The Analysis Of "Plastic Instability" Phenomenon Of The Equal-thickness Spherical Shell Under Uniform Intrinsic Pressure

The spherical tank is a pressure vessel used for saving and transporting kinds of gas, liquefied gas and liquid. It has been widely used in such fields as petroleum, chemical industry, petrifaction, metallurgy, light industry, astronautics, nuclear power industry, and so on. Unfortunately, some defects will be encountered unavoidably when being manufactured and used. How to evaluate the impact of these defects on bearing capacity is a challenging problem. This is important for the security, enhancing the economic efficiency and excavating the potential bearing ability.The corr(?)lated mechanics is the key for designing spherical tank successfully. This work aimed to analyze the plastic limit load of the spherical shell and provide some theoretical introductions for the designing of the spherical tank. Herein, various models of spherical shell with different thickness, different flaw and different loads were analyzed using finite element method. Moreover, the concept and method testing of stress-strain relation through twisting solid spherical shaft were introduced in this work. In succession, the virtual work principle was applied to deduce the limit load of the thin spherical shell under large deformation. These results were significant for the designing and using of the spherical tank, and also for introducing actual projects.The problems here were geometrical nonlinear and material nonlinear questions. Different models with or without defects were analyzed and compared under three kinds of loads. These results were compared with those obtained though virtual work principle. The point accounting for the partial plastic instability was marked. This implied that we can guarantee the security and stability of the spherical tank through monitoring the stress or strain distribution and radial displacement.The spherical shell has been widely used in engineering projects. But less fundamental studies devised theoretically on the large deformation of spherical...