Cooperative application of holography and finite element modeling in determining critical vibration behavior of printed wiring boards

A PWB (printed wiring board) with dimensions of 6.5"/spl times/5.5" and attached with several bolts along the perimeter as constraints was acoustically vibrated and studied using CAH (computer-aided holometry). The frequency and shape of the first (primary) and second resonant modes, revealing the full field displacements and strains of the PWBs, were recorded automatically. Zero-displacement regions were also recorded for possible locations of strategic components. Finite element (FE) modeling using eigenvalue calculations was applied to correlate with the CAH results. Adjusting the boundary conditions in the modeling effort so as to match the experimental results proved to be the tricky task in the FE analysis since the mode shapes were extremely sensitive to boundary constraints.<
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