Beams, plates and shells are used in many applications where there can be subjected to short duration loads due to impacts or pressure blasts. Here the response of such distributed systems is examined using the modal expansion technique for pulse shapes typically observed during impacts and explosions. The objective is to gain an understanding of the behavior of these structures. For beams and plates the natural frequencies are generally well separated and, typically, a small number of modes participate in the response. Pulses can be classified as being either short, long, or intermediate in comparison with the period of the fundamental vibration mode. Very different behaviors are observed for the three types of pulses. For short pulses, the response depends on impulse applied not on the shape of the pulse and it can be accurately predicted by the response to an equivalent impulse. For long pulses, the maximum response depends on the magnitude of the load applied. For shells, the effect of curvature can be significant and result in several modes with close frequencies. In that case the response is more complicated since many modes participate in the response. In this work, the criteria are developed for predicting the response of each mode to a various pulses and determine how many modes participate in the response. The results obtained are applicable with any other analysis method including the finite element method.

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