Modelling single and double-lap repairs on composite materials

The present work is dedicated to the study of single and double-lap repairs on composite materials, using the ABAQUS (R) software and special developed interface finite elements including a cohesive mixed-mode damage model based on the indirect use of Fracture Mechanics. The objectives of this work are to evaluate the stress distributions and the residual strength under tensile loading of a repaired composite plate. It was verified that the main parameters concerning the good performance of the repair are the specimen geometry, stacking sequence and patch thickness. The numerical model allowed the simulation of damage initiation and growth. Different kinds of failure modes of these joints were observed. The influence of the properties of the layers and of the adherend/adhesive, as well as adhesive/patch interfaces in the damage modes was also evaluated. One of the main findings is related to the important influence that the strengths of the adhesives have on the failure mode, whilst adhesive and interface fracture toughness present a little influence on this phenomenon. Some conclusions were drawn about design guidelines of composite repairs. (c) 2005 Elsevier Ltd. All rights reserved.