An effective planar triangular element with drilling rotation
A modified Allmans triangular planar element with drilling degree of freedom is formulated. The basic formulation is similar to the original Allmans element, but a constraint is introduced which ensures that the drilling degree of freedom is a true rotation in elasticity. The new element keeps all the advantages of Allmans element, but has no spurious energy mode. It also shows that the drilling parameter of the present element can correctly carry over the twist moment to the other kinds of element at nodes. A few examples are given for illustration.
finite element drilling freedom triangle membrane shell