Abstract
Dynamic analysis of equipment attached to shock excited vehicles is greatly simplified by spectral analysis. Using the modal shock design values to provide estimates of the maximum values of critical stresses in a base driven structure is a standard procedure used by the Navy for heavy equipment. This paper presents new results for design analysis that uses shock design values for those cases where the points of attachment between the equipment and the vehicle move differently from each other. This problem is commonly labeled the multi-foundation problem. The paper adopts the modal analysis approach and links the design rules of shock design analysis to bounding solutions derived from modal analysis. The design rule proposed for the multiple foundation case in this study requires the availability of the design shock values at different points of attachment between equipment and foundation. The method is easily programmable and can accommodate various equipment foundation models. A series of numerical experiments were conducted to establish a bench mark evaluation for the newly developed design rule. Comparison between the current standard procedures and the new design rule showed that the new rule estimates critical stresses that are closer to their true maximum values thus presenting an improvement over the current standard procedures.
