Elastic-plastic stress-strain state and strength of thick-walled pipe under the action of internal pressure

The task of calculating a plane axisymmetric elastic-plastic stress state of a thick-walled steel cylindrical pipe under the action of uniform internal pressure is considered. Thick-walled steel pipes are used in mechanical engineering, in heat engineering and heat-and-power engineering, in oil-producing and oil-refining industries, in the chemical industry. When loading in a pipe, two limiting states are realized: the elastic and plastic resistance of the material for two limiting values of pressure. For an intermediate pressure value, the cross-section of the pipe consists of two concentric annular zones – an inner elastic-plastic zone and an outer elastic zone. The exhaustion of the bearing capacity of the pipe occurs when the elastic-plastic deformation zone, spreading from the inner surface of the pipe, reaches its outer surface. Therefore, the presence of an elastic deformation zone at the outer surface of the pipe does not lead to the destruction of the structure. The aim of the work is to create an analytical technique for determining the calculated internal pressure, satisfying the strength condition under elastic-plastic deformation of steel cylindrical thick-walled pipes of different geometry, and leading to the most complete realization of the mechanical properties of the material. Recommendations on the effective search for the specified internal pressure are given.