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{{DISPLAYTITLE:Review of Efforts Using Whole Joint Models for Frictional Interfaces in Structures by Matt Allen, June 2026}}
==Review of Efforts Using Whole Joint Models for Frictional Interfaces in Structures==

Matthew S. Allen

Professor, Brigham Young University

June 16, 2026

===Abstract:===

It is extremely expensive to model frictional contact in detail in full order finite element models, as each timestep requires an iterative solution where contact and friction are addressed over surfaces that may be defined by thousands of nodes. As a result, reduced order modeling techniques have been developed that significantly decrease the time needed to predict the response of a system. Multi-Point Constraints (MPCs) are frequently used to reduce contacts to single pairs of nodes, between which friction or contact elements can more easily be incorporated. With the number of interface nodes reduced, Hurty/Craig-Bampton reduction can be used to significantly lower the computational expense required. However, few works have investigated how spidering affects the accuracy of the model, as compared to a high-fidelity truth model. This presentation first summarizes work to date in which this approach has been used to model bolted and riveted structures, and how the results have compared to measurements. Then, a purely computational case study is presented which allows one to probe the contact mechanics in detail to evaluate the effectiveness of this approach. Several types of MPCs are applied to a benchmark model comprised of two cantilever beams with a frictional joint connecting their free ends. A two-dimensional model is used so that the quasi-static response of a high-fidelity truth model can be computed and compared to that of the reduced models. The linearized modes of the reduced model are compared to those of the truth model, to see which spidering approaches produce the best accuracy. The models are then compared in terms of their ability to capture the amplitude-dependent natural frequency and damping of the fundamental mode of the assembly.  The model is then used to predict the nonlinear response of modes that were not used in the process of model development to understand the accuracy of the model as a whole. 

 
===Biography:===

Prof. Matt Allen joined the faculty of the Mechanical Engineering Department at BYU in 2021. Prior to that, he taught for 15 years in the department of Engineering Physics at the University of Wisconsin-Madison.  He received a B.S. in Mechanical Engineering from BYU, M. S. and PhD degrees from the Georgia Tech in 2005 and was a post-doc at Sandia National Laboratories.  He enjoys playing sheep’s head (Bavarian card game) during breaks at IMAC, practicing his Spanish, trying new kinds of ice cream and skiing, hiking, biking or almost anything to do with mountains. His current interests include: nonlinear dynamic systems, experimental/analytical substructuring techniques, damping and nonlinearity due to bolted interfaces, system identification, biomechanical systems, ... or in other words just about anything related to structural dynamics! 

==Video Presentation ==
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[[Category:Seminar_Series]]