An assessment of two fundamental flat triangular shell elements with drilling rotations

An approach for adding drilling rotations to the constant strain triangle, such that the added rotation stiffness contributes a minimum to the strain energy of the triangle is presented. The element is combined with a bending triangle to produce a flat shell element having six-degrees-of-freedom per node. Allman’s triangle with true drilling rotations is also combined with the same bending element. These two facet shell elements are examined for their capacity to accurately simulate inextensional bending of general thin shells. A novel eigenvalue procedure and specially designed inextensional bending patch tests for thin shells are applied. Selected practical thin shell problems are also solved.