Finite Element Analysis For Piping With Axial Inner Surface Cracks

Fracture mechanics is applied widely in the practical engineering along with the theory of fracture mechanics mature as well as the computer technology developed rapidly.At present,it has practical significance that the theory of fracture mechanics is used in the Fracture Analysis of pipes which in service. However,the result of the fracture parameters is can't be used directly to make Fracture Analysis for the structure which has the especial crack.In this paper,based on fracture mechanics,the straight pipe which contained axial inner surface cracks are analyzed by the finite element analysis(FEA)method and ANSYS software.Finite element models are established for straight pipe which contain axial inner surface crack in different situations(different crack size,different load conditions).They are analyzed and calculated.The stress intensity factor(KI)which contained the axial inner surface crack in different situations in linear-elasticity is calculated,and is transformed to correction coefficient F of stress intensity factor.FittedThe main contents in this paper include:(1)According to the theory of fracture mechanics,the way for solution of plane crack top's stress intensity factor is analyzed and studied;the ANSYS software of finite element analysis is applied to set up crack plate,crack pipe finite element model;the accuracy and the reliability of modeling as well as the application of the Shell93 unit is confirmed in this paper,and foundation is built stably for later work.(2)Models for axial inner surface crack of straight pipeline in different situations are established by FEA; KI in linear-elasticity under inner-pressure is calculated. The result of the finite element is picked up,charts of KI changing along with the different influence factors are plotted,and rule of change is analyzed and discussed.(3)The stress intensity factor shape correction coefficient F is solved further,graphs are drawn up,its change rules are summarized and discussed.(4)stress around crack and distribution of strain field under inner-pressure are analyzed. The result of the finite element is picked up and rule of change is analyzed and discussed.(5)Under pressure load, analy the multiple cracks stress intensity factor of the mutual influence of pipeline wall thickness.Discuss impact of stress intensity factor under the thickness of pipeline,the depth of crack and the distance between the crack.(6)Introduct the stress-strain relations,and make the finite element analysis for piping with axial inner surface cracks. Research the stress-strain field under inner-pressure.