A review of explicit finite element software for composite impact analysis

As explicit finite element (FE) codes improve and advanced material models become available, such tools will find more widespread application within the aerospace industry, as `what-if simulations become more manageable with increasing computing power and greater modeling realism. This paper describes the investigation of three commercial explicit FE analysis packages, LS-Dyna, MSC.Dytran, and Pam-Shock, to determine their capabilities in predicting barely visible impact damage (BVID) in composite structures. The investigation is conducted by first determining the suitability of the codes in constructing an FE model of a stiffened panel, solving for BVID and retrieving results. The results are in turn compared to experimental data in order to gauge the suitability of the codes for composite design and analysis. Comparisons of the FE simulations to experimental data include damage development and degradation, as well as the time-history responses. The Chang-Chang failure theory with brittle degradation was used for both LS-Dyna and MSC.Dytran, while the biphase model was used for Pam-Shock. Results indicated that the general shape of the force-time curves as well as the peak forces were predicted reasonably well. However, all simulations predicted a trough that was much less significant than the test results, as well as a shorter impact duration.