Issue 5 https://popups.uliege.be/2684-6500/index.php?id=349 Issues fr Wed, 19 Aug 2026 14:38:23 +0200 Wed, 19 Aug 2026 14:39:16 +0200 https://popups.uliege.be/2684-6500/index.php?id=349 0 Local Models to Identify the Nonlinear Behavior of a Bolted Joint. https://popups.uliege.be/2684-6500/index.php?id=350 Previous studies have shown that one can create an efficient model for bolted structures by spidering the interface to a pair of nodes, and then connecting them with a nonlinear Iwan element. However, no method has been developed for predicting the parameters of the Iwan element from first principles; in all studies to date, experimental vibration measurements have been acquired and optimization has been used to solve for the Iwan parameters that best reproduce the measurements. This work investigates an alternative strategy that uses a local finite element model in which the bolt and surrounding area are modeled in detail with contact, Coulomb friction and the applied preload. A series of static loads are then applied to this local model and the resulting nonlinear force-displacement behavior is extracted and used to identify either a linear spring or an Iwan element that captures the predicted behavior. The identified springs and Iwan elements are then inserted into a reduced-order model of the structure, and the effective, amplitude-dependent natural frequency and damping of several modes of the structure can be computed, or dynamic transient analysis performed. This work evaluates the proposed modeling strategy using two-dimensional models of cantilever beams containing one and three bolts. In each case, the frequency and damping behavior of the reduced order models, whose Iwan elements were identified using the proposed procedure, are compared those of a truth model. The results show that, while each bolt in a structure can be loaded quite differently, the proposed procedure provides a reasonable approximation to the damping behavior of a joint, predicting the average nonlinear damping in the system within a factor of 1.5-3. Wed, 19 Aug 2026 14:46:39 +0200 https://popups.uliege.be/2684-6500/index.php?id=350