Abstract
In this research, in order to solve the cause of the impeller for large-sized fan by which the crack entered during actual operation at the joint part of the main board and Blade, vibration and stress analysis using the finite element method were performed. The analysis result showed that the cause of a crack of impeller is for concentration stress to occur in the joint part of the main board and Blade owing to the wave phenomenon of the side board by centrifugal force. Then, the structure optimization by pseudo-inverse method was performed for the purpose of stress reduction. When the design variables were made into the board thickness of an element, design restrictions condition was made into the stress which generates a crack part and repetition calculation was performed, stress was able to be reduced to the target value by calculation of four calculations.
