Dynamic Response of Structures and Materials to Impulsive Loads

This report is divided into three main subjects, e. g., beam response to impulsive loads of fuel-air explosions (FAE), effect of fuel-air explosions in confined unpressurized containers, and the effect of intense impulsive loads from surface blasts on material removal and degradation of a concrete semi-half space. Investigation into the response of small ductile beam elements subjected to blast loadings indicates a need for analysis of beams including gross deformation, axial constraints, and complete failure. The response of small beams to fuel-air explosions fall in a transition between a static mechanism and a traveling plastic hinge mechanism. Equations of motion, based on a strength of material approach, are derived for both mechanisms. The same general shock transmission and reflection of detonation waves are found to be operative in both confined and unconfined fuel-air explosions. The ratio of the reflected pressure to the static pressure of a detonation wave is dependent only on the ratio of specific heats and reaches a maximum of 2.6 for a specific heat ratio of infinity. Computational models are available and have been used with some success for prediction of cratering, material removal and material degradation for certain rock media and could be used for concrete; however, development of constitutive models for concrete is still in the fundamental stage. More fundamental research, especially experimental and theoretical work on material characterization, is needed before a reasonable damage estimation of concrete subjected to intense impulsive loads can be obtained.