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A statistical model validation process was used to determine predictive confidence bounds for mass and natural frequency predictions applied to 1) stamped crossmember and 2) truck frame finite element models. For the crossmember, modal performance measure sensitivity to variation parameters was determined using a designed experiment based on a set of 121 finite element model analyses and field tests of 7 hardware samples, A similar experiment based on a set of 8 finite element model analyses and field tests of 8 hardware samples of the truck frame was conducted. Statistical measures were used to compare and test distributions of computer model and field outputs with the intent of computing confidence bounds for the selected performance statistics.

FASTAR is an interactive graphics post processor to MSC NASTRAN created to do modal animation, structural modifications, frequency response and sensitivity analysis using either analytical results obtained from solutions 63, 67 or 71 of MSC NASTRAN or modal data obtained from experimental measurements. In addition, complex modes may be computed in FASTAR using the modal viscous damping matrix from solution 71 of NASTRAN and a state space formulation. Further viscous damping modifications may be made to the structure with the possibility of creating critically damped modes. For each complex mode, FASTAR identifies the amount of damping present. Correlation of analytical and experimental modal data may be made visually using a split screen display. In addition, a modal assurance criterion (i. e. MAC) may be computed for each pair of analytical and experimental modes by finding nodal coordinate matches and ignoring rotational degrees of freedom.