On the Modal Surrogacy of Joint Parameter Estimates in Bolted Joints
The Surrogate system hypothesis for jointed mechanics proposes that the influence of a jointed interface on an otherwise linear system is identical irrespective of the structural features of the so-called far-field linear structure. The implication, if the hypothesis finds support, is that the characterization of a joint in a single structural context can be used for developing predictive models of completely different structures, albeit with identical joint configurations. In critical applications such as aerospace, this can potentially lead to a more cost-effective design flow enabling tighter design optimization. In order to evaluate the hypothesis, the major influences on the nonlinear behavior of a jointed structure has to be delineated and studied individually as well as in combinations. Proceeding in the spirit of previous investigations where the effect of far-field structures and joint interface modeling approaches have been tackled, the current investigation studies the so-called “modal surrogacy” of a structural system. The investigation serves to understand the sufficiency of modeling the nonlinear behavior in lower modes to make high-modal nonlinear predictions. The Brake-Reuß Beam (BRB), which is an assembly of two monolithic beams connected together using a bolted lap joint with three bolts, is used as a test specimen for the current investigations. Due to the presence of regions with zero static pre-stress in the interface, considerable separation combined with stick & slip has been numerically as well as experimentally observed. This leads to significant nonlinear effects in the response of the system and thus serves as a convenient benchmark for the current work.
KeywordsJoint mechanics Multi-objective optimization Interface modeling Friction Parameter identification Nonlinear modal response
The authors thank the participants of the Nonlinear Mechanics and Dynamics (NOMAD) Research Institute of 2016 for the experimental data and Robert M. Lacayo for helpful discussions.
Funding: This material is based upon work supported by the National Science Foundation under Grant Number 1744327.
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