Naoki Asano

A Personal Computer Aided Finite Element Method of Inverse Analysis for Searching and Identification of Unknown Boundary Condition.

This paper presents an inverse analysis method for the searching and the identification of unknown boundary condition in a finite element method (FEM) on a small memory capacity machine such as a personal computer. This method is formulated by extending an influence function method. Following two calculation processes are adopted in the method: (1) an alternative calculation process which searches the unknown condition and obtains a relative nodal load distribution, and (2) a calculation process which determines a nodal load ratio of the distribution in (1). Both the distribution and the ratio are obtained through a same stiffness matrix in the FEM equation. Then, the paper also describes an efficient calculation method in the determination of both the distribution and the ratio using the answer of the extention of the influence one. Therefore, the extention of the influence one makes it possible to execute the efficient calculation of the inverse analysis for the identification of unknown boundary condition. Finally, the validity of the inverse analysis method is comfirmed from the numerical solution of a three-dimensional inverse finite element model, as an example of an elastic structure with reinforced members under tension, carried out on a small memory capacity machine.

A Personal Computer Aided Finite Element Method for Identification of Unknown Boundary Condition in Elastoplastic State.

This paper presents an inverse analysis method for the identification of unknown boundary condition in elastoplastic state, using a finite element method (FEM) on a small memory capacity machine such as a microcomputer and a personal computer. This inverse analysis method is composed of following two calculation processes: an identification process which obtains a solution in elastic state, and a direct analysis in elastoplastic state based on the identified results from. For efficient identification, uses a penalty function method and an attack technique based on both accelerative moving lower and upper bounds. A zooming identification method is available for improvement of the identification accuracy. adopts a triple-tandem-type substructuring method as an efficient calculation method. Therefore, we establish an efficient inverse analysis method for the identification of unknown boundary condition in elastoplastic state. Finally, the validity of the inverse analysis method is confirmed from the numerical solution of a three-dimensional finite element model, as an example of V-shaped grooved structure with reinforced members under tension, executed on a small machine.

A hybrid type of virtual work principle for elastic impact contact problems.

衝撃接触のハイブリッド型仮想仕事の原理(H原理)では,2物体の接触面上の付帯条件を緩和するために,種々なラグランジュ未定常数(L乗数)が必要になる.本論文では加速度の付帯条件を緩和するL乗数の拡張を提案し,物理的意味を考慮した.その結果,変位と加速度の条件は同じL乗数で緩和できる.種々な接触,分離の状態に適用できるH原理を構成し,その妥当性を2個の縦衝突弾性棒の二次元FEM解析によって確かめた.