A pragmatic orthotropic elasticity-based damage model with spatially distributed properties applied to short glass-fibre reinforced polymers

Petter Henrik Holmström,Arild Holm Clausen,Torodd Berstad,David Morin,Odd Sture Hopperstad

doi:10.1016/j.ijsolstr.2021.111142

Abstract

This article presents a simple progressive damage model for quasi-brittle materials, combining orthotropic elasticity with a scalar damage model including spatial variation of the damage initiation strain and the crack band method for softening regularization. The model’s performance is first analyzed from a numerical point of view and then demonstrated for tensile tests (0°, 45° and 90°), open-hole tensile tests (0°) and three-point bending (0° and 90°) tests of short fibre-reinforced polypropylene with 15 wt.% and 30 wt.% glass fibres. Despite its simplicity, the model captures the anisotropic elastic and inelastic behaviour observed in experiments. The model is applicable for orthotropic brittle or quasi-brittle materials, where the variability in elastic properties is negligible and the orientation dependency of the fracture strain is small or not relevant for the application.

Highlights

Development of phenomenological models for progressive failure of anisotropic materials has been an active area of research for several decades
Applications are found in e.g. the automotive, aeronautical, aerospace and wind energy industry and include brittle and quasi-brittle materials, such as polymer matrix composites (PMCs), metal matrix composites (MMCs), ceramic matrix composites (CMCs) and concrete
For the 90 simulations of polypropylene with 15 wt.% E-glass fibres (PP15), the model is able to predict the correct maximum stress level, but not the increased ductility observed in the 90 tests compared to 0 tests

Summary

Introduction

Development of phenomenological models for progressive failure of anisotropic materials has been an active area of research for several decades. Applications are found in e.g. the automotive, aeronautical, aerospace and wind energy industry and include brittle and quasi-brittle materials, such as polymer matrix composites (PMCs), metal matrix composites (MMCs), ceramic matrix composites (CMCs) and concrete. It is of great importance that the industry has access to computationally efficient, robust and sufficiently accurate material models with parameters which are easy to identify from standard tests. Progressive failure models for quasi-brittle materials are often formulated within the framework of continuum damage mechanics (CDM) and may combine isotropic, transverse isotropic or orthotropic elasticity with a failure initiation criterion and a damage evolution rule. Some frequently applied criteria for describing the onset of material degradation are the maximum stress, maximum strain, Tsai and Wu (1971), Hashin (1980), Puck and

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