1. 3-8. While the goal of tuning a model should be to match the test mode shapes, it is typically not feasible to tune each individual mode shape coefficient. Because of this, it is often simpler to examine the cross-orthogonality between the test and analysis mode shapes defined as follows:
2. At SDRC, we have applied design sensitivity methods successfully to a number of different structures. Many examples have been previously published in the literature'4-24. The four examples presented here have not been published previously. The first example is a Telstar satellite built by General Electric AstroSpace. A modal test was performed on this structure, and the results compared to a preliminary MSWNASTRAN FEM of the structure. The model was then upiated using MSWNASTRAN and SDRCKORDS to modify the thickness of various panels and the stiffness of interface springs. The comparison of the initial vs. final (tuned) frequency errors is presented in Table 1.