The dynamics of assembled structures excited by friction

This thesis reports on numerical and experimental techniques which allow for the assessment and reduction of friction-induced limit cycle oscillations in assembled systems by employment of mechanical joints and contact interfaces. The focus is thereby on automotive friction brakes. Experimental forced vibration studies from a friction brake assembly are presented to quantify the impact of mechanical joints on the global damping level in a friction brake and to study amplitude dependency introduced by joints. In addition, a minimal model is employed to highlight how joints and contact interfaces affect the branching behaviour of periodic solutions. Having completed pre-studies, a concept is introduced which allows for ranking of mechanical joints according to their impact on vibration amplitude. This approach is then applied to operational as well as forced vibration deflection shapes of an automotive friction brake. Afterwards, the most active and, consequently, the most relevant joints are studied and experimentally characterized. Using a finite-element friction brake model a case study is conducted to reveal the influence of joints on limit cycle oscillations. The studies include a comparison of limit cycle oscillation reduction in terms of Young's modulus variation of the brake disc and joint manipulation. After having manipulated surface topography and integrity in joints, different specimens are tested at a brake dynamometer concerning performance in terms of noise, vibration, harshness, i. e. number of noise events as well as average and maximum sound pressure level. To allow for correlation of noise, vibration, harshness performance and surface properties, height maps and Abbott-Firestone curves of the surfaces are provided.