Residual Strength Prediction by Numerical Analyses of CFRP Plates Repaired with Flush Scarf Bonded Patch

The widespread use of CFRP laminates in many industrial fields and especially in the aerospace industry, introduces a large number of issues regarding the repair procedures to be adopted due to various kinds of damages. This work aims at providing a numerical FE modelling procedure in order to obtain, for composite laminates repaired by flush scarf bonded patch, accurate results in terms of prediction of the residual strength with the lowest computational cost. The numerical analyses have been developed by using the commercial finite element code ANSYS®. Data from literature, numerical and also experimental, have been used in order to validate the proposed methodology. The stress distribution within the adhesive film and the final residual strength of repaired laminates, loaded in tension, has been used as reference parameters for comparison purpose. Progressive Failure Analysis (PFA) has been performed on composite laminates comparing different mesh modelling approaches and different elastic-plastic material models for the adhesive. As far as the mesh modelling approach is concerned, solid layered and not layered finite elements have been investigated, while in order to simulate the mechanical behaviour of the adhesive, two different material models have been compared: BISO (Bilinear ISOtropic hardening) and ANISO (ANISOtropic plasticity). The results of the numerical analyses performed on the above laminates, provide useful information regarding the advantages and disadvantages of both modelling methods and of both material models of the adhesive, in terms of accuracy and computational costs.