EVOLUTIONARY NATURAL FREQUENCY OPTIMIZATION OF THIN-PLATE BENDING VIBRATION PROBLEMS

This paper extends the evolutionary structural optimization method to the solution for maximizing the natural frequencies of bending vibrati on thin plates. Two kinds of constraint conditions are considered in t he evolutionary structural optimization method. If the weight of a tar get structure is set as a constraint condition during the natural freq uency optimization, the optimal structural topology can be found by re moving the most ineffectively used material gradually from the initial design domain of a structure until the weight requirement is met for the target structure. However, if the specific value of a particular n atural frequency is set as a constraint condition for a target structu re, the optimal structural topology can be found by using a design cha rt. This design chart describes the evolutionary process of the struct ure and can be generated by the information associated with removing t he most inefficiently used material gradually from the initial design domain of a structure until the minimum weight is met for maintaining the integrity of a structure. The main advantage in using the evolutio nary structural optimization method lies in the fact that it is simple in concept and easy to be included into existing finite element codes . Through applying the extended evolutionary structural optimization m ethod to the solution for the natural frequency optimization of a thin plate bending vibration problem, it has been demonstrated that the ex tended evolutionary structural optimization method is very useful in d ealing with structural topology optimization problems.