EXPERIMENTAL AND NUMERICAL FREE VIBRATION ANALYSIS OF BOLTED CONNECTIONS WITH RESPECT TO MECHANICAL CLEARANCES

摘要

In service, wear at the contact of the bolted joint can change significantly the resonance condition of the whole mechanical system in relation to the operating regime defined in the design process. For three different magnitudes of clearances in the bolted joint, the experimental examination of the resonance frequencies of the pinned-clamped beam specimen is carried through the detailed analysis of the hammer test results. For clearances above 5μm at the bolted joint, the measured frequencies cannot be predicated analytically or numerically by using the known manners. Applying the finite element (FE) results from the performed non-linear static contact analyses of the bolted joint, effective normal and tangential contact stiffness are determined. Then, a dynamic FE model of the bolted joint is worked out. For this FE model, the numerical lowest eigenfrequencies of the specimen are computed in very good agreements with the experimental results for all considered clearances. By applying the proposed FE static and dynamic procedures for the bolted joint, the resonance sensitivity of the mechanical system with pinned connections can be predicated numerically with respect to the wear process on the contact.