Modal Stress Recovery

Modal stress recovery (MSR) is an analysis-independent alternative to stress recovery analysis. During the modal basis generation phase, the FE code can also pre-compute additional information for lately combining the modal coordinates to the FE stresses in Adams.

Substituting in equation (6) and combining equations (8) and (9) yields:

where:

and:

Here, is the ortho-normalized modal stress matrix that identifies the stress component associated with each orthogonalized mode shape.

Therefore, assuming that the reduction of the full set of mode shapes of the flexible body to a subset is correct and comprehensive of all the required effects, the stress distribution related to the body deformation can be calculated in a similar way to the one used for physical displacements (equation (6)).

If the modal stress matrix has been computed by the FE code and stored in the MNF for the flexible body, it is possible to perform MSR in Adams. It is also possible to perform MSR in the FE code or in the fatigue code, such as MSC.Fatigue, with the modal coordinates from Adams and the modal stress matrix from the FE code's database.

By combining the modal stress matrix with the modal coordinates as in equation (10), it is possible to calculate stress components with very good accuracy and a computational time much shorter than a full dynamic analysis in the FE code.

Likewise, for strains we have:

and

where: