有限要素法のボルト結合モデルにおける経験的パラメータのベイズ最適化を用いた推定

抄録

At liftoff, launch vehicles are subject to harmful acoustic loads due to the intense acoustic waves generated by propulsion systems. Dominant acoustic modes inside payload fairings are payload fairings correlated with ring mode of structure. Experimental and numerical modal analyses were conducted for a simplified fairing model to obtain the ring modes appeared from 10 kHz to 20 kHz. Although axisymmetric ring modes were obtained by the numerical modal analysis using Finite Element Method (FEM), asymmetric ring modes were obtained in the experiment. The deformation of ring modes were considered to be caused by bolt connections in the simplified fairing model, so, Bayesian optimization was applied to Finite Element Method analysis to estimate inhomogeneity of the bolt connections. Preliminary numerical experiment was conducted to study the application of Bayesian optimization in Finite Element Method for estimating bolt connections, then, this method was applied to the simplified fairing model. Asymmetric bolt connection was obtained in Bayesian optimization in Finite Element Method, and the ring mode shape obtained by the Finite Element Method showed reasonable agreement with the experimental result. The comparison confirmed the usefulness of this method.