  We consider two cantilevered beams undergoing frictional impacts at the free
end. The beams are designed to be of similar geometry so that they have
distinct but close natural frequencies. Under harmonic base excitation near the
primary resonance with the higher-frequency fundamental bending mode, the
system shows a strongly modulated non-periodic response. The purpose of this
work is to analyze to what extent the non-periodic vibro-impact dynamics can be
predicted. To this end, we use a recently developed modeling and simulation
approach. The approach relies on component mode synthesis, the massless
boundary concept and an appropriate time stepping scheme. Unilateral contact
and dry friction are modeled as set-valued laws and imposed locally within the
spatially resolved contact area. A linear model updating is carried out based
on the natural frequencies and damping ratios identified in the regime without
impacts. The nonlinear simulation of the steady-state response to forward and
backward stepped sine excitation is compared against measurements. The results
are in very good agreement, especially in the light of the uncertainty
associated with the observed material loss in the contact region and the
nonlinear behavior of the clamping.
