固有振動数データを用いた偏平シェルの境界条件同定  [in Japanese] Identification of Boundary Conditions in Shallow Shells by Using Frequency Data  [in Japanese]

A technique is proposed for identifying both in-plane and out-of-plane boundary conditions of laminated composite, thin shallow shells of rectangular planform. The values of natural frequencies are generally governed by the aspect ratio, curvature ratios and material constants that are measurable relatively easily, but it is very difficult to estimate accurately the boundary conditions that imply the degree of constraints along the edges. Particularly, unlike flat plates, the in-plane and out-of-plane displacements are coupled in the shell, and this increases significantly the number of possible combinations of edge constraints. Thus the identification of shell boundary conditions is an important but complicated problem in the shell design, and in this report the identification technique is introduced by combining an efficient vibration analysis and a simple genetic algorithm (GA). Numerical test showed that this technique is successful in identification of correct boundary conditions.