Large deformation, damage evolution and failure of ductile structures to pulse-pressure loading

In this paper, a model is developed for an elastic perfectly-plastic structural beam system subjected to general pulse-pressure loadings - this may be either impulsive or non-impulsive - which is capable of capturing large non-linear deformation, ductile damage evolution and its consequential failure. The proposed model is an extension of Schleyer and Hsu (2000) by incorporating interactions between bending, membrane stretch and transverse shear in the fully plastic stress state, and uses damage mechanics to capture the loss of integrity at the supports and the subsequent beam detachment. Predictions by the model were validated against existing experimental data from literature and to three-dimensional finite element models developed in this paper. Parametric studies were performed to elucidate the effects of loading duration on the mode of deformation by the beam and the critical conditions governing their transition. The efficacy of Youngdahl's (1970; 1971) technique on desensitising pulse shape effects is also investigated using different pressure pulse profiles and it will be shown that the technique is successful only for monotonically decaying pulse-pressures.