STRUCTURE DYNAMIC MODEL REDUCTION TECHNIQUE BASED ON LOCAL INTERPOLATION

Based on complex structural finite element model, a new reduction method of structural dynamic model using local interpolation is proposed in this paper. The displacement of a node in the finite element model is obtained through interpolation of the displacements of the condensation nodes it attaches to. Every entry of the dynamic condensation matrix is formed by interpolation functions. To improve accuracy of the reduction method, the shape function of the non-conforming element is adopted as the interpolation function to lower the reduced structural stiffness after condensation, and the eigenvalues and eigenvectors are ameliorated through inverse iteration on the finite element model. To enhance efficiency of the reduced method, regular grids which just encompass the structure are employed to generate the condensation points. Due to the regularity of the grids, we can easily determine the condensation points to which a node in the finite element model attaches. Finally, mode analyses of three machine tool components demonstrate the effectiveness and the feasibility of the reduction method proposed in this article.