Effect of a local axisymmetric imperfection on the buckling behaviorof a circular cylindrical shell under axial compression

A combined theoretical and experimental investigation has been carried out on the effects of certain types of local axisymmetric imperfections on the buckling of cylindrical shells un der axial compression. Buckling loads have been calculated for a variety of "dimple " imper fections. Results have been obtained for constant thickness shells with middle surface variations from the geometry of a perfect cylinder as well as for shells with local axisymmetric thickness variations. Nonlinear prebuckling elrects and edge conditions are taken into ac count. In the experimental program a series of seven photoelastic plastic circular cylindrical shells each containing a local axisymmetric dimple centered at mid-length were tested under pure axial compression. All cylinders were constructed by the spin-casting technique and the local imperfection was cut on both the inner aud outer walls using a hydraulic tracer-tool apparatus in conjuuction with a metal template. A broad range of imperfection amplitudes and wavelengths was investigated. The experimental results were in good agreement with the theoretical predictions. C [3(1 1'2)]112 T HE presence of shape imperfections in circular cylindrical E = modulus of elasticity shells subjected to axial compressive loading has now bee