom. Na njima su provedena ispitivanja u skladu s normom HRN EN ISO 527 – 4: 1997 Plastika – Određivanje rasteznih svojstava – 4. dio: Uvjeti ispitivanja izotropnih i ortotropnih plastičnih kompozita ojačanih vlaknima. Određene su vrijednosti rastezne čvrstoće, rasteznog modula elastičnosti i konačnog istezanja. Rezultati su uspoređeni s minimalnim zahtjevima Hrvatskog registra brodova (HRB) za kompozite ojačane staklenim vlaknima. Rezultati su pokazali da oba kompozita zadovoljavaju zahtjeve. Za potrebe ispitivanja gorivih svojstava postupkom ručne laminacije dobivene su dvije vrste kompozita ojačanih s dva sloja staklenih vlakana i tri sloja lanenih. Kod prvog su staklena tkanja u vanjskim slojevima i tri lanena između njih, dok su kod drugog naizmjenično slagana tkanja, počevši i završivši s lanenim. Ispitivanje je provedeno prema normi DIN 53 438, na dva načina za obje vrste kompozita: I. izlaganje ruba plamenu, gdje su rezultati pokazali da će kompozit s lanenim vlaknima u vanjskom sloju brže gorjeti i II. površinsko izlaganje plamenu, pri kojem nije došlo do zapaljenja ni kod jednog kompozitnog materijala. Composites reinforced with glass fibers are hybridized with flax. An analysis of tensile properties and fire properties were made depending on the type and stacking of the reinforcements. For the purposes of testing the mechanical properties, two types of composites were obtained by the vacuum infusion: the first composite was made of four layers of fibers with glass fibers in the outer layer and flax fibers in the middle. The second composite was made of four layers of glass fibers only. Composites are connected with epoxy resin. Tests were conducted on them in accordance with the standard HRN EN ISO 527 – 4: 1997 Plastics – Determination of tensile properties – Part 4: Test conditions for isotropic and orthotropic fiber – reinforced plastic composites. The values of tensile strength, tensile modulus of elasticity and ultimate elongation were determined. The results were compared with the minimum requirements of the Croatian Register of Shipping (CRS) for composites reinforced with glass fibers. The results showed that both composites meet the requirements. For the purposes of testing fire properties, two types of composites were made by manual lamination. In the first one, there are glass weaves in the outer layers and three linens between them, while in the second one, the weaves are arranged alternately, starting and ending with the linen. The test was carried out according to DIN 53 438, in two ways for both types of composites. Firstly, exposing the edge to a flame, where the results showed that the composite with flax fibers in outer layer will burn faster and secondly, surface exposure to flame, during which no composite material ignited.

In communication theory, discrete-time end-to-end channel models play a fundamental role in developing advanced transmission and equalization schemes. Most notable, the discrete-time linear, dispersive channel with additive white Gaussian noise (AWGN) is often used to model point-to-point transmission scenarios. In the last decades, numerous transmission methods for such linear channels have emerged and are now applied in many digital transmission standards. With the advent of high-speed CMOS technology, those schemes have also been adopted in applications for fiber-optical transmission with digital-coherent reception. Many of the applied techniques (e.g., coded modulation, signal shaping, and equalization) are still designed for linear channels whereas the fiber-optical channel is inherently nonlinear. A channel model which obtains the (discrete-time) output symbol sequence from a given (discrete-time) input symbol sequence by an explicit input/output relation is highly desirable to make further advances in developing strategies optimized for fiber-optical transmission. In the past two decades, considerable effort was spent developing channel models for fiber-optical transmission with good trade-offs between computational complexity and numerical accuracy. Most of the early work is, however, concerned with the phenomenology in the optical domain alone, i.e., both the source and the effect of fiber nonlinearity is studied in the continuous-time, optical domain not considering the transmitter and/or receiver front-ends. Here, one promising strategy is, e.g., based on the so-called perturbative approach where non-linear effects are considered as small perturbations to the optical signal. By now, the optical community is faced with a vast number of models based on the perturbation premise, each model with its own assumptions, simplifications, and objectives. The connection between already existing models using complementary views (e.g., one in time-, the other in frequency-domain) is often unclear. A detailed and rigorous derivation for some prominent models is still pending. E.g., the transition from the original continuous-time to the more relevant discrete-time end-to-end model lacks a comprehensive, system-theoretic analysis. Hence, in this dissertation, nonlinear fiber propagation is assessed from a systems-theoretic point of view with applications for communication systems. Based on the theory of nonlinear systems, the present work aims to connect the dots between various, existing channel models, unifying and comparing the different approaches. To that end, the perturbation approach in continuous-time is revisited with a special emphasis on the dual representations of nonlinear systems in time and frequency. From that, a discrete-time end-to-end fiber-optical channel model is derived which includes the transmit-side pulse shaping, the receive-side matched filtering, and T-spaced sampling. As before, two complementary representations of the now time-discretized end-to-end model are present—one in (discrete) time domain, the other in 1/T-periodic continuous-frequency domain. The time-domain formulation coincides with the well-known pulse-collision picture. The novel frequency-domain picture incorporates the sampling operation via an aliased and hence 1/T-periodic formulation of the nonlinear system. This gives rise to an alternative perspective on the end-to-end input/output relation between the spectrum of the discrete-time transmit symbol sequence and the spectrum of the receive symbol sequence. Both views can be extended from a regular, i.e., solely additive model, to a combined regular-logarithmic model to take the multiplicative nature of certain distortions into consideration. A novel algorithmic implementation of the discrete and periodic frequency-domain model is presented. The derived end-to-end model requires only a single computational step and shows good agreement in the mean-squared error sense compared to the oversampled and inherently sequential split-step Fourier method.

Silanized glass fibers are popular reinforcements of acrylic denture base materials. To increase the number of surface hydroxyl groups and to improve interfacial adhesion between the matrix and reinforcements, acid or base treatments of glass fibers are commonly performed before the silanization. However, limited data are available on the effect of these treatments on the mechanical properties of acrylic matrix composite materials used for denture base applications. In this work, before the silanization of a woven glass fiber fabric (GF) with 3-(trimethoxysilyl) propyl methacrylate, activation pretreatments using HCl and NH4OH aqueous solutions have been performed. To characterize the glass surface, FTIR spectroscopy was used. Specimens of cured acrylic denture base resin and composites were divided into five groups: (1) cured acrylic denture base resin-control group; (2) composite with non-silanized GF; (3) composite with silanized GF; (4) composite with NH4OH activated and silanized GF; (5) composite with HCl activated and silanized GF. The flexural and impact properties of specimens were evaluated by means of three-point-bending tests and Charpy impact testing, respectively. The residual reactivity of the samples was analyzed using differential scanning calorimetry. The results of mechanical testing showed that acid and base pretreatments of the glass fabric had a positive effect on the flexural modulus of prepared composites but a negative effect on their impact strength. Possible interfacial adhesion mechanisms and the diffusion control of isothermal cure reactions due to vitrification have been discussed.

Recently, glass fiber reinforced polypropylene is commonly used in scientific and industrial applications such as marine, aerospace, automotive, and construction industries among other materials because of their low cost, lightweight, easy processing, and high reliability. For those promising characteristics, researches have been undertaken for understanding the thermal and mechanical behaviors of polypropylene. The main objective of this study is to investigate the mechanical properties of polypropylene (PP) and glass fiber reinforced polypropylene (GFPP) pipes, which are used in water distribution networks and compressed air systems. Tensile tests were performed at different cross-head speeds at room temperature while, flexural tests were conducted at different cross-head speeds with five distinct temperatures 23, 35, 50, 70, and 90 °C. The experimental results show that both materials are sensitive to cross-head speed, temperature, and holding time. Additionally, the percentage of elongation at break and toughness of GFPP are lower than that of PP. However, the elastic modulus and yield stress of GFPP are higher than that of PP at the same cross-head speed. On the other hand, the bending energy and the dissipated energy of GFPP are higher than that of PP under all cross-head speeds and testing temperatures. PP gains 20.4% and GFPP gains 15.2% bending energy with raising cross-head speed from 5 to 50 mm/min. Also, a decrease in flexural modulus for both materials occurs with raising temperature from 23 to 50 °C.

Pri izdelavi poliestrskih cevi ojačenih s steklom na strojih za neprekinjeno navijanje filamentov se na mandrin simultano ovija tudi do 385 niti. Trenutno se sila v niti upravlja le z napenjalci, ki napenjajo vse niti naenkrat, ki pa ne opravljajo funkcije enakomernega in konstantnega individualnega napenjanja niti. Predstavljene so poliesterske cevi ojačene s steklom, njihova izdelava na strojih za neprekinjeno navijanje filamentov, steklena vlakna in uporaba Eitelweinove enačbe ob napenjanju niti. S programom Solidworks smo zasnovali dinamični napenjalec, ga umestili v trenutni sistem in na njem opravili preračune. Določili smo dve statični in eno dinamično komponento ter opravili izračune v enajstih točkah postavljenega koordinatnega sistema. Za vsako točko smo ugotovili silo, ki je potrebna, da je dinamična komponenta v njej uravnotežena. Zasnovan dinamični napenjalec je sposoben balansirati motnje v razponu vhodne sile v niti od 1,41 N do 13,73 N. Dosegli smo želeno, da dinamični napenjalec silo v niti poveča glede na velikost vhodne sile niti, bolj poveča manjšo vhodno silo kot pa poveča večjo vhodno silo. In the production of glass-reinforced polyester tubes on machines for continuous filament winding, up to 385 threads are wound simultaneously on the mandrel. Currently, the force in the threads is only managed by tensioners that tension all the threads at once, but which do not perform the function of uniform and constant individual thread tension. Glass-reinforced polyester tubes, their production on continuous filament winding machines, glass fibers and the use of the Eitelwein equasion for threads tensioning are presented. Using the Solidworks program, we designed a dynamic tensioner, placed it in the current system and performed calculations on it. We determined two static and one dynamic component and performed calculations in eleven points of the established coordinate system. For each point, we determined the force required to balance the dynamic component in it. The designed dynamic tensioner is able to balance disturbances in the range of input force in the threads from 1.41 N to 13.73 N. We have achieved the desired that the dynamic tensioner increases the force in the threads according to the size of the input force of the threads, it increases the smaller input force more than it increases greater input force.

The issue of upgrading and strengthening the reinforced concrete (RC) infrastructure has become of great importance. Recently, textile-reinforced mortar (TRM) was used in the field of structural strengthening. In the current study, using of TRM for flexural retrofitting of one-way reinforced concrete (RC) slabs was experimentally and theoretically investigated. The parameters examined included; the number of TRM layers (1, 3, 5 layers) and the strengthening configuration fully and partially). For this purpose, eight specimens were prepared and tested under three points- loading up to failure. The result showed that the TRM increases substantially the flexural capacity of RC slabs. The highest flexural capacity increase recorded was 103 %. It was also noted that increasing the number of retrofitting layers resulted in different increases in the flexural capacity. It was also shown that the strengthening configuration plays an important role in the effectiveness of the technique. The fully covered approach showed higher loading capacity than the partial cover technique provided that the same TRM layer is applied. Finally, the ultimate moment of the strengthened specimens was calculated theoretically and compared with that obtained experimentally. The results of calculations showed a good agreement between the theoretical and experimental results.

Nowadays, due to the increase in the amount of traffic and the number of axles, the use of additives in asphalt concrete has become common. In recent decades, one of the goals of engineers in asphalt technology has been to increase the bearing capacity and improve the tensile strength of asphalt mixtures. One of these effective additives in this matter is fiber. Fibers mainly contribute to the reinforcement of asphalt mixtures. Accordingly, in this research, the properties of asphalt mixtures reinforced with 5-component fibers and glass fibers have been investigated. 5-component fibers are added in 0.05, 0.075 and 0.01% of the weight of stone materials and glass fibers are added in 0.1, 0.2 and 0.3% of the weight of stone materials in asphalt mixtures and finally based on performance characteristics including Marshall resistance, indirect tension, moisture sensitivity, dynamic creep and resilient modulus are the most optimal among the above percentages. According to the results of this research, 5-component fibers have the best results in many of the mentioned characteristics at 0.075 percent and glass fibers at 0.2 percent.

Lanena i staklena vlakna imaju usporediva mehanička svojstva, no povezivanje polarnih bioloških vlakana s apolarnom polimernom matricom predstavlja problem kod prenošenja opterećenja s matrice na ojačalo. U ovom radu istražen je utjecaj vrste smole i ojačala na rastezna svojstva kompozita. Epoksidna (EP) i poliesterska smola (UP) ojačane su lanenim i staklenim vlaknima. Načinjeni su kompoziti UP/lan, UP/staklo, EP/lan te dva kompozita EP/lan/staklo slagana na način da su staklena vlakna u jednom od njih u sredini, dok su kod drugog u blizini vanjskih ploha. Rezultati ispitivanja uspoređeni su s pravilima Hrvatskog registra brodova (HRB) za kompozite ojačane staklenim vlaknima. Rastezna svojstva istraženih kompozita bolja su od minimalnih propisanih vrijednosti s izuzetkom posljednjeg hibrida kod kojeg je došlo do grešaka pri izradi. Kompozit ojačan staklenim vlaknima superioran je kompozitima s lanenim vlaknima, što pokazuje važnost dobre povezanosti matrice i ojačala. Međutim rastezna svojstva kompozita s lanenim vlaknima također su u skladu s pravilima HRB-a. Flax and glass fibers have comparable mechanical properties, but the adhesion of polar biological fibers with an apolar polymer matrix presents a problem in transferring the load from the matrix to the reinforcement. In this work, the influence of the type of resin and reinforcement on tensile properties of composites was investigated. Epoxy (EP) and polyester resin (UP) are reinforced with flax and glass fibers. Composites UP/flax, UP/glass, EP/flax and two composites EP/flax/glass were prepared in such a way that the glass fibers in one of them are in the middle plane, while in the other they are near the outer surfaces. The test results were compared with the rules of the Croatian Register of Shipping (CRS) for composites reinforced with glass fibers. The tensile properties of the investigated composites are better than the minimum prescribed values, with the exception of the last hybrid composite, where manufacturing errors occurred. Composites reinforced with glass fibers are superior to those with flax fibers, which shows the importance of a good bonding between the matrix and the reinforcement. However, the tensile properties of composites with flax fibers are also in accordance with the CRS rules.

The aim of this study is to investigate the influence of different glass fibers made of commercial silicate, borosilicate, and laboratory-made iron–phosphate compositions, on the preparation of polylactic acid (PLA) composites and their structural and physical properties. The thermal, structural, and electrical properties of prepared PLA–glass fiber composites were studied using differential scanning calorimetry, X-ray diffraction, microscopy, and impedance spectroscopy. The structural as well as morphological, thermal, and electrical properties of all PLA–glass composites were found to be very similar and independent of the composition and aspect ratio of glass fibers. All types of glass fibers improve mechanical properties, increase thermal stability, and decrease the electrical conductivity of PLA, thereby producing mechanical strong electrically insulating composite material with potential in various applications.

This paper presents an innovative approach towards the development of a green concrete. The geopolymer is an environmentally friendly construction/repairing material. In addition, glass fibers are helpful to influence the strength properties and to reduce hair line cracks and bleeding in concrete. This study is based on the use of fly ash and glass fibers as a partial replacement of cement and, subsequently, its effect on compressive strength and split tensile strength of concrete. The geopolymer is manufactured after the process of geopolymerization between class F fly ash and alkali activator fluid (sodium silicate and sodium hydroxide). In geopolymer concretes (GPC), an inorganic polymer called aluminosilicate will act as a binder, the same as conventional concrete has Portland cement (OPC)-generated C-S-H gel. The glass fibers are added in the ratios of 3%, 6%, and 10% by weight of cement. To check the effect of geopolymer and glass fibers on compressive strength and split tensile strength of concrete, concrete cubes of size 150 × 150 × 150 mm and concrete cylinders of size 150 × 300 mm with or without geopolymer and glass fibers were casted and cured for 7, 14, 21, and 28 days. The compressive strength and split tensile strength of all concrete cubes and cylinders were determined by compression testing machine. The findings of the research study revealed that concrete having geopolymer and glass fibers used as a partial replacement of cement showed lesser strength as compared to conventional concrete. Concrete having glass fibers showed reduced workability and more segregation as compared to geopolymer concrete and normal concrete. However, the concrete made either with geopolymer or glass fibers is economical as compared to conventional concrete.

Geopolymer concrete is typically characterized by a brittle behavior and limited crack resistance. This study evaluates the performance of ambient-cured slag-fly ash blended geopolymer concrete reinforced with glass fibers. Two types of glass fibers were used exclusively or as a hybrid combination. The workability of glass fiber-reinforced geopolymer concrete was assessed using the slump, compaction factor, and vebe time. The compressive strength, splitting tensile strength, and modulus of elasticity were used to characterize the mechanical properties, while water absorption, sorptivity, abrasion resistance, and ultrasonic pulse velocity were employed in evaluating the durability. Experimental results showed that the slump and compaction factor decreased by up to 75% and 18%, respectively, with glass fiber addition but less significantly in mixes reinforced with hybrid fiber combinations. Meanwhile, the vebe time increased by up to 43%. Hybrid glass fibers led to superior mechanical and durability properties compared to plain mixes and those reinforced with a single type of glass fiber, even at higher volume fractions. The compressive strength, splitting tensile strength, and modulus of elasticity increased by up to 77%, 60%, and 85%, respectively. While the water absorption decreased by up to 42%, the sorptivity, abrasion resistance, and ultrasonic pulse velocity increased by up to 67%, 38%, and 280%, respectively. Analytical regression models were established to predict the mechanical and durability characteristics of glass fiber-reinforced slag-fly ash blended geopolymer concrete and were compared to those of design codes.

Sandwich panels represent a lightweight solution with additional properties as insulation compared to traditional solutions used for building enclosures. In this study, a technology based on vegetal FRCM (fabric reinforced cementitious matrix) provides an economical, sustainable and competitive solution. The research introduces a composite design made of different vegetal fabrics (hemp and sisal) and mortar as skins of the sandwich and a core of extruded polystyrene. Both composite skins were connected with different types of connectors including vegetal designs. An experimental campaign of sandwich panels included four-point bending tests and a later development of numerical models capable of reproducing the experimental results. The results obtained show that the use of vegetal fabrics and connectors were as competitive for the development of effective composite action as synthetic fabrics (glass fiber). This study has been partially carried out within the project ‘‘Desarrollo de paneles industriales prefabricados tipo sándwich con materiales compuestos de matriz cementicia (FRCM) y con digitalizacion ´ BIM incorporada. PANELPLUS’’, funded by the Spanish Ministry of Science, Innovation and University through the Torres Quevedo program. The materials support of Sika AG and Mapei Spain S.A. is acknowledged. Authors want to thanks the research project SEVERUS (RTI2018- 099589-B-I00) of the Spanish Research Agency. The contribution of PhD. Lluis Gil is also acknowledged. Second author is a Serra Húnter Fellow.

Glass fibers slowly dissolve and age when exposed to water molecules. This phenomenon also occurs when glass fibers are inside fiber-reinforced composites protected by the matrix. This environmental aging results in the deterioration of the mechanical properties of the composite. In structural applications, GFRPs are continuously exposed to water environments for decades (typically, the design lifetime is around 25 years or even more). During their lifetime, these materials are affected by various temperatures, pH (acidity) levels, mechanical loads, and the synergy of these factors. The rate of the degradation process depends on the nature of the glass, sizing, fiber orientation, and environmental factors such as acidity, temperature, and mechanical stress. In this work, the degradation of typical industrial-grade R-glass fibers inside an epoxy fiber-reinforced composite was studied experimentally and computationally. A Dissolving Cylinder Zero-Order Kinetic (DCZOK) model was applied and could describe the long-term dissolution of glass composites, considering the influence of fiber orientation (hoop vs. transverse), pH (1.7, 4.0, 5.7, 7.0, and 10.0), and temperature (20, 40, 60, and 80 °C). The limitations of the DCZOK model and the effects of sizing protection, the accumulation of degradation products inside the composite, and water availability were investigated. Dissolution was experimentally measured using ICP-MS. As in the case of the fibers, for GFRPs, the temperature showed an Arrhenius-type influence on the kinetics, increasing the rate of dissolution exponentially with increasing temperature. Similar to fibers, GFRPs showed a hyperbolic dependence on pH. The model was able to capture all of these effects, and the limitations were addressed. The significance of the study is the contribution to a better understanding of mass loss and dissolution modeling in GFRPs, which is linked to the deterioration of the mechanical properties of GFRPs. This link should be further investigated experimentally and computationally.

El següent treball planteja una de les possibles aplicacions que podria tenir la implementació d'un “digital twin”, en aquest cas, en un procés industrial de pultrusión d'un perfil de fibra de vidre. Però podria adquirir-se en qualsevol altra mena de procés industrial. Aquesta eina (un “digital twin”) permet originar una rèplica digital d'un producte, servei o, en aquest cas, un procés. Després, mitjançant una sèrie de sensors físics que capten i envien informació en temps real, permeten monitorar diversos subprocessos dins del procés principal, podent així tenir una visió més àmplia i un control a distància d'aquest. Per a ensenyar aquesta tècnica i els seus molts usos, en aquest projecte s'ha optat per realitzar un digital twin d'un procés de fabricació d'un perfil recte de fibra de vidre mitjançant pultrusión. En aquest, es detalla pas a pas, des del disseny en 3D del procés mitjançant un programa de CAD, com la programació i la posterior implementació de les diferents plataformes complementàries necessàries per a dur a terme aquest procés, com MQTT, IOT, Grafana i NODE-XARXA. Aquests seran els intermediaris per a poder captar i transmetre la informació captada pels sensors i tenir-la ben expressada i monitorada en el nostre digital twin. D'aquesta manera s'espera mostrar de manera clara i senzilla les múltiples possibilitats, aplicacions i oportunitats que té aquesta eina. El siguiente trabajo plantea una de las posibles aplicaciones que podría tener la implementación de un “digital twin”, en este caso, en un proceso industrial de pultrusión de un perfil de fibra de vidrio. Pero podría adquirirse en cualquier otro tipo de proceso industrial. Esta herramienta ( “digital twin”) permite reproducir una réplica digital de un producto, servicio o, en este caso, un proceso. Después, mediante una serie de sensores físicos que captan i envían información en tiempo real, permite monitorizar varios subprocesos dentro del proceso principal, pudiendo así tener una visión más amplia y un control a distancia del mismo. Para enseñar esta técnica y sus muchos usos, en este proyecto se ha optado por realizar un digital twin de un proceso de fabricación de un perfil recto de fibra de vidrio mediante pultrusión. En este, se detalla paso a paso, desde el diseño en 3D del proceso mediante un programa de CAD, como la programación y la posterior implementación de las diferentes plataformas complementarias necesarias para llevar a cabo este proceso, como MQTT, IOT, Grafana y NODE-RED. Estos serán los intermediarios para poder captar y transmitir la información captada por los sensores y tenerla bien expresada y monitorizada en nuestro digital twin. De esta forma se espera mostrar de forma clara y sencilla las múltiples posibilidades, aplicaciones i oportunidades que tiene esta herramienta. The following paper proposes one of the possible applications that could have the implementation of a "digital twin", in this case, in an industrial process of pultrusion of a fiberglass profile. But it could be acquired in any other type of industrial process. This tool (a "digital twin") allows to originate a digital replica of a product, service or, in this case, a process. Then, by means of a series of physical sensors that capture and send information in real time, they allow to monitor several threads within the main process, thus being able to have a wider vision and a remote control of the same. To teach this technique and its many uses, in this project has chosen to make a digital twin of a process of manufacturing a straight profile of fiberglass by pultrusion. In this, we detail step by step, from the 3D design of the process through a CAD program, such as the programming and subsequent implementation of the different complementary platforms necessary to carry out this process, such as MQTT, IOT, Grafana and NODE-RED. These will be the intermediaries to capture and transmit the information captured by the sensors and have it well expressed and monitored in our digital twin. In this way it is expected to show clearly and easily the multiple possibilities, applications and opportunities that this tool has.

In this study, the effect of adding nanosize additive to glass fiber reinforced composite plates on mechanical properties and surface milling was investigated. In the light of the investigations, with the addition of MWCNTs additive in the composite production, the strength of the material has been changed and the more durable composite materials have been obtained. Slots were opened with different cutting speed and feed rate parameters to the composite layers. Surface roughness of the composite layers and slot size were examined and also abrasions of cutting tools used in cutting process were determined. It was observed that the addition of nanoparticles to the laminated glass fiber composite materials played an effective role in the strength of the material and caused cutting tool wear.

The main goal of this paper is the evaluation of the properties reversibility of glass fiber reinforced polymers (GFRPs) under discontinuous exposure to aggressive environmental conditions, typical of marine applications. To this aim, the GFRP manufactured through vacuum infusion process has been initially aged in humid conditions (i.e., exposure to salt-fog at 35 ◦C) for 15 and 30 days and then stored under controlled dry conditions (i.e., 50% R.H. and 23 ◦C) for times varying between 0 and 21 days. In order to evaluate the recover capability of this material, its water uptake has been monitored along the quasi-static flexural properties during the entire humid/dry cycle. Moreover, both 3D optical and scanning electron microscopes (SEM) have been used to analyze the morphology of fractured samples at different humid and dry times, thus correlating the properties evolution of the composite with its morphology. The main outcome of the present paper is an evident performances recovery shown by the investigated composite during the drying phase. Indeed, despite its flexural strength and modulus were reduced by about 20% and 10% after 30 days of salt-fog exposition, the GFRP composite evidenced a complete recovery of its initial mechanical performances after long drying times (i.e., 21 days). These findings clearly indicate that although some degradation phenomena occurred during the humid phase, their effects on both strength and stiffness of the investigated composite have proven to be mainly reversible.

To strengthen the mechanical properties of a fiber-reinforced plastic without deteriorating its toughness caused by adding nanomaterial, multiscale hybrid composites (MHC) composed of polyamide 6 (PA6), woven glass fibers (WGFs), nanoclay, and various additives were fabricated and characterized. A surfactant was used to improve the dispersion of the nanoclay in the composite, and a compatibilizer and toughening agent were added to enhance the interfacial interactions between the nanoclay and PA6 and the toughness of the MHC, respectively. In addition, the WGFs were pretreated with atmospheric-pressure air plasma to enhance the interfacial bonding between the WGF and the mixture composed of PA6/nanoclay/compatibilizer/toughening agent, which constitutes the matrix. The optimal composition of the PA6 mixture, optimal content of the nanoclay, and optimal conditions of the plasma pretreatment of the WGF surface were experimentally determined. A suitable manufacturing process was employed using a material composition that maximizes the mechanical properties of the MHC by mitigating the toughness deterioration owing to nanoclay addition. An appropriate quantity of the nanoclay increased the tensile properties as well as the elongation at the break of the MHC because the toughening agent prevented the reduction in the degree of elongation caused by increasing the clay content to a certain extent. Moreover, the plasma treatment of the WGF enhanced the flexural properties and impact resistance of the MHC. Therefore, not only the tensile strength, modulus, and elongation at the break of the PA6 nanocomposite, which constitutes the matrix of the MHC, increased up to 39.83, 40.91, and 194.26%, respectively, but also the flexural strength and modulus, absorbed impact energy, and penetration limit of the MHC increased by 20.2, 26.8, 83.7, and 100.0%, respectively.

Given the time-consuming and complex nature associated with the aging of composites, a novel fabric pre-aging method was developed and evaluated for static and fatigue testing. It allows for investigating sizing and interphase-related aging effects. This fast method is independent of the diffusion processes and the composites’ thickness. Moreover, the new methodology offers enhanced analysis of the sizing, interphase, and fiber-related degradation of composites without aging them by conventional accelerated procedures or under severe maritime environments. For validation purposes, fiber bundle, longitudinal, and transverse tensile tests were performed with five different glass fiber inputs. Significant differences in the durability of composites were found for pre-aging and classical aging, respectively. The impacts of degradation of the single constituents on the fatigue life are identified by cyclic testing of untreated, pre-aged, and wet-aged composites. Here, it is evident that the interphase strength is likewise essential for the tension-tension fatigue performance of unidirectional composites, as is the fiber strength itself. In summary, the presented method provides industry and academia with an additional opportunity to examine the durability of different fibers, sizings, and composites for design purposes following a reasonable methodology. Given the time-consuming and complex nature associated with the aging of composites, a novel fabric pre-aging method was developed and evaluated for static and fatigue testing. It allows for investigating sizing and interphase-related aging effects. This fast method is independent of the diffusion processes and the composites’ thickness. Moreover, the new methodology offers enhanced analysis of the sizing, interphase, and fiber-related degradation of composites without aging them by conventional accelerated procedures or under severe maritime environments. For validation purposes, fiber bundle, longitudinal, and transverse tensile tests were performed with five different glass fiber inputs. Significant differences in the durability of composites were found for pre-aging and classical aging, respectively. The impacts of degradation of the single constituents on the fatigue life are identified by cyclic testing of untreated, pre-aged, and wet-aged composites. Here, it is evident that the interphase strength is likewise essential for the tension-tension fatigue performance of unidirectional composites, as is the fiber strength itself. In summary, the presented method provides industry and academia with an additional opportunity to examine the durability of different fibers, sizings, and composites for design purposes following a reasonable methodology.

Hybrid composite samples with different carbon and glass fiber layers arrangement were produced by resin transfer molding (RTM) in an attempt to disclose the effects of low temperature on their flexural and low velocity impact behavior. Flexural tests were carried out at T = −50°C and the failure modes were examined, while impact tests, always at T = −50°C, were performed at penetration and at indentation in the range from 10 J to 30 J. The damage extension was accurately evaluated by ultrasonic non-destructive testing. The results were then compared with the room temperature ones obtained in a previous paper to highlight the influence of the temperature. The compression after impact tests were carried out at room temperature for samples previously impacted at both room and low temperature to assess the damage tolerance of the different hybrid configurations. Stacking sequence was found to govern both the flexural and impact behavior of laminates. At low temperature, the flexural strength and modulus values improved over the corresponding room temperature values irrespective of the stacking sequence, while an easier damage propagation and less residual strength were detected in dynamic loading.

Based on the wave absorption model of 3D woven fabric and the zero-reflection equations, a new structural design method of 3D electromagnetic (EM) wave-absorbing woven fabrics was obtained. The 3D woven fabrics fabricated by the proposed method had the structure of a bidirectional angle interlock. Continuous S-2 glass fibers were used as the matching layer of this 3D woven fabric, and continuous carbon fibers were used as the absorbing layer. The absorbing layer satisfied the equivalent EM parameters under the condition of zero reflection. The results of the simulation and experiment showed that the performance trends of the 3D wave-absorbing fabric obtained by this method were consistent with the theory, which verified the correctness of the structure design method. The 3D fabrics obtained by this method have the advantages of wide absorbing frequencies and good absorbing performance (−20 dB). This structural design method also has theoretical guiding significance for the development of 3D wave-absorbing fabrics.

A considerable effort to understand the bolted joints’ mechanical behavior in pultruded profiles has existed in the literature over the past decades. However, most investigations focused on the single-bolt connections, and only a few works considered single-lap joints. This paper investigates the mechanical performance of a single-lap connection of pultruded glass fiber-reinforced polymer (GFRP) plates owning to the experimental data deficit in the literature. Tensile tests of specimens with different geometries generate a database comprising 80 single-bolt joints. The shear-out failure was predominant for the considered GFRP pultruded plates, with the end length mainly affecting the load-bearing capacity. Hart-Smith’s theoretical model overestimated the ultimate resistance of all considered joints—the exceptionally low efficiency of the GFRP composite points out the necessity of additional means for strengthening the drilled connections. Additionally, finite element (FE) software Abaqus simulated the bolted joints; this study employs the user-defined subroutine experimentally verified in the literature. In the considered examples, the ultimate resistance prediction error decreased from 25.7% to 2.9% with increasing the plate thickness (from 4 mm to 8 mm) and width (from 25 mm to 35 mm), which proves the reasonable adequacy of the simplified FE model and makes it a valuable reference for further bolted joints’ development.

La Directiva sobre eficiencia energetica de los edificios 2010/31/EU (EPBD) fue modificada por la Directiva 2018/844 del Parlamento Europeo para, entre otras cosas, acelerar la renovacion profunda de los edificios en la Union Europea (UE). Segun esta actualizacion, los Estados miembros deberian crear un camino claro hacia el logro de un parque de edificios con cero emisiones en la UE para 2050, respaldado por hojas de ruta nacionales con hitos e indicadores de progreso nacionales, y por financiacion e inversion publicas y privadas. Queda patente que la prioridad de la Comision Europea para conseguir la verdadera descarbonizacion de las ciudades, debe ser, ademas de limitar las emisiones de los edificios nuevos, rehabilitar energeticamente los edificios existentes. Espana cuenta con una Estrategia a largo plazo para la rehabilitacion energetica en el sector de la edificacion en Espana que ha sido valorada como la mejor estrategia de toda la Union Europea. Esta estrategia tiene un caracter cualitativo y resulta de interes otorgarle datos cuantificables basados en los objetivos ya conseguidos que permitan articular politicas claras y eficaces. Esta comunicacion tiene como objetivo presentar los resultados del Informe de evaluacion sobre politicas publicas de rehabilitacion residencial en Espana (2013-2017) resultado del Proyecto de Investigacion “utilizacion sostenible de recursos naturales” financiado por Ministerio para la Transicion Ecologica (MITECO) en la convocatoria 2018. Este informe ha permitido dotar de valores cuantificables los ahorros energeticos y emisiones conseguidos en el periodo estudiado. Para ello se ha elaborado una metodologia de investigacion para el seguimiento y evaluacion de las politicas publicas y las iniciativas privadas acerca de la regeneracion y rehabilitacion urbanas, se han desarrollado indicadores y se han realizado recomendaciones futuras que ayuden a medir los objetivos y resultados, singularmente en lo relativo al ahorro energetico. Los resultados ponen en evidencia la falta de medida por parte de las administraciones publicas, y muestran que estamos lejos de los objetivos. Este estudio ha sido realizado por el Observatorio Ciudad 3R –Rehabilitacion. Renovacion. Regeneracion-, el cual surge en 2017 enmarcado en la linea estrategica de trabajo de la Fundacion Ecologia y Desarrollo (ECODES), e intenta dar respuesta a uno de los Objetivos de Desarrollo Sostenible (ODS), relativo a las “Ciudades y comunidades sostenibles” (objetivo 11). Abstract The Directive on Energy Efficiency of Buildings 2010/31 / EU (EPBD) was amended by Directive 2018/844 of the European Parliament to, among other things, accelerate the deep renovation of buildings in the European Union (EU). According to this update, Member States should create a clear path towards achieving a zero-emission building stock in the EU by 2050 supported by national roadmaps with national milestones and indicators of progress, and by public funding and investment and private. It is clear t the European Commission's priority to achieve the true decarbonisation of cities must be, in addition to limiting emissions from new buildings, to energetically renovation of existing buildings. Spain has a long-term Strategy for energy rehabilitation in the building sector in Spain that has been valued as the best strategy in the entire European Union. This strategy is qualitative in nature, and it is interesting to provide it with quantifiable data based on the objectives already achieved that allow the articulation of clear and effective policies. This communication aims to present the results of the Evaluation Report on public policies for residential renovation in Spain (2013-2017) resulting from the Research Project "sustainable use of natural resources" funded by the Ministry for Ecological Transition (MITECO) in the call 2018. This report has made it possible to provide quantifiable values for the energy savings and emissions achieved in the period studied. A research methodology has been developed for the monitoring and evaluation of public policies and private initiatives about urban regeneration and renovation, indicators have been developed and future recommendations have been made to help measure the objectives and results, particularly regarding energy saving. The results show the lack of measure by public administrations and show that we are far from the objectives. This study has been carried out by the Observatorio Ciudad 3R –Renovation. Renewal. Regeneration-, which arises in 2017 framed in the strategic line of work of the Ecology and Development Foundation (ECODES) and tries to respond to one of the Sustainable Development Goals (ODS), related to "Sustainable Cities and Communities" (objective 11).

This paper experimentally investigates the effect of steel and glass fibers on the engineering properties of concrete. To achieve this, 0.3%, 0.6%, and 0.9% by volume fraction of steel and glass fibers are added in concrete mixtures with water-to-cement (W/C) ratios 0.35 and 0.45. For each ratio of water to cement, 21 cubic samples for compressive strength tests, 14 cylindrical samples for tension strength tests, and also 14 prismatic samples for three-point flexural strength tests were prepared. The experimental results show that adding 0.3% to 0.9% % steel fibers for concrete increases simultaneously the compressive, tension, and also flexural strengths in comparison with plain concrete. Adding glass fibers only between 0.3% to 0.6% increases the compressive strength. The results reveal that the best range for reinforcing concrete with steel fiber is 0.3% to 0.9 %, and glass fiber is 0.3% to 0.6 % by volume fraction of fiber to improve the engineering strengths concrete. As a rule of thumb, the tension and flexural strengths of concrete could be explained as 8% and 13% of the compressive strength, respectively.

This paper experimentally investigates the effect of steel and glass fibers on the engineering properties of concrete. To achieve this, 0.3%, 0.6%, and 0.9% by volume fraction of steel and glass fibers are added in concrete mixtures with water-to-cement (W/C) ratios 0.35 and 0.45. For each ratio of water to cement, 21 cubic samples for compressive strength tests, 14 cylindrical samples for tension strength tests, and also 14 prismatic samples for three-point flexural strength tests were prepared. The experimental results show that adding 0.3% to 0.9% % steel fibers for concrete increases simultaneously the compressive, tension, and also flexural strengths in comparison with plain concrete. Adding glass fibers only between 0.3% to 0.6% increases the compressive strength. The results reveal that the best range for reinforcing concrete with steel fiber is 0.3% to 0.9 % and glass fiber is 0.3% to 0.6 % by volume fraction of fiber to improve the engineering strengths concrete. As a rule of thumb, the tension and flexural strengths of concrete could be explained as 8% and 13% of the compressive strength, respectively.

The construction sector is responsible for relevant environmental impacts and one of its most crucial points is the use of concrete. Geopolymers represent the most promising green and ecological alternative for common Portland cement and cementitious materials, due to its proven durability, mechanical and thermal properties. This work presents an experimental and comparative study of adhesion at the fiber-matrix interface between glass fibers and carbon fibers added to the geopolymer matrix. This analysis was performed by pull-out test, whereby it was found that the greatest efficiency was obtained by reinforcing with the glass fibers, incorporated at 2 mm in the geopolymer matrix. As results, the adhesion between the fibers and the geopolymer structure can be assessed, as well as the optimum length of application.

In this paper, compression, flexural, tensile and abrasion tests are instituted by the addition of Bacillus megaterium MTCC with glass and steel fibers. The fundamental goal regarding this examination assignment is by segregate than apprehend calcite encouraging microscopic organisms yet in conformity with appearing at the reasonableness over these microorganisms because of utilizes among cement in conformity with enhancing its multiplication yet strength. Microorganisms in imitation of remain fused of cement duly after remaining soluble inferior proof by undergoing the high pH on cement and endospore-shaping after standing up to the mechanical anxieties actuated into cement during blending. They must show excessive urease work in conformity with inspiring calcium carbonate as calcite. Bacterial traces had been separated beyond soluble base exams on an embodied manufacturing range yet have been tried for urease movement, the dynamic in conformity with body endospores or precipitation over calcium carbonate. Considering its outcomes, she has been identified so Bacillus megaterium BSKAU, Bacillus licheniformis BSKNAU or Bacillus flexus BSKNAU. The effects have been contrasted Bacillus megaterium yet MTCC 1684 obtained from Microbial Type Culture Collection or bio life LTD, Hyderabad, India. In that trial with the aid of utilizing Bacillus megaterium MTCC1964 (105 cells/ml over blending water) or calcium lactate (5 g/lit) is utilized. The metal filaments 0 %, 0.5 %, 1.0 %, or 1.5 % yet glass strands 0 %, 0.5 %, 1.0 %, 1.5 % and 2.0 % added in accordance with the sure and reckon the stress esteems because 7, 14 and 28 days. In this effect, we watched high-pressure multiplication within glass filaments at 1% than steel strands at 1.5 %. These stage regarding glass strands then steel strands added according to the bacterial strong at to that amount factor discern the strain exorcism because blocks, pliancy because court of justice yet flexural attribute because bars at 7, 14, 28, 60 years old days. we either count the UPV take a look at for shapes and cantrobro take a look at because courthouse at 28 days historic and 60 days. SEM trial is done after discovering the propinquity concerning caco3 among Bacterial cement.

Composite materials are used for improving the parameters of common materials because of their high properties. Because of these properties and their variety they can be used for different types of common materials such as steel, concrete, wood. In this paper is about composite materials based on glass fibers and carbon fibers used as reinforcement which is applied on wood elements such as beams and then tested for bending.

Hypothesis: Using glass fiber in acrylonitrile-butadiene-styrene (ABS) composites has its limitations by increasing the final price (cost) of the product, abrasions in processing machines, the environmental and health problems during recycling as well as the reduction in impact strength of the composite. This study was carried out to evaluate the effect of silane-treated wollastonite, with a needle structure similar to glass fiber, as an alternative to glass fiber in order to eliminate the drawbacks of ABS/glass fiber composites, on the mechanical properties of ABS/wollastonite composites and compared with ABS/glass fiber composites.Methods: The ABS composites were produced using two types of wollastonite with different geometrical specifications. Dispersion of wollastonite in ABS matrix was evaluated using the SEM micrographs, and the mechanical properties of the composites were determined based on tensile and Izod impact testes. Then, the suitable wollastonite was selected and the ABS/wollastonite composites properties such as tensile, impact strength, thermal and dynamic-mechanical properties were compared with the ABS/glass fiber composites properties at similar percentage of reinforcement phase.Findings: The experimental results showed that the geometrical specification, especially the length/diameter ratio of wollastonite has a significant effect on the impact strength of the ABS composite as a result of good interfacial interaction between the filler and polymer matrix. The results showed significant improvement in the impact strength of ABS/wollastonite composites compared with that of ABS/glass fibers, while the modulus and strength as well as the Vicat softening temperature were acceptable compared with those of ABS/glass fibers composites. According to the results, ABS/wollastonite composites can be a good alternative to ABS/glass fiber composites in many applications.

Düzlem içi ve düzlem dışı dalgalanma, sürekli fiber takviyeli kompozitlerden yapılmış kavisli bölgelere sahip parçalarda kaçınılmaz kusurlardır. Bu kusurlar mikro, mezo (katman seviyesi) ve makro ölçekli (parça seviyesi) olabilir. Bu çalışmada, L şekilli laminatların kavisli bölümünün dış yüzeyinde yapay bir düzlem dışı fiber dalgası oluşturulmuştur. Elde edilen fiber dalgalanmaları, numunelerden alınan mikrogörüntüler kullanılarak deneysel olarak karakterize edilmiştir. Fiber dalgalanmaların kavisli kiriş mukavemeti ve numunelerin delaminasyonuna etkisi eğme testleri ile belirlenmiştir. Ayrıca, fiber dalgalanmasının eğri kesitteki birim şekil değiştirme dağılımına etkisi Sayısal Görüntü Korelasyonu (SGK) tekniği kullanılarak ölçülmüştür.

WOS: 000519806700073, In this study, composites composed of glass fiber reinforced-epoxy laminates interleaved with electrospun polyvinylchloride (PVC) nano-fibres were designed for radar absorption investigations. The laminated composites which were produced in special molds were obtained by placing woven glass fibers between each of PVC nanofiber mats, and the composites were produced in three different forms as pure, multi-walled carbon nanotubes doped and graphene doped. The morphologies of the PVC nanofiber mats were analyzed by scanning electron microscope. The radar absorption efficiencies of the composites in the individual and different combinations were measured in the 3-8 GHz frequency band. Experimental results show that the produced graphene-added composite material has improvable microwave absorption effect at several points in 3-8 GHz band to provide excellent absorption in future studies. The graphene doped structure was found to have a certain absorption characteristic up to 33.82% at a constant frequency. Besides, various strong absorption frequency points have been obtained in the related frequency range. The cascaded graphene doped composite layers can provide broadband absorption for stealth technology.

Increasing demand for energy-efficient means of transport has steadily intensified the trend towards lightweight components. Thermoplastic glass fiber composites (organo sheets) play a major role in the production of functional automotive components. Organo sheets are cut, shaped and functionalized by injection molding to produce hybrid components, such as those used in car door modules. The cutting process produces a considerable amount of production waste, which has thus far been thermally recycled. This study develops a closed mechanical recycling process and analyzes the different steps of the process. The offcuts were shredded using two shredding methods and implemented directly in the injection-molding process. Using tensile tests and impact bending tests, the material properties of the recycled materials were compared with the virgin material. In addition, fiber length degradation via the injection-molding process and the influence of the waterjet-cutting process on the mechanical properties are investigated. Recycled offcuts are both comparable to new material in terms of mechanical properties and usability, and are also economically and ecologically advantageous. Recycling polypropylene waste with glass fiber reinforcement in a closed loop is an effective way to reduce industrial waste in a sustainable and economical production process.

In this study, mechanical testing of glass bead (GB), glass fiber (GF), and hybrid (GB/GF) composites was carried out. Following that, drilling tests were undertaken on glass bead/fiber-reinforced hybrid Polyamide 66 (PA66) polymer composites. The purpose of this study is to determine the mechanical properties of the cutting elements and the effect of cutting parameters (spindle speed and feed rate) and reinforcement ratios on thrust force and surface roughness (Ra). The contribution of the cutting parameters to the investigated outcomes was determined using statistical analysis. Optical microscopy and scanning electron microscopy (SEM) was used to inspect the hole quality and damage mechanisms. The results revealed that the feed rate was the most contributing factor to thrust force (96.94%) and surface roughness (63.59%). Furthermore, in comparison to other hybrid composites, the lowest Ra value was obtained as 0.95 µm in samples containing 30% GB, while the Ra value was 1.04 µm in samples containing 10% GF + 20% GB. Polymer PA reinforced with 30% GF had the highest strength, modulus of elasticity, impact strength, and hardness. © 2022 by the authors. Licensee MDPI, Basel, Switzerland. Karabük Üniversitesi: FDT-2020-2340 Funding: This research was funded by Karabük University, grant number FDT-2020-2340.

U ovom radu istraživan je utjecaj različitih tretmana površine tkanih staklenih vlakana na mehanička svojstva polimernih kompozitnih materijala, s matricom od poli (metil-metakrilat)-a koji se koristi za izradu baze proteze. Prije silanizacije staklenih vlakana provedena je aktivacija površine pomoću vodenih otopina klorovodične kiseline, HCl, i amonijevog, hidroksida, NH4OH. Površina stakla karakterizirana je FTIR spektroskopijom. Mehanička svojstva uzoraka procijenjena su pomoću vlačnog pokusa, ispitivanja udarnog rada loma i savijanja u tri točke. Preostala reaktivnost uzoraka analizirana je pomoću diferencijalne pretražne kalorimetrije (DSC). In this work, effects of different surface treatments of woven glass fibers, on mechanical properties of PMMA matrix composite materials, used for denture base applications, have been studied. Before the silanization of glass fabric activation pretreatments were performed, using HCl and NH4OH aqueous solutions. To characterize glass surface FTIR spectroscopy was used. Mechanical properties of composite specimens were evaluated by means of tensile, impact, and three-point-bending tests. The residual reactivity of the samples were analyzed using differential scanning calorimetry.

Bird strike, volcanic rock, hailstones, micrometeoroids, or space debris can cause damage to aircraft and space vehicles, therefore their composite materials must have high impact resistance to maximize safety. In a 55% wt. CaCO3 compression molded short glass fiber polyester GFRP-BMC (bulk molded compound), shortening the nominal 6.4 mm fiber length formulation, by 30 min extended mixing, to 0.44 mm was found to increase Charpy impact values, auc, without a change in the compression molding equipment. Specimens were cut from square panels in a spiral configuration in conformity with ASTM D 6110-02 for orthotropic panels, the flow direction approximately radially outward from the charge. At a median-fracture probability of Pf = 0.50, extended mixing improved auc by 29%, from 7.43 to 9.59 kJm−2, and for each solidification texture angle, namely, 0 to 90 (random), 71, 45 and 18 deg, the auc increased by 25% (6.26 to 7.86 kJm−2), 18% (9.36 to 11.07 kJm−2), 35% (7.68 to 10.37 kJm−2), and 20% (6.96 to 8.36 kJm−2), respectively. This strengthening can be explained by an increased number of thermal compressive stress sites between the glass fiber and matrix due to a difference in the coefficient of thermal expansion (CTE) during cool-down, and shrinkage, with an increased number of spaces between fibers, |Sf| from 217 to approximately 2950 per mm3, enhancing impact energy.

The strategy of combining the traditional reinforcement of glass fibers (GF) with lighter hollow glass microspheres (HGM) can afford to fulfill the need for potential light-weight and high-strength modern materials required in various sectors, such as automotive and aerospace industry applications. This work fabricated composites of PA6/GF/HGM by melting blending in a co-rotating twin-screw extruder, and subsequently, injection molded. The effects of HGM content on the density, morphological and mechanical properties were investigated and the PA6/GF/HGM composites properties were compared to the properties of the traditional PA6/GF (70/30) wt% composite, widely used today in automotive industries. With the increase of HGM amount in the formulations, a reduction of between 3 and 12% in density was achieved with a slight reduction in its mechanical properties, showing that this new strategy can be applied to replace the PA6/GF (70/30) wt% composite, providing a considerable weight reduction for these materials.

Projecte sorgit de la preocupació per la preservació del medi ambient i la contribució a reduir les emissions de CO2 produïdes en la fabricació, utilització i posterior reciclat dels materials compostos reforçats amb fibra de vidre. Es decideix plantejar objectivament la vertadera viabilitat de substituir les fibres de vidre per una fibra natural que garanteixi un comportament mecànic similar a l’obtingut utilitzant fibres de vidre com a reforç en materials compostos. Es fabriquen uns compostos només diferenciats pel tipus de reforç i caracteritzats a partir d'assajos de tracció i flexió. Gràcies als resultats dels assajos s'avaluen les diferències entre compostos i es determina el potencial de les fibres naturals. Posteriorment, s'avalua a través de simulacions i anàlisis d'esforços, si és factible aplicar aquests compostos en la fabricació de la cúpula de la moto elèctrica de l'equip de competició UPC Vilanova E3 Team. Per acabar, es detallen totes les consideracions de reciclabilitat i sostenibilitat que objectivament cal tenir en compte en tractar amb aquests materials. Proyecto surgido de la preocupación por la preservación del medio ambiente y la contribución a reducir las emisiones de CO₂ producidas en la fabricación, utilización y posterior reciclado de los materiales compuestos reforzados con fibra de vidrio. En este trabajo se plantea objetivamente la verdadera viabilidad de sustituir las fibras de vidrio por una fibra natural que garantice un comportamiento mecánico similar al obtenido utilizando fibras de vidrio como refuerzo en materiales compuestos. Se fabrican unos compuestos solo diferenciados por el tipo de refuerzo y caracterizados a partir de ensayos de tracción y flexión. A partir de los resultados de los ensayos se evalúan las diferencias entre compuestos y se determina el potencial de las fibras naturales. Posteriormente, se evalúa mediante simulaciones y análisis de esfuerzos si es factible aplicar estos compuestos en la fabricación de la cúpula de la moto eléctrica del equipo de competición UPC Vilanova E3 Team. Para finalizar, se detallan todas las consideraciones de reciclaje y sostenibilidad que objetivamente se deben tener en cuenta al tratar con estos materiales. This project stems from concern for preserving the environment and contributing to reduce carbon emissions produced in the manufacture, use and recycling of fibre-reinforced composite materials. It is decided to objectively establish the proper feasibility of replacing glass fibres with a natural fibre that ensures similar mechanical behaviour to that of glass fibres. The manufacture of composites is differentiated only by the type of reinforcement and is characterised by tensile and flexural testing. The results of the tests allow us to evaluate the differences between compounds and the potential of natural fibres is determined. In addition, simulations and effort analysis were conducted to evaluate whether these compounds were feasible for use in the manufacture of electric motorcycle domes for the UPC Vilanova E3 Team competition team. To conclude, all considerations of recyclability and sustainability that must be objectively taken into account are made.

Concrete structures are exposed to water throughout their service life. Nowadays, fiber-reinforced concrete is the most preferred concrete due to its superior mechanical properties. However, good mechanical properties alone cannot protect concrete against the environmental conditions it may encounter during its service life. In particular, water is an inevitable factor faced by concrete elements. In this study, the permeability properties of concrete produced with different combinations of four different fibers were investigated. Hybrid fiber concrete (HFC) was made using the central composite design method. Steel, glass fiber, synthetic, and polypropylene fibers were hybridized among themselves, and the aggregate and paste phases of concrete were hybridized with electric arc furnace slag aggregate (EAFS) and fly ash (FA), respectively. Ultrasonic pulse rate, rapid chloride permeability (RCP), capillary water absorption capacity, and carbonation depth (CD) of HFC were determined. Statistically significant and nonsignificant parameters for each response were determined. Simultaneous substitution of EAFS and FA reduced the capillarity coefficient and CD of HFC. The RCP of HFC depends mainly on two factors: binder dosage and steel fiber ratio. The most suitable fiber for reducing CD was glass fiber. The estimated RCP, ultrasonic pulse velocity (UPV), and capillary water absorption capacity (CWAC) results were compared with the control sample, and the results were 81%, 114%, and 86% of the control sample.

O uso de diferentes reforços em uma única matriz permite expandir ainda mais a gama de propriedades de materiais compósitos, incluindo a resistência ao impacto, em comparação ao uso de um único reforço. Assim, o objetivo desta tese é investigar a influência da hibridização de laminados de fibras de aramida com fibras de vidro de alto desempenho, fabricados por infusão a vácuo, na permeabilidade, em diferentes carregamentos mecânicos, em situações de impacto balístico e na resposta a ensaios de indentação quase estática (QSI), visando melhorar a processabilidade dos laminados e a capacidade de absorção de impacto e resistência a penetração. Primeiramente, foram estudados cinco diferentes laminados de vidroR/aramida/epóxi, com cinco camadas. Foram realizadas medidas de permeabilidade aparente no plano dos reforços e ensaios mecânicos (tração, compressão, flexão e short beam) dos compósitos finais. No estudo posterior, laminados vidro-S2/aramida/epóxi foram produzidos com 12 camadas, sendo cinco híbridos, um com apenas aramida (K12) e outro com vidro-S2 (Gl12). Um laminado de vidro-S2 extra foi produzido com 18 camadas (Gl18). Os ensaios de impacto balístico foram realizados de acordo com a EN 1522 FB3, foram determinas as curvas balísticas para obtenção da velocidade limite balística (VBL). No terceiro estudo, laminados de vidro-S2/aramida/epóxi foram produzidos em oito configurações diferentes, com fibras de aramida ([K]4S), com fibras de vidro-S2 ([G]8S), e seis híbridos, [G6K5], [G8K4] [G10K3], [K2G4]S, [G2K]S2 e [G4K2]S, mantendo uma espessura de ≈4 mm. O efeito da hibridização e do empilhamento foi investigado nas propriedades de flexão, short beam, análises dinâmicomecânicas (DMA), e QSI. A hibridização melhorou a qualidade final dos laminados, com redução da quantidade de vazios (%Vv). A inclusão de tecidos de vidro-R aumentou a permeabilidade em relação à aramida, e um efeito sinérgico foi identificado. A inclusão de tecidos de vidro-R fornece uma maior resistência e rigidez em tração e flexão, e maiores resistências a compressão e short beam, sendo os valores mais altos para o laminado puro de vidro-R. Analisando os impactos balísticos ≈430 m/s, tanto o K12 quanto o Gl18 foram perfurados, mas o laminado Gl18 absorveu maior energia , com uma espessura inferior ao laminado K12 (205 J e 177 J, respectivamente). O híbrido com três camadas de vidro-S2 e nove de aramida (Gl3K9) foi capaz de absorver maior energia (190 J) em comparação ao K12, apesar de apresentar menor espessura e densidade de área. Os laminados com seis camadas de vidroS2 e seis de aramida, G6K6, [GlK]6 e K6G6, apresentaram desempenho semelhante em relação à velocidade limite balística, com um pequeno aumento na Eabs quando a aramida estava na superfície de impacto. Diferenças significativas nas propriedades mecânicas e dinâmicomecânicas (efeito do empilhamento) foram observadas para os híbridos [K2G4]S, [G2K]2S, [G4K2]S e [G8K4]. O fator de adesão (A), obtido através dos resultados dos ensaios de DMA, apresentou a correlação mais próxima com a capacidade de absorção de energia dos laminados. Um efeito híbrido positivo foi observado para os laminados com fibras de vidro-S2 na superfície superior ([G6K5] e [G8K4]) nos ensaios de QSI, o laminado [G6K5] apresentou uma resistência à penetração e energia absorvida (9,9 kN e 55 J, respectivamente) maior que a dos laminados puros [G]8S (5,9 kN e 41 J) e [K]4S (8,6 kN e 46 J). Ao todo, a hibridização dos laminados de aramida com vidro pode levar a uma processabilidade aprimorada por infusão a vácuo e permitir uma gama de propriedades mecânicas, sendo uma alternativa na expansão das aplicações para laminados rígidos de aramida. E a hibridização de laminados de aramida com vidro-S2 pode aumentar a capacidade de absorção de impacto e a resistência à penetração, otimizando a aplicação em componentes submetidos a cargas de impacto balístico e de baixa velocidade mantendo a capacidade de suporte de cargas. Using different reinforcements in a single matrix allows you to further expand the range of properties of composite materials, including impact resistance, compared to using a single reinforcement. Thus, the objective of this thesis is to investigate the influence of the hybridization of laminates of aramid fibers with high-performance glass fibers, manufactured by vacuum infusion, on the permeability values, under different mechanical loads, in ballistic impact situations and in response to quasi-static indentation (QSI) tests, aiming to improve the processability of laminates and the impact absorption capacity and penetration resistance. First, five different R-glass/aramid/epoxy laminates with five layers were studied. Apparent in-plane permeability measurements were carried out in the reinforcements and mechanical tests (traction, compression, bending and short beam) of the final composites. In the subsequent study, S2-glass/aramid/epoxy laminates were produced with 12 layers, five of which were hybrids, one with only aramid (K12) and the other with S2-glass (Gl12). An extra S2-glass laminate was produced with 18 layers (Gl18). Ballistic impact tests were performed in accordance with EN 1522 FB3, ballistic curves were determined to obtain the ballistic limit velocity (VBL). In the third study, S2-glass/aramid/epoxy laminates were produced in eight different configurations, with aramid fibers ([K]4S), with S2-glass fibers ([G]8S), and six hybrids, [G6K5], [G8K4] [G10K3], [K2G4]S, [G2K]S2 and [G4K2]S, maintaining a thickness of ≈4 mm. The effect of hybridization and stacking sequence was investigated on properties of flexure, short beam, dynamic-mechanical analysis (DMA), and QSI. Hybridization improved the final quality of the laminates, with a reduction in the voids content (%Vv). The inclusion of R-glass fabrics increased permeability relative to aramid, and a synergistic effect was identified. The inclusion of R-glass fabrics provides greater strength and stiffness in tensile and flexure, and greater compressive and short beam strengths, the highest values being for pure R-glass laminate. Analyzing ballistic impacts ≈430 m/s, both K12 and Gl18 were perforated, but the Gl18 laminate absorbed more energy, with a lower thickness than the K12 laminate (205 J and 177 J, respectively). The hybrid with three layers of S2-glass and nine of aramid (Gl3K9) was able to absorb higher energy (190 J) compared to K12, despite having lower thickness and areal density. Laminates with six layers of S2-glass and six layers of aramid, G6K6, [GlK]6 and K6G6, performed similarly with regard to ballistic limit velocity, with a small increase in Eabs when the aramid was on the impact surface. Significant differences in mechanical and dynamicmechanical properties (stacking effect) were observed for the hybrids [K2G4]S, [G2K]2S, [G4K2]S and [G8K4]. The adhesion factor (A), obtained through the results of the DMA tests, presented the closest correlation with the energy absorption capacity of the laminates. A positive hybrid effect was observed for laminates with S2-glass fibers on the upper surface ([G6K5] and [G8K4]) in the QSI tests, the laminate [G6K5] showed a penetration resistance and absorbed energy (9.9 kN and 55 J, respectively) greater than that of the pure laminates [G]8S (5.9 kN and 41 J) and [K]4S (8.6 kN and 46 J). Altogether, hybridization of aramid laminates with glass can lead to improved processability by vacuum infusion and allow for a range of mechanical properties, being an alternative in expanding applications for rigid aramid laminates. And the hybridization of aramid laminates with S2-glass can increase the impact absorption capacity and penetration resistance, optimizing the application in components subjected to low velocity and ballistic impact loads while maintaining load bearing capacity.

Coating processes are emerging for new applications related to remanufactured products from End-of-Life materials. In this perspective, their employment can generate interesting scenarios for the design of products and solutions in circular economy frameworks, especially for composite materials. This chapter would give an overview of coating design and application for recycled glass fiber reinforced polymers on the base of the experimentation made within the FiberEUse project. New cosmetic and functional coatings were developed and tested on different polymer composite substrates filled with mechanically recycled End-of-Life glass fibers. Afterwards, recycled glass fiber reinforced polymer samples from water-solvable 3D printed molds were successfully coated. Finally, new industrial applications for the developed coatings and general guidelines for the coating of recycled glass fiber reinforced polymers were proposed by using the FiberEUse Demo Cases as a theoretical proof-of-concept.

U ovom završnom radu napravljena su četiri različita polimerna kompozita za izradu kojih su korištena poliesterska i epoksidna smola te staklena i lanena vlakna. Kompoziti su bili izrađeni postupkom vakuumske infuzije te su na njima provedena ispitivanja savojnih i međuslojnih svojstava u skladu s normama HRN EN ISO 14125 : 1998 i HRN EN ISO 14130 : 1997. Ispitivanjima su određene vrijednosti prividne međuslojne smične čvrstoće, savojnog modula elastičnosti, savojne čvrstoće, deformacije prilikom loma te masenog udjela vlakana. Dobiveni rezultati uspoređeni su sa zahtjevima Hrvatskog registra brodova (HRB) za kompozite ojačane staklenim vlaknima koji se uobičajeno koriste u maloj brodogradnji. Rezultati su pokazali kako je kompozit poliesterska smola / staklena vlakna postigao najbolje rezultate i zadovoljio sva svojstva, dok su ostali ispitani kompoziti zadovoljili samo jedno mehaničko svojstvo i to je bio savojni modul elastičnosti. Preostala svojstva biokompoziti nisu zadovoljili, a najbliže propisanim podacima bili su kompozit epoksidna smola / lanena vlakna i hibridni kompozit poliesterska smola / lanena i staklena vlakna, dok je kompozit poliesterska smola / lanena vlakna postigao najlošije rezultate. Analizom je zaključeno kako kompoziti ojačani biorazgradivim vlaknima imaju potencijal postati kvalitetna zamjena kompozitima sa staklenim vlaknima, ali su potrebna daljnja istraživanja koja bi trebala poboljšati postupak izrade biokompozita i povezanost između matrice i ojačala. Four different polymer composites were made out of polyester resin, epoxy resin, glass fibers and flax fibers. Composites were produced by vacuum infusion and subjected to examinations of flexural and interlaminar properties in accordance with HRN EN ISO 14125 : 1998 and HRN EN ISO 14130 : 1997 standards. Examinations have determined the values of apparent interlaminar shear strength, flexural modulus of elasticity, flexural strength, deformation at break and mass fraction of fibers. The obtained results were compared with the requirements of the Croatian Register of Shipping (CRS) for glass fibers reinforced composites which are usually used in small shipbuilding. The results showed that the polyester resin / glass fibers composite has accomplished the best results and satisfied all the properties. On the other hand, the remaining tested composites have satisfied only one mechanical property and that was the flexural modulus of elasticity, whereas the other properties were not achieved. Epoxy resin / flax fibers composite and polyester resin / flax and glass fibers hybrid composite had the results closest to the prescribed one, whilst the polyester resin / flax fibers composite has achieved the worst results. The analysis concluded that biodegradable fibers reinforced composites have the potential to become a high-quality substitute for glass fibers reinforced composites, but further research, which will improve the production of biocomposites and connection between the matrix and the reinforcement, is needed.

Мета дослідження полягає в тому, щоб показати вплив упаковки на оптоволоконний кабель, який переносить концентроване сонячне випромінювання. Це сонячне випромінювання взято в певний день і годину в Wilaya Уаргла, Алжир. У дослідженні ми розробили математичну модель і отримали диференціальні рівняння за допомогою програми MATLAB, використовуючи властивості як пластикових, так і скляних волокон для нормальної та гексагональної упаковок шляхом вибору певного значення енергії на виході кабелю. Проаналізувавши отримані результати, ми порівняли їх з результатами попередніх досліджень для двох типів скловолоконних та пластикових кабелів у випадках гексагональної та нормальної упаковок. Результати показали, що температура оптоволоконного кабелю з гексагональною упаковкою нижча, ніж температура оптоволоконного кабелю з нормальною упаковкою незалежно від типу волоконного матеріалу. Крім того, загальна кількість сонячного випромінювання, необхідна для передачі через оптоволоконний кабель із гексагональною упаковкою, менша, ніж необхідна для передачі через звичайний оптоволоконний кабель для отримання тієї самої енергії на виході кабелю. The aim of this study is to show the impact of the packing on a fiber optic cable carrying concentrated solar radiation using a solar equivalent cutting center. This solar radiation is taken on a specific day and hour in Wilaya of Ouargla-Algeria. In this study, we developed a mathematical model and obtained differential equations using the MATLAB program, using the properties of both plastic and glass fibers for normal and hexagonal packing by choosing a certain energy value at the cable output. After analyzing the obtained results, we compared them with the results of previous studies for two types of fiberglass and plastic cables in the cases of hexagonal and normal packing. The results showed that the temperature of the hexagonally packed fiber optic cable was lower than that of the normally packed fiber optic cable regardless of the type of fiber material. In addition, the total amount of solar radiation required to be transmitted through the hexagonal-packed fiber optic cable is less than that required to be transmitted through the conventional fiber optic cable in order to get the same energy at the cable output.