ECCOMAS 2024

Finite Element Formulations for Axisymmetric Solids: A New Approach Based on the Petrov-Galerkin Method

  • Zähringer, Felix (Karlsruhe Institute Of Technology)
  • Betsch, Peter (Karlsruhe Institute Of Technology)

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It is evident from numerous studies that the quality of the results of finite element (FE) simulations is highly dependent on the chosen mesh. Especially in the case of highly distorted meshes, large discrepancies between the numerical and the analytical solution can be observed. This also applies to FE formulations for linear elastic axisymmetric solids, which are in the focus of the current contribution. One possible remedy for the problem of mesh sensitivity is the Petrov-Galerkin method. Several FE formulations have already been developed for solids using this method (cf. [1], [2], [3]), which show significantly improved properties in terms of mesh sensitivity. In contrast to the Bubnov-Galerkin method, which is used for most FE formulations, the Petrov-Galerkin method is characterized by the fact that different ansatz spaces are selected for the test and trial functions. More precisely, so-called metric shape functions, which are constructed in the physical space, are used as an ansatz for the trial functions, while Lagrangian shape functions are employed for the approximation of the test functions. In the current contribution, it will be discussed to what extent Petrov-Galerkin-based formulations also represent a useful alternative to the common Bubnov-Galerkin formulations when simulating linear elastic axisymmetric solids. To this end, insights are given into the development of Petrov-Galerkin FE formulations. The two methods are then compared using numerical examples. REFERENCES [1] Rajendran S, Liew KM. A novel unsymmetric 8-node plane element immune to mesh distortion under a quadratic displacement field, Int J Numer Methods Eng. 2003; 58:1713-1748. https://doi.org/10.1002/nme.836 [2] Xie Q, Sze KY, Zhou YX. Modified and Trefftz unsymmetric finite element models, Int J Mech Mater Des. 2016; 12:53-70. https://doi.org/10.1007/s10999-014-9289-3 [3] Pfefferkorn R, Betsch P. Mesh distortion insensitive and locking-free Petrov-Galerkin low-order EAS elements for linear elasticity, Int J Numer Methods Eng. 2021; 122(23):6924-6954. https://doi.org/10.1002/nme.6817