Investigation of Modal Iwan Models for Structures with Bolted Joints

Application of Viscous and Iwan Modal Damping Models to Experimental Measurements From Bolted Structures

“…Future works will further explore the validity of the modal model, by using inputs at other locations and other types of inputs. To date, experimental and analytical results have suggested that this approach can be very successful, except perhaps at very high force levels when serious macro slips occur [6].…”

“…However, damping is often a relatively weak effect and experiments have often shown that the modes of structures with joints are typically quite linear and uncoupled. This suggests that one might be able to model the structure as a collection of uncoupled linear modes, each with nonlinear damping characteristics [6], and this is precisely the approach adopted in this work.…”

“…The energy dissipation for each mode of a system can be computed from measurements of its free response. The procedure for processing measurements was presented in [6] and will be reviewed briefly below.…”

“…The parameters, {F S , K T , K ∞ , χ, β}, of the modal Iwan model can be found using a graphical approach as described in [6]. First, the experimental energy dissipated per cycle, D Exp , and stiffness, K Exp , are obtained using a Hilbert transform as described in [11].…”

“…On the other hand, when a small number of modes are active in a response, recent measurements have suggested that a simpler model may be adequate. Segalman et al recently applied the 4-Parameter Iwan model in a modal framework to describe both discrete joint simulations and experimental data from structures with bolted joints [5,6].…”