Theoretical modeling and parallel programming of a nonlinear composite finite shell element based on a mixed global-local variational principle

In this thesis, a contribution is made to the theoretical and numerical modeling of thin-walled structures made of fiber-reinforced composites. The global-local finite shell element presented further develops a nonlinear finite shell element emanating from a mixed variational principle. A local field equation is introduced, by which the local displacements and the interlaminar stresses are derived. The global-local finite shell element has five or six global degrees of freedom, three displacements and two or three rotational parameters, since all other fields are eliminated by numeric procedures on an element level. Additionally, an alternative possibility to derive the interlaminar shear stresses is proposed, which can be applied in shell and plate elements. The addition of the local part of the model leads to a significant increase in computation time, due to the unknowns introduced on an element level. For this reason, the finite element software used in the implementation of the finite shell element is adapted to modern computer architectures with multiple cores and shared memory by parallelizing the implemented code.