A Study of Failure Strength for Fiber-Reinforced Composite Laminates with Consideration of Interface

Junjie Ye,Yumin He,Yuanying Qiu,Zhi Zhai,Xuefeng Chen

doi:10.1155/2015/158578

Abstract

Composite laminates can exhibit the nonlinear properties due to the fiber/matrix interface debonding and matrix plastic deformation. In this paper, by incorporating the interface stress-displacement relations between fibers and matrix, as well as the viscoplastic constitutive model for describing plastic behaviors of matrix materials, a micromechanical model is used to investigate the failure strength of the composites with imperfect interface bonding. Meanwhile, the classic laminate theory, which provides the relation between micro- and macroscale responses for composite laminates, is employed. Theory results show good consistency with the experimental data under unidirectional tensile conditions at both 23°C and 650°C. On this basis, the interface debonding influences on the failure strength of the [0/90]sand [0/±45/90]scomposite laminates are studied. The numerical results show that all of the unidirectional (UD) laminates with imperfect interface bonding provide a sharp decrease in failure strength in theσxx-σyyplane at 23°C. However, the decreasing is restricted in some specific region. In addition, for [0/90]sand [0/±45/90]scomposite laminates, the debonding interface influences on the failure envelope can be ignored when the working temperature is increased to 650°C.

Highlights

For improving material properties and satisfying special functional requirements, composites become one of the most important materials nowadays and are widely used in aerospace, energy sources, and so forth [1,2,3,4]
The results indicated that the high-fidelity generalized method of cells (HFGMC) shows a higher accuracy than the generalized method of cells (GMC) for perfecting the transverse response of composites with imperfect interface bonding
While the Timetal 21S matrix, which is described by a generalized viscoplasticity with potential structure (GVIPS), is considered to be elastoplastic material, the relationship between the inelastic strain rate εiİj and the deviatoric stress components sij in the GVIPS can be written as follows [23]: εiİj

Summary

Introduction

For improving material properties and satisfying special functional requirements, composites become one of the most important materials nowadays and are widely used in aerospace, energy sources, and so forth [1,2,3,4]. For the continuous fiber-reinforced composites, the subcell displacement field function ũi(β,γ) with higher order components in the HFGMC, as well as the subcell average stress variations Si(jβ(γm)n), can be written as follows [19, 20]: ũi(β,γ) = εijxj + Wi((β00,γ)) + y2(β)Wi((β10,γ)) + y3(γ)Wi((β01,γ)). According to [19], with consideration of the interfacial bonding influences on continuous fiber-reinforced composites, the stress relation between the neighboring subcells along with 2 directions can be written as ui(βγ) (y2(β) hβ 2. Where the parameters Rj(βi γ) and σjIi(βγ) indicate the interface displacement debonding coefficients and the interface stress components between fiber and matrix, respectively. The nonlinear stress-strain behaviors of composites with imperfect interface bonding can be acquired through implementing subcell average stress components into (1). From (10), it can be found the thermal residual stress components in the RVE can be acquired once the macroscopic average strain components are confirmed

Unidirectional Tensile Response of Composite Laminates

Failure Envelope Investigation of Composite Laminates

A 400 600 800

Findings

Conclusions