Shell181 element in contact problems? Ansys

[lavecchiasignora]

Hi all I really need your help. Is it completely wrong to analyze a layered composite structure with the shell181 element if I should analyze the results in the contact area? I mean I cant get the stresses in the thickness direction but since I am using Tsai-Wu equation to predict failure that formula only uses 2D, i.e. plane stress assumptions if im only looking at a lamina at one time?

thank you