Effect of geometric variability on the elastic properties of composites (original) (raw)
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Elastic Behavior of Woven Fabric Composites: III -- Laminate Design
Journal of Composite Materials, 1992
Two-dimensional woven fabric composite models were developed for the elastic analysis of WF composites in Part I of this paper. The effect of undulation of yarn and fabric thickness on the elastic properties of woven fabric lamina was studied. The study was extended to woven fabric laminates and the effect of laminate configuration on the elastic properties was analyzed in Part II. In the present paper, the effect of gap between two adjacent yams on the elastic properties of woven fabric lamina and the effect of laminate configuration for different number of layers on the elastic properties of woven fabric laminates for different material systems are studied. An optimum gap between adjacent yarns gives higher Young's moduli, and it depends upon the fabric structure and material system. A basic building block is found which gives higher elastic properties than with any other configuration with the same number of layers. Such a basic building block can then be used for making thicker laminates. The comparison of woven fabric laminates with UD cross-ply laminates indicated that, in general, the material system with lower degree of orthotropy is desirable for woven fabric composites. KEY WORDS: woven fabric composite, laminate design, gap between adjacent yarns, laminate configuration, shift of lamina, basic building block, degree of orthotropy. distribution.
Prediction of on-axes elastic properties of plain weave fabric composites
Two fabric composite models are presented for the on-axes elastic analysis of two-dimensional orthogonal plain weave fabric lamina. These are twodimensional models taking into account the actual strand cross-section geometry, possible gap between two adjacent strands and undulation and continuity of strands along both warp and fill directions. The shape functions considered to define the geometry of the woven fabric lamina compare well with the photomicrographs of actual woven fabric lamina cross-sections. There is a good correlation between the predicted results and the experimental values. Certain modifications are suggested to the simple models available in the literature so that these models can also be used to predict the elastic properties of woven fabric laminae under specific conditions. Some design studies have been carried out for graphite/epoxy woven fabric laminae. Effects of woven fabric geometrical parameters on the elastic properties of the laminae have been investigated.
Influence of the Geometric Parameters on the Elastic Properties of Textile Polymeric Composites
2016
The textile polymeric composites define a class of advanced materials, utilising fabrics as reinforcement. The geometry, as well as the structure of textile reinforced polymeric composites, are much more complex than that of composites reinforced with unidirectional fibres. The mechanical properties of textile reinforced composites are influenced by several parameters such as fibre material, the internal geometry of the fabric, number of counts, size of gap between adjacent yarns, height of woven layer, undulation and thickness of the composite lamina. Each of these factors can influence the structural behaviour and can be modelled based on its specific length scale. This paper is focused on the modelling procedures of the in-plane stiffness characteristics, specific to satin reinforced laminated composites. The method used is a compromise between the continuous and pure discrete approaches and it is associated with a mesoscopic analysis of the repetitive unit cell (RUC). The elasti...
Predicting Effective Constitutive Constants for Woven-Fibre Composite Materials
2021
A meso-scaled finite element model is developed aiming at the study the mechanical properties of wovenfibre composites regarding different weave pattern. A Representative Volume Element (RVE) is constructed and the Uniform Displacement Boundary Conditions (UDBC) are applied in order to obtain the stiffness tensor of such composites. Two different types of woven-fibre composites are evaluated by the introduced model-Eglass/Vinylester plain-weave and 2/2 Twill E-glass/Epoxy. The results from computational homogenization are compared to both experimental and numerical works from literature, showing good agreement. It is verified that the boundary conditions applied to the RVE play a significant role in the homogenization results.
Strain Rate Effects on the Mechanical Behavior of Carbon-Thermoplastic Matrix Woven Composites
Abstract Carbone long fiber thermoplastic laminates are considered for structural parts design of an automotive frame. Knowledge of the crashworthiness and dynamic behavior of this material is essential for the structure design. The proposed contribution concerns the application of an optimized approach dedicated to the experimental characterization of the overall dynamic mechanical behavior of a Twill woven carbon-polyamide laminate. The methodology aims to report the strain rate effect on the material response with an attempt to isolate the inherent inertial disturbances in the specimen attributed to the test system. The procedure, already developed in previous work, is applied to a tensile test performed until the specimen total failure for 3 specific relative orientations of fiber: 0°, 90° and ± 45°. The tests are carried out for a strain rate range from the quasi-static (10-4 s-1) up to 300 s-1. The behavior of the material appears to be strain rate sensitive especially for the...
2017
Woven composites such as carbon and glass fabric-reinforced polymers (C/GFRPs) laminates are increasingly employed in aerospace structures and sports products. In these applications, they are usually subjected to large-deflection quasi-static and dynamic bending deformations during service. Such loading conditions induce damage within the material at various scale levels affecting their strength, stiffness and energy-absorbing capability. Further, FRPs especially made of carbon fibres are inherently brittle, proven to sudden and catastrophic failure without yielding like ductile materials. For this purpose, mechanical behaviour of woven CFRP and GFRP composites in onand off-axis orientations is first quantified by carrying out large-deflection quasi-static bending tests followed by dynamic ones employing an Izod type impact tester. Both types of laminates of various orientations were tested at loads increasing up to failure to determine their energy-absorbing capability. The obtaine...
Carbon/Epoxy Woven Composite Experimental and Numerical Simulation to Predict Tensile Performance
Advances in Materials Science and Applications, 2015
Currently, there is demand for the utilisation of woven composites in aerospace and industrial applications, mostly due to their superior strength-to-weight ratio and thermal properties, as opposed to conventional materials. However, the mechanical behaviour of woven composites is not on par with traditional materials. The central objective of this study is to develop an understanding of three-dimensional woven composites through the improvement of accurate numerical models that are also validated with experimental results. Five specimens were fabricated using American Society for Testing and Materials (ASTM D3039) guidelines to study the mechanical performance of carbon/epoxy. The experimental tensile tests results and the finite element analysis outcomes for the carbon/epoxy composite agree with each other, with 5.05 percentages of error, which validates the numerical results.
Characterization of mechanical behavior of woven fabrics: Experimental methods and benchmark results
Composites Part A: Applied Science and Manufacturing, 2008
Textile composites made of woven fabrics have demonstrated excellent mechanical properties for the production of high specific-strength products. Research efforts in the woven fabric sheet forming are currently at a point where benchmarking will lead to major advances in understanding both the strengths and the limitations of existing experimental and modeling approaches. Test results can provide valuable information for the material characterization and forming process design of woven composites if researchers know how to interpret the results obtained from varying test methods appropriately. An international group of academic and industry researchers has gathered to design and conduct benchmarking tests of interest to the composite sheet forming community. Shear deformation is the dominative deformation mode for woven fabrics in forming; therefore, trellis-frame (picture-frame) and biasextension tests for both balanced and unbalanced fabrics have been conducted and compared through this collaborative effort. Tests were conducted by seven international research institutions on three identical woven fabrics. Both the variations in the setup of each research laboratory and the normalization methods used to compare the test results are presented and discussed. With an understanding of the effects of testing variations on the results and the normalization methods, numerical modeling efforts can commence and new testing methods can be developed to advance the field.
Non-linear finite-element simulations of the tensile tests of textile composites
2015
The main aim of this paper is to find if it is possible to identify material parameters using only three force-displacement dependencies, each for a different angle between the loading force and the principal material directions. The tested materials are textiles made of epoxy resin and fibers in the form of a glass plain weave, a glass quasi-unidirectional weave, a carbon plain weave, a carbon quasi-unidirectional weave, an aramid plain weave and an aramid quasi-unidirectional weave. The plain weave has theoretically 50 % of the fibers in the first and 50 % in the second principal material direction. The quasi-unidirectional weave has theoretically 90 % of the fibers in the first and 10 % in the second principal material direction. Seven types of specimens for each material were subjected to experimental tests. The first principal material direction of each material forms an angle between 0 ° and 90 ° with a step of 15 ° with the applied loading force. The results show that it is p...
Mechanical characterisation of composite materials with 3D woven reinforcement architectures
2016
The use of traditional two-dimensional (2D) fibre preforms can be associated with poor outof-plane and interlaminar mechanical performance, particularly in response to impact loads. Such preforms comprise multiple plies which necessitate labour-intensive ply cutting and assembly steps. 3D woven textiles, due to the incorporation of through-thickness yarns, have been found to exhibit superior out-of-plane mechanical properties whilst simultaneously reducing ply-assembly time and cost (single-piece preform construction). Their delamination resistance and damage tolerance have been extensively investigated over the last number of years; however, there is a paucity of published work on their inplane and out-of-plane mechanical properties when compared to their 2D counterparts. Thus, this research details a comprehensive mechanical characterisation of an orthogonal 3D woven composite in comparison with a suitable 2D laminate. Composite panels have been manufactured with Henkel’s Loctite ...