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Composite materials are used in high-performance applications where achieving low weight is of concern. Since their introduction in the early 1960s, composite materials consisting of strong fibers in a polymer matrix have received considerable success. Because of the great variety of fiber and matrix combinations, there is no general data base of m...
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... 5. Inherent in this presentation is an assumption of plane stress, where the out-of-plane stresses σ 3, τ 23 , and τ 13 shown in Fig. 1 are assumed to be small and neglected. Such
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... materials used for advanced applications such as airframes, space structures, race cars, and sporting goods employ continuous fiber reinforcements in the form of a ply. Figure 1 shows two types of such plies where unidirectional fibers and woven fabric bundles are impregnated by a polymer resin to form the ply. For most composites in use today, the ply is the basic unit or building block, whether it is in the design, the analysis, or the fabrication process stage. This lamina may be a unidirectional prepreg, a fabric, a chopped strand mat, or another fiber form. However, some composites are made from dry pre-made fiber forms subsequently impregnated with liquid resin, for example, vacuum- assisted resin transfer molding (VARTM). 1 Still, such composites utilize well-recognizable plies. Hence, whatever the material form of the fabrication process, the properties of the individual ply (regions, layers, or whatever form the composite takes) must be known for design and analysis purposes. Determination of the stiffness and strength properties of the individual ply will be the topic of this article. Typical fiber and resin properties are listed in Table 1. 2 It is noted that glass fibers are relatively dense, and as a result are less attractive for extreme light-weight applications such as air frames and space frames. The fibers are much stiffer and stronger than the matrix resins and typically break at smaller strains. The ply unit is highly orthotropic, especially the unidirectional ply (Fig. 1a), where the stiffness and strength along the fiber direction (x 1 ) are much higher than in directions transverse to the fiber (x 2 and x 3 ). The woven fabric ply (Fig. 1b), is more balanced and has similar properties in the x 1 and x 2 directions, but has low out-of-plane stiffnesses and strengths due to the planar 0 ◦ and 90 ◦ fiber pattern. To achieve a material more resistant to out-of-plane loads, there have been several developments to orient fibers in the thickness direction (x ) or to stitch a laminate preform with planar ...
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... but such composites are used only for special applications demanding high strength in the thickness direction. Test methods used for composite materials were initially very similar to those used for testing metals and plastics, but it was soon realized that the highly orthotropic behavior and peculiar failure modes of composite materials demanded specialized test methods. Aerospace companies developed their own procedures and test methods such as the “Boeing compression test”. 3 Several test methods were developed for measuring the same property. Some tests were easy to use but produced unreliable test results, while other more complex test methods produced reliable results given the operator possessed appropriate skills. In the US, the government sponsored much of the early development work to generate a database and standardized test methods. Such attempts, however, were largely unsuccessful because of the continuous emergence of new materials that did not respond to loads in the same manner as the earlier developed ones. Despite the many obstacles discussed here, consensus organizations, such as ASTM and ISO, have made tremendous progress in developing test procedures suitable for composite materials. Most of the test methods reviewed and described in this article and numerous other composite tests are described in Vol. 15 of The ASTM Annual Books of Standards . 4 It should be pointed out that the tests reviewed here are intended for basic materials characterization, that is, tension, compression, and shear, and such tests are considered well established. Still, new basic tests continue to appear while other tests are fading from use. Many other tests exist. 4 (See also Tarnopolski and Kincis, 5 and Adams et al. 6 ) The basic unit (ply) considered, Fig. 1, may be loaded by any of the six stress components illustrated in Fig. 2, i.e., σ 1 , σ 2 , σ 3 , τ 23 , τ 13 , and τ 12 . σ 1 , σ 2, and σ 3 are the normal stresses while τ 23 , τ 13 , and τ 12 are the shear stresses. Associated with these stresses are the strains ε 1 , ε 2 , ε 3 , γ 23 , γ 13 , and γ 12 , defined in a standard small strain manner. 7 It must be pointed out that stresses and strains vary very much throughout the volume of the composite ply. The fibers are much stiffer than the matrix, (see Table 1), and fiber- to-matrix modulus ratios, E f / E m , of the order of 100 are not uncommon. As a result, the matrix may deform more than the fibers when the composite is under load, especially under loadings transverse to the fiber direction. As a result, concepts such as stress and strain refer to suitable defined volume averages, (see Hashin 8 for ...
Citations
... In addition to low weight, other advantages of composite materials include corrosion resistance and chemical stability, thermal and electrical conductivity, as well as low coefficient of thermal expansion [2]. [5] Due to their high stiffness, immediate and fatigue strength, composites reinforced with carbon fibers with matrixes based on polymer thermosetting resins (CFRP) are the most widely used in aviation [4]. Reinforcement in this type of composite may take the form of roving strips, fabrics, mats or short fibers, e.g. ...
... However, the flat fiber arrangement of 0-90° is the reason for the lower strength in the x3 direction. Such fabric-reinforced composites, in which the weight of the warp is comparable to the weight of the weft, are the most commonly used type of orthotropic composite [5,6]. The properties of the composite depend so strongly on the direction of reinforcement orientation due to the fact that the strength of carbon fibers is up to 100 times greater than that of the polymer matrix [7]. ...
... The initial stiffness of the composites in variant B is several times lower than the stiffness in load variant A and clearly decreases with the increase of strain. Researchers in other publications also point out differences in the strength of orthotropic composites depending on the orientation of carbon fibers as a source of possible problems [5]. ...
The aim of the research was to determine the basic strength properties of orthotropic composites in terms of their use in the repair of aircraft airframes. The objects of the tests were three types of composites reinforced with carbon fibers: produced using the wet method with a thickness of 2.5 mm, commercial with a thickness of 2 mm and commercial with a thickness of 7.3 mm. Specimens cut out from the first two types of materials were subjected to a static tensile test with a force applied in the direction of the fibers and at an angle of 45°, which enabled the determination of tensile strength and modulus of elasticity. Specimens made of 7.3 mm thick composite were subjected to four-point bending and tensile tests to determine Young's modulus, compression and impact strength, also taking into account two directions of load application. The values of stresses and Young's modulus determined in this way indicate much lower strength and stiffness of orthotropic composites apart from the reinforcement fibers’ directions, which is the basis for replacing them with quasi-isotropic composites in repairs of aircraft airframes.
... Measurements of wettability and bond strengths are essential techniques to obtain such information. However, it must be noted that one single method often proves to be inadequate because of the heterogeneous nature of composite materials, and several methods have to be employed in tandem (Park and Seo, 2011b;Tsai et al., 1992;Lila et al., 2019;Carlsson et al., 2013). ...
Composite materials are made of two different materials that have distinct physical and chemical properties. Composites find applications in various engineering domains as they offer improved material properties, such as better strength and lower stiffness, over their constituent materials. The use of composites in biomedical engineering has grown rapidly over the last few decades. To replace and/or repair damaged tissues and/or organs, various implants and grafting/substitute materials are required that should ideally have unique mechanical characteristics matching the concerned host tissue. Composite materials are preferred over traditional biomaterials such as metals, ceramics, and polymers in many healthcare-related applications. In this article, an overview of composite materials in various biomedical engineering applications is discussed, highlighting the latest developments and future trends. First of all, the structure and composition of natural composite materials in the human body are presented along with cellular responses observed in composite materials when implanted. Characterization and fabrication techniques of composite materials are highlighted next. Thereafter, the use of composite materials in several hard- and soft-tissue applications are elaborated.
... Aramid fibers possess excellent vibration damping resistance compared to carbon and glass fibers. Therefore, characteristics of polymer matrix aramid composites are studied in literature [4]. ...
In this study, numerical analysis of a composite spring with a nonlinear elastic force-displacement relationship was performed. Due to the lightness and durability of composite materials, their use in the automotive industry is increasing and production methods allow for a high performance spring design. The behavior of a pair of composite leaf springs working in tandem with the cross-section profiles of the leaf springs to be obtained by using the involute curve of the spur gear pairs under load was examined in detail by numerical method, and the desired behavior was obtained. In the analyzes performed using Ls-Dyna software, samples were produced and many mechanical tests were performed for the determination of material parameters. The results obtained from these tests were used as the required material parameters in numerical analysis. The leaf spring thickness that will give the desired non-linear elastic behavior under 400 N load used in numerical analysis has been determined and successfully targeted force-elongation behavior has been created.
... Most of the work has been done on pressure or temperature triggered load-coupled effects, which are often hybridized with an electrical trigger [24][25][26], except if the electricity is not exclusively implemented as e.g., piezoelectric generated effect to enable shape-memory effects [27,28]. However, the focus is mainly put on the demonstration and feasibility of demonstrators [29,30], whilst the mechanical properties related to structure-property interactions, especially for microstructure analysis, are considered in a limited way [31,32]. Therefore, profound knowledge and an adequate quantitative investigation regarding the performance and mechanical behavior of fiber reinforced elastomers combined with an external trigger is necessary. ...
The focus of this research is to quantify the effect of load-coupling mechanisms in anisotropic composites with distinct flexibility. In this context, the study aims to realize a novel testing device to investigate tension-twist coupling effects. This test setup includes a modified gripping system to handle composites with stiff fibers but hyperelastic elastomeric matrices. The verification was done with a special test plan considering a glass textile as reinforcing with different lay-ups to analyze the number of layers and the influence of various fiber orientations onto the load-coupled properties. The results demonstrated that the tension-twist coupling effect strongly depends on both the fiber orientation and the considered reinforcing structure. This enables twisting angles up to 25° with corresponding torque of about 82.3 Nmm, which is even achievable for small lay-ups with 30°/60° oriented composites with distinct asymmetric deformation. For lay-ups with ±45° oriented composites revealing a symmetric deformation lead, as expected, no tension-twist coupling effect was seen. Overall, these findings reveal that the described novel test device provides the basis for an adequate and reliable determination of the load-coupled material properties between stiff fibers and hyperelastic matrices.
... Initially, the test methods applied to composite materials were quite similar to those used for testing the most widely used materials such as metals or plastics. However, it was soon realized that the highly orthotropic and anisotropic behavior and peculiar failure modes of composite materials demanded specialized test methods [150]. [152,153]. ...
... However, many shear test methods are not capable of generating the entire curve, and sometimes not even a portion of it [150]. In cross-ply or plain weave laminates, a shear test is likely to produce shear strengths closer to the ideal shear strength of the composite material, because premature failures are less likely to occur. ...
!!!!!! Note !!!!!! Note !!!!!!! Note
(From this thesis, some papers are published so far, please cite my research work in your manuscripts through my papers provided in my google scholar account. Thanks!)
https://scholar.google.com/citations?user=NvknN7AAAAAJ&hl=en
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The use of fiber-reinforced polymer composites (FRPCs), due to their excellent mechanical and geometrical properties, namely high strength to weight ratio and ease of manufacturing, has gained a great deal of attention in many industries such as aerospace, defense, marine to name but a few. Currently, the most applicable FRPC laminates are fabricated with thermosetting (TS) organic resins, which exhibit great mechanical properties with a medium curing temperature range. Nonetheless, these TS-based laminates have the significant disadvantage of poor out-of-plane properties, as they exhibit brittle behavior that can increase the susceptibility of delamination, especially in impact applications. In recent years, the requirements for: material recyclability, high impact resistance, good vibration dampening characteristics, higher fracture toughness, and post formability, prompted the development of thermoplastic (TP) FRPC laminates.
FRPC laminates with traditional TP resins, namely PEEK, Cyclic Butylene Terephthalate, Polyurethanes, require high processing temperature and costly equipment. As a result, compared to TS resins, they are rarely used. Recently, Arkema company was able to introduce Elium® resin (a reactive methyl methacrylate (MMA) liquid TP resin), which can cure at room temperature, and moreover, is suitable for vacuum-assisted resin infusion (VARI). Considering this, in this study, FRPCs consisting plain weave ultra-high molecule weight polyethylene (UHMWPE) fiber, plain weave carbon fiber, and their hybrid systems with different stacking sequence are fabricated by VARI at ambient temperature to introduce novel TP FRPC laminates. Furthermore, a new generation of TP fiber metal laminates (FMLs) is proposed in this study which can be manufactured at room temperature. For this, titanium alloy sheets (Ti-6Al-4V) are used for fabricating hybrid titanium composite laminates (HTCLs). HTCLs have shown to enjoy better mechanical properties when compared to traditional FMLs and FRPCs, especially in the aeronautical, marine, military, and offshore applications both at room and elevated temperatures as well as harsh environmental conditions. They are outstanding in terms of stiffness, yield stress, fatigue, and high-velocity impact properties; however, there are some challenges regarding their fabrication, surface treatment, and mechanical properties. As a result, Ti-6Al-4V sheets are used to fabricate HTCLs with UHMWPE fabrics, carbon fabrics, and their hybrid FRPC systems to introduce a new generation of TP FMLs manufactured at room temperature to compare their mechanical properties with those of equivalent FRPC laminates and traditional FMLs in the literature. To investigate the feasibility of TP Elium® resin for fabricating TP structures, ASTM standard tests of tensile, compression, shear (both intralaminar and interlaminar), flexural, and low-velocity impact (LVI) are conducted to determine the mechanical properties of the newly developed FRPCs and HTCLs with the aim of comparing the results with those of TS counterparts and also providing a more comprehensive data for theoretical analyses. In addition, fractographic analyses are performed to have a better understanding of the behavior of those new TP laminates. In addition to experimental investigations, the mechanics of structure genome (MSG) and a finite element (FE)-based micromechanics approaches are conducted to evaluate the effective mechanical properties of the TP FRPC laminates. For this end, through a two-step and the asymptotic homogenization approach, elastic properties of FRPC laminates are computed, which are compared with those obtained from experimental tests. Afterward, MSG and the commercial finite element code ABAQUS are combined to simulate the low-velocity impact behavior of the aforementioned laminates.
... Regarding in-plane shear characteristics, as the shear response of a composite material is commonly nonlinear, a full characterization requires generating the entire shear stress-strain curve to failure. However, many shear test methods are not capable of generating the entire curve, and sometimes not even a portion of it [38]. Here, the Iosipescu shear test is applied, which is provided in ASTM D 5379 [36]. ...
The current study investigates the low-velocity impact behavior of newly developed ultra-high molecular weight polyethylene (UHMWPE) fiber-reinforced polymer composites (FRPCs) manufactured at room temperature with an innovative liquid methylmethacrylate (MMA) thermoplastic resin, Elium®. Because of the extremely high molecular mass, UHMWPE fibers exhibit outstanding impact strength and energy dissipation properties. Thus, to evaluate the out-of-plane mechanical properties of the newly developed laminates and compare the results with those of traditional thermosetting and thermoplastic laminates, impact tests at various energy levels from 15 J to 40 J are conducted. Different impact characteristics, namely maximum load, displacement, absorbed energy, structural integrity, and damage failure modes are analyzed for Elium®-based laminates and compared with those of thermosetting laminates fabricated with UHMWPE fibers. During the tests, the thermoplastic composite laminate showed a ductile behavior and developed extended plasticity. The results revealed that the newly developed thermoplastic structures at room temperature can obtain higher impact load and lower absorbed energy up to 40 % compared to those thermosetting counterparts. Furthermore, it was found that replacing the thermosetting resin with the thermoplastic resin significantly improved the structural integrity of the laminate by 240%.
... Regarding in-plane shear characteristics, as the shear response of a composite material is commonly nonlinear, a full characterization requires generating the entire shear stress-strain curve to failure. However, many shear test methods are not capable of generating the entire curve, and sometimes not even a portion of it [38]. Here, the Iosipescu shear test is applied, which is provided in ASTM D 5379 [36]. ...
... Nevertheless, there is a challenges in the used of PFRP for bridges which seems to be lack of historical precedent structural data. In addition the great variety of fibre and resin combinations and also concern with the scarcity in relation with the characteristics of PFRP which is need to be assessed, make the design of composites structures required accurate experimental determination of the mechanical properties of PFRP [7]. Some progress has been made on experimental PFRP studies. ...
The development of polymer technology has been increased for the past 20 years. Most of the polymer based product is
available for aviation, automotive, industrial, and infrastructure purposes include bridges. But, information concern with
the used of polymer materials for bridge structures are scattered. In this paper, characterisation was made to investigate
the applicability of pultruded fibre reinforced polymer (PFRP) for bridges as structural elements. Several experiments
test was then carried out to determine the physical and mechanical properties of PFRP. Some results are compared with
the available pre-standard of PFRP for structures. Afterwards, an ageing test was undertaken to observe the effect of
temperature on the mechanical properties of PFRP. Comparison with the pre-standard of PFRP for structures show that
the physical characteristics are satisfied the minimum requirements. In the mechanical part, the tensile and flexural
properties of tested PFRP are conform with the pre-standard of PFRP, whereas the compressive strength was below the
recommendation of the pre-standard. From ageing test under high temperature, the PFRP strength is possible to increase
or decrease. Enhancement of mechanical strength could be generated by polymer cross-linking reactions which takes
place after the production of PFRP and accelerated by high temperature. While, the decreasing of strength is related to
the delamination process of the fibre.
... Studies comparing microscale to macroscale performance (bypassing mesoscale testing) of novel aromatic and aliphatic sized fibers have also been conducted by Downey & Drzal [31]. Macroscale IFSS values were significantly greater than microscale, which was attributed to both testing variability and complex stress redistributions of SBS laminates [32,33]. Studies comparing mesoscale and macroscale properties have also been conducted, albeit infrequent, investigating the effects of different resin systems on IFSS [34,35]. ...
... Among the most important industries that have decided to use these materials are: aerospace, automotive, sports, among others [3,4]. Composites have had great acceptance since its introduction in the sixties, but due to the different fiber-matrix combinations, there is no complete information on the mechanical properties of these compounds [5]. ...
In this work, we investigate the behavior under compression for a nylon-matrix composite, reinforced with Kevlar, fiberglass, and carbon fiber. The composite is produced by additive manufacturing (AM) using fused deposition modeling (FDM). The specimens are printed with the Markforged Mark Two 3D printer, following the ASTM D3410 standard. The tests are performed by changing the reinforcement material, the filling pattern is fixed to a triangular shape, the angle at 0° and we use 12 layers for all the specimens. Kevlar reinforcement shows a non-linear elastic response for the stress-strain curve, whilst carbon fiber and fiberglass reinforcements show linear elastic behavior. Results indicate that the incidence of a particular failure mode is highly dependent on the type of material used in the reinforcement.
