Numerical prediction of the low-velocity impact damage and compression after impact strength of composite laminates

Wei Tan,Louis N S Chiu,Mark Price,Brian G Falzon

doi:10.1088/1757-899x/74/1/012015

Abstract

Low-velocity impact damage can drastically reduce the residual mechanical properties of the composite structure even when there is barely visible impact damage. The ability to computationally predict the extent of damage and compression after impact (CAI) strength of a composite structure can potentially lead to the exploration of a larger design space without incurring significant development time and cost penalties. A three-dimensional damage model, to predict both low-velocity impact damage and compression after impact CAI strength of composite laminates, has been developed and implemented as a user material subroutine in the commercial finite element package, ABAQUS/Explicit. The virtual tests were executed in two steps, one to capture the impact damage and the other to predict the CAI strength. The observed intra-laminar damage features, delamination damage area as well as residual strength are discussed. It is shown that the predicted results for impact damage and CAI strength correlated well with experimental testing.

Highlights

Composite materials are increasingly used in the aerospace and automotive industries due to their high specific stiffness and strength, the susceptibility to damage from low-velocity impact event is one of the major design concerns
When subjected to impact loading, the composite structure can be degraded through various failure mechanisms including matrix cracking, fibre breakage and delamination
A limited number of studies on predicting the compression after impact (CAI) strength of damaged composite structures are available in the literature

Summary

Introduction

Composite materials are increasingly used in the aerospace and automotive industries due to their high specific stiffness and strength, the susceptibility to damage from low-velocity impact event (i.e. falling tools, runway debris etc.) is one of the major design concerns. When subjected to impact loading, the composite structure can be degraded through various failure mechanisms including matrix cracking, fibre breakage and delamination. Impact damage can dramatically reduce the residual mechanical properties of the structure even with barely visible impact damage. It is essential to develop a reliable tool for the prediction of the impact damage process and evaluation of corresponding residual strength. A limited number of studies on predicting the CAI strength of damaged composite structures are available in the literature. Uda et al [1] investigated failure mechanisms of impact-damaged UT500/Epoxy and AS4/PEEK CFRP laminates subjected to compression fatigue. A model where both virtual tests (impact and CAI) are performed on composite sandwiches can be found in Davies et al [4]. González et al [5] proposed a 3D FE model with inter-laminar and intra-laminar damage using a rigorous thermodynamic framework for drop-weight

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