工作機械構造における固有振動数および固有振動数間隔に関する最適化設計

抄録

A new design optimization method was developed for increasing or decreasing the natural frequency at an arbitrary degree of natural mode and maximizing the frequency interval between adjacent natural frequencies, in order to improve dynamic characteristics with respect to forced vibration, noise and feed drive performance of machine tools. This paper describes the theory and principle and the procedure of the new method, and proves its effectiveness by demonstrating computed results on an example machine tool structure model. Design modifications are worked out based on the computed result of the dynamic characteristics of the initial design, followed by further sets of analysis and modification under the constraint of constant total volume of material. The optimization is performed in two steps. First, the evaluation of the energy distributions through the complete structure at the objective natural frequency provides design modifications continuing until roughly optimum design points are obtained and reduction of design parameters taking part in the optimization are determined. Secondly, a mathematical direct search method (simplex method) identifies the true optimum design point. This process of optimization which combines the evaluation of energy distributions and the direct search method effectively and practically determines the optimum design solution.