Shell versus Solid Modelling Across FEA Solvers
When to use shell versus solid elements across Abaqus, ANSYS and Nastran — and the practical trade-offs for thin-walled and thick structures.
Engineering Task
Deciding whether to model a structure with shell or solid elements across different FEA solvers.
Decision Criteria
| Criterion | Shell | Solid |
|---|---|---|
| Thickness / span ratio | < 1/10 | > 1/10 |
| Through-thickness stress | Not captured | Captured |
| Bending accuracy | Excellent (S4R) | Needs 3+ elements through thickness (C3D8R) |
| Efficiency | High — 1 element through thickness | Low — many elements through thickness |
| Geometry preparation | Midsurface extraction needed | Direct from CAD |
| Interlaminar stress | Not available | Available |
Solver-Specific Notes
- Abaqus: S4R for general shells, S8R for curved; C3D8R for solids with reduced integration
- ANSYS: SHELL181 for thin shells; SOLID186 for second-order solids
- Nastran: CQUAD4 with PSHELL for shells; CHEXA with PSOLID for solids
- All solvers: shells require midsurface geometry and thickness assignment; solids use the CAD directly