Effect of Various Parameters on the Effective Properties of a Cracked Ply

Abstract

Damage in composite materials accumulates in a diffuse manner. Accounting for this damage in a progressive failure analysis requires an accurate measure of the degraded stiffness coefficients. This paper describes micromechanics models for predicting the effect of distributed cracks on the engineering properties (extensional moduli, shear moduli, and Poisson's ratios). Quasi-3D and 3D finite element methods were employed to determine the effective material properties of the cracked ply. Analyses were performed for various material systems, damage states, and adjacent (to the cracked ply) ply properties. The results show that the effective properties of cracked ply are very sensitive to the initial properties of a cracked ply. These properties are also found to be sensitive to the adjacent ply properties and orientation. However, they are not much affected by cracks in the adjacent plies. Relationships describing the sensitivity of the effective properties to the adjacent ply properties and the initial properties of a cracked ply were obtained. These relationships are useful for explaining the degradation behavior of laminates. Quantitative measures are presented for the errors introduced when shear-extension-coupling terms are ignored when calculating effective properties. Also, it was proven that transverse matrix cracks only affect the diagonal terms in the effective compliance matrix for certain configurations.

Prediction of Delamination Growth and Opening Near Intersection of Transverse Matrix Cracks and Delamination

“…where Á h i denotes volume averaging and u i , @u i =@x , and d , are the displacements, the volume-averaged displacement gradients, and the vector of periodicity, respectively [6,7]. By exploiting the symmetries and antisymmetries, the boundary condition for a portion of the RVE can be obtained.…”

Numerical simulation of matrix micro-cracking in short fiber reinforced polymer composites: Initiation and propagation

“…Detailed discussion on the periodic boundary conditions can be found in Ref. [64,65]. The constraints are imposed in ABAQUS by multi-point constraints (MPC).…”

Effect of Delaminations on Opening of Transverse Matrix Cracks

“…Due to the assumptions, all cross sections of the laminate parallel to the x 2 x 3 -plane deform the same (that is, there is no dependence on the x 1 -coordinate, except for the u 1 displacement). Therefore, one could perform a quasi-3D finite element analysis, which uses a 2D mesh, instead of a full 3D finite element analysis [11]. Herein, a full 3D model with a single layer of elements was used.…”