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Determination of the Limits of QuasiStatic and Dynamic

David Hills (University of Oxford), Matthew Brake (Sandia National Laboratories)

Contact Mechanics

Tue 10:45 - 12:15

Barus-Holley 163

Frictional interfaces are common in many jointed and built-up structures; however, our understanding of the precise phenomena governing these interfaces is somewhat limited. These interfaces, which exhibit complex, nonlinear behaviour, are often sources of energy dissipation, wear, and potential failure mechanisms. Accurate models of frictional interfaces are needed in order to understand the stresses, dynamics, and responses of a system under various loadings. However, due to the nonlinearity introduced by the frictional interface, numerical computation of the response of a system containing these interfaces can be intensive, even when assuming a simplified, Coulomb friction model. Numerous techniques exist that each requires different assumptions for an analysis. One categorical divide in techniques is between quasi-static analyses and dynamic analyses. Quasi-static analyses require that the excitation frequencies be small enough such that wave propagation effects are negligible, but allows for a high fidelity treatment of the localized stress and displacement fields. Dynamic analyses, conversely, necessitate either large, impractical simulations that model the frictional interface in high fidelity, or simplified simulations that regularize the application and effects of friction in exchange for computational efficiency. In what follows, these two phenomenologically different methods are compared in order to ascertain the regimes over which each of these methods is valid. A system composed of two rotational bars aligned end-to-end is considered as an illustrative example, and the effect of coupling between the torsional and axial response is investigated. Understanding of the extent of the inertial dominated and stiffness dominated regimes offers insight into the contribution of wave propagation effects to the system's response at the frictional interface, and determines the limits of application of each type of analysis.