Identification method on stiffness weak part of cantilever structure on machine tool based on flexibility matrix

Abstract

Identifying the weak link of structural stiffness is one of the important issues in improving machine tool stiffness. Aiming at the cantilever structure in machine tool, this paper proposes a new weak index to identify the weak link of stiffness. The weak index is based on the modal parameters obtained by vibration test method. In this method, the weak parameter matrix is obtained by multiplying the difference between the reciprocal of the flexibility matrix of the overall structure and the stiffness matrix of the overall structure. The diagonal elements of the weak parameter matrix are extracted to obtain the weak index. And the change of weak index is adopted to identify the weak link of structural stiffness. The method of element stiffness reduction is used to simulate the weak link of stiffness, so as to verify the proposed method. Finite element simulation is used to verify different noises and single and multiple stiffness weak links. The method is verified by numerical examples of cantilever beam and elastic support beam structure. It has higher recognition accuracy under noise interference, which is more advantageous than the flexibility difference method. Finally, an experimental study on the elastic supported cantilever beam structure and the tailstock of machine tool are carried out to verify the effectiveness of the method.

Keywords

cantilever structure of machine tool weak link of structural stiffness flexibility matrix modal analysis finite element simulations

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