A Mixed Co-rotational Curved Triangular Shell Element

An advanced 6-node co-rotational curved triangular shell element is presented in this paper. In the element, each node has five degrees of freedom, of which there are two rotational degrees of freedom. The conversion between the local node variables and overall node variables becomes very simple, with reasonably defining vectorial rotational variables. Compared with the traditional rotation variables, this increment of vectorial rotation can be directly superimposed, so it's very convenient for the computation. the proposed element based on advanced co-rotational method and adopted vectorial rotational variables, which can exclude the rigid-body part from the displacement of the nodes,has a great advantage for large displacement and large rotation analysis.In order to overcome widespread locking phenomenon in shell calculation, mixed formulation is introduced in the paper, in which part of conforming shear strains and membrane strains are replaced by corresponding assumed strains in Hellinger-Reissner functional. The local tangent stiffness matrix result from this method repalce the original tangent stiffness matrix, to eliminate the impact of locking phenomenak, and achieve the purpose of improving the precision modules. Lastly, nine classical flat plate and curved shell problems are solved to test the reliability, computational efficiency and accuracy of the proposed element foumulation, comparing the results of the relevant literatures.