Effect of fibre transverse isotropy on micro-residual stresses in polymeric composites

Abstract

In this paper, the influence of transversely isotropic behaviour of the fibre on micro-residual stress fields is investigated. For this purpose, the energy method is utilized to predict the micro-structural stresses in polymer matrix composites under uniform thermal loads. The representative volume element (RVE) considered here includes a transversely isotropic fibre embedded in an isotropic polymer matrix. Based on the energy method, a three-dimensional closed-form solution for micro-residual stresses is obtained. The analytical results are evaluated with a finite element solution. The analysis shows that the transversely isotropic behaviour of the fibre greatly increases the fibre and matrix axial residual stresses in comparison with the isotropic fibre assumption. Fibre anisotropy has a significant effect on the interfacial shear stress distribution, in contrast with the interfacial radial stress field. Both the finite element solution and analytical method result in a similar behaviour for micro-residual stresses distribution along the fibre length. However, the finite element method cannot satisfy the stress-free condition for the residual shear stress at the fibre end due to the stress singularity.

Numerical analysis of cracked aluminum plate repaired with multi-scale reinforcement composite patches

“…D ranges from 0 to 1, when D has the value of 1, the debonding has wholly happened. Stress components at the contact area are affected by the damage and define as follow: (19) As indicated in the equation (19), when D is 1 the stress components becomes zero, which means debonding entirely happens. Figure 26.…”

“…In this study, CNT as reinforcement for nanocomposites, carbon fiber as reinforcement for composite materials, and epoxy as the matrix are considered. CNT 18 is supposed as elastic isotropic material, and high modulus carbon fiber 19 is supposed as transitively isotropic material. For modeling of the epoxy, 20 an elastic-plastic model is employed.…”

Residual Stress in Engineering Materials: A Review

“…Based on the CLT, an analytical framework to predict residual stresses in terms of temperature changes and thermal cycling conditions was developed in the study by Ghasemi et al [134] The accuracy of predicting the curing residual stress relies on a proper constitutive model containing various influential factors, namely, "thermal expansion," "cure chemical shrinkage," "layers architecture," and "material degradation or relaxing during curing." In addition to the CLT, residual stresses in polymer composites can be analytically determined via different micromechanical methods, namely, "elasticity solution," [135] "cylinder theory," [136] "Elshelby theory," [137] "energy method," [138] "the cure hardening instantaneous linear elastic (CHILE) model," [139] and "viscoelastic model." [140] Given the 2D nature of the elasticity theory, the out-of-plane stress components and the material anisotropy and fiber length are not considered in this method.…”

“…The accuracy of predicting the curing residual stress relies on a proper constitutive model containing various influential factors, namely, “thermal expansion,” “cure chemical shrinkage,” “layers architecture,” and “material degradation or relaxing during curing.” In addition to the CLT, residual stresses in polymer composites can be analytically determined via different micromechanical methods, namely, “elasticity solution,” [ 135 ] “cylinder theory,” [ 136 ] “Elshelby theory,” [ 137 ] “energy method,” [ 138 ] “the cure hardening instantaneous linear elastic (CHILE) model,” [ 139 ] and “viscoelastic model.” [ 140 ] Given the 2D nature of the elasticity theory, the out‐of‐plane stress components and the material anisotropy and fiber length are not considered in this method. The cylinder theory fits the plane‐strain conditions, meaning that this solution cannot be used for fibers of finite length.…”