Buckling failure analysis of PMMA spherical pressure hull

This paper focused on the influence of imperfections and thickness-to-radius(t/R) ratios on critical load of PMMA spherical pressure hull by using theoretical and numerical methods. The failure modes and critical loads of pressure hull were studied based on thick-shell strength theory and buckling theory. Results confirmed that the failure mode of spherical pressure hull is related to t/R ratios. In the numerical analysis, linear and nonlinear methods were used to study the influence of imperfections and t/R ratios on strength and stability of spherical pressure structures. Taking modal imperfection as initial geometric imperfection, structural strength was a function of initial geometric imperfection when t/R ratios was fixed. For spherical pressure hulls with initial imperfections, buckling analysis revealed that the strength of spherical hulls with same initial geometric imperfections decreased almost linearly with the increase of t/R ratios. In addition, for all spherical shells, when defect amplitude reached more than 0.35 times of shell thickness, critical load reduced to minimum, and then did not decrease anymore.