Thermal buckling of cylindrical shell with temperature-dependent material properties : conventional theoretical solution and new numerical method

Even though the thermal buckling behavior of shells has been investigated for many years, until now the thermal buckling problem with temperature-dependent material properties still cannot be solved by the existing commercial finite element codes. Therefore, the conventional theoretical solution of the critical temperature rise of cylindrical shell with the temperature-dependent material properties is first derived in this work. Then, an innovative numerical approach is developed by introducing the bisection method and a user subroutine of ANSYS to overcome the shortcoming of existing finite element codes. The results prove that the temperature-dependent material properties have a great negative influence on the ability of the thermal buckling resistance of the cylindrical shell. As a result, the subroutine of ANSYS developed in this work provides a convenient design method for engineers to avoid the complicated theoretical calculation

Numerical simulation on transverse buckling behavior of submarine pipeline with defects

Local or overall initial geometric defects may inevitably occur in the manufacturing, laying and operation of submarine pipelines. To study the transverse buckling behavior of pipelines with defects laid on the seabed surface, the nonlinear numerical model for transverse thermal buckling of pipelines with 5 kinds of initial geometric defects was established firstly, and then the accuracy of the finite element model was verified. The influence of defect types and nonstraightness on the transverse buckling behavior of pipelines was emphatically analyzed. The results show that the transverse buckling deformation poses a great threat to the safe operation of submarine pipelines. The greater the nonstraightness, the smaller the critical temperature rise will be, and the more prone the pipelines will be to the transverse thermal buckling. Under the condition of the same nonstraightness, the smaller the absolute value of curvature at the center of the initial geometric defect of the pipeline, the stronger the transverse thermal buckling resistance will be. Finally, based on the dimensionless analysis method, the general expression was proposed for calculating the critical temperature rise of submarine pipelines with various common initial geometric defects, and it is anticipated to provide a reference for the thermal buckling design of submarine pipelines