A progressive damage model for simulating lightning strike on composite material

This work presents a progressive damage model incorporating strain and heating rate effects for the analysis of composite specimen damage resulting from artificial lightning strike test. A failure model has been developed for use in COTS FE software, within user material subroutines (ABAQUS/Explicit, VUMAT). The approach utilises scaling factors and thermal degradation behaviour from published works to modify the key material properties to reflect the effects of combined strain and thermal loading. Hashin and Puck failure criteria are also applied to predict the initiation of damage prior to strain softening of the material. The approach is benchmarked in its component parts against appropriate literature before being used to provide predictions for the damage within a lightning strike analysis framework. The framework includes an initial plasma model of the artificial lightning strike which predicts specimen surface loads (electrical, thermal, pressure); a coupled thermal-electric model which predicts specimen temperature resulting from the applied electrical load due to resistive heating; a third, dynamic, coupled temperature-displacement, explicit model which predicts the material state due to the thermal load, the resulting thermal-expansion and due to the lightning plasma applied pressure loading. Within the third model the new material subroutine is used to predict intralaminar damage, along with cohesive surfaces and the mixed-mode relationship proposed by Benzegagh and Kenane to predict interlaminar damage. The failure model and the complete analysis approach is demonstrated for the first time for an unprotected composite specimen exposed to lightning test Waveform B.