Finite Element Micromechanics for Stiffness and Strength of Wavy Fiber Composites

Garnich, Mark R.; Karami, G.

doi:10.1177/0021998304039270

Cited by 94 publications

(50 citation statements)

References 17 publications

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“…The crimped strands have greater through-thickness deflections and tend to straighten out through flexural deformation rather than carrying the load entirely in tension. Previous studies have also reported reduction in stiffness with increasing crimp level [30,31]. The L 3 laminate has the highest flexural modulus, which may be attributed to the lowest crimp level in the constituting fabric and the highest fiber fraction percentage in the laminate.…”

Section: Flexural Properties Of the Compositesmentioning

confidence: 76%

Comparison of mechanical and ballistic performance of composite laminates produced from single-layer and double-layer interlocked woven structures

et al. 2013

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(Faisalabad campus), PakistanTextile structures have become quite popular as reinforcement materials in composite laminates due to their high impact-damage tolerance and energy absorption ability. The impact performance of textile composites is not only affected by the type of fiber/ matrix but also by the fabric structure used as reinforcement. The aim of this study was to compare the mechanical and ballistic performance of composite laminates reinforced with single-layer and double-layer interlocked woven fabrics. Kevlar V R 229 multifilament yarn was used for preparation of all the fabric structures and epoxy resin was used as the matrix system. The composites were produced using a hand lay-up method, followed by compression molding. The mechanical and ballistic performance of composites reinforced with single-layer and double-layer interlocked woven fabrics was investigated in this study. The energy absorption and mechanical failure behavior of composites during the impact event were found to be strongly affected by the weave design of the reinforcement. The composites reinforced with doublelayer interlocked woven fabrics were found to perform better than those comprising single-layer fabrics in terms of impact energy absorption and mechanical failure.

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Section: Flexural Properties Of the Compositesmentioning

confidence: 76%

Comparison of mechanical and ballistic performance of composite laminates produced from single-layer and double-layer interlocked woven structures

et al. 2013

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“…In order to show the dependence of mechanical properties on wrinkle severity, elastic modulus reduction data is collected from five different references (Altmann et al, 2015;Karami and Garnich, 2005;Garnich and Karami, 2004;Rudd et al, 1999;Woo and Whitcomb, 1997) and presented in Fig. 4.…”

Section: Adverse Effects Of Fiber Undulation On Mechanical Propertiesmentioning

confidence: 99%

Process Induced Defects in Liquid Molding Processes of Composites

Hamidi

Altan

2017

International Polymer Processing

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Liquid Composite Molding (LCM) processes are cost efficient manufacturing alternatives to traditional autoclave technology for producing near-net shape structural composite parts. However, process induced defects often limit wider usage of LCM in structural applications. Thorough knowledge of these defects, as well as their formation mechanisms and prevention techniques, is essential in developing improved LCM processes. In this article, process induced defects in liquid molding processes of composites, categorized into preform, flow induced and cure induced defects, are reviewed. Preform defects are further presented as fiber misalignment and fiber undulation (waviness and wrinkling). The respective causes, detrimental effects, and possible prevention methods of these defects are presented. Thereafter, flow induced defects are classified as voids and dry spots. Dry spot formation mechanisms in LCM processes and available prevention techniques are summarized. In addition, void formation mechanisms, adverse effects on composite properties, and removal techniques are presented. Cure induced defects include microcracks, void growth and geometrical distortions (warpage and spring-in). Each of these defects are discussed along with their underlying causes as well as their control and reduction schemes.

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“…2, the finite element discretization of three RUCs, at fiber cross angles of 0 o , 45 o and 90 o is shown. The periodicity and constraint constraints as well as the loading conditions are described in [9][10][11][12].…”

Section: Repeating Unit Cellmentioning

confidence: 99%

“…Composite #1 is composed of E-glass fibers [19] and an epoxy matrix [11]. Both of these materials are isotropic in nature and the E-glass fiber has a much higher modulus of elasticity than the epoxy and it also has a significantly lower CTE.…”

Section: Materials Inputmentioning

confidence: 99%

“…The micromechanics model to be used here has been examined for other composite characteristic evaluations. The model has been adapted to determine the elastic behavior of bidirectional [10] as well as viscoelastic behavior of fibrous materials [11]. The model can evaluate the thermal expansion of complete anisotropic materials where shear strains are expected due to temperature change.…”

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confidence: 99%

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Thermoelastic Characterization and Evaluation of Residual Stresses in Bi-Directional Fibrous Composites

et al. 2008

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The thermoelastic behavior of bi-directional fibrous composites will be studied through the use of a finite element-based micromechanical model. The model is used to study the effect of the crossing angle of the fibers on the composite's coefficient of thermal expansion (CTE) and the residual thermal stresses that develop after a temperature change. The effect of the fiber volume fraction (V f ) on the same results is also studied. For anisotropic materials, one can see that in addition to normal strains, shear strains will also be developed due to temperature change. This method will lend itself to evaluate the coefficients of thermal expansions not only due to normal expansion, but also due to shear expansion for composites with no principal directions. In this micromechanical model, parallelepiped unit cells incorporating the fibers at different cross angles are created to represent the periodic microstructure of the angular bi-directional composite. The volume averaged stresses per unit temperature of the individual constituents are used to study the residual thermal stresses that develop. Two different sets of materials are used to test this model. Results show that when the fiber's cross angle is not 0 o or 90 o , shear strains are created. Also, residual stresses in the unit cell are functions of the cross angle between the fibers.

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Finite Element Micromechanics for Stiffness and Strength of Wavy Fiber Composites

Cited by 94 publications

References 17 publications

Comparison of mechanical and ballistic performance of composite laminates produced from single-layer and double-layer interlocked woven structures

Comparison of mechanical and ballistic performance of composite laminates produced from single-layer and double-layer interlocked woven structures

Process Induced Defects in Liquid Molding Processes of Composites

Thermoelastic Characterization and Evaluation of Residual Stresses in Bi-Directional Fibrous Composites

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