An assumed natural strain technique for 2D solid-shell elements

With the combination of the enhanced assumed strain (EAS) and assumed natural strain (ANS) techniques in the removal of shear and volumetric locking, the solid-shell formulation requires a minimum set of enhanced modes, and this results in a competitive approach when compared with other fully EAS solid elements in terms of computational costs. Moreover, the latter reportedly suffers difficulties when dealing with very thin plate and shell structures due to the severe transverse shear locking. The paper presents an alternative solid-shell formulation, in which the ANS technique is applied to the upper and lower surfaces instead of at the mid-surface of the solid-shell element as
previously adopted. The numerical results show the accuracy and efficiency of the proposed technique.