Elastic Behaviors of Stitched Multi-Axial Warp Knit Fabric Composites

2006 ◽  
Vol 306-308 ◽  
pp. 817-822 ◽  
Author(s):  
Heoung Jae Chun ◽  
H.W. Kim ◽  
Joon Hyung Byun
Keyword(s):  
Composite Materials ◽  
Elastic Properties ◽  
Structural Integrity ◽  
Experimental Results ◽  
Fiber Volume ◽  
Representative Volume ◽  
Fabric Composites ◽  
Out Of Plane ◽  
Stress States ◽  
Warp Knitted Fabric

The purposes of stitching multi-axial warp knitted fabric preform prior to the fabrication of the composite materials by resin-transfer molding technique are to improve the resistance to delamination and to increase the out-of-plane properties of the composite materials for structural integrity. The influence of the through-the-thickness stitching on the elastic properties and behaviors of the multi-axial warp knit fabric composites is studied. An analytical model based on the representative volume is proposed to predict the elastic properties of the stitched multi-axial warp knit fabric composite materials. The fiber volume ratios determined by geometric parameters set by the representative volume and elastic behaviors of the in-situ constituent materials are used for the predictions. The crucial step in the analysis is to correlate the averaged stress states in the constituents by adopting bridging matrix. The predicted results are compared with the experimental results. It is found that the predicted results are in reasonably good agreement with the experimental results.

ELASTIC PROPERTY PREDICTION OF THE STITCHED MULTI-AXIAL WARP KNIT FABRIC COMPOSITES

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4022-4027 ◽  
Author(s):  
HEOUNG-JAE CHUN ◽  
HYUNG-WOO KIM ◽  
JOON-HYUNG BYUN
Keyword(s):  
Composite Materials ◽  
Elastic Properties ◽  
Cross Sections ◽  
Averaging Method ◽  
Geometric Parameters ◽  
Suggested Model ◽  
Fabric Composites ◽  
Out Of Plane ◽  
Experimental Values ◽  
Good Agreement

In order to improve the resistances to delamination, damage tolerance, some in-plane and out-of-plane properties of composite materials, a through-thickness reinforcement must be provided. This through-thickness reinforcement is achieved by stitching multi-axial warp knit (MWK) fabrics used as preforms for the fabrication of composite materials. The MWK fabrics are constructed with layers of insertion fiber bundles in the warp, weft and bias directions. In order to correlate the microstructure of a preform with the elastic properties of stitched MWK composite, the analytical model for stitched MKW composite is developed. The overall geometry and geometric parameters of a representative volume are determined from the photomicrographs of cross sections of the fabricated composite specimens. The various elastic properties of MWK fabric composites are predicted as functions of various geometric parameters using an averaging method. The experimental results are compared with the predicted results in order to validate the suggested model. It is found that the predicted elastic properties are in reasonably good agreement with the experimental values.

Predictions of Elastic Properties of Multi-Axial Warp Knitted Fabric Composites

2004 ◽  
Vol 261-263 ◽  
pp. 1499-1504 ◽  
Author(s):  
Heoung Jae Chun ◽  
K.S. Ryu ◽  
Joon Hyung Byun
Keyword(s):  
Elastic Properties ◽  
Averaging Method ◽  
Three Dimensional ◽  
Design Parameters ◽  
Fabric Composite ◽  
Fabric Composites ◽  
Out Of Plane ◽  
Experimental Values ◽  
Warp Knitted Fabric ◽  
Good Agreement

An analytical model was proposed to predict the elastic properties of multi-axial warp knitted (MWK) fabric composites for three-dimensional structures. The characteristics of MWK fabric composites are the assemblage of multilayers of rovings in the warp, weft and bias directions for in-plane reinforcement and out-of-plane stitches by knitting rovings to provide through-the- thickness reinforcement. For analysis, a representative volume of the MWK fabric composite was identified. The geometric limitations, effects of stitch fibers and design parameters of MWK composites are considered in the model. Then, the elastic properties of MWK fabric composites are predicted by using an averaging method. The experiments are also conducted on the MWK fabric composites to compare the predicted results with the experimental results for the verification of suggested model. The predicted elastic properties are in reasonably good agreement with the experimental values. Finally the effects of design parameters of the MWK fabric composites are discussed.

A general micromechanical model to predict elastic and strength properties of balanced plain weave fabric composites

2017 ◽  
Vol 51 (20) ◽  
pp. 2863-2878 ◽  
Author(s):  
MM Shokrieh ◽  
R Ghasemi ◽  
R Mosalmani
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Elastic Properties ◽  
Present Model ◽  
Micromechanical Model ◽  
Homogenization Method ◽  
Plain Weave ◽  
Weave Fabric ◽  
Fabric Composites ◽  
Out Of Plane

In the present research, a micromechanical-analytical model was developed to predict the elastic properties and strength of balanced plain weave fabric composites. In this way, a new homogenization method has been developed by using a laminate analogy method for the balanced plain weave fabric composites. The proposed homogenization method is a multi-scale homogenization procedure. This model divides the representative volume element to several sub-elements, in a way that the combination of the sub-elements can be considered as a laminated composite. To determine the mechanical properties of laminates, instead of using an iso-strain assumption, the assumptions of constant in-plane strains and constant out-of-plane stress have been considered. The applied assumptions improve the accuracy of prediction of mechanical properties of balanced plain weave fabrics composites, especially the out-of-plane elastic properties. Also, the stress analysis for prediction of strain–stress behavior and strength has been implemented in a similar manner. In addition, the nonlinear mechanical behavior of balanced plain weave composite is studied by considering the inelastic mechanical behavior of its polymeric matrix. To assess the accuracy of the present model, the results were compared with available results in the literature. The results, including of engineering constants (elastic modulus and Poisson’s ratio) and stress–strain behavior show the accuracy of the present model.

Automated RVE computations for evaluation of microdamage initiation in structural stitched non-crimp fabric composites

2020 ◽  
Vol 54 (30) ◽  
pp. 4751-4771
Author(s):  
Gerrit Pierreux ◽  
Danny Van Hemelrijck ◽  
Thierry J Massart
Keyword(s):  
Cross Sections ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Fiber Direction ◽  
Fiber Volume ◽  
Damage Initiation ◽  
Processing Step ◽  
Fabric Composites ◽  
Out Of Plane ◽  
Generate Unit

This contribution presents an approach to generate unit-cell models of structural stitched non-crimp fabric composites. Resin-rich regions and out-of-plane undulations caused by the stitching yarn are represented by initially straight discretised lines, while the stitching yarn is represented initially by a single discretised line which can be transformed into a multi-line configuration to model stitch cross-section variations. The discretised lines are shaped by geometrical operations with a contact treatment and boundary conditions being used to account, respectively, for line interactions and to control the shape of the bottom and top surfaces of each lamina respectively. A fiber-reinforced distorted zone with local variations in fiber volume fraction and fiber direction is modelled in cross-sections of the lamina in a post-processing step. Models for different stacking sequences and stitching parameters are then automatically generated and subsequently being in the stiffness calculation and damage initiation assessment using finite element based mechanical simulations.

scholarly journals A Comparison of Experimental and Computation Results of Finding Effective Characteristics of Elastic Properties of Polymer Layered Composites from Carbon and Glass Fabrics

2021 ◽  
pp. 88-105
Author(s):  
A. Yu Muyzemnek ◽  
T. N Ivanova ◽  
E. D Kartashova
Keyword(s):  
Composite Materials ◽  
Elastic Properties ◽  
Computational Methods ◽  
Experimental Studies ◽  
Tensile Tests ◽  
Layered Composite ◽  
Experimental Results ◽  
Effective Characteristics ◽  
Shear Moduli ◽  
Bridge Model

Anisotropy of mechanical properties of the entire material and each of its layers is characteristic for polymer layered composite materials, as well as the fact that production processes of the composite material and parts from it are often combined in time. In this case, the elastic properties and strength of the material will be different not only in the thickness of the part, but also at each point. All this leads to a complication of the design process, which is due to the need to determine the elastic properties and strength of the polymer layered composite materials, taking into account the structure of the entire material and each of its layers. This work aims at evaluating the existing computational methods of finding effective characteristics of elastic properties by comparing computation results obtained by various methods with each other, as well as with the experimental results related to elastic properties of polymer layered composite materials from carbon and glass fabrics. We estimated the computational methods of finding effective characteristics of the elastic properties of composites based on the experimental results of finding the characteristics of the elastic properties of polymer layered composite materials made of carbon and glass fabrics, differing in density and type of weaving. The experimental values of the effective characteristics of elastic properties were determined as a result of standard tensile tests of laboratory specimens. As a result of the study, it was found that all the considered models and methods give consistent results when calculating the longitudinal modulus of elasticity E 11, the results of calculating shear modulus E 33 and shear moduli G 12 and G 23 are less consistent for all the considered materials. The comparison of the results of the experimental studies and computations showed that the Chamis model and the bridge model are better than other models to predict the values of the longitudinal elastic modulus.

Processing technique and geometric model of an imperfect orthogonal 3D braided material

2016 ◽  
Vol 47 (3) ◽  
pp. 297-309 ◽  
Author(s):  
Wensuo Ma ◽  
Zhenyu Ma ◽  
Jianxun Zhu
Keyword(s):  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Geometric Model ◽  
Processing Technique ◽  
Experimental Results ◽  
Automatic Process ◽  
Fiber Volume ◽  
Representative Volume ◽  
Volume Unit ◽  
3D Orthogonal Woven

A novel 3D braided material was found based on the traditional 3D orthogonal woven process. The mesostructure of novel 3D braided material is similar to the 3D orthogonal woven material, but only coincide in the Z-direction. The processing technique is easy to operate in automatic process. The representative volume unit has been proposed to establish geometric model. The fiber volume fraction of novel 3D braided material is analyzed and its value is higher than the traditional 3D orthogonal woven material ones. The experimental results show that the braided process of the imperfect orthogonal 3D braided material is rational and feasible.

Property Prediction of Composites with Different Fiber Volume Fractions by Representative Volume Element Method

2013 ◽  
Vol 275-277 ◽  
pp. 1605-1609
Author(s):  
Nan Zhang ◽  
Cheng Hong Duan
Keyword(s):  
Elastic Properties ◽  
Representative Volume Element ◽  
Fiber Volume Fraction ◽  
Empirical Equation ◽  
Volume Fraction ◽  
Volume Element ◽  
Fiber Volume ◽  
Finite Element Software ◽  
Representative Volume ◽  
Properties Of Composites

In this paper, a representative volume element (RVE) model of composites with different fiber volume fraction is established by ANSYS finite element software. The stiffness matrix of the RVE model can be calculated by studying its stress field, and then the elastic properties of composites could be obtained. By comparing with the results from NASA empirical equation, the reliability of the method can be proved. This is a new way to predict the elastic properties of composites.

Experimental investigation of the tensile and bending behavior of multi-axial warp-knitted fabric composites

2016 ◽  
Vol 88 (3) ◽  
pp. 333-344 ◽  
Author(s):  
Xiaoping Gao ◽  
Danxi Li ◽  
Wei Wu ◽  
Si Chen
Keyword(s):  
Volume Fraction ◽  
Orientation Distribution ◽  
Knitted Fabric ◽  
Fiber Volume ◽  
Molding Method ◽  
Fabric Composite ◽  
Fabric Composites ◽  
Static Tensile ◽  
Bending Behavior ◽  
Warp Knitted Fabric

An experimental study was carried out on the tensile and bending behavior of multi-axial warp-knitted fabric composites. Five specimens reinforced with multi-axial warp-knitted fabric/epoxy were manufactured by a vacuum-assisted resin transfer molding method. Quasi-static tensile and three-point bending tests were carried out in a number of orientations relative to the stitching direction: quadriaxial, triaxial, biaxial (±45° and 0/90°) and unidirectional. The results of the tests revealed that the quadriaxial and biaxial (±45°) samples showed quasi-isotropic behavior, whereas the other laminates showed anisotropic behavior. The influence of fiber volume fraction and the orientation distribution of the constituent material on the tensile and bending behavior were also analyzed. The relationships between the stress and strain and the tensile and bending behavior of different multi-axial warp-knitted fabric composite were obtained by polynomial fitting.

Ceramic Fiber - Fluoropolymer Composites for Electronic Packaging Materials

1989 ◽  
Vol 155 ◽  
Author(s):  
John D. Bolt
Keyword(s):  
Fiber Composites ◽  
Short Fiber ◽  
Dielectric Constants ◽  
Woven Fabric ◽  
Ceramic Fiber ◽  
Fiber Volume ◽  
Woven Fabric Composites ◽  
Fabric Composites ◽  
Out Of Plane ◽  
Thermal Conductivities

ABSTRACTAluminum nitride (AIN), alumina and aramid fibers have been incorporated into epoxy and fluoropolymer matrices. The fluoropolymer composites have dielectric constants less than 3.4 and losses below 0.3%, measured out-of-plane. In-plane and out-of-plane thermal conductivities of the AIN-fluoropolymer composites averaged 5.2 and 1.3 W/mK, respectively, at fiber volume fractions of 0.26 to 0.29. In-plane thermal conductivities of woven fabric composites were accurately predicted by mixing rules; for non-woven and short fiber composites, thermal conductivities were less than predicted. These composites had higher out-of-plane thermal conductivities due to out-of-plane components of the fiber orientations.

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