The Shifted Boundary Method for Nonlinear Elasticity and Thermo-elasticity
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Embedded/immersed/unfitted boundary methods obviate the need for body-fitted meshing or continual re-meshing in many applications involving rapid response, rapid prototyping and design. Unfortunately, many finite element embedded boundary methods are also difficult to implement due to: (a) the need to perform complex cell cutting operations at boundaries, (b) the necessity of specialized quadrature formulas, and (c) the consequences that these operations may have on the overall conditioning/stability of the ensuing algebraic problems. We present a new, stable, and simple embedded boundary method, named “Shifted Boundary Method” (SBM), which eliminates the need to perform cell cutting. Boundary conditions are imposed on a surrogate discrete boundary, which encircles a surrogate computational domain constituted of only full elements (no cuts). We then construct appropriate field extension operators by way of Taylor expansions, with the purpose of preserving accuracy when imposing the boundary conditions. We demonstrate the SBM on large-scale linear and nonlinear solid mechanics problems, including thermo-mechanical effects [1,2]. References: [1] K. Li, J.G. Michopoulos, A. Iliopoulos, J.C. Steuben, G. Scovazzi. Complex-geometry simulations of transient thermoelasticity with the Shifted Boundary Method. Computer Methods in Applied Mechanics and Engineering, 418: 116461, 2024. [2] N.M. Atallah, C. Canuto, G. Scovazzi. The shifted boundary method for solid mechanics. nternational Journal for Numerical Methods in Engineering, 122(20): 5935--5970, 2021.