Numerical investigation of a crash test of a composite helicopter subfloor structure

Composite energy-absorbing aircraft structures are being studied within a European Commission research programme (CRA-SURV - Design for Crash Survivability). One of the aims of the project is to evaluate the current capabilities of crashwortkiness simulation codes for modelling future composite primary structures. In this paper, a detailed analysis is presented of a generic module of a composite helicopter subfloor structure, subjected to crash loading. 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 that pre-test simulations with only coupon data as input are capable of providing a reasonable overall representation, but to closely match the behaviour df the test, a significant amount of post-test work is required. The calibration of the post-failure material properties proved to be more crucial than the behaviour up to initial failure. The representation of fabric materials was found to be inadequate and a new fabric material model is under development 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.