産業機器を対象とした随伴変数法に基づく材料定数同定法の提案

抄録

There are several problems such as noise and performance degradation in industrial transformers. In transformers, coils and iron core are distorted by magnetostriction and induce vibration. The vibration generates the noise on the boundary surface of them. And the vibration causes deterioration of the performance of the transformers. In order to reduce the noise and avoid the deterioration, we need to estimate the vibration characteristics of transformers at the design phase. The natural frequency analysis using finite element method is an essential process to estimate the vibration characteristics. However, it is very difficult to identify the material constants of the iron core because this material is composed of many thin plates. And although a laminated material made of thin plates can be regarded as a linear anisotropic material, its material constant cannot be theoretically estimated. In this paper, we verified the accuracy of the first derivative calculated based on adjoint variable method. The first derivative of a natural frequency with respect to material constant is derived based on the adjoint variable method. In this method, the first derivatives can be calculated by using the result of a finite element analysis and some additional operations. And we believe that the material constant identification problem can be solved efficiency by using the first derivatives. It is necessary to check the accuracy of the first derivatives when we solve the problem by using the first derivatives. So, we verified the accuracy of the first derivatives by comparing the amount of change in the natural frequency of the target equipment estimated based on first derivatives and the amount of change in the natural frequency of the target equipment calculated by the results of finite element method analysis.