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This comprehensive experimental study investigates the influence of operating temperatures ranging from −50 °C to 256 °C on the mechanical properties of various high-performance thermosets regularly used as matrix polymers for composites. The resins are either crucial for specific industry sectors or challenging to obtain because they are part of commercial prepreg systems. The research focuses on the temperature-dependent tensile and compressive strength of those materials and provides a wide database of mechanical properties. This paper summarizes the mechanical properties on the one hand in terms of a strength versus temperature scale, which allows an easy comparison for engineering applications. And on the other hand, it demonstrates that the thermo-mechanical properties are mainly dependent on the polymer's glass transition temperature. More precisely, three approaches to estimate the temperature dependence of the strength of thermosets with reduced testing effort are applied and presented. While one is based on the assumption that strength depends linearly on the environmental temperature, the others focus on the distance or the ratio of the environmental temperature to the glass transition temperature. This data set and the resulting correlations provide the community with valuable material data and allow to forecast the thermo-mechanical behavior of most thermosets in the future with significantly reduced effort. [Display omitted] [ABSTRACT FROM AUTHOR]

The paper deals with the vibration effect on the porous structure of alloyed steel. It is shown that the use of vibration in this mode affects positively decreasing porosity and the nature of the pores in size distribution in the ingot. Mechanical properties of the ingot, such as tensile strength and toughness, after the vibration action are also improved. [ABSTRACT FROM AUTHOR]

Molting in crustaceans involves significant changes in the structure and function of the exoskeleton as the old cuticle is shed and a new one is secreted. The flimsy new cuticle takes several days to harden and during this time crabs rely on a hydrostatic skeletal support system for support and movement. This change from a rigid to a hydrostatic skeletal support mechanism implies correlated changes in the function, and thus mechanical properties, of the cuticle. In particular, it must change from primarily resisting compression, bending and torsional forces to resisting tension. This study was designed to explore the changes in the mechanical properties of the crustacean cuticle as the animals switch between two distinct skeletal support mechanisms. Samples of cuticle were removed from blue crabs, Callinectes sapidus, at 1 h (soft-shell stage), 12 h (paper-shell stage), and 7 days (hard-shell stage) following molting. We measured and compared the flexural stiffness, Young's modulus of elasticity (in tension), and tensile strength for each postmolt stage. We found that the hard-shell cuticle has a flexural stiffness fully four orders of magnitude greater than the soft-shell and paper-shell cuticle. Although the soft-shell cuticle has a Young's modulus significantly lower than that of the paper-shell and hard-shell cuticle, it has the same tensile strength. Thus, the soft-shell and paper-shell cuticles are unable to resist the significant bending forces associated with a rigid skeletal support system, but can resist the tensile forces that characterize hydrostatic support systems. The mechanical properties of the cuticle thus change dramatically during molting in association with the change in function of the cuticle. These results emphasize the significant role that mechanics plays in the evolution of the molting process in arthropods, and possibly other ecdysozoans. [ABSTRACT FROM AUTHOR]

This paper provides a state-of-the-art report on the up-to-date research on the emerging 3D concrete printing technology from the concrete materials perspective. It reviews the recent research focused on understanding and characterizing the rheological necessities of the concrete printing process and discusses how the researchers are tailoring compatible mix proportions for the 3D concrete printing process by using eco-friendly binders, waste aggregates, chemical admixtures, and nano-additives. This paper systematically evaluates anisotropic behavior in the mechanical properties of printed concrete and establishes an order for anisotropic behavior in the compressive, flexural, and tensile strengths along three different axes (X, Y, and Z axes) of printed concrete. It evaluates the ratio of flexural strength to the compressive strength of printed concrete along the above three axes. This article explains the influence of variation of printing process parameters on the mechanical properties and discusses reinforcement approaches used for increasing structural performance. The microstructure at the interface of adjacent layers and also at the interface of the reinforcement-cement matrix is discussed. The recent research on the durability performance of printed concrete is critically discussed and future research needs for 3D concrete printing are identified in this paper. [ABSTRACT FROM AUTHOR]

To improve the performance of pure tantalum manufactured by selective laser melting (SLM) and meet its application requirements in medicine and industry, this paper studied the influence of SLM process parameters on the as-built surface morphology and mechanical performance, and successfully obtained a sample with a relative density of over 99%, ultimate tensile strength of 706Mpa and fracture elongation over 32%. It's found that the scanning speed has a significant influence on the microstructure. Moreover, the fractured morphology shows that it is easy to cause cracks at the lower energy density. However, at a higher energy density, it is easy to induce defects such as keyhole induced pores. The appropriate process parameters of additive manufacturing matching the pure tantalum with higher relative density and better mechanical properties have precious value for its application in medicine and industry. • The effect of scanning speed on the properties of SLM tantalum was investigated. • Orthogonal scanning strategy was conducted to the SLM process of tantalum. • Pores and grain refinement of SLM tantalum can be balanced by scanning speed. [ABSTRACT FROM AUTHOR]

Weld line problem which occurs in polymer parts produced by plastic injection method and affects appearance and strength on a large scale was researched in this paper. The three parameters affecting operation were called injection pressure, injection time, and packing pressure which influence the quality of weld line on the polymer products were researched. A joint which enables two different parts used in different places to be joined together and its subjection to a certain loan were discussed. Considering the usage area of the part, composite of glass fiber reinforced polyamide (PA 6 GFR 30) was chosen as the material, and the design process of the part was implemented. Samples were prepared by altering the determined injection parameters. Weld line of the produced samples were subjected to tensile strength test. Their structure parts were examined under the SEM, and the results were gathered. [ABSTRACT FROM AUTHOR]

Equal channel angular rolling (ECAR) is a severe plastic deformation (SPD) process in order to achieve ultrafine-grained (UFG) structure. In this paper, the mechanical properties of ECAR process using artificial neural network (ANN) and nonlinear regression have been illustrated. For this purpose, a multilayer perceptron (MLP) based feed-forward ANN has been used to predict the mechanical properties of ECARed Al5083 sheets. Channel oblique angle, number of passes and the route of feeding are considered as ANN inputs and tensile strength, elongation and hardness are considered as the outputs of ANN. In addition, the relationship between input parameters and mechanical properties were extracted separately using nonlinear regression method. Comparing the outputs of models and experimental results shows that models used in this study can predict and estimate mechanical properties appropriately. Where, the performance of ANN model is better than the correlations to predict mechanical properties. Finally, the developed outputs of neural network model are used to analyze the effects of input parameters on tensile strength, elongation and hardness of ECARed Al5083 sheets. [ABSTRACT FROM AUTHOR]

Generally, to produce film-type thermoplastic composites with good mechanical properties, high-performance reinforcement films are used. In this case, films used as a matrix are difficult to impregnate into tow due to their high melt viscosity and high molecular weight. To solve the problem, in this paper, three polypropylene (PP) films with different melt viscosities were used separately to produce film-type thermoplastic composites. A film with a low melt viscosity was stacked so that tow was impregnated first and a film with a higher melt viscosity was then stacked to produce the composite. Four different composites were produced by regulating the pressure rising time. The thickness, density, fiber volume fraction (Vf), and void content (Vc) were analyzed to identify the physical properties and compare them in terms of film stacking types. The thermal properties were identified by using differential scanning calorimetry (DSC) and dynamical mechanical thermal analysis (DMTA). The tensile property, flexural property, interlaminar shear strength (ILSS), and scanning electron microscopy (SEM) were performed to identify the mechanical properties. For the films with low molecular weight, impregnation could be completed fast but showed low strength. Additionally, the films with high molecular weight completed impregnation slowly but showed high strength. Therefore, appropriate films should be used considering the forming process time and their mechanical properties to produce film-type composites. [ABSTRACT FROM AUTHOR]

At the first step, this paper describes a developed model for tensile strength of interphase layers (σ k ) in polymer nanocomposites. The “σ k ” is expressed as linear, exponential and power functions of the distance between nanoparticles and polymer matrix (x k ). Afterwards, the predictions of these equations at the central layer of interphase (the average strength) are compared to the calculations of interphase strength (σ i ) by several micromechanical models including the developed Leidner-Woodhams and Pukanszky models to choose the best equation which expresses “σ k ”. The calculations are carried out for several reported samples. The equation which expresses the “σ k ” as a power function of “x k ” shows the best results compared to others. Also, its predictions significantly depend to an exponent as “Z” which demonstrates the level of interphase properties. According to the chosen equation, the “σ m ” and “σ p ” play positive roles in “σ i ” predictions at low “Z” value, but a high “Z” eliminates the effect of “σ m ” on the tensile strength of interphase layers. [ABSTRACT FROM AUTHOR]

This paper presents a mathematical model for simulating Tempcore process, the model consisting of three successive parts. Thermal model is used to predict the temperature distribution across the bar over its whole quenching and self-tempering rout. The output of this model is used to calculate the area of martensite formed in outer layer and ferrite–pearlite heart. The composite rule of mixtures (ROM) is used to correlate the tensile yield strength of the bar with the martensite and ferrite–pearlite volume fraction. The model is capable of predicting the effect of various process parameters namely; bar diameter, rolling temperature, number and setting of cooling nozzles, cooling water flow rate and quenching time on the thermal conditions across the bar during different stages of the process, structure formed and tensile behavior of the rebar. A good agreement is found between the predicted results and the experimental data for B500B steel with diameters from 10 to 16 mm and yield strength varied from 400 MPa to 700 MPa. [ABSTRACT FROM AUTHOR]

Discarded florescent tubes and graphite rods obtained from dumped primary cells have been processed to obtain glass and graphite particles. 80 µm glass and graphite particles were used as reinforcements in epoxy resin, LY 556 cured with HY 931 hardener to produce epoxy resin hybrid composites. The morphology, mechanical properties, thermal stability and wear resistance characteristics of the epoxy resin glass/graphite hybrid composites were studied. The thermogravimetric analyser TGA 701 was used to examine the thermal stability of the epoxy resin glass particle/graphite composites. Addition of graphite and glass particles enhanced the strength, thermal stability and wear resistance of the epoxy resin. However, tensile strain and impact energy absorption of the epoxy resin hybrid composites started declining at 6 wt% of glass particle addition. The increase in wear rate of the composites with an increment in applied loads is attributable to increase in the normal reaction between the examined sample surfaces and the emery paper. Furthermore, the increase in wear resistance with an increment in wt% of glass particle additions is attributable to good interfacial adhesion between matrix and the fillers. The textural and appearance differences between the scanning electron micrographs of the control and epoxy resin hybrid composites is attributable to the presence of new phases due to exothermic and cross linking reaction between the matrix and the fillers. Hence, new vital engineering composites peculiar to automobile, aerospace and building industries have been produced. [ABSTRACT FROM AUTHOR]

This paper aims at investigating the effect of alkali treatment and water ageing on several short Alfa fibre reinforced polypropylene composites. For this purpose, different composites with untreated and treated fibres were elaborated by extrusion and injection moulding processes and subjected to water ageing. The obtained results showed that the alkali treatment enhances significantly the Young’s modulus and tensile strength of the Alfa fibre reinforced polypropylene composites and reduces their loss during water ageing. The acoustic emission analysis showed that the use of alkali treatment plays a major role in the improvement of the fibre-matrix interface of both unaged and aged composites. [ABSTRACT FROM AUTHOR]

Tensile properties of Ni-base single crystal superalloy plate specimens with and without a hole at room temperature were studied in the present paper. During the testing process, an ARAMIS system based on the digital image correlation technique and in-situ scanning electron microscopy were employed to in-situ observe the strain distribution and slip traces development on the sample surfaces. It was demonstrated that the yield stress was decreased with the appearance of a hole due to the stress concentration. The results were analyzed based on the stress and strain states of specimens and the slip traces development observed on specimen surfaces. [ABSTRACT FROM AUTHOR]

This paper systematically investigates the effect of artificial aging (AA), solution (SHT), and T6-like (solution followed by artificial aging (SHA)) heat treatments on the microstructural evolution and mechanical properties of selective laser melted TiN/AlSi10Mg composites. Results show that the microstructure and mechanical properties reveal inconspicuous changes after AA where the eutectic fibrous Si networks remain. However, SHT vanishes the Si networks, precipitates and coarsens Si particles, and eventually softens the Al matrix, leading to a significant decrease in tensile strength and hardness of heat-treated composites and an increase in ductility. The addition of TiN nanoparticles plays a significant role in microstructural evolution during heat treatment. By increasing solution temperature from 460 °C to 540 °C, Mg 2 Si phase precipitates out of the Al matrix, followed by AlFeSi intermetallic at 500 °C and AlSiTi intermetallic at 540 °C, respectively. Interestingly, unexpected enhancements of hardness (from 91.5 ± 2.3 HV to 105.9 ± 2.1 HV) and tensile strength (from 268.7 ± 2.5 MPa to 336.8 ± 1.5 MPa) are achieved as the solution temperature increases. This abnormal phenomenon is attributed to the precipitation hardening by the Mg 2 Si precipitate and needle-like intermetallics, which overcomes the effects of microstructural coarsening and matrix softening. This paper sheds light on how the mechanical properties of as-built TiN/AlSi10Mg composites can be tailored using different heat treatment techniques. • TiN/AlSi10Mg composites are fabricated by SLM and then heat treated. • The AlFeSi and AlSiTi intermetallics are formed at different solution temperatures. • The unexpected increase of hardness and strength is attributed to precipitate hardening. • The mechanical properties are found to be highly microstructural-dependent. [ABSTRACT FROM AUTHOR]

In this paper, the effect of Sc alloying on the microstructure and mechanical properties of as-cast Zr-containing Al-Cu alloys is investigated by microstructure characterization, thermal analysis and first-principles calculations, and the related mechanisms is discussed. The results show that when the Sc content is 0.3%, the grains and Al 2 Cu eutectic structure in the alloy can achieve the best refining effect. The strength and plasticity of the alloy are synergistically improved, and its ultimate tensile strength, yield strength and elongation are 211.3 MPa, 310.6 MPa and 6.3%, which are 43.5%, 35.1% and 50.0% larger than that of the base alloy (without Sc addition), respectively. When the Sc content is increased to 0.4%, the grain refinement is limited. This is because Al 3 (Sc,Zr) is coagulated, and the Al/Al 3 Sc interfacial energy is higher under Sc-rich conditions and the nucleation ability is poor. According to the calculation results of interfacial energy, the order of heteronucleation ability of α-Al is Al 3 (Sc,Zr)> Al 3 Zr> Al 3 Sc. And it is accompanied by a decrease in mechanical properties, which is because cracks are easily formed at the connection between the coarse W phase and the matrix, and stress concentration is easily caused during the deformation process. Furthermore, the solidification paths of alloys with different Sc contents are predicted by thermal calculation. When the Sc content is 0.3%, the alloy will generate metastable Al 3 (Sc,Zr) and stable Al 3 Sc during solidification. And the distribution of petal-like dispersoids is observed as linear clusters and blocky clusters in the experiment. [Display omitted] • The microstructural refinement mechanism induced by Sc alloying is consummated based on experiments and first-principles calculations. • The evolution process of the precipitates in Al-Cu alloys with different Sc contents is elucidated by thermal analysis. • Microalloying is an effective method to increase the strength and ductility of as-cast high-Cu-content Al-Cu alloys. [ABSTRACT FROM AUTHOR]

In this paper, the Mg-9Gd-4Y–2Zn-0.5Zr (wt%) alloy after one pass of upsetting and extrusion was subjected to the rotating shear extrusion (RSE) method and backward extrusion (BE) method at 420 °C. Compared with the BE method, torsion deformation and shear deformation were synthetically introduced to the RSE process. The RSE technique had the advantages of a low forming load, large strain and more sufficient deformation. The results demonstrated that the RSE method had more advantages than the BE method in terms of grain refinement and mechanical performance improvement. The average grain size of the RSEed alloy was refined from ~22 µm of the original alloy to ~8.5 µm. In addition, the proportion of dynamic recrystallization (DRX) increased from ~56% of the original alloy to ~83% via the RSE process. The degree of fragmentation of the lamellar and block-shaped LPSO phases in the RSEed alloy was more intensive than that of the BEed alloy, and the particle phase distribution among the crystal grains was more uniform. The RSEed alloy presented a single texture and a strong [2−1−10] orientation component and effectively weakened the texture intensity. The ultimate tensile strength (UTS), tensile yield strength (TYS) and elongation (EL) of the RSEed sample were 350 MPa, 258 MPa and 17%, respectively. Compared with the BEed sample, the mechanical properties of 325 MPa (UTS), 240 MPa (TYS) and 12% (EL) had higher strength and toughness. After the same T5 (200 ℃/90 h) heat treatment, the mechanical properties of the RSEed sample could reach 420 MPa (UTS), 280 MPa (TYS) and 13% (EL), while BEed sample were 371 MPa (UTS), 273 MPa (TYS) and 10% (EL). Additionally, compared with the BEed alloy, the mechanical properties of the RSEed alloy are better due to finer grains, broken LPSO phases, dispersed particle phases and texture modification. • The RSE process could be effectively reduced the forming load and produce more strain than BE. • The LPSO phases are broken to a greater extent and granular phases are more distributed during the RSE process. • The RSE method could greatly change the texture and orientation of the initial alloy. • The RSE method could improve the strength and toughness of the alloy. [ABSTRACT FROM AUTHOR]

• Zn-0.8Mg-0.2Sr was successfully extruded in the temperature range 150–300 °C. • Materials extruded at 150 and 200 °C dominated by fine-grained microstructure. • Elongation increased with lower extrusion temperature and higher extrusion ratio. • Various deformation mechanisms dominated under different loading. Zinc-based alloys containing elements well-tolerated by the organism (Mg, Ca, Sr) are considered as perspective biodegradable materials for an application like medical devices such as fixations of fractured bones or even stents. In the presented paper we characterize the relations between microstructure and mechanical properties of extruded Zn-0.8Mg-0.2 Sr alloy (wt%) depending on various parameters like extrusion temperature (150–300 °C) and ratio (11 or 25). Typical analysis including SEM with EBSD and mechanical tests indicate a strong dependence of obtained data on both extrusion temperature and ratio. Relatively wide range of elongation to fracture (2–22%) and anisotropy in compression yield strengths regarding loading direction (50–150 MPa) are explained by the huge effect of grain size, material texture and also the existence of dislocation substructures in materials extruded at elevated temperatures. Based on obtained results, appropriate extrusion conditions (200 °C, extrusion ratio 25) are suggested to reach the combination of superior mechanical properties 244 MPa, 324 MPa and 22% for tensile yield strength, ultimate tensile strength and elongation to fracture, respectively. [ABSTRACT FROM AUTHOR]

In order to develop high-strength and high-conductivity copper alloys with better comprehensive properties, the effects of Si addition on the mechanical properties, electrical conductivity and microstructure of CuCrZr alloy were investigated in this paper. The addition of Si element can improve the hardness, strength and ductility of CuCrZr alloy. The optimal peak aging parameter for CuCrZrSi alloy is 430 °C for 3 h, the hardness 228.92 HV, the tensile strength 646.76 MPa, and the elongation after fracture 10.67%. Compared with the CuCrZr alloy under the same process, the mechanical properties are increased by 10.3%, 11.9% and 16.9%, respectively. The conductivity is 4 ± 1%IACS lower than that of the sample without Si addition. The addition of Si element refines the deformation substructure and produces more Σ3n (n = 1, 2, 3) grain boundaries, thus providing more nucleation sites and higher driving forces for the precipitation phases. In both CuCrZr and CuCrZrSi alloys, the fine precipitation phases (<10 nm) fcc-Cr phase and orthorhombic-Cu 8 Zr 3 phase, together with coarse precipitation phases (>100 nm) bcc-Cr phase and hcp-Zr phase can be observed. The orientation relationship among the two fine precipitation phases and the matrix is (1 ¯ 1 ¯ 1) [ 1 1 ¯ 0 ] C u ∥ (1 ¯ 1 ¯ 1) [ 1 1 ¯ 0 ] C r ∥ (133) [ 0 1 ¯ 1 ] C u 8 Z r 3 . The Si element tends to precipitate together with the Cr phase and Zr phase, and acts to refine and spheroidize the precipitation phases. [Display omitted] • The Si addition improves the hardness, strength and plasticity of CuCrZr alloy. • The Si tends to co-precipitate with Cr and Zr from the copper matrix during aging. • The CuCrZrSi alloy has finer deformation substructures and more ∑3n CSL boundaries. • The Si addition can refine and spheroidize the precipitates of CuCrZr alloy. • The precipitation phases are fcc-Cr, bcc-Cr, hcp-Zr and Cu 8 Zr 3 phases in both alloys. [ABSTRACT FROM AUTHOR]

Metastable high entropy alloys possesses excellent ductility and toughness, but its low strength hinders its engineering applications. Therefore, many studies have been carried out to improve the strength of metastable high entropy alloys while maintaining high ductility. In this paper, a new high entropy alloy is fabricated by selective laser melting (SLM) with the addition of Si powder into Fe50Mn30Co10Cr10 metastable high entropy alloy powders, with compositions (Fe50Mn30Co10Cr10) 100-x Si x (x = 0, 1, 3, 5). The results show that the yield strength and ultimate tensile strength of Si-containing metastable high-entropy alloys gradually increase with the increase of Si elements, and the performance is far better than that of without Si addition. The Si element increases the metastability of the γ(FCC) phase in the high-entropy alloy, and promotes the phase transformation-induced plasticity by adjusting the twinning strain during the deformation process; so that the total elongation of the material prepared by SLM can reach 30% and above. The combined effect of multiple strengthening mechanisms such as dislocation, deformation twinning, and phase transformation has greatly increased the strength of high-entropy alloys. In addition, the excellent strength-ductility combination of the alloy containing Si element indicates that the composition has good printability for laser additive manufacturing, which can provide a reference for expanding the diversification of high-entropy alloys in the additive manufacturing process. • Si-containing Fe50Mn30Co10Cr10 metastable high-entropy alloys were fabricated by selective laser melting. • During the tensile test, the fraction of HCP phase in Si-containing alloys gradually increased. • The addition of Si significantly improves the strength and ductility of SLMed metastable high-entropy alloy. [ABSTRACT FROM AUTHOR]

The paper presents test results concerning an effect of the heat treatment on microstructure and mechanical properties of eutectic EN AC-AlSi12CuNiMg (EN AC-48000) alloy according to the EN 1706:2010 (tensile strength - Rm, hardness - HB 10/1000/30) modified with strontium. Solution heat treatment and ageing treatment temperature ranges were selected on base of heating (melting) curves recorded with use of the ATD method. Temperatures of the solution heat treatment were 500, 520, and 535°C ±5°C, while the solution time ranged from 0.5 to 3 h (0.5; 1.5 and 3 h). Temperature of the solution heat treatment amounted to 180, 235 and 310°C, while the ageing time ranged from 2 to 8 h (2, 5 and 8 h). Obtained results have enabled determination of optimal parameters of the T6 heat treatment in aspect of improvement of tensile strength Rm and hardness HB of the alloy, with reduced time of individual treatments and determination of mathematical relationships enabling prediction of these mechanical properties. [ABSTRACT FROM AUTHOR]

In this paper the main mechanical properties of concrete produced with recycled aggregates obtained from crushing both structural and non-structural lightweight concrete are characterized. Various concrete mixes with replacement ratios of 20%, 50% and 100% of two types of coarse lightweight aggregates (LWA) by recycled lightweight concrete aggregates (RLCA) were studied in terms of their compressive strength, tensile strength, modulus of elasticity and abrasion resistance. Generally the experimental results show that all the studied properties are improved with the introduction of RLCA. In particular, concrete with RLCA has higher structural efficiency than the reference concrete, with LWA alone. It is thus concluded that more cost-effective structural lightweight concrete (LWC) can be produced with the introduction of RLCA. Moreover, it is shown that the RLCA obtained from non-structural lightweight concrete can be used to produce structural LWC. There is a slight reduction of the concrete's mechanical properties when the stronger LWA is replaced with the more porous RLCA obtained from non-structural lightweight concrete. [ABSTRACT FROM AUTHOR]

The results of the selected mechanical properties i.e. ultimate tensile strength (UTS), yield stress (YS), elongation (EL), reduction of area (RA), hardness (HV) and impact strength (KCV) of the common, S235JR grade steel, are presented in the paper. A strong relationship between the above mentioned properties and cooling rates after hot rolling of rods, made of this steel, was found. Additionally, the possibility of further enhancing of mechanical properties (UTS and YS) by the controlled, dynamic cold working, was shown. The use of such deformation, through changes in the microstructure allows for the upper yield stress (YS) increase - app. 10% and ultimate tensile strength UTS - app. 5%. Simultaneously, very high indicators of plasticity (EL, RA) and impact strength (KCV) are retained, as they were immediately after the rolling. The possibility of improving the mechanical properties of rods made of this steel grade has a great technological and commercial importance for its manufacturers, as well as for their final users. [ABSTRACT FROM AUTHOR]

A novel ternary Ti-15Zr-10Nb alloy with innovative microstructural and mechanical properties and very good long-term corrosion resistance in simulated physiological solutions was studied in this paper. Optical and scanning electron microscopy (SEM) observations revealed α+β biphasic Widmanstatten microstructure with characteristic interleaving lamella of α and β phases. Energy dispersive spectroscopy (EDS) measurements gave good compositional homogeneity with wt.% contents of 75±5% for Ti, 15±2% for Nb, and 10±2% for Zr. The XRD pattern was indexed to a biphasic crystalline structure containing the hexagonal α phase with calculated lattice parameters of a=2.92Å, c=4.63Å and the cubic β phase with calculated lattice parameter of a=3.19Å. The alloy has very good mechanical properties: Young's modulus of 64GPa, very close to that of the human bone; superior ultimate tensile strength, appropriate 0.2% yield strength and strain to fracture to those of Ti. The alloy native passive film has a thickness of 5.5±0.5nm and contains protective TiO2, ZrO2 and Nb2O5 oxides (X-ray photoelectron spectroscopy - XPS analysis). The cyclic voltammetry in Ringer's solutions indicated a nobler electrochemical behaviour of the alloy in comparison with Ti due to the beneficial influence of the alloying elements, which participate with their oxides to the compactness, thickening, reinforcement of the native passive film. The electrochemical impedance spectra were modelled with an electric equivalent circuit comprising two time constants: for inner, compact layer and outer, porous slightly inferior protective layer. [ABSTRACT FROM AUTHOR]

The investigation of strain-rate effects on the mechanical response and characteristics of thin free-standing films is crucial for the design and fabrication of more reliable MEMS devices. It is also of high interest from the scientific and materials engineering views. In this paper we present a novel apparatus and a procedure for tensile testing of thin free-standing films under a wide range of strain rates from quasistatic to high, almost comparable with those obtained in Hopkinson bar tests. To provide this capability, a unique displacement measurement method is applied and a micro device which meets several strict requirements is implemented. We describe recent results of quasistatic experiments performed on pure aluminum free-standing thin films. A high rate experiment which demonstrates the setup capabilities is also presented. The micro-device measured properties are compared with finite element analysis results. [ABSTRACT FROM AUTHOR]

The reuse system proposed by the authors is an overall business system for realizing a cyclic reuse flow through the processes of design, fabrication, construction, maintenance, demolition and storage. The reuse system is one of the methods to reduce the environmental burden in the field of building steel structures. These buildings are assumed to be demolished within approximately 30 years or more for physical, architectural, economic and social reasons in Japan. In this paper, focusing on building steel structures used for plants, warehouses and offices without fire protection, the performance of steel structural members for reuse is evaluated by a non-destructive test. First, performance evaluation procedures for a non-destructive test, such as mechanical properties, chemical compositions, dimension and degradation, are shown. Tensile strengths are estimated using Vickers hardness measured by a portable ultrasonic hardness tester, and chemical compositions are measured by a portable optical emission spectrometer. The weldability of steel structural members is estimated by carbon equivalent and weld crack sensitivity composition using chemical compositions. Finally, the material grade of structural members of the building steel structure for reuse is estimated based on the proposed procedures. [ABSTRACT FROM AUTHOR]

This paper presents the results of experimental research on the strength properties of porous structures with different degrees of density manufactured of Ti6Al4V titanium alloy by Laser Power Bed Fusion. In the experiment, samples with diamond structure of porosity: 34%, 50%, 73% and 81% were used, as well as samples with near-zero porosity. Monotonic tensile tests were carried out to determine the effective values of axial modulus of elasticity, ultimate tensile strength, offset yield strength, ultimate elongation and Poisson ratio for titanium alloys with different porosities. The paper also proposes relationships that can be easily used to estimate the strength and rigidity of a porous material manufactured by 3D printing. They were obtained by the approximation of two quotients. The first one refers to the relationship between the tensile strength of a material with a defined porosity to the strength of full-filled material. The second similarly determines the change in the value of the axial modulus of elasticity. The analysis of microscopic observations of fracture surfaces and also microtomography visualization of the material structure are also presented. [ABSTRACT FROM AUTHOR]

Aluminum matrix composites (AMCs) reinforced by CNTs as lightweight structural materials gain extensive attention. However, the crucial issue limited its application breadth is the poor interfacial bonding between the matrix and CNTs. In this paper, novel TiO 2 nanoparticles-coated CNTs (TiO 2 @CNTs) fabricated by the alcohol-thermal method were used as the reinforcement to prepare AMCs via high-intensity ultrasonic-assisted casting. The microstructure, wettability, interfacial bonding, and mechanical properties of TiO 2 @CNTs/ADC12 composites were investigated in detail. By incorporating TiO 2 nanoparticles on the surface of CNTs, the contact angle was reduced from 140.5° to 119°, indicating a significant improvement in the wettability of CNTs to aluminum melt. TEM results revealed that TiO 2 nanoparticles homogenously dispersed on the surface of CNTs acted as an interlayer structure between CNTs and matrix, locking the CNTs and improving the CNTs-Al interfacial bonding. The semi-coherent interface was formed at the TiO 2 /α-Al interface, and the mismatch of (001) TiO2 //(100) Al is only 6.52%, indicating a good lattice space matching between TiO 2 and α-Al matrix. The TiO 2 @CNTs/ADC12 composite with 1.2 wt% TiO 2 @CNTs displayed high mechanical properties with yield strength and ultimate tensile strength of 196 MPa and 262 MPa, which were 54% and 29% higher than those of the matrix (127 MPa and 203 MPa), respectively. The better mechanical properties may be attributed to good interfacial bonding caused by the semi-coherent interface created by the TiO 2 interlayer, leading to an effective load transfer from matrix to CNTs. [Display omitted] • Uniform and dense TiO 2 nanoparticles were coated on the surface of CNTs to tailor the CNTs-Al interface. • The wettability of CNTs to aluminum melt was improved by coating TiO 2 nanoparticles with smaller contact angle. • The semi-coherent interface was formed at TiO 2 /α-Al interface, which significantly improved the interfacial bonding. • The mechanical properties of TiO 2 @CNTs/ADC12 composite were significantly increased by coating TiO 2 nanoparticles. [ABSTRACT FROM AUTHOR]

• The ultra-high strength Mg-9.5Gd-4Y-2.2Zn-0.5Zr alloy was prepared by a simple process: pre-ageing before extrusion. • The densely distributed fine precipitates in the fine grain region can enhance capacity of Mg matrix to accommodate strain. • The yield strength, ultimate tensile strength and elongation of the alloy are: 461 MPa, 535 MPa and 6.1%, respectively. In this paper, the effect of pre-ageing treatment on the mechanical properties, microstructure, and fracture behavior of the extruded Mg-9.5Gd-4Y-2.2Zn-0.5Zr (wt%) alloys was studied. The results show that the poor mechanical properties of the solution-extruded (SE) sample with a bimodal microstructure are attributed to the deformation incompatibility between different regions (deformed grain region, fine grain region and bulk-shaped long period stacking ordered (LPSO) phases), which is prone to crack initiation and propagation. In contrast, pre-aged sample with various morphological phases (lamellar-shaped LPSO phases, granular-shaped β phases and bulk-shaped LPSO phases) promotes the dynamic recrystallization (DRX) by the particle-stimulated nucleation (PSN) mechanism during extrusion, which results in the pre-aged-extruded (PE) sample having a more homogeneous microstructure with a finer and higher percentage of dynamically recrystallized grains. The densely distributed fine precipitates in the dynamically recrystallized region and homogeneous microstructure can enhance the capacity of the different regions to accommodate strain, and avoid premature fracture of the alloy without sufficient work hardening. Therefore, the PE sample has excellent strength-ductility synergy, and its yield strength (YS), ultimate tensile strength (UTS) and elongation (EL) were 408 MPa, 476 MPa and 8.3%, respectively. The YS and UTS of the PE sample after further ageing treatment (PEA sample) increased to 461 MPa and 535 MPa, respectively. [ABSTRACT FROM AUTHOR]

In the present paper, the effect of B 4 C addition on elevated temperature tensile properties and creep resistance of as-cast Ti–43Al–6Nb–1Mo–1Cr alloy has been characterized. Experimental results reveal that 0.2 at. % B 4 C can improve the ultimate tensile strength and elongation of alloy at 800 °C. The steady-state creep rate of alloy with the addition of B 4 C decreases from 2.3 × 10−6 s−1 to 5.2 × 10−7 s−1 at 800 °C under 300 MPa. The stress exponent (n) and the apparent activation energy (Q C) of alloy with the addition of B 4 C are measured to be 3.18 at 800 °C and 416.410 kJ/mol under 300 MPa, respectively. Combining microstructure observation, the dominant creep deformation mechanisms of Ti–43Al–6Nb–1Mo–1Cr-0.2B 4 C alloy at 800 °C under 300 MPa are mechanical twinning and dislocation slipping pinned by solute carbon atoms. During creep, the α 2 lamellar dissolution and α 2 /γ interface migration occur simultaneously, and the dynamic recrystallization at colony boundary effectively alleviates the stress concentration resulting from dislocation pile-ups. In addition, the initiation of cavities as well as the propagation and coalescence of cracks are the main creep fracture features. Particularly, TiB can prevent dislocation motion and prolong the crack propagation path to increase creep resistance. • The addition of 0.2 at. % B 4 C improved the elevated temperature tensile and creep properties of Ti–43Al–6Nb–1Mo–1Cr alloy. • The tensile creep behavior of the B 4 C-bearing TiAl alloy was investigated. • The dynamic precipitation of α 2 phase occurred inside TiB during creep. • The creep fracture mechanism of B 4 C-bearing TiAl alloy was proposed. [ABSTRACT FROM AUTHOR]

This paper studied the combined effects of matrix-to-reinforcement particle size ratio (PSR) and SiC volume fraction on the mechanical properties of extruded Al-SiC composites. A powder metallurgy technique (PM) of cold pressing at 500 MPa followed by hot extrusion at 580 °C was adopted to produce Al/SiC composite. Aluminum powder of size 60 μm and silicon carbide with different sizes, i.e., 50, 20, and 8 μm, were used. Three different volume fractions of SiC were employed, i.e., 5, 10, and 15 %, for each investigated size using a constant extrusion ratio of 14.36. The effect of matrix-to-reinforcement PSR on the reinforcement spatial distribution, fabricability, and resulting mechanical properties of a PM-processed Al/SiC composite were investigated. It has been shown that small ratio between matrix to reinforcement particle size resulted in more uniform distribution of the SiC particles in the matrix. As the PSR increases, the agglomerations and voids increase and the reinforcement particulates seem to have nonuniform distribution. In addition, the agglomerations increased as the volume fraction of the SiC increased. It has also been shown that homogenous distribution of the SiC particles resulted in higher yield strength, ultimate tensile strength, and elongation. Yield strength and ultimate tensile strength of the composite reinforced by PSR (1.2) are higher than those of composite reinforced by PSR (7.5), while the elongation shows opposite trend with yield strength and ultimate tensile strength. [ABSTRACT FROM AUTHOR]

The aim of the research reported in this paper is to assess the mechanical performance of concrete containing different percentages of fine aggregates produced from waste generated by the marble quarrying industry (0, 20, 50, and 100% of the total volume of aggregates). More specifically, the workability and bulk density of fresh concrete were measured and the compressive strength, splitting tensile strength, modulus of elasticity, and abrasion resistance of hardened concrete were determined. In general, concrete containing secondary fine aggregates proved to have worse mechanical properties than conventional concrete made with primary siliceous sand, basalt, and granite fine aggregates. This poorer performance was more noticeable when the replacement percentage was higher. However, the reduction in mechanical performance is acceptable and does not compromise use of these secondary aggregates in structural concrete. [ABSTRACT FROM AUTHOR]

In this paper, we explore the glycosylation conditions (glucomannan content, reaction time, temperature and humidity) to probe the relationship between glycosylation and mechanical properties of soy protein isolate (SPI) film. The mechanical properties were characterized by studying the tensile strength (TS) and elongation at break (EB). Furthermore, degree of glycosylation, free glucomannan content, surface hydrophobicity, sulfhydryl groups content, lysine and arginine content of glycosylation soy protein with different reaction time were investigated to certify the significant effect of glycosylation on mechanical properties of soy protein film. What is more, the comparison of TS and EB, contact angle values and water vapor permeability of glycosylation SPI (GSPI), SPI and mixture of SPI and glucomannan films showed the excellence of GSPI. At the end, the analysis of scanning electron microscope was applied to reveal the effect of glycosylation on the structure of films. These results suggested that glycosylation with glucomannan is an ideal method to enhance the mechanical properties of soy protein isolate film. [ABSTRACT FROM AUTHOR]

Abstract: The present paper explores the aptness of old newspapers as a source of reinforcing fibers for composite materials. Different percentages of newspaper fibers, obtained by wet (ONPF) and by dry processes (CONPF), were compounded with polypropylene (PP). A coupling agent was added to the compound to improve the interface between matrix and reinforcing fibers. Tensile test were performed to obtain the mechanical properties of the composite materials. Composite materials reinforced with sized glass fiber (GF) were also prepared and tested. The mechanical properties of the materials were compared. A fiber tensile strength factor (FTSF) and a fiber tensile modulus factor (FTMF) were proposed to evaluate the contribution of the reinforcement fibers to the tensile properties of the composite materials. Finally a pump body, made with GF/PP composites was modeled and tested to obtain the nodal stresses and deformations under nominal pressure. A list of ONPF, CONPF reinforced composite materials was proposed to replace the GF/PP. A body pump was mold injected with a CONPF/PP composite, was assembled in a water pump and tested under nominal working conditions. [Copyright &y& Elsevier]

Organically modified hydrotalcite is a recent class of organoclay based on layered double hydroxides (LDH), which is anionically modified with environmental friendly ligands such as fatty acids. In this paper the influence of hydrotalcite compounded/dispersed by means of two different processes for production of plates and fibers of polyolefin nanocomposites will be compared. A polyethylene matrix, suitable for fiber production, was firstly compounded with various amounts of hydrotalcite in the range of 0.5-5% by weight, and then compression moulded in plates whose thermomechanical properties were evaluated. Similar compositions were processed by using a co-rotating twin screw extruder in order to directly produce melt-spun fibers. The incorporation of clay into both bulk and fiber nanocomposites enhanced the thermal stability and induced heterogeneous nucleation of polyethylene crystals. Hydrotalcite manifested a satisfactory dispersion into the polymer matrix, and hence positively affected the mechanical properties in term of an increase of both Young's modulus and tensile strength. Tenacity of nanocomposite as spun fibers was increased up to 30% with respect to the neat polymer. Moreover, the addition of LDH filler induced an increase of the tensile modulus of drawn fibers from 5.0 GPa (neat HDPE) up to 5.6-5.8 GPa. [ABSTRACT FROM AUTHOR]

In this paper, nanocrystalline (nc) AZ91 magnesium alloy bulks, with average grain sizes of ∼15 nm, were processed via the combined processing of hydrogenation-disproportionation-desorption-recombination (HDDR), spark plasma sintering (SPS) and hot extrusion. The effects of different sintering temperatures and holding times on the sintering properties of magnesium alloy were analyzed and the optimum SPS sintering process parameters of nanocrystalline AZ91 powder were determined. The tensile strength of nc AZ91 magnesium alloy rods is up to 267 MPa at room temperature. Meanwhile, when the grain size is less than 20 nm the particular mechanical behavior of nc magnesium alloy emerged, which implies an inverse Hall-Petch relationship. • We produced the nc magnesium alloy bulks by the combination of HDDR, SPS and hot extrusion with average grain sizes ∼15 nm. • Grain sizes of nc AZ91 powders prepared by HDDR have little change after high temperature sintering and hot extrusion. • The tensile strength of nc AZ91 magnesium alloy rods is up to 267 MPa at room temperature. • The yield strength value of the nc A91 bulk prepared in this paper may be an inverse Hall-Petch relationship curve. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) printing of continuous fiber-reinforced composites has been developed in recent decades as an alternative means to handle complex structures with excellent design flexibility and without mold forming. Although 3D printing has been increasingly used in the manufacturing industry, there is still room for the development of theories about how the process parameters affect microstructural properties to meet the mechanical requirements of the printed parts. In this paper, we investigated continuous carbon fiber-reinforced polyphenylene sulfide (CCF/PPS) as feedstock for fused deposition modeling (FDM) simulated by thermocompression. This study revealed that the samples manufactured using a layer-by-layer process have a high tensile strength up to 2041.29 MPa, which is improved by 68.8% compared with those prepared by the once-stacked method. Moreover, the mechanical–microstructure characterization relationships indicated that the compactness of the laminates is higher when the stacked CCF/PPS are separated, which can be explained based on both the void formation and the nanoindentation results. These reinforcements confirm the potential of remodeling the layer-up methods for the development of high-performance carbon fiber-reinforced thermoplastics. This study is of great significance to the improvement of the FDM process and opens broad prospects for the aerospace industry and continuous fiber-reinforced polymer matrix materials. [ABSTRACT FROM AUTHOR]

Nano graphite platelets (NGPs) belong to the carbon family and have a huge impact on the construction industry. NGPs are used as multi-functional fillers and have the potential to develop reinforcing within cementitious composites. In this paper, NGPs were incorporated in cementitious composites to investigate the effects of NGPs on the fresh, mechanical, durability, and microstructural properties of concrete. Five mixes were prepared with intrusion of NGPs (0%, 0.5%, 1.5%, 3%, and 5% by weight of cement). The properties studied involved workability, air content, hardened density, compressive strength, tensile strength, flexural strength, sorptivity, ultrasonic pulse velocity (UPV), water absorption, and external sulfate attack. The workability and percent air content decrease by 22.5% and 33.8%, respectively, for concrete with 5% NGPs compared to the control mix. The specimens containing 5% of NGPs revealed the hardened density, compressive, tensile, and flexural strength to increase by 11.4%, 38.5%, 31.6%, and 44.34%, respectively, compared to the control mix. The results revealed that the incorporation of 5%NGPs in cementitious composites reduces the sorptivity and water absorption by 32.2% and 73.9%, respectively, whereas, it increases the UPV value by 7.5% compared to the control mix. Furthermore, the incorporation of NGPs provided better resistance against external sulfate attacks. SEM–EDX spectroscopy was carried out to investigate its microstructural analysis. [ABSTRACT FROM AUTHOR]

Reduced graphene oxide (rGO) is active to bind with proteins so rGO based nanocomposites (membranes) can be explored for their use as bio fluid sensors. For this purpose, PVDF is a good polymer which provides flexible PVDF composite membrane. To achieve stiffer rGO/PVDF based composites, rGO/PVDF was modified with PMMA and PTFE due to their useful properties in the field of membranes. This paper reports the hydrophilic and thermally stable (up to 326 °C) rGO filler based PVDF/PMMA/PTFE thin membranes (nanocomposite) synthesized with solvent casting technique. An enhancement in the elasticity (80%) and tensile strength (566%) was observed due to PTFE. The increased rGO content in PVDF/PMMA/PTFE matrix was found to increase the tensile strength and capacitance of the membrane, while decreasing the elongation at break (stiffness). Dip sites identified by AFM in the fabricated stiff membranes also exhibit a water absorbing nature, demonstrating their possible use in a FET towards the sensing of biomolecules. [Display omitted] • rGO/Polymer(s) (PVDF, PMMA & PTFE) membranes prepared by casting method. • Thermally stable up to 326 °C, capacitive and hydrophilic thin nanocomposites • Enhanced Young's modulus and tensile strength due to PTFE • Conduction via connectivity and tunneling of rGO in composite [ABSTRACT FROM AUTHOR]

[Display omitted] • Corrax stainless steel based SLM were prepared under different process parameters. • Many lath martensite (above 99%) and LAGBs (above 50%) were formed in SLMed samples. • The best process parameter was determined as 190 W-1.1 m·s−1. • The sample under the optimal parameter, exhibited superior mechanical properties. • Dislocation strengthening dominated the strengthening mechanism of the SLMed sample. In this paper, selective laser melting (SLM) was used to manufacture corrax stainless steel samples under different parameters. It was found that the SLMed samples were mainly composed by lots of fine martensite (including cellular structure, cellular dendritic grains and blocky grains), and trace austenite. During SLM forming process, a large number of low-angle grain boundaries (LAGBs) and high-density dislocations were formed in the matrix. Meanwhile, the samples showed weak texture and no obvious preference orientation. Moreover, the relative density of all SLMed samples reached above 90%, and the relative density was above 97% when the laser energy density was 54.13–78.19 J·mm−3. Under the optimal process parameters of P = 190 W, V = 1.1 m·s−1, the relative density of sample reached above 99.52 ± 0.09%, while the sample exhibited the best mechanical properties, including the highest microhardness (374.2 ± 6.5HV), yield strength (YS = 946 ± 7.3 MPa), ultimate tensile strength (UTS = 1084 ± 3 MPa) and elongation (EL = 17.64 ± 0.18%). Moreover, the strengthening mechanisms of SLMed samples mainly included grain boundary strengthening, dislocation strengthening and precipitation strengthening, while dislocation strengthening played a dominant role. Besides that, the fracture mechanisms of SLMed samples belonged to ductile fracture, except for the samples prepared with laser energy density below 54.13 J·mm−3. [ABSTRACT FROM AUTHOR]

• The morphology of martensite evolved from parallel-sided plates or laths to acicular plates with increasing Cu content. • The 14–20% of the martensite partitioning interfaces was constituted of {10 1 ̅ 1} twin boundaries. • Cu addition lead to the improvement on the microhardness and tensile strength. In this paper, Ti-Cu alloys were in-situ fabricated by selective laser melting (SLM) with 1.25, 2.5 and 5 wt% Cu contents, namely Ti-1.25Cu, Ti-2.5Cu and Ti-5Cu, respectively. The microstructural characteristic and mechanical properties of Ti-Cu alloys were systematically investigated. The results showed that the SLM-fabricated Ti-Cu alloys have a fine microstructure, and the morphology of martensite exhibited a transition from parallel-sided plates or laths to acicular plates with increasing Cu content. Due to the accommodation effect of the martensitic transformation strain, the 14–20% of the martensite partitioning interfaces was constituted of {10 1 ̅ 1} twin boundaries. The microhardness, yield strength and ultimate tensile strength were enhanced synergistically with increasing Cu content, which can be attributed to the combined effects of grain-boundary strengthening, solid-solution strengthening, dislocation strengthening and precipitation strengthening. [ABSTRACT FROM AUTHOR]

The paper presents the results of studies on the effects of heat treatment and cold-work parameters on the mechanical properties and microstructure of the tungsten heavy alloy (WHA) with the composition W91-6Ni-3Co. Tungsten heavy alloy (WHA) is used in conditions where strength, high density, and weight are required. The material for testing as rod-shaped samples was produced by the method of powder metallurgy and sintering with the participation of the liquid phase and then subjected to heat treatment and cold swaging. The study compares the effect of degree deformation on the strength, hardness, microhardness, and microstructure of WHA rods. The conducted tests showed that heat treatment and cold-work allowed to gradually increase the strength parameters, i.e., tensile strength σ u t s , yield strength σ y s , elongation ε, hardness, and microhardness. These processes made it possible to increase the tensile strength by over 800 MPa (from the initial 600 MPa after sintering to the final value of over 1470 MPa after heat treatment with cold swaging deformation with reduction of 30%) and the hardness from 32 to 46 HRC. [ABSTRACT FROM AUTHOR]

In the present paper, the Mg-11Gd-2Y-1Zn alloys with different Al addition were fabricated by the gravity permanent mold method. The effect of Al content on microstructure evolution and mechanical properties of as-cast Mg-11Gd-2Y-1Zn alloy was studied by metallographic microscope, scanning electron microscope, XRD and tensile testing. The experimental results showed that the microstructure of as-cast Mg-11Gd-2Y-1Zn alloy consisted of α-Mg phase and island-shaped Mg3 (RE, Zn) phase. When Al element was added, Al2RE phase and lamellar Mg12REZn (LPSO) phase were formed in the Mg-11Gd-2Y-1Zn alloy. With increasing Al content, LPSO phase and Mg3 (RE, Zn) phase gradually decreased, while Al2RE phase gradually increased. There were only α-Mg and Al2RE phases in the Mg-11Gd-2Y-1Zn-5Al alloy. With the increase of Al content, the grain size decreased firstly and then increased. When the Al content was 1 wt.%, the grain size of the alloy was the minimum value (28.9 μm). The ultimate tensile strength and elongation increased firstly and then decreased with increasing Al addition. And the fracture mode changed from intergranular fracture to transgranular fracture with increasing addition. When Al addition was 1 wt.%, the maximum ultimate tensile strength reached 225.6 MPa, and the elongation was 7.8%. When the content of Al element was 3 wt.%, the maximum elongation reached 10.2% and the ultimate tensile strength was 207.7 MPa. [ABSTRACT FROM AUTHOR]

Electrospinning is an innovative new fibre technology that aims to design and fabricate membranes suitable for a wide range of tissue engineering (TE) applications including vascular grafts, which is the main objective of this research work. This study dealt with fabricating and characterising bilayer structures comprised of an electrospun sheet made of polycaprolactone (PCL, inner layer) and an outer layer made of poly lactic-co-glycolic acid (PLGA) and a coaxial porous scaffold with a micrometre fibre structure was successfully produced. The membranes' propriety for intended biomedical applications was assessed by evaluating their morphological structure/physical properties and structural integrity when they underwent the degradation process. A scanning electron microscope (SEM) was used to assess changes in the electrospun scaffolds' structural morphology such as in their fibre diameter, pore size (μm) and the porosity of the scaffold surface which was measured with Image J software. During the 12-week degradation process at room temperature, most of the scaffolds showed a similar trend in their degradation rate except the 60 min scaffolds. The coaxial scaffold had significantly less mass loss than the bilayer PCL/PLGA scaffold with 1.348% and 18.3%, respectively. The mechanical properties of the fibrous membranes were measured and the coaxial scaffolds showed greater tensile strength and elongation at break (%) compared to the bilayer scaffolds. According to the results obtained in this study, it can be concluded that a scaffold made with a coaxial needle is more suitable for tissue engineering applications due to the improved quality and functionality of the resulting polymeric membrane compared to the basic electrospinning process. However, whilst fabricating a vascular graft is the main aim of this research work, the biological data will not present in this paper. [ABSTRACT FROM AUTHOR]

In this paper, polysulfide-based elastomers were successfully prepared through a simple one-pot thiol-ene click reaction of the liquid polysulfide oligomer with bisphenol-A diacrylate resin. Real-time Fourier transform infrared spectroscopy (FTIR) analysis showed that the molecular weight of the liquid polysulfide oligomer had no effect on mercaptan functional group conversion. The obtained elastomers continued to keep low temperature flexibility of polysulfide except Elastomer-LP3, which was due to higher content of bisphenol-A structure. All the samples had a tensile strength of over 0.7 MPa, which was comparable to that of polysulfide polymer cured by metal oxide. Moreover, the samples exhibited higher thermal stability than metal oxide cured polysulfide. This vulcanization methodology will provide a fast, efficient, and environmentally friendly approach (without metal oxides and plasticizers) for preparing polysulfide elastomers. [ABSTRACT FROM AUTHOR]

Abstract: This paper focuses on mechanical tests on the ITER correction coils (CC) and Feeder jacket 316L stainless steel material. During manufacture, the conductor will be compacted and spooled after cable insertion. Therefore, sample jackets were prepared under compaction in order to simulate the status of conductor during manufacturing. Yield strength (0.2% offset), ultimate tensile strength, Young''s modulus and elongation at failure shall be reported. The mechanical properties of materials were measured at 300K and low temperature (<7K). The cryogenic test results show that the present jackets have very high properties. It is concluded that the results meet the ITER requirement. [Copyright &y& Elsevier]

Abstract: This paper presents an experimental and analytical study into the strengthening and toughening of sandwich composite joints by z-pinning. Cleats connecting the vertical stiffener and horizontal base panel to T-shaped sandwich joints were reinforced in the through-thickness direction with pins. Tensile (stiffener pull-off) tests revealed that pinning increased the ultimate fracture load and fracture energy by resisting crack growth along the cleat–skin and skin–core interfaces, which were the weakest points in the unpinned joint. The peak fracture load and fracture energy increased with the volume content of z-pins. The strengthening and toughening effect of the pins was analysed using multiple pin pull-out tests performed on the sandwich composite material. It is shown that elastic deformation, debonding and pull-out of the pins from the face skins to the sandwich composite is the primary toughening mechanism of the pinned T-joints. The pin pull-out process, which is the cause for the high strengthening and toughening of the T-joints, is analysed using bridging traction modelling. [Copyright &y& Elsevier]

This paper presents the results of a study on the effect of high temperatures on the mechanical properties of high-strength concretes. Mixtures were prepared with water to cementitious material ratios of 0.40, 0.35, and 0.30 containing silica fume at 0, 6, and 10% cement replacement. After heating to 100, 200, 300, and 600°C, the compressive strength, the splitting tensile strength, and the corresponding ultrasonic pulse velocity were measured. A substantial loss of strength was observed for all compositions at 600°C, particularly the silica fume concretes in spite of the superior mechanical properties provided by silica fume at room temperature. The average residual compressive and splitting tensile strengths of the concretes at 600°C were 30 and 25% of the room-temperature strengths, respectively. It was found that the rate of the splitting tensile strength loss is higher than the rate of the compressive strength loss at elevated temperatures and that the ultrasonic pulse velocity measurements slightly underestimates the residual strength of the high-strength concretes after exposure to temperature over 200°C. [ABSTRACT FROM AUTHOR]

This paper presents the effect of severe plastic deformation obtained using the cold hydrostatic extrusion (HE) method on the mechanical and structural properties of polyamide 6 (PA6). As a result of the plastic strain, a significant increase in ultimate tensile strength and tensile modulus were observed. Tensile strength rose by almost 500%, up to the level of 508 MPa, whereas the tensile modulus rose by about 65%. Flexural modulus increase was also observed to 3230 MPa, i.e., by approx. 160%. As a result of high plastic deformation, the structure of the polyamide 6 changed significantly, as evidenced by its fibrous nature as presented in the results of the scanning electron microscopy inspection (SEM). The surface quality of products investigated was tested using profilometry. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) has the advantages of providing materials with lightweight microporous structures and customized features, and being environmentally safe. It is widely used in medical sciences, the aerospace industry, biological research, engineering applications, and other fields. Among the many additive manufacturing methods, fused deposition modeling (FDM) is relatively low-cost, wastes less raw material and has a lower technical threshold. This paper presents a study on 3D printing based on FDM by changing two printing parameters, namely the printing temperature and filling percentage. The produced polylactic acid (PLA) material was analyzed through tensile and Shore D hardness tests and the differences in mechanical properties before and after the UV curing process were analyzed. The results show that increasing the filling percentage or increasing the printing temperature can effectively improve the tensile Young's modulus, ultimate tensile strength, elongation, and Shore hardness of the material. The UV curing process could enhance the rigidity and hardness of the material significantly but reduced the strength and toughness of the material. These findings could benefit researchers studying FDM with the goal of achieving sustainable manufactured materials. [ABSTRACT FROM AUTHOR]

Extruded profiles/sections are increasingly used in the transport industry for lightweight structures. In this paper, a wide thin-ribbed aluminium profile with asymmetric Z-shape, was manufactured by a novel sideways extrusion process proposed by the authors. A comparative study was conducted by utilising the direct/forward extrusion process at the same extrusion temperature and speed, in which the different process mechanics, resulting microstructures and mechanical properties of profiles have been investigated by experiments and finite element modelling. It was revealed that, compared with sideways extrusion, although the design of a die pocket in forward extrusion induces preform and avoids the use of the large-diameter billet and extrusion container/press needed for extruding wide profiles, it requires a greater extrusion force due to work-piece upsetting necessary to fill the die pocket and leads to a lower effective strain in the profile rib. EBSD characterisation of the regions with an equal effective strain indicated that an increased shear strain is more efficient for obtaining fine grains with a higher average misorientation angle. In the same region of the profile rib made from the two different processes, sideways extrusion results in greater grain refinement due to greater effective strains, and a slightly greater texture intensity was found due to the intensive shear deformation. Tensile tests on formed profiles revealed that sideways extrusion leads to a higher yield strength (YS) and ultimate tensile strength (UTS) but a relatively lower elongation to failure, due to the combined effects of grain refinement, GND and texture intensity enhancement. Compared with the billet, the profile formed by forward and sideways extrusion has a YS increased by about 60% and 79% respectively, and an UTS increased by about 74% and 80% respectively in the extrusion direction, demonstrating an advantage of the sideways extrusion process in improving material strength under the same extrusion condition. [Display omitted] • Wide thin-ribbed aluminium profiles were manufactured by sideways and forward extrusion at the same condition. • Deformation mechanisms, resulting microstructures and mechanical properties for the two processes were compared. • Sideways extrusion requires a lower extrusion force but results in higher effective strains in the profile rib. • Sideways extrusion leads to greater grain refinement, yield strength and ultimate tensile strength. • Strength and ductility are improved simultaneously for the profile formed by sideways extrusion at elevated temperature. [ABSTRACT FROM AUTHOR]