A correct reproduction of thickness effect can be accurately described by the use of three-dimensional solid elements.In addition to convenient formulation for constitutive law,solid element provides a straightforward extension to geometrically non-linear problems,particularly in the presence of large rotations,since only translational degrees of freedom are involved.Also,compared with shell elements,it is valid to consider double-sided contact because of real physical nodes on top and bottom surfaces without any further modification.However,for low order elements,as thickness/length ratio value tends to zero,the transverse shear-locking phenomenon becomes more evident.Also,plasticity leads to isochoric deformation,which is the main source of the volumetric locking phenomenon.Concerning bending dominant problems,it is difficult to use a single layer of solid elements due to the limitation of integration points along thickness direction.Multi-layered solid element increases the CPU time dramatically.In order to overcome these drawbacks,a new single layer solid-shell element is developed based on a one-point quadrature scheme,but allowing multiple integration points along thickness.A physical stabilization scheme,based on convective coordinate system,is used to control hourglass modes efficiently.To avoid thickness and volumetric locking behaviors,the formulation applies Simo and Rifai's Enhanced Assumed Strain method [3].The background theory for this element and numerical simulations for validation purposes are presented.Assessments show that the present formulation is efficient for linear and nonlinear shell applications.
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