Evaluation of Forced and Self-Excited Vibrations at the Design Stage of Machine-Tool Structures

Abstract

This paper proposes a method for evaluating forced and self-excited vibrations at the design stage of machine-tool structural systems. Cross modal flexibilities between the forced excited and the displacement pick-up points are analyzed. The relationships between the highest allowable values of receptance and vibrational displacement, and the static compliance and modal flexibility are clarified. Then the algorithms of the evaluative methods which use those analyses are given. Using the proposed method, natural modes which must be disregarded in the evaluation of the characteristics can be determined, (1) even when directional orientations of the excited force at points in regard change greatly as a result of states of operations or cannot be definitely determined, and (2) even if damping properties are not clearly known. Designers can judge whether or not a given structural design has vibrational defects. The procedures of the evaluative method are exemplified with numerical examples.