300. Optimum Design for Transient Loading

Paper

Abstract

This paper was presented at the Twenty-first National Conference of the Society of Aeronautical Weight Engineers at Seattle, Washington, May 14 – 17, 1962. This paper discusses a procedure for synthesis of flexible mechanical systems, or structures, is developed, where the total systems weight is to be minimized. The types of flexible systems treated are those with discrete flexible members, and which may be approximated by linear, single-degree-of-freedom-systems. The mass of the flexible members is included in the response calculations by constructing an equivalent, single-mass system. The procedure then followed is to express the response, e.g., displacement, of the equivalent system in terms of the mass of the flexible members; this requires the use of stiffness-mass relationships. The response is then minimized with respect to the mass of the flexible members whose optimum mass distribution results. This is done for systems with a given concentrated mass supported by an arbitrary number of series-connected flexible members. Relationships are developed for systems with two flexible members; design curves are presented for two types of loading, pure impulse and the rectangular step pulse. Examples show the reductions in peak displacement response of up to 25% can be obtained. The method as presented can be used to furnish a minimum weight system when the desired peak response is specified.