Stress on Bottom or Top Face of Each Ply
Displacement and strain fields are continuous through thickness for a composite. However, stress fields in general are discontinuous due to different material properties and orientations across plies. For example, under pure bending typical variation of longitudinal strain and longitudinal stress through thickness are shown. There is a jump in the stress at the interface between two different plies.
You can plot the stress for each ply separately at top and bottom faces.
Maximum Stress Across All Plies
You can plot the maximum stress values of the specified component (envelope plot) across all plies. For each node the maximum stress across all plies (including top and bottom face) is plotted.
Stress Along Material Directions
You can plot stress for each ply along the ply orientation direction or transverse direction (on surface) for each ply.
Interlaminar Shear Stress
Apart from stress components available for non-composite models, you can plot the interlaminar shear stress in the junction between two different plies. Interlaminar shear stresses arise due to elastic property and ply angle mismatch across different plies in composites. High interlaminar shear stresses lead to delamination (cracking in interface between adjacent plies) in composites. Delamination ultimately limits the life of a composite "laminate".
Interlaminar shear stresses are plotted in local coordinate system. To understand the local coordinate system for each face of shell, see ply angle.