Non-FEA Composite Panel Pressure Only Loading

[garyjh]

Currently comparing three analysis methods using the same CFC material and a QI lay-up. The 3 metrhods are Hypersizer as a non-FEA stand alone panel, ESDU 93011 and MSC PATRAN/NASTRAN, with pressure loading only. The panel is simply supported i.e. fixed in translation but not rotation. Panel a/b ratio 2.5:1, 2:1, 1.5:1 & 1:1. The ESDU 93011 & NASTRAN (using non-linear SOL106) methods max panel deflection match exactly but the Hypersizer does not, by a long way.

I have read the "HyperSizer_Analysis_Loading_-_Panel_Pressure.HME" and it looks like it gives good correlation with NASTRAN for edge moments. The ESDU method is based on the elastic, non-linear, large deflection, moderate rotation and orthotropic thin plate theory presented in BASU, A.K. CHAPMAN, J.C. "Large deflection behaviour of transversely loaded rectangular orthotropic plates", Proceedings of the Institution of Civil Engineers, Vol. 35, pp. 79-110, 1966.

Are the Hypersizer method based on linear, small deflection theory? Why such a big difference when same panel sizez, boundary contraints, A & D matrices the same, same pressure, etc.?

[August]

Based on the fact that your laminate is QI, and the max a/b ratio is 2.5, HyperSizer is using the Rayleigh-Ritz method to analyze the plate with applied pressure. This method assumes a linear response with displacements that are small compared to the thickness. If your applied pressure is high and deflections are large, then this solution will start to deviate from a non-linear FEA solution since SOL 106 accommodates large displacements.

The deflection that HS calculates should be accurate up to the point where failure occurs. Does your applied pressure take that into account? Try reducing the applied pressure and see if it improves the match.

Also, I would suggest comparing the moments in the plate because these are what the failure criteria calculations will be based on. From our point of view, it is more important to get these correct than deflections.

-August