Hello everyone,

I have developed a Python program based on Classical Laminate Theory (CLT) that calculates the local and global stress-strain values for each ply angle of a composite laminate at three specific positions: top, middle, and bottom of the ply. The program outputs stress values such as σ₁, σ₂, and τ₁₂ (local axes) for these points.

To validate my code, I modeled the same laminate structure in ABAQUS using a 3D deformable shell section. In the simulation, ABAQUS provides stress outputs S11, S22, and S12 at different integration points for each ply. These results also correspond to the top, middle, and bottom of each ply, but instead of a single value, ABAQUS gives a range of stress values across the surface (due to the finite element mesh).

Here is my confusion:

• In CLT, the stress at a point (e.g., top of the first ply) is a single value, while ABAQUS provides multiple values at that same layer’s top due to the mesh and integration points.
• I want to know how to meaningfully compare these results to verify the accuracy of my CLT-based code.
• Should I take an average of the ABAQUS values at each ply position, or compare the peak value, or use nodal vs. element integration points?
• I am using shell section assignment with composite layup, and the mesh is sufficiently refined.

Has anyone dealt with similar validation between analytical CLT and FEM results in ABAQUS? What is the best practice to ensure a fair and meaningful comparison?

Any insights or references would be greatly appreciated.