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The aim of this study is to characterize E-glass/epoxy unidirectional fiber reinforced composites using the digital image correlation method with virtual extensometer, which is a less laborious method than strain gauges, compare the results and investigate whether virtual extensometers can be used instead of strain gauges. Measurements in tensile and Iosipescu shear tests were made with both strain gauge and virtual extensometer. Unlike full-field strain measurements in literature, the strains were measured using virtual extensometers. Tensile test and in-plane shear test results gave very consistent results. The differences between the strain gauge and the virtual extensometer for the tensile and in-plane shear tests were less than 3% in the linear region. However, the out-of-plane shear test showed a larger difference of 8.6%. This study showed that the 2D digital image correlation method with virtual extensometers is highly sufficient to find the elasticity moduli and shear moduli in tensile and shear tests in the linear region. In addition, after the damage has started, more measurement data can be obtained with virtual extensometers than with strain gauges.

Gıda endüstrisinde, geleneksel yöntemlere alternatif olabilecek yeni muhafaza ve işleme teknolojilerinin kullanımı giderek önem kazanmaktadır. Bu yeni ve özellikle ısıl olmayan tekniklerin gıdaların güvenliğini arttırma, kalite kayıplarını azaltma, üretimde verim artışını sağlama gibi çok önemli avantajları bulunmaktadır. Bu yeni teknolojilerden biri olan Vurgulu Elektrik Alan (Pulsed Electric Field-PEF) tekniği, son yıllarda üzerinde önemle durulan bir yöntem olarak göze çarpmaktadır. Bu yöntem hem sıvı hem de katı gıdalarda değişik amaçlarla kullanılmakta olup optimizasyona yönelik çeşitli çalışmalar yapılmaktadır. Diğer yandan, PEF tekniğinin et ve su ürünlerinde de gerek muhafaza amacıyla, gerekse diğer meydana getirdiği olumlu özellikler (ürünün fonksiyonel özelliklerini geliştirmesi, kurutma, kürleme ve dondurma gibi işlemleri hızlandırması) nedeniyle kullanımına dair yakın zamanda çeşitli çalışmalar mevcuttur. Bu bakımdan bu derleme çalışmasında, PEF tekniğinin et ve su ürünlerinde hangi amaçlar için kullanılabileceği üzerine detaylı bilgiler verilmeye çalışılmıştır.

In this study, traditional pickled pepper was produced in 3 different formulations by using whey cheese and cheese crumbs, which are obtained as a by-product in the cheese-making process. In the scope of the study, the microbiological, chemical and sensory properties were examined during the 5 months of storage period. The initial E. coli contents of the samples were determined as 3.71, 2.73, 4.72 log cfu/g respectively and it was not detected in any of the group at the end of the 21st day. The 2nd group was the most acceptable in terms of taste (5.9-6.6), smell (6.2-6.6) and visual appearance (6.3-6.7) for 4 months. It was observed that there was no change in the chemical parameters of all groups that could negatively affect consumption during the storage period. As a result of the study, it was shown that a high value-added product can be produced by using dairy by-products. Bu çalışmada, süt endüstrisinde yan ürün olarak elde edilen düşük katma değerli kırık peynirler ve lor peyniri kullanılarak 3 farklı formülasyonda geleneksel peynirli (sütlü) biber üretimi gerçekleştirilmiştir. Çalışma kapsamında, ürünlerin mikrobiyolojik, kimyasal ve duyusal özellikleri 5 aylık depolama süresi boyunca incelenmiştir. Mikrobiyolojik analizlere göre, örneklerin başlangıçtaki E. coli içeriği sırasıyla 3.71, 2.73, 4.72 log kob/g olarak belirlenmiş ve 21. günün sonunda hiçbir grupta tespit edilmemiştir. Duyusal analiz sonuçlarına göre, 2. grup 4 ay boyunca tat (5.9-6.6), koku (6.2-6.6) ve görsel açıdan (6.3-6.7) en çok beğenilen grup olmuştur. Kimyasal analiz sonuçları göz önüne alındığında ise, depolama süresince tüm grupların parametrelerinde tüketimi olumsuz yönde etkileyebilecek bir değişikliğin olmadığı gözlenmiştir. Çalışma sonucunda, süt endüstrisi yan ürünleri kullanılarak katma değeri yüksek bir ürünün üretilebileceği ortaya konmuştur.

In this study, the mechanical behavior of sandwich plates with functionally graded core under low-velocity impact loads was investigated experimentally. Sandwich plate with functionally graded core has two different structures (metal–ceramic), and the upper and lower surfaces are pure metal (Al) and the internal layers of the plate are manufactured with gradually varying material composition through the plate thickness. The low-velocity impact tests were conducted on both upper and lower surfaces of specimens using CEAST low-velocity impact device, and the contact force–time and the energy–time graphs were plotted. Metallographic and micromechanical examinations were carried out on the specimens after impact tests. As a result of the metallographic and micromechanical examinations, the material composition variation through the specimen thickness was obtained in accordance with the rule of the theoretical mixture. As a result of impact tests (v = 4 m/s) on upper surface (ceramic-rich side), crack damages occurs on the plates with n = 10.0 material composition, whereas the specimens with n = 1.0 and n = 10.0 material compositions have crack damages after impact tests on its lower surfaces (metal-rich side). Impact force on the ceramic-rich upper surface provides to meet the transferred load waves through the plate thickness by metal-rich bottom surface. This situation makes the structure more resistant against damage. Moreover, the upper and lower surfaces of the functionally graded structure reinforced by ductile pure metal layers provide an important contribution to protection of functional integrity of the structure against damage.

This paper presents a numerical model to determine the ballistic performance of functionally graded plates under normal and oblique impact. Functionally graded plates consist of metal (Al 6061) and ceramic (SiC) components. The volume fraction of the two components varying throughout the thickness of the functionally graded plates were tailored according to a power-law. The Mori-Tanaka micro-mechanics model was used for determining the local material properties in the graded region of the plates. In the ballistic analyses, the deformation and damage conditions of the functionally graded plates having metal-rich (n = 0.1), linear (n = 1.0) and ceramic-rich (n = 10.0) material compositions were investigated at five different projectile impact angles such as 0 degrees, 15 degrees, 30 degrees, 45 degrees, 60 degrees. In addition, ballistic limit velocity, which is an important parameter in armor design, has been determined at different projectile impact angles of functionally graded plates. It was found that the material composition gradient as well as projectile impact angle played a significant role on the ballistic performance of the plates.

© 2020 Taylor & Francis Group, LLC.Geometrically nonlinear and elastoplastic behavior of a circular FGM (functionally graded material) plate under mechanical loading–unloading condition is investigated employing three-dimensional finite element method (FEM) modeling. The through-thickness material distribution of the FGM plate is defined by a power-law variation. The elastic mechanical properties and the elastoplastic material behavior of the FGM plate described respectively by the Mori–Tanaka scheme and the TTO (Tamura–Tomota–Ozawa) model are implemented in the FEM model. The FEM model is validated presenting a very good agreement with the studies from the literature. The influences of nonlinearity, especially the elastoplastic and elastoplastic with geometrically nonlinear behavior, load parameter and thickness-to-radius ratio in terms of nonlinearity, and material composition on the mechanical behavior of the FGM plate are examined. The FEM results are evaluated in terms of the permanent central deflection and the plastic equivalent stress distributions of the FGM plate. The results indicate that a considerable difference occurs between the elastoplastic and elastoplastic with geometrically nonlinear behavior of the FGM plate in terms of both the permanent central deflection and the plastic equivalent stress distributions except ceramic-rich composition that has almost a linear–elastic material behavior, and the geometrical nonlinearity becomes an important parameter with increasing load parameter and decreasing thickness-to-radius ratio. The combination of geometrical and material nonlinearities exhibits a significant influence on the nonlinear mechanical behavior of the FGM plate under plastic deformation.

The motivation in the preference of confectionery products consists of the perception formed during the purchase and consumption. This perception is a direct determining factor in the repeated purchasing behavior of the consumer. Also, the products must meet consumer demands. For this reason, it is very important to understand the confectionery quality characteristics, the factors affecting them, and their interaction with each other. In this context, the effects of major and minor components used in innovative soft confectionery products on quality should be considered first. As with all other foods, new ingredient(s) incorporated into the formulation and processing changes have significant effects on the quality characteristics of soft confectionery products. Therefore, in this review study, after giving information about soft confectionery products and their quality characteristics, the interactions of especially innovative components and processes that have important effects on these foods were discussed in detail.

In the present study, a novel method was developed to determine honey adulteration. Natural sunflower honey (A), adulterated honey (B), indirectly adulterated honey obtained by feeding of bee colonies using sugar syrup (C), mixtures of them (AB and AC), and two additional natural sunflower honey samples coming from different geographical regions (D and E) were examined after seeding at different levels (1, 5, 10%, w/w) of crystallized honey. The physico-chemical property, FT-IR spectra, thermodynamic property (T-p and Delta H), flow behavior [storage (G ') and loss (G '') modulus], and microstructural changes of the samples were investigated. According to the obtained results, natural sunflower honeys showed different visco-elastic and flow behaviors from adulterated honeys. The microstructure properties were also different and more homogeneous, and faster crystallization was detected in natural honey (A). The results of this study notably show that honey adulteration can be determined by examining honey crystallization behaviors. Therefore, it is thought that the industry will benefit from this easy and simple method instead of time-consuming, expensive, and complex methods used for determining honey adulteration.

Zeytin ağacının meyvesinden hiçbir saflaştırma (rafinasyon) işlemine tabi olmadan sadece mekanik veya diğer fiziksel yöntemlerle elde edilen natürel (doğal) zeytinyağının (Virgin olive oil, VOO) üretim süreci son yıllarda stabil kalmıştır. Günümüzde ise, kaliteli natürel zeytinyağlarının endüstriyel anlamda üretilebilmesi için geleneksel kesikli üretimin, sürekli üretim sistemine dönüştürülmesi ve üretim kapasitelerinin iyileştirilmesi için gelişmiş makinelerin tasarlanması ve oluşturulması amaçlanmaktadır. Bu bakımdan, gıda ürünlerinin işlenmesinde keşfedilen yeni teknolojilerden biri olan vurgulu elektrik alan (Pulsed electric field, PEF) uygulaması, birçok gıdanın işlenmesinde başarılı bir şekilde uygulanabildiği gibi natürel zeytinyağının üretiminde de verimi arttırmak ve aynı zamanda yüksek kalitede son ürün elde etmek için önerilmektedir. Bu derlemede, PEF işleminin temel prensipleri ile bu tekniğin zeytinyağının üretim verimine etkisi ve son ürünün kalitesi üzerindeki rolünün ortaya konması amaçlanmıştır.

The food industry is in search of innovative processing technologies that are capable of providing food safety and improving quality with low processing costs and fast operations. As a new technique, cold plasma (CP) fulfills these requirements and thus gained significant attraction from researchers. Apart from general microbial inactivation purposes, CP can effectively modify the food macromolecules through reactions with reactive plasma species. In this context, this review focuses on the interactions between reactive plasma species and proteins, lipids, and polysaccharides. It also covers the changes in interfacial and mechanical properties of proteins and polysaccharides, effects on oleogels and xerogels, modifications in the allergenicity of proteins, and trans-free hydrogenation of oils. On the other hand, the concepts underlying the interactions between reactive plasma species and these macromolecules and the effects of processing parameters should be better understood, thus further studies should focus on these aspects.

Şekerleme endüstrisi, listenin neredeyse sınırsız olduğu, her yaş grubu tarafından talep gören, açlık ve susuzluğu gidermenin ötesinde özellikle haz almak amacıyla tüketilen çeşitli ürünleri içermektedir. Söz konusu ürünlerin yüksek kalorili olması, aşırı tüketimlerinin özellikle fazla şeker alımı ile ilişkilendirilebilen çeşitli hastalıklara neden olması ve tüketicilerin daha sağlıklı ürün gruplarına yönelmesi gibi nedenler, diğer gıda sektörlerinde olduğu gibi bu sektörde de üretilen ürünlere yönelik birtakım değişikliklerin yapılmasını zorunlu kılmıştır. Bu bakımdan günümüzde araştırmacılar, sektörde var olan şekerleme ürünlerinin üretiminde ve ürün içeriğinde değişiklikler yapıp, farklı ve yenilikçi yaklaşımlar kullanarak henüz yeni olan fonksiyonel şekerleme ürünlerinin üretimi üzerinde çalışmaktadırlar. Bu çalışma kapsamında, şekerleme endüstrisinde yoğun bir şekilde üretilen ve oldukça rağbet gören, sert şeker, yumuşak şeker, çikolata ve sakız ürünlerine fonksiyonellik kazandırılması amacıyla yapılan bilimsel çalışmalar derlenmiştir.

In this study, dried grape (Cabernet sauvignon) pomace (DGP) as a by-product of wine production was used in the chocolate spread (CS) instead of various amounts of sugar and milk originated powders (MOP; skimmed milk and demineralized whey powder 1:1, w/w). The formulations of CS samples were determined using mixture design method. The sugar, MOP and DGP concentrations changed between 35 and 50, 0.066-8.000 and 0.23-15 g/100 g, respectively. According to the results, the consistency coefficient (K) and flow behavior index values of CS samples changed between 8.10 and 28.50 Pas.s(n) and 0.52-0.71, respectively. In addition, firmness and spreadability parameters were determined between 0.80-1.42 N and 2.15-4.24 N mm, respectively. Total phenolic content in CS samples ranged from 3415 to 13,754 mg GAE/kg and their digestibility ranged between 25% and 84%. Also, the digestibility of resveratrol was determined between 47.6% and 95.7% at different DGP concentrations. All of the established models successfully described the relation with R-2 values higher than 0.800. Textural and rheological parameters as well as sensory characteristics of the samples indicated that DGP may be used as a healthy and low-cost ingredient in CS formulation to partially substitute sugar and MOP. Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [TOVAG-2170054] This work was funded by the Scientific and Technological Research Council of Turkey (TUBITAK), Project No: TOVAG-2170054.

Nowadays, the use of plant-based by-products obtained after food processing has gained importance, as these products are nutritious and cheap. The aim of this study was to determine the effects of grape skin and seed powders with different particle sizes (100, 200, 288 and 415 μm) on the texture, sensory, color, and rheological properties of soft candies. According to the results, the particle size of the grape-derived components was a significant factor for the texture parameters, especially hardness, adhesiveness, chewiness, and resilience. In sensory analyses, samples containing grape seed and skin powder with a particle size of 100 and 200 μm received the highest score and particles were not felt by the panelists. Also, the use of grape seed and skin powder decreased the L* value of the soft candies compared to the control group, which was parallel to the decrease in the particle size. It was found that r values of model fitting of rheological data can be correlated with sensory results. In conclusion, it was shown that grape-derived components can be successfully used in the formulation of soft candy if particle size was adjusted below 200 μm.

The composition of chewing gum and the interaction between its components are quite complex. Although these factors have great importance on product quality, they have not been adequately studied. In this study, effects of the content of minor (lecithin, sorbitol, glycerin) and major ingredients (gum base, powdered sugar, and glucose syrup) of chewing gum on textural and sensorial properties were investigated by d -optimal mixture design approach. According to the results, powdered sugar and lecithin generally increased aroma durability during chewing, and glucose syrup increased the softness and chewability of the gum. It was revealed that the hardness and resilience texture parameters are the most important parameters to determine appropriate sensorial texture in chewing gum. The optimum composition causing the best liking for aroma duration was found as 17.9 % gum base, 25.65 % glucose syrup, 55.15 % powdered sugar, 0.3 % lecithin, 0 % glycerin, and 0 % sorbitol.

BACKGROUND Wheat germ (WG) is a valuable by-product of the commercial milling industry and is used as a functional ingredient in various foods. Therefore, in this study, it is aimed to utilize defatted wheat germ (DWG) (1%, 3%, 5%, 10%) in chewing gum formulation, which is a different food matrix besides the conventional structures, and investigate the release kinetics of phenolics from DWG incorporated chewing gums with a new centrifugation method. RESULTS According to the results, it was observed that DWG was a good source of total phenolics (2254.15 mg GAE kg(-1)). Based on the results obtained from texture profile and sensory analyses, DWG addition did not cause any reverse effect on the chewing gum texture. Centrifugation method was used to indirectly simulate the physical effects of the chewing process. In particular, after 5 min of chewing and centrifugation, phenolic release levels were 59.07% and 59.41%, respectively. The model used in the previous studies showed a better correlation than Korsmeyer-Peppas model for ABTS (2,2 '-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid), CUPRAC (cupric ion reducing antioxidant capacity), and DPPH (2,2-diphenyl-1-picrylhydrazyl) assay results. CONCLUSION The results showed that phenolics release from gum base polymer matrix might be dominated by erosion of matrix due to chewing action. Similar phenolic release kinetics were obtained by centrifugation and chewing methods. Therefore, centrifuge equipment can be used to simulate the chewing forces acting on the gum when optimization is performed. (c) 2019 Society of Chemical Industry Namik Kemal University Scientific Research CommitteeNamik Kemal University [NKUBAP.03.YL.17.133] The authors would like to thank the Namik Kemal University Scientific Research Committee for the funding provided for this study through the project NKUBAP.03.YL.17.133.

This study investigates damage mechanisms and deformation of honeycomb sandwich structures reinforced by functionally graded face plates under ballistic impact. The honeycomb sandwich structure consists of two identical functionally graded face sheets, having different material compositions through the thickness, and an aluminum honeycomb core. The functionally graded face sheets consist of ceramic (SiC) and aluminum (Al 6061) phases. The through-thickness mechanical properties of face sheets are assumed to vary according to a power-law. The locally effective material properties are evaluated using the Mori–Tanaka scheme. The effect of material composition of functionally graded face sheets on the ballistic performance of honeycomb sandwich structures was investigated using the finite element method and the penetration and perforation threshold energy values on ballistic performance and ballistic limit of the sandwich structures are determined. The contribution of the honeycomb core on the ballistic performance of the sandwich structure was evaluated by comparing with spaced plates (without honeycomb core) in terms of the residual velocity, kinetic energy, and damage area.

Apple seeds are among the major natural sources of antioxidants and can be used in various industries. In this regard, antioxidant activity, total phenolic content, and individual phenolic compounds analyzes of defatted apple seed flours were firstly done in our study. According to these analyzes, total phenolic content, DPPH and ABTS radical scavenging activity of defatted seed flours were determined between 2861 and 5141 mg GAE/kg defatted seed, 21.45–43.56 μmol, and 291.50–391.79 μmol Trolox/g defatted seed, respectively. It was observed that the content of phloridzin represented 52–67% and 75–83% of the total phenolics that measured by the Folin-Ciocalteu assay and HPLC method, respectively. In the second part, chewing gums including defatted seeds were prepared and characterized in terms of phloridzin dissolution. The novel model described dissolution kinetics of phloridzin from chewing gum better than Higuchi and Korsmeyer-Peppas models. The results demonstrated that 5 min was enough for the dissolution of almost all phloridzin (88.43–96%) determined by centrifugation method and according to the model parameters, the chewing gum formulation can be optimized for providing controlled dissolution. In conclusion, chewing gum could be a suitable delivering material for phloridzin uptake, and apple seeds, a valuable agricultural by-product, could be evaluated in this way.

In this experimental study, high velocity impact behavior of honeycomb sandwich structures with Al6061/B 4 C FGM face plates subjected to 0.30 caliber fragment simulating projectile impact was investigated via a single-stage gas gun. The material composition of the FGM face plates was represented according to a power-law variation through the plate thickness. The specimens were produced for six types of face plates, Al6061 and five different FGM face plates from metal-rich to ceramic-rich composition. Impact test results of the specimens were evaluated in terms of their damage and deformation mechanisms . The test results stated that the material composition variation of the FGM face plates was a highly influential parameter for damage modes, energy absorbing capacity, and impact resistance of the sandwich structure, and the honeycomb core contributed to the energy absorbing capacity of the sandwich structure with the plastic buckling of the cell walls and lateral crushing deformations.

This paper presents the results of an experimental and numerical study on aluminium honeycomb sandwich structures under low-velocity impact loadings. In order to investigate the impact behavior of honeycomb sandwich structures, which is consisted of two identical aluminium facesheets and an aluminium honeycomb core, an experimental study was carried out by using a drop-weight impact test system. Using this system, the contact forces and absorbed energies were measured to determine the influence of impact energy for one configuration of the sandwich structure. According to these results, a numerical model by finite element method of sandwich structures was developed, which is in good agreement with experimental results in terms of contact forces and deformations. Later, the effect of the cell size and the height variation of aluminum honeycomb core on the impact response of sandwich structures were investigated using the improved numerical model. The obtained numerical and experimental results were interpreted in detail.

In this study, it was aimed to investigate the potential of sugared and sugar-free chewing gum as a functional food with the addition of microencapsulated pomegranate peel extract (MEPPE) at different amounts. Application of certain chewing times (0, 1, 3 and 5 min) to MEPPE-incorporated gums resulted in a higher release rate of punicalagin and ellagic acid from sugar-free gum matrix than sugared gum matrix (P < 0.05). According to exponential rise model, sugared and sugar-free gums could release 38.3% and 75.6% of ellagic acid, 82.5% and 94.8% of punicalagin depending on the chewing time, respectively. Incorporation of MEPPE did not cause significant changes in quality parameters of chewing gum such as colour and texture. Therefore, the results indicated that chewing gum could be used as a carrier for bioactive compounds and depending on the bulk sweetener used was an effective factor in the release kinetics.

The study presents a comparative numerical investigation on ballistic performance of ceramic/metal armor structures. 2D axisymmetric numerical model was developed for ballistic impact simulations using LS-DYNA ® finite element software. The armor structures included combinations of boron carbide (B 4 C), Al6061-T6 and 4340 steel constituents. The interfaces in the armor structure were modelled with an epoxy resin adhesive. In order to define proper material behavior, Johnson-Holmquist-Ceramics material model for B 4 C and Plastic-Kinematic material model for Al6061-T6, 4340 steel and epoxy resin was used . The armor structures were subjected to 7.62 mm ogive-nosed steel projectile impact. In the first section, the influence of back plate material on the ballistic performance of the armor structure for bi-layers ceramic/metal configuration (ceramic front face and metal back plate) was investigated for Al6061-T6 and 4340 steel materials under same thickness and areal density. In the second section, the effect of removing half thickness of the metal constituent from the back plate and placing on the front face was investigated for both Al6061-T6 and 4340 steel materials. Finally, the influence of adhesive thickness on the ballistic performance of the armor structure was investigated. Perforation response of the armor structures were examined in terms of residual velocity of the projectile and damage mechanisms of the armor structure.

The aim of this study is to determine the ballistic impact response of a novel sandwich structure consisting of aluminum honeycomb and Al/SiC functionally graded face sheets and develop a compatible numerical model with experiments. The experiments were carried out by a single-stage gas gun system and numerical simulations were performed using the explicit finite element code, LS-DYNA (R). The mechanical properties of the functionally graded face sheets through the thickness were considered in accordance with a power-law distribution. The Mori-Tanaka scheme was used in order to determine the effective material properties of the functionally graded face sheets at a local point. In order to simulate the elastoplastic behavior of the functionally graded face sheets, Tamura-Tomota-Ozawa model was implemented in the numerical model. The ballistic performance of the sandwich structure was investigated for metal-rich (n=0.1), linear (n=1.0), and ceramic-rich (n=10.0) compositions of the functionally graded face sheets. The results indicated that the ceramic fraction of the functionally graded face sheets was quite influential on energy absorption capability, damage mechanism, and impact resistance of the sandwich structure. The sandwich structure with linear functionally graded face sheets showed the highest ballistic performance in terms of damage and deformation shapes of the entire sandwich structure among investigated material compositions., The aim of this study is to determine the ballistic impact response of a novel sandwich structure consisting of aluminum honeycomb and Al/SiC functionally graded face sheets and develop a compatible numerical model with experiments. The experiments were carried out by a single-stage gas gun system and numerical simulations were performed using the explicit finite element code, LS-DYNA®. The mechanical properties of the functionally graded face sheets through the thickness were considered in accordance with a power-law distribution. The Mori–Tanaka scheme was used in order to determine the effective material properties of the functionally graded face sheets at a local point. In order to simulate the elastoplastic behavior of the functionally graded face sheets, Tamura–Tomota–Ozawa model was implemented in the numerical model. The ballistic performance of the sandwich structure was investigated for metal-rich (n = 0.1), linear (n = 1.0), and ceramic-rich (n = 10.0) compositions of the functionally graded face sheets. The results indicated that the ceramic fraction of the functionally graded face sheets was quite influential on energy absorption capability, damage mechanism, and impact resistance of the sandwich structure. The sandwich structure with linear functionally graded face sheets showed the highest ballistic performance in terms of damage and deformation shapes of the entire sandwich structure among investigated material compositions.

In this study, the three-dimensional free vibration analysis of an adhesively bonded functionally graded tubular single lap joint was carried out using the finite element method. The functionally graded tubes of the adhesive joint are composed of ceramic (Al2O3) and metal (Ni) phases varying through the tube thickness. The adhesive material properties, such as modulus of elasticity, Poisson's ratio, and density were found to have negligible effect on the first ten natural frequencies and mode shapes of the adhesive joint. The optimal design parameters of the adhesive joint, such as overlap length, inner radius of the inner tube, outer and inner tube thicknesses, and the through-the-thickness material composition variation were searched using both the artificial neural networks (ANNs) and the genetic algorithms (GAs). For this purpose, the natural frequencies and modal strain energy values were calculated for an adhesive joint with random geometrical properties and material compositions through the tube thicknesses, and were used for training the proposed artificial neural network models. The outer tube thickness, the inner tube-inner radius, and the compositional gradient exponent had considerable effect on the natural frequencies, mode shapes, and modal strain energies of the functionally graded tubular single lap joint, whereas the overlap length and the inner tube thickness had a minor effect. The GAs integrated with ANNs was employed to determine optimal design parameters satisfying both maximum natural frequency and minimum modal strain energy conditions for each natural mode of the tubular adhesive joint.

A comparative numerical investigation on low-velocity impact response of a metal/ ceramic functionally graded sandwich beam (FGSB) is performed by the commercial finite element (FE) software, LS-DYNA[Formula: see text]. The mechanical properties of the FG core are represented by a power-law depending on the volume fractions of the constituents. The effective elastic properties and elastoplastic behavior of the FG core are defined by Mori–Tanaka method and TTO (Tamura–Tomota–Ozawa) model, respectively. The effects of number of layers, compositional gradient, impact energy, and impact side are investigated. The simulation results indicated that both number of layers and compositional gradient have almost no effect on the kinetic energy history. In other respects, the compositional gradient exhibits a considerable effect, and the number of layers has a minor effect on the contact force history. Increasing impact energy does not have a considerable effect in terms of number of layers whereas it exhibits a significant effect in terms of compositional gradient on the percentage difference between the peak contact forces. Finally, the impact side does not influence the contact force history for all number of layers and compositional gradients.

The three-dimensional impact behaviours of functionally graded (FG) circular plates were studied under a drop-weight. The functionally graded circular plate was composed of ceramic (SiC) and metal (Al) phases and the through-thickness mechanical properties through the region between the metal and ceramic layers vary continuously according to a power-law distribution of the volume fraction of the ceramic. The through-thickness material properties of the FG circular plate were determined using the Mori-3Tanaka scheme. The effects of layer number and compositional gradient exponent as well as impactor velocity and plate radius on the elastic impact response of the FG circular plates were investigated. The compositional gradient exponent, impactor velocity and plate radius played an important role on the impact response of the FG circular plates, whereas the layer number through the plate thickness had a minor effect. In addition, the failure strains in all layers were determined using Tamura-Tomota-Ozowa (TTO) model in order to predict the damage regions in each layer through the thickness of FG circular plates. (C) 2010 Elsevier Ltd. All rights reserved.

Geometrically nonlinear analysis of functionally graded circular plates subjected to mechanical and thermal loads is carried out in this paper. The Green–Lagrange strain tensor in its entirety is used in the analysis. The locally effective material properties are evaluated using homogenization method which is based on the Mori–Tanaka scheme. In the case of thermally loaded plates, the temperature variation through the thickness is determined by solving a steady-state heat transfer (i.e. energy) equation. As an example, a functionally gradient material circular plate composed of zirconium and aluminum is used and results are presented in graphical form.

Konjuge linoleik asit (KLA), yağ asidi zincirinde iki adet doymamıfl çift bağ içeren linoleik asidin (LA)çeflitli pozisyonel ve geometrik izomerlerini ifade etmektedir. İzomerler, LA'nın gevifl getiren hayvanlarınrumeninde stearik aside bakteriyel biyohidrojenasyonu esnasında ara ürün olarak veya memeli salgıbezi ve adipoz dokularında ?9-desaturaz enzimi aracılığıyla trans vaksenik asidin desatürasyonu ilesentezlenmektedir. KLA izomerleri birçok gıdada bulunmakla birlikte ağırlıklı olarak gevifl getirenhayvanlardan elde edilen et ve süt ürünlerinde bulunmaktadır. KLA izomerlerinin sağlık üzerine çeflitliolumlu etkilerinin olduğu, bununla beraber oluflturabilecekleri potansiyel endifleler de bazı arafltırmalardabelirtilmifltir. KLA üretimi sadece rumen bakterilerine özgü olmayıp; bazı laktik asit ve propiyonik asitbakterilerinin yanı sıra süt ürünlerinden, insan ve hayvan bağırsağından izole edilen mikroorganizmalarında üretimde yer aldığı belirlenmifltir. Bu türlerin baflta süt endüstrisi olmak üzere gıda sanayinde KLAile zenginlefltirilmifl geleneksel veya yeni fermente ürünlerin üretiminde kullanılması büyük önem arzetmektedir Conjugated linoleic acid (CLA) is a common term of various positional and geometric isomers of linoleicacid (LA) which contains two unsaturated double bonds in the fatty acid chains. Isomers are synthesizedas an intermediate product during the bacterial biohydrogenation of LA to stearic acid in the rumen ofruminants or from the conversion of trans vaccenic acid by the ?9-desaturase enzyme in the mammaryglands and adipose tissues. CLA isomers are found in many foods, but mainly present in meat and dairyproducts obtained from ruminant animals. Although there are diverse positive effects of CLA isomerson health, some potential concerns that can be caused by these compounds have been stated in somestudies. CLA production is not specific to rumen bacteria; it was determined that some lactic acid andpropionic acid bacteria as well as microorganisms isolated from the milk products, human and animalintestines involved in the production. Therefore, use of these microorganisms in food industry, especiallywithin the dairy branch, for the production of traditional or new fermented products enriched with CLAis a great importance

In this study, three-dimensional free vibration and stress analyses of an adhesively bonded functionally graded single lap joint were carried. The effects of the adhesive material properties, such as modulus of elasticity, Poisson's ratio and density were found to be negligible on the first ten natural frequencies and mode shapes of the adhesive joint. Both the finite element method and the back-propagation artificial neural network (ANN) method were used to investigate the effects of the geometrical parameters, such as overlap length, plate thickness and adhesive thickness; and the material composition variation through the plate thickness on the natural frequencies, mode shapes and modal strain energy of the adhesive joint. The suitable ANN models were trained successfully using a series of free vibration and stress analyses for various random geometrical parameters and compositional gradient exponents. The ANN models showed that the support length, the plate thickness and the compositional gradient exponent played important role on the natural frequencies, mode shapes and modal strain energies of the adhesive joint whereas the adhesive thickness had a minor effect. In addition, the optimal joint dimensions and compositional gradient exponent were determined using genetic algorithm and ANN models so that the maximum natural frequency and the minimum modal strain energy conditions are satisfied for each natural frequency of the adhesively bonded functionally graded single lap joint. (c) 2006 Elsevier Ltd. All rights reserved.

This study investigates three-dimensional thermal residual stresses occurring in an adhesively-bonded functionally graded single-lap joint subjected to a uniform cooling. The adherends are composed of a through-the-thickness functionally graded region between Al2O3 ceramic and Ni metal layers. Their mechanical properties were calculated using a power law for the volume fraction of the metal phase and a 3D layered finite element was implemented. In a free single-lap joint the normal stress sigma(xx) was dominant through the overlap region of the upper and lower adherends and along the adhesive free edges, whereas the transverse shear stress sigma(xy) concentrations appeared only along the free edges. The peel stress sigma(yy) and the transverse shear stress sigma(xy) became dominant along the free edges of the adhesive layer. In addition, the von Mises stress decreased uniformly through the adherend thickness from compressive in the top ceramic-rich layer to tensile in the bottom metal-rich layer. In addition, the layer number had only a minor effect on the through-the-thickness stress profiles after a layer number of 50, except for the peak stress values in the ceramic layer. In a single-lap joint fixed at two edges both adherends underwent considerable normal stress sigma(xx) concentrations varying from compressive in the top ceramic-rich layer to tensile in the bottom metal-rich layer along the free edges of both adherend-adhesive interfaces, whereas the peel stress sigma(yy) and transverse shear stress reached peak levels along the left and right free edges of the adhesive layer. The layer number and the compositional gradient exponent had only minor effects on the through-the-thickness von Mises stress profiles but considerably affected the peak stress levels. The free edges of adhesive-adherend interfaces and the corresponding adherend regions are the most critical regions, and the adherend edge conditions play more important role in the critical adherend and adhesive stresses. Therefore, the first initiation of the joint failure can be expected along the left and right free edges of the upper and lower adherend-adhesive interfaces.

In this study three-dimensional elastic stress state of an adhesively bonded single lap joint with functionally graded adherends in tension was investigated. The adherends compose of a functionally gradient layer between a pure ceramic (Al2O3) layer and a pure metal (Ni) layer. Stress concentrations are observed along the free edges of the adhesive layer and through the corresponding zones in the upper and lower adherends. The adhesive layer experiences stress concentrations along the left and right free edges in the horizontal plane, and the normal stresses and the shear stress are critical. Whereas the middle overlap region has a uniform low stress distribution the zones in the upper adherend corresponding to the left free edge of the adhesive layer and the zones in the lower adherend corresponding to the right free edge of the adhesive layer are subjected to higher stresses. The normal stress sigma(xx) among the normal stresses and the shear stress sigma(xy) among the shear stresses are dominant in both upper and lower adherends. The normal stress sigma(xx) changes uniformly from compression in the ceramic layer to tension in the metal layer through the upper plate-thickness and from tension in the ceramic layer to compression in the metal layer through the lower plate-thickness. In the adhesive layer, the normal stress sigma(yy) becomes peak at the left free edge of the upper adherend-adhesive interface and at the right free edge of the lower adherend-adhesive interface and then decreases uniformly across the adhesive layer towards the other adherend-adhesive interface. The functionally gradient region across the adherend thickness was modelled using the layers with the mechanical properties calculated based on the power law. However, a layer number larger than 20 has a minor effect on the through-thickness profiles and magnitudes of von Mises and normal stresses in both the adherends and the adhesive. In addition, increasing the ceramic phase in the material composition (compositional gradient exponent n) of the functionally gradient region does not affect the through-thickness profiles of von Mises and normal stresses in the adherends and adhesive whereas their magnitudes in the ceramic rich layer of both adherends and along the adherend-adhesive interfaces increase considerably. On the contrary, the layer number and compositional gradient exponent have an evident effect on the through-thickness profiles and magnitudes of the critical stress components in the adherends and adhesive layer of the functionally graded adhesively bonded joints. (C) 2004 Elsevier Ltd. All rights reserved.

Adhesive bonding technique is used successfully for joining the carbon fibre reinforced plastics to metals or composite structures. A good design of adhesive joint with either simple or more complex geometry requires its stress and deformation states to be known for different boundary conditions. In case the adhesive joint is subjected to thermal loads, the thermal and mechanical mismatches of the adhesive and adherends cause thermal stresses. The plate-end conditions may also result in the adhesive joint to undergo large displacements and rotations whereas the adhesive and adherends deform elastically (small strain). In this study, the thermal and geometrically non-linear stress analyses of an adhesively bonded composite tee joint with single support plus an angled reinforcement made of unidirectional CFRPs were carried out using the non-linear finite element method. In the stress analysis, the effects of the large displacements were considered using the small displacement–large displacement theory. The stress states in the plates and the adhesive layer of the tee joint configurations bonded to a rigid base and a composite plate were investigated. An initial uniform temperature distribution was attributed to the adhesive joint for a stress free state, and then variable thermal boundary conditions, i.e. air flows with different velocity and temperature were specified along the outer surfaces of the tee joints. The thermal analysis showed that a non-uniform temperature distribution occurred in the tee joints, and high heat fluxes took place along the free surfaces of the adhesive fillets at the adhesive free ends. Later, the geometrical non-linear thermal-stress analysis of the tee joint was carried out for the final temperature distribution and two edge conditions applied to the edges of the vertical and horizontal plates (HP). High stress concentrations occurred around the rounded adherend corners inside the adhesive fillets at the adhesive free ends, and along the adhesive–composite adherend interfaces due to their thermal–mechanical mismatches. The most critical joint regions were adhesive fillets subjected to high thermal gradients, the middle region of HP, the region of the vertical plate corresponding to the free end of the vertical adhesive layer–left support interface. In addition, the support length had a small effect of reducing the peak stresses at the critical adherend and adhesive locations.

The adhesive joints consist of adhesive layer and adherends with different mechanical and thermal properties. In case the adhesive joint is subjected to a temperature difference, thermal stresses arise in the adhesive joint due to the thermal and mechanical mismatches of the adhesive layer and the adherends. If the thermal expansion of the adhesive joint is restrained the stresses in the adhesive and adherends can reach considerable levels. In this study, the geometrically non-linear thermal stress analysis of an adhesively bonded tee joint with double support was carried out using the finite element method. The configurations of the adhesive tee joint bonded to a rigid base and to a flexible horizontal plate were considered. It was assumed that the adhesive tee joint is subjected to variable thermal boundary conditions, that is, air flows with different temperature and velocity parallel and perpendicular to outer surfaces of the tee joint. In order to determine the thermal strains with respect to a reference temperature, it is necessary to know the final temperature distributions through the adhesive tee joint. The heat transfer analysis of the tee joint showed that high heat fluxes occurred inside the adhesive fillets at the adhesive free ends whereas the vertical and horizontal plates experience uniform low-temperature distributions. Based on the final temperature distribution of the adhesive tee joint its geometrical non-linear stress analysis was carried out considering large displacement effects for two plate edge conditions in which the edges of the vertical and horizontal plates were fully or partly constrained. The stress analyses showed that high stress concentrations occurred inside the adhesive fillets around the adhesive free ends. The surfaces of the vertical and horizontal plates near the free ends of the adhesive–plate interfaces and the adhesive–support interfaces also experience stress concentrations. The adhesive tee joint was subjected to the highest stresses in the adhesive layer and plates when the edges of the horizontal and vertical plates were fully fixed. In addition, increasing the effect of the support length resulted in increases in the peak stresses at the critical locations of the adhesive layer and the plates.

In this study, the. geometrically non-linear thermal stress analysis of an adhesively bonded tubular single lap joint subjected to airflows having different temperature and velocity outside and inside its inner and outer tubes was carried out using the incremental finite element method. Since the thermal expansion coefficients of tubes and adhesive were different the thermal strains arising along the adhesive-tube interfaces resulted in high thermal stresses in the adhesive layer and tubes for different end conditions applied to the ends of its outer and inner tubes. The joint region was considerably deformed, and serious stress concentrations occurred around the adhesive free ends. This effect became more evident in cases the tube edges were fully restrained. The peak thermal adhesive and tube stresses occurred at the free ends, of the adhesive-tube interfaces. In addition, increasing the overlap length had an effect of reducing the peak adhesive and tube stresses, and an optimum overlap length/joint length ratio of 0.2 was determined. (C) 2002 Elsevier Science B.V. All rights reserved.

Since adhesive joints consist of adhesive and adherends with different mechanical and thermal properties, the adhesive and adherends present different stress and strain states under thermal loads due to the thermal-mechanical mismatches. Thermal strains result in serious stresses even though the adhesive joints are not restrained. In this study, the thermal stress analysis of an adhesively bonded single lap joint (SLJ) was carried out considering the large displacement effects. In the thermal analysis, the outer surfaces of the SLJ are assumed to be subjected to air flows with different temperature and velocity. The final temperature distribution in the adhesive joint was used to compute thermal strains. Later, the geometrical non-linear stress analysis of the SLJ was carried out for four adherend edge conditions using the incremental FEM. Thermal strain concentrations were observed inside the adhesive fillets around the free ends of the adhesive layer. The top and bottom surfaces of the adherends also experienced high thermal stresses. The detailed analysis showed that the most critical adhesive regions were the free ends of the adhesive-adherend interfaces. It was observed that thermal loads caused serious stress and strain concentrations in joint members as well as the structural loads (Structural adhesive joints in engineering. London: Elsevier Applied Science; 1984). In order to reduce the peak stresses at the critical adhesive and adherend regions increasing the overlap length was not beneficial for all adherend edge conditions. (C) 2002 Elsevier Science Ltd. All rights reserved.

This study investigates damage mechanism and deformation of honeycomb sandwich structures reinforced by functionally graded plates under ballistic impact effect by means of explicit dynamic analysis using ANSYS LS-DYNA. The honeycomb sandwich structures consisted of two identical functionally graded (FG) facesheets having different material compositions through the plate thickness and an aluminum honeycomb core. The functionally graded facesheets were composed of ceramic (SiC) and metal (Al6061) phases. The through-thickness mechanical properties of facesheets were determined based on a power-law distribution of the volume fraction of the constituents. The locally effective material properties were evaluated using homogenization method which based on the Mori-Tanaka scheme. In the analyses, theoretical models which based on micro structural model of functionally graded materials were used. The effect of material composition of functionally graded facesheets on the ballistic performance of honeycomb sandwich structures was investigated and the penetration and perforation threshold energy values which are the most considerable parameters on ballistic performance and ballistic limit of the sandwich structures were determined.

Functionally graded materials have been increasingly used in the design of impact resistant structures. A functionally graded plate with a tailored ceramic to metal through-thickness gradient combines the superior features of ceramics and metals in the same material system. The ceramic-rich side provides good protection against projectiles, while the metal-rich side oers toughness and strength to maintain the integrity of the structure as much as possible. Thus, the ceramic plates are used for single impact applications, whereas the FGM can be used multiple impact applications with high ballistic performance. In this study, the damage and deformation mechanisms of aluminum plates and functionally graded sandwich plates have been investigated and their performances were compared to each other under ballistics impact loadings. The functionally graded sandwich plate is composed of a mixture of ceramic (SiC) and metal (Al) phases, at a ratio of which is determined by a power-law distribution of the volume fraction. In the ballistics tests with 9 mm Parabellum projectiles, having a brass jacket and a lead core were used. Both aluminum and functionally graded sandwich plates were manufactured by means of the powder stacking-hot pressing method, their ballistic tests were performed and it was determined that functionally graded sandwich plates have a better ballistics performance than an aluminum plate by examining almost a full penetration of projectile to the aluminum plate while a signicant penetration to the functionally graded sandwich plate was not observed.

This paper addresses low-velocity impact behaviour of functionally graded clamped circular plates. An experimental work was carried out to investigate the impact behaviour of FG circular plates which is composed of ceramic (SiC) and metal (Al) phases varying through the plate thickness by using a drop-weight impact test system. The influence of the compositional gradient exponent and impactor velocity on the contact forces and absorbed energies was concentrated on the tests. The explicit finite element method, in which a volume fraction based elastic plastic model (the TTO model) was implemented for the functionally graded materials, was used to simulate their drop-weight impact tests. Effective material properties at any point inside FGM plates were determined using Mori-Tanaka scheme. The experimental and numerical results indicated that the compositional gradient exponent and impactor velocity more effective on the elasto-plastic response of the FG circular plates to a low-velocity impact loading. The comparison at the theoretical and experimental results showed that the use of the TTO model in modelling the elasto-plastic behaviour of FG circular plates results in increasing deviations between the numerical and experimental contact forces for ceramic-rich compositions whereas it becomes more successful for metal-rich compositions. (C) 2013 Elsevier Ltd. All rights reserved., This paper addresses low-velocity impact behaviour of functionally graded clamped circular plates. An experimental work was carried out to investigate the impact behaviour of FG circular plates which is composed of ceramic (SiC) and metal (Al) phases varying through the plate thickness by using a drop-weight impact test system. The influence of the compositional gradient exponent and impactor velocity on the contact forces and absorbed energies was concentrated on the tests. The explicit finite element method, in which a volume fraction based elastic–plastic model (the TTO model) was implemented for the functionally graded materials, was used to simulate their drop-weight impact tests. Effective material properties at any point inside FGM plates were determined using Mori–Tanaka scheme. The experimental and numerical results indicated that the compositional gradient exponent and impactor velocity more effective on the elasto-plastic response of the FG circular plates to a low-velocity impact loading. The comparison at the theoretical and experimental results showed that the use of the TTO model in modelling the elasto-plastic behaviour of FG circular plates results in increasing deviations between the numerical and experimental contact forces for ceramic-rich compositions whereas it becomes more successful for metal-rich compositions.

In this study, the interaction between the Nitinol stent and the artery with plaque was investigated using finite element method. The occurring pressure values during the cardiac contraction (systolic) and loosening (diastolic) were applied as loading to the modeled system with Nitinol stent. In the light of the stress values, the suitability of the Nitinol stent in an artery with plaque was investigated. In the analysis, Nitinol stent was assumed to be shape memory alloy, and artery and plaque were assumed to behave linearly elastic. As a result, the stress and deformations in the plaque and artery due to the interference of Nitinol stent were discussed and concluded that the structure of artery with plaque can be expanded in accordance with Nitinol stent.

This experimental study addresses the effect of ceramic reinforcement on the impact performance of functionally graded (FG) circular plates. The FG circular plates were produced from two different ceramic (SiC or Al 2 O 3 ) and metal (Al) combinations using powder stacking-hot pressing technique. The Al/SiC FG circular plates exhibited better impact resistance than Al/Al 2 O 3 FG circular plates. The effect of ceramic particle size was also investigated on the impact performance of specimens with different composition variations. A ceramic particle size of 50 μm improved the impact performance. In addition, the material composition and impactor velocity also affected the impact performance. Thus, the contact force increases as the composition changes from metal-rich to ceramic-rich. The peak contact force increases with increasing the velocity of impactor.

In this study three-dimensional elasto-plastic analysis of functionally graded (FG) circular plates under low-velocity impact loads is presented The FG circular plate is composed of ceramic (SIC) and metal (AI) phases varying in a predetermined fashion through the plate thickness The elasto-plastic behaviour of the FG circular plate is described by the TTO model In the analyses the ceramic phase is taken to be an isotropic elastic material whereas the metal phase is taken to be elasto-plastic material in accordance with the TTO model The locally effective material properties were evaluated using homogenization method which is based on the Mori-Tanaka scheme The effects of compositional gradient exponent and Impactor velocity on the elasto-plastic Impact response of the FG circular plates are investigated and results are presented graphical form The compositional gradient exponent and Impactor velocity have significant effects on the elasto-plastic impact response of the FG circular plates The elasto-plastic impact response of FG circular plates is similar to those of homogeneous plates Therefore the TTO model can be used to describe the mechanical behaviour of FG plates beyond the elastic range assuming that the material response is essentially governed by the spreading of plasticity in the metal phase (C) 2010 Elsevier Ltd All rights reserved

This study investigates the three-dimensional free vibration behaviour of an adhesively bonded functionally graded single lap joint. The functionally graded plates of the adhesive joint are composed of ceramic (Al2O3) and metal (Ni) phases varying through the plate thickness. The effects of geometrical parameters, such as plate width, plate thickness and overlap length, especially the effect of the similar and dissimilar material composition variations through-the-thicknesses of both upper and lower plates on the natural frequencies and corresponding mode shapes of the adhesive joint were also investigated using both the finite element method and the back-propagation artificial neural network (ANN) method. A series of the free vibration analyses were carried out for various random values of the geometrical parameters and the through-the-thickness material composition so that a suitable ANN model could be trained successfully. The proposed ANN models indicated that increasing plate thickness and compositional gradient exponent resulted in increases in the first 10 frequencies whereas the overlap length has negligible effect. In contrast, the natural frequencies decrease suddenly with increasing the plate width. For the plate width > 50 mm, the natural frequencies become very low and the effect of the other design parameters on the natural frequencies becomes minor. In case the upper and lower plates have similar or dissimilar material composition variations the mode shapes were affected considerably, but the natural frequencies. (C) 2009 Elsevier Ltd. All rights reserved.

In this study, the post-buckling analysis of functionally graded cylindrical shells was carried out using the non-linear finite element method. The longitudinal shell edges were hinged under a central transverse concentrated load. The shells were composed of ceramic (Al2 O3 ) and metal (Ni) phases and the mechanical properties at the region between the metal and ceramic layers vary continuously through the shell thickness according to a power-law distribution of the volume fractions of the constituents. The arc-length method was implemented. The effects of material composition and layer number as well as various shell thicknesses on the post-buckling response of the functionally graded cylindrical shells were investigated. The functionally graded shells exhibit both snap-through and snap-back post buckling behaviours. The layer number through the shell thickness has a minor effect on the post-buckling behaviour whereas the compositional gradient exponent varies from 0.1 to 10.0 the snap-through behaviour becomes more obvious whilst both the snap-through and snap-back behaviours appear for a thinner shell.Copyright © 2007 by ASME