DISPLACEMENT-DEPENDENT DRY FRICTION DAMPING OF A BEAM-LIKE STRUCTURE

The flexural vibration of a beam-like structure damped with a displace ment dependent Coulomb friction force has been examined. Due to the ge ometry of the dry friction damping element, the friction force grows l inearly with the beam's transverse displacement. Harmonic excitation o f the system is analyzed using first order harmonic balance and then u sing an ''exact'' time domain method. The stick-slip behavior of the s ystem has also been studied. Even though the only source of damping is dry friction, the system was seen to exhibit damping characteristics similar to linear structural damping. The equivalent natural frequency and equivalent viscous damping were also investigated, and found to d epend on the amplitude of response and on the design parameters of the frictional interface. In particular, the overall damping levels as we ll as the amount of stick-slip motion are seen to depend strongly on t he amount of displacement dependence. Another significant result was t he appearance of two stable steady-state solutions at certain paramete r values. The results suggest that the overall characteristics of mech anical systems may be improved by properly configuring frictional inte rfaces to allow normal forces to vary with displacement. (C) 1996 Acad emic Press Limited