Lay-up optimisation of fibre metal laminates based on fatigue crack propagation and residual strength

Abstract

A methodology to design and optimise fibre metal laminates for improved fatigue and damage tolerance properties is presented. The lay-ups are defined in a systematic manner where the number and thickness of metal layers are varied and the lay-ups are divided into grades in which the amount and orientation of the fibre plies in the fibre layers are defined. The optimisation procedure is implemented with genetic algorithms and the lay-ups are designed such that the fatigue crack propagation or residual strength criteria is satisfied. The design criteria are evaluated using prediction methods and fitness approximations of these prediction methods. The latter evaluation aims to speed up the optimisation procedure. The functions of the fitness approximation are verified against the prediction methods and the design solutions of both evaluation methods are in compliance with each other. In conclusion, the procedure managed to find the optimal solutions within the design space while an improvement in computation time is achieved with the use of fitness approximation.