Contact interaction of bandage and hollow cylinder under various inner pressure

Abstract

The process of contact interaction of steel cylinder pipeline and bandage in presence of inclusion in surface layer of pipeline under the bandage studied. There is the fixed variable of time on the inner surface of pipeline. Two variants of interaction between pipeline and bandage are considered: rigid connection and frictional contact. In addition, various kinds of unsteady load are considered. The surface of inclusion could be described as part of ellipsoid. Corresponding problem could be considered as mathematical model of the pipeline with the near-surface volume defects after repair. The study described the stress-strain state of pipeline and the influence of load changing character and mechanical parameters on the concentration of stresses near the defect zone. The problem was solved using finite element package ANSYS 11. Model twenty-node finite element structural SOLID95 used to construct the finite element, which is modeling elastic deformations. Further for contact surfaces the elements CONTA174 and TARGE170 were used. We selected FULL TRANSIENT analysis with an optimal partition in time for simulation of the dynamic process so that the selected partition provides sufficient accuracy for the resulting solutions of finite element mesh. Consequently using larger time step simulation shows less accurate results. For different partitions of areas the optimal time step was determined. Taking into account the nonlinearity of the problem, an asymmetric solver was used for the solution. In calculations the main attention was paid to calculation of maximum values for the effective stress in the pipe, which, as shown by preliminary calculations, are in point at the interface between the pipe and inclusions. Based on these results it can be concluded that for the considered dynamic and static problems effective stress at the same internal pressures do not differ from each other. Obviously, this is due to the fact that the considered thin-walled structures have negligible inertia.