The [(±45/0)_2]_s graphite–epoxy laminate described in Example Problem 12.1 is again subjected to type S4 simple supports along all four edges and a uniform transverse load q(x,y) = 30 kPa. However, the plate is now also subjected to uniform in-plane stress resultants N_{xx} = N_{yy}. Use a Ritz analysis to determine the maximum out-of-plane displacement for 0 < N_{xx} = N_{yy} < 100 kN/m.
Question 12.2: The [(±45/0)2]s graphite–epoxy laminate described in Example...
As was the case for Example Problem 12.1, solutions for this problem can be obtained using program SYMM (described in Section 12.6). Multiple solutions were obtained using the specified range in N_{xx} and N_{yy}, and 100 terms were used in the displacement field in all cases.
Results are summarized in Figure 12.5. The maximum displacement occurs at the center of the plate (i.e., at x = 150 mm, y = 75 mm). As would be expected, the in-plane tensile stress resultants tend to reduce out- ofplane displacement. For N_{xx} = N_{yy} = 0 a maximum out-of-plane displacement of 8.03 mm is predicted. In contrast, if tensile stress resultants N_{xx} = N_{yy} = 100 kN/m are applied the maximum out-of-plane displacement is reduced to 0.71 mm.
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