Investigation of burst failure of a thick-walled spherical vessel with plastic orthotropy under internal and external pressures

Based on Hill's anisotropic theory, theoretical solutions for the burst pressure and the corresponding equivalent stresses and strains for a thick-walled spherical pressure vessel made of a ductile material with plastic orthotropy are obtained. The effects of the plastic orthotropy, strain hardening, ratio of the external to internal radius of the vessel, and external pressure on the burst pressure is considered. It is found that the external pressure affects the burst pressure, while the corresponding equivalent stresses and strains have nothing to do with the external pressure.