A REFINED SEMI-ANALYTIC DESIGN SENSITIVITIES BASED ON MODE DECOMPOSITION AND NEUMANN SERIES IN REDUCED SYSTEM

축소모델에서 강체모드 분리와 급수전개를 통한 준해석적 민감도 계산 방법

In sensitivity analysis, semi-analytical method(SAM) reveals severe inaccuracy problem when relatively large rigid body motions are identified for individual elements. Recently such errors of SAM resulted by the finite difference scheme have been improved by the separation of rigid body mode. But the eigenvalue should be obtained first before the sensitivity analysis is performed and it takes much time in the case that large system is considered. In the present study, by constructing a reduced one from the original system, iterative method combined with mode decomposition technique is proposed to compute reliable semi-analytical design sensitivities. The sensitivity analysis is performed by the eigenvector acquired from the reduced system. The error of SAM caused by difference scheme is alleviated by Von Neumann series approximation.