A review of micromechanics based models for effective elastic properties of reinforced polymer matrix composites

Thermal conductivity and tortuosity of porous composites considering percolation of porous network: From spherical to polyhedral pores

Evaluation of the effect of PyC coating thickness on the mechanical properties of T700 carbon fiber tows

Short fiber reinforced composites have a variety of micro-structural parameters that affect their macro-mechanical performance. A modeling methodology, capable of accommodating a broad range of these parameters, is desirable. This paper describes a micro-mechanical model which is developed using Finite Element Analysis and Orientation Averaging. The model is applicable to short fiber reinforced composites with a wide variety of micro-structural parameters such as arbitrary fiber volume fractions, fiber aspect ratios and fiber orientation distributions. In addition to the Voigt and Reuss assumptions, an interaction model is developed based on the self-consistent assumption. Comparisons with experimental results, and direct numerical simulations of Representative Volume Elements show the capability of the model for fair predictions.

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A finite element based orientation averaging method for predicting elastic properties of short fiber reinforced composites

Air voids produced in the manufacturing process have significant influence on the mechanical performances of single fiber bundle in carbon fiber-reinforced composites. The microscale finite element model of fiber bundle with voids is developed to predict mechanical properties and failure mechanisms. The failure responses of fiber and matrix in bundle are initiated by the maximum stress and Stassi failure criteria. The sudden stiffness degradation law is adopted to capture brittle behaviors. Both available theoretical models for voids and non-voids are used to validate the numerical model without voids and with different percentages of voids including 0.15, 0.5, 1, 2, 3, 4 and 5%. Effects of void contents on stress–strain responses of bundle are studied. The matrix damage development is studied regarding transverse compression and out-of-plane shear loading. The micro-stress analysis of matrix and voids in three-RUC model under different loadings is performed. The simulated elasticity and strength properties correlate well with theoretical results for voids and non-voids. The strengths and moduli gradually decrease with increasing void contents except longitudinal properties. The stress concentrations of bundle are mainly influenced by the loading direction.

Microscale finite element analysis for predicting effects of air voids on mechanical properties of single fiber bundle in composites

Numerical study of the effects of irregular pores on transverse mechanical properties of unidirectional composites

Numerical simulation with progressive damage criterion is implemented to investigate the effect of porosity on the bending properties of 2D cross-ply carbon/carbon (C/C) composites. The mechanical properties of Pyrocarbon matrix regarding the change of porosity are calculated by using Mori-Tanaka approach. Combining with the stiffness degradation scheme, the ultimate bending strengths are calculated in Abaqus though a user-defined subroutine (USDFLD). Delamination is modelled by inserting cohesive elements between two adjacent plies. A good agreement is obtained when the FEM results are compared to three-point bending experiments. The FEM results show that the bending strength decreases greatly with the increase of porosity. When the porosity reaches up to 18%, the bending strength is decreased by 57%. The major fracture behaviors are interlamination delamination and continuous crack damage in 90° plies. With the increase of porosity, more severe interlamination delamination will be slightly aggravated. In addition, the increase of porosity will also accelerate the damage in 90° plies.

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Wenjing Ma

Papers

Numerical study of the effects of irregular pores on transverse mechanical properties of unidirectional composites

Numerical evaluation of the influence of porosity on bending properties of 2D carbon/carbon composites