Buckling Analysis of Torpedo’s Cylindrical Shell

Torpedo is a self-propelled weapon. It can be launched above or below the water surface. Torpedo’s different internal parts are housed in cylindrical, conical and spherical shell structures. Underwater applications require the minimization of the structural weight of shell structure for increased buckling strength, speed, and operating distance. To serve this purpose lightweight material such as Al-Cu alloy is preferred for the manufacturing of torpedo’s cylindrical shell. Here in the present investigation, unstiffened cylindrical shell structural member of the torpedo is considered for the evaluation of its linear buckling strength when the torpedo is subjected to hydro-static pressure under the sea water. Linear buckling analysis which is also called Eigen buckling analysis is done on unstiffened cylindrical shell geometry by using ANSYS R14.5 software. The values obtained for linear buckling strength from empirical equations mentioned in British Standards Institution, BS 5500 (now superseded by PD 5500) ‘Unfired Fusion Welded Pressure Vessels’ are validated with those results from ANSYS R14.5 and are observed to be closer to each other. The variation of the failure stress of an unstiffened cylindrical shell due to buckling for the variation of its thickness is also observed using both the empirical and simulation using ANSYS R14.5 approaches and are compared using the corresponding plots. And also, the critical buckling pressures of an unstiffened cylindrical shell with a constant thickness for the formation of different number of lobes for the simply supported boundary conditions are calculated by using empirical relations and this variation is observed using the corresponding plot. For these analyses numerical examples are considered.