Optimization of Damping in Self-Excited Mechanical Systems

Self-excited vibrations, such as squealing of disc brakes or galloping of overhead transmission lines, are often accompanied by undesired phenomena. In a linearized description, stability of such systems strongly depends on the structure of the damping matrix.
In this context, the present thesis addresses two major objectives. First, a deeper understanding is promoted regarding the influence of velocity proportional forces on the stability of linear mechanical systems featuring circulatory and gyroscopic terms. Analytical investigations deliver detailed insights into the required structure of the damping matrix either for stabilization or the avoidance of destabilization. Second, stability is assessed by means of quantitative measures. On this basis, a technique for stability optimization is established. The method relies on decomposing the damping matrix into component matrices which are associated with distinct physical origins. Suitable variation of these submatrices yields a reduced tendency of self-excitation. Serving as representative examples, various models of disc brakes and overhead transmission lines are studied numerically at different levels of complexity.