Virtual testing activities for the development of a hybrid thermoplastic composite material for the NHYTE project

Abstract

Designing composite structures with a good level of confidence and accuracy requires access to allowables values. The allowables generation is extremely time and cost consuming. In fact, various layups, experimental tests and environmental conditions have to be taken into account for each material to be characterized. Moreover, each test configuration needs many repetitions to obtain a statistical evaluation of the mechanical property. A robust alternative to reduce the experimental time and costs is the use of virtual allowables calculated and predicted thanks to advanced multiscale simulations. This paper deals with the activities of virtual testing carried out in the European NHYTE Project for the development and characterization of a hybrid thermoplastic composite material for the aerospace sector. The main aim has been to reduce tests and risk associated with the use of the hybrid composite in aerospace structures. This can be achieved by lowering the probability of failure of primary structures through the use of A-basis or B-basis strength allowables as design values. For this purpose, coupons of the hybrid thermoplastic composite have been accurately analysed using virtual tests. Starting from a micromechanics approach and taking into account the different constituents (PEEK matrix, PEI films and fibre reinforcement), a material model has been implemented; then it has been propagated to different scales until the element level. For virtual testing to be useful in the certification process, this numerical model has been validated by a synergic approach, correlating the simulation results with the experimental data carried out by Applus+ Laboratory. At the end, it has been possible to demonstrate that the resulting models are an excellent tool to speed up the certification process for complex structures, as required in the Aeronautical industry.