Numerical investigation of a crash test of a composite helicopter subfloorstructure

Composite energy-absorbing aircraft structures are being studied within a E uropean Commission research programme (CRA-SURV - Design for Crash Survivab ility). One of the aims of the project is to evaluate the current capabilit ies of crashwortkiness simulation codes for modelling future composite prim ary structures. In this paper, a detailed analysis is presented of a generi c module of a composite helicopter subfloor structure, subjected to crash l oading. The analysis is performed with the explicit finite element code PAM -CRASH and is compared with the results of a drop test. It has been found t hat pre-test simulations with only coupon data as input are capable of prov iding a reasonable overall representation, but to closely match the behavio ur df the test, a significant amount of post-test work is required. The cal ibration of the post-failure material properties proved to be more crucial than the behaviour up to initial failure. The representation of fabric mate rials was found to be inadequate and a new fabric material model is under d evelopment as a result. The importance of modelling frictional effects was highlighted, and a mesh density study showed the model to be robust over a range of mesh densities. (C) 2001 Elsevier Science Ltd. All rights reserved .