Publications

Effects of experimental methods on the measurements of a nonlinear structure

Catalfamo, S.; Smith, Scott A.; Morlock, F.; Brake, M.R.W.; Reuß, P.; Schwingshackl, C.W.; Zhu, W.D.

This paper continues the investigation from a paper presented at IMAC XXXIII that looked into the influence of various experimental setups on the nonlinear measurements of structures with mechanical joints. The previous study reported how the system stiffness and damping was affected by the force input method, boundary conditions and measurement techniques. However, during the stepped sine excitation experiments the parameters for the control schemes were neglected. In this paper, different control strategies, namely force and acceleration control, are used to observe how the parameters affect the measurements at different levels of excitation. The experiments are conducted on bolted beams containing a lap joint with different boundary conditions. The beams are excited by a shaker using a stepped sine signal using narrow bandwidths around three of the natural frequencies. The results show that acceleration amplitude control can produce cleaner transfer functions compared to the force amplitude control method.