TY - GEN A1 - Stammen, Lisa T1 - A two-field isogeometric formulation with different continuities T2 - Virtual International Conference on Isogeometric Analysis / Solids and structures, 26.-29. Sept. 2021, Lyon (France) N2 - Isogeometric Analysis (IGA), which was founded by Hughes et al. [1], tries to unify Computer-aided design (CAD) and finite element analysis (FEA) by using the same model for geometry representation and analysis. Therefore, in contrast to common finite element analysis, non-uniform rational B-splines (NURBS) and other kinds of splines are used as shape functions instead of the usual polynomials. Due to the exact representation of the geometry, analysis results can be improved [1, 2]. For mixed formulations, stresses and/or strains or pressures are approximated independently and in addition to the usual displacement approximation. Using, this kind of method is more robust and offers more accurate results. Hence, such formulations can be employed to solve incompressible elasticity problems, for instance [3]. Recent investigations, e.g. [4], have already combined isogeometric analysis and mixed formulations in order to benefit from the advantages of both methods. In this contribution, a mixed isogeometric method is proposed in order to improve the analysis results and counteract different locking phenomena. Therefore, spline basis functions are used and the displacement shape functions of a two-dimensional isogeometric plane stress and plane strain element are supplemented by independent stress shape functions. These additional stress shape functions are chosen to be of one order lower compared to the displacement shape functions, but with adapted continuity. Evaluating the errors of the calculated displacements and stresses for a plane stress and an incompressible elasticity plane strain problem, it is shown that the proposed method can lead to an improved accuracy of results compared to a standard isogeometric formulation. Furthermore, the influence of different continuities on the convergence behavior and the accuracy of the results is investigated. Y1 - 2021 UR - https://iga2021.sciencesconf.org/program/graphic/date/2021-09-27 ER -