Study of the Effect of Shape Processing of a Specimen on the Modal Properties

Abstract

When the dynamic design of a structure is carried out by using finite element method, the dynamic characteristics of the member of the structure have to be identified in advance. Especially, the damping property of the actual complex shaped member is sometimes assumed to be the same as the one of a simple shaped member with the same material. The damping properties often become a function of the frequency, so it is not certain whether we can apply the dynamic characteristics of the simple shaped member to the complex shaped one or not. In this study, a beam specimen made of steel is adopted, and the modal properties of both uniform shaped specimen and L-shaped one are identified; then the influence of the shape processing is investigated on the damping property. As a result, it is recognized that the damping property is high in the low-frequency band and low constant in the high-frequency band. Furthermore, the damping property of the L-shaped specimen is higher in the low-frequency band than the case of uniform specimen, while it is almost the same in the higher-frequency band.