In ANSYS Workbench, particularly with the ACP (Ansys Composite PrepPost) module, the approach to defining the material and structural properties of shell elements is different from the method in ANSYS APDL. While APDL allows you to directly define the ABD matrix through the SECTYPE command, Workbench focuses on composite layups and material definition through the ACP module, which doesn't directly expose the SECTYPE command or its equivalent functionality.

Here are your options in ANSYS Workbench:

1. Using ACP for Composite Layups

• In ACP, you define the composite structure using ply-by-ply specifications. Each ply has a material assigned, and its thickness, orientation, and stacking sequence contribute to the overall behavior of the shell.
• ACP automatically calculates the ABD matrix based on the laminate properties you define. While you can't directly input the ABD matrix, you can achieve the same effect by carefully defining the material properties, thickness, and orientation of the layers.

2. Importing APDL Commands

• If you need the exact control offered by the SECTYPE command in APDL, you can integrate custom APDL commands within Workbench using the "Command Snippet" tool. This allows you to execute APDL code (e.g., defining the SECTYPE and ABD matrix) alongside your Workbench analysis.
• Workflow:Set up your geometry, meshing, and boundary conditions in Workbench. Insert a Command Snippet in the appropriate location of your analysis tree. Use the APDL commands (e.g., SECTYPE, SECDATA) to define the ABD matrix for your shell elements.

3. Using APDL for Full Control

• If you require complete control over the ABD matrix and other advanced features, you may consider exporting your model from Workbench to APDL, where you can define the material using SECTYPE as you mentioned.

Recommendations:

• If your design relies heavily on precise ABD matrix control and ACP doesn’t meet your needs, combining ACP for geometry and APDL for detailed material modeling might be the best option.
• For cases where ACP suffices, focus on properly defining material properties and ply orientations, as the ABD matrix will naturally reflect those inputs.

I am not working on this field specifically; however, based on my knowledge of stress analysis in both APDL and WB, what I am sure about is that the Ansys WB has all the tools and solution possibilities that the APDAL has. So, just keep working on it, and you'll find the solution for your case.

Good luck.