FEA programs simulate the real world but the outputs are only accurate if the input models, material data and operational parameters are accurate as well. In most cases not all the external influences are known and, at best, may only be estimated.

Results from the stress, strain or displacement plots are approximations only and in all safety critical situations it is necessary to subject prototype parts and assemblies to testing.

FEA models for analysis are generally simplified versions of the actual design. Where symmetry is found models are often subdivided and assumptions made regarding the forces applied which may not be reflected in the completed structure.