Finite Element Model/Test Correlation

ASD’s unique approach and additional upfront work in the pretest analysis phase has significantly reduced the effort required in the finite element model correlation phase. ASD’s correlation effort involves a significant amount of visual mode shape comparisons between test and analysis. ASD’s correlation effort involves only physically realizable/justifiable changes to the finite element model. ASD does not utilize correlation practices involving automated model updating “optimization” algorithms or changing structural material properties to correlate finite element models to test.

Finite element model to test correlation is demonstrated with comparisons of mode shapes, frequencies, and effective modal mass. This correlation is further demonstrated mathematically via cross-orthogonality and modal assurance criteria.

On multiple occasions, ASD has been brought in by the client when prior attempts by other contractors to correlate the structural model to test were unsuccessful, resulting in NASA specifying uncertainty factor which significantly reduced the load carrying capability of the subject structure. Each time, ASD correlated the structural models to NASA’s specifications which eliminated the uncertainty factors all together.