Dynamic behavior of bolted assemblies

This thesis investigates the dynamic behavior of bolted assemblies with a focus on nonlinear friction phenomena. The aim is to deepen the understanding of how key parameters such as the number of bolts, tightening torque and tightening sequence influence the system’s natural frequencies, stiffness and damping. A series of experiments were conducted on a test system, where each beam was subjected to both impact hammer tests and controlled swept sine and stepped sine excitations. The vibrational responses were recorded using accelerometers and processed in MATLAB to extract frequency response functions (FRFs) and amplitude-dependent damping ratios. The results show that damping varies with excitation amplitude and bolt torque, distinct frequency shifts occur at microslip thresholds within the contact interface and that the tightening sequence has a limited influence on the system’s response in the presence of machined contact surfaces. These findings contribute to the development of predictive tools for simulating bolted structures by improving the representation of contact phenomena in the interface.