A co-rotational triangular finite element for large deformation analysis of smooth, folded and multi-shells

A six-node co-rotational curved triangular shell finite element with a novel rotation treatment for folded and multi-shell structures is presented. Different from other formulations, rotations are not represented by axial (pseudo) vectors, but components of polar (proper) which additivity commutativity lead to symmetry the tangent stiffness matrices in both local global coordinate systems. In system, two smallest director defined as nodal rotational variables. Similarly, each system adopted variables nodes located either on smooth shells or away non-smooth intersections. At intersections multi-shells, three selected an orthogonal triad initially oriented along axes. As such, vectorial enable simple additive update all incremental-iterative procedure, resulting significant enhancement computational efficiency large deformation analysis. To alleviate membrane shear locking phenomena, assumed strain method employed obtaining internal force vector. The effectiveness presented formulation verified analyzing several benchmark problems smooth, undergoing displacements rotations.