Extensions of an Optimization Technique to Frequency Band and Thermal System Design Problems.

摘要

In this report, extensions of techniques of structural and mechanical system optimization are considered. Specifically, tow problems are considered: (1) structural optimization with constraints on bands of admissible frequencies, and (2) design of thermal systems. In the first problem, the frequency constraints are imposed in such a way that the natural frequencies of the structure do not lie within any prohibited band. This is a very practical problem, and a properly imposed frequency band constraint can avoid catastrophic failure of the system. Sensitivity Analysis for the frequency constraints is developed in the report. The proposed method is applied to a 25 member space truss. In the second problem, optimal design of thermal insulation of a tube is is considered. The problem is first formulated as a finite dimensional nonlinear programming problem and later it is treated as a continuous optimal design problem. The Nusselt number for forced convection at the inner wall is assumed constant to represent the mechanism of heat convection, and an empirical formula for free convection at outer surface is used. The ambient temperature and the inner radius of the tube are assumed to be constant. (Author)