Simulation Plane Crack Propagation Based On Vector Form Intrinsic Finite Element

Vector form intrinsic finite element method(VFIFE)was first introduced by Professor E.C.Ting at Purdue University.It is an effective numerical analysis method to combine Vector mechanics theory and numerical calculation.VFIFE uses point value to describe members' spatial location and time history,considers unit in reverse movement after the virtual form pure deformation,permits free to increase or decrease the node,which can overcome the drawbacks of traditional methods.VFIFE uses Newton's equation of motion and explicit solution,not necessary to calculate stif5ness matrix,which can well solve mechanical problems such as contact,collision,fracture,etc.This thesis analyzes municipal pipeline crack propagation process based on VFIFE.The studies in the thesis mainly includes:(1)Based on the basic theory of VFIFE,the basic formulas of vector finite element plane triangle element were derived.Two numerical examples were showed the accuracy of the theoretical derivation and the reliability of the MATLAB program.(2)One-dimensional stress wave propagation in SHPB was simulated based on VFIFE.This paper introduced in detail the impact iteration step,the number of element of the bullet and incident bar,and the critical iteration step and so an.(3)The whole process of crack propagation was analyzed based on theory of VFIFE,which calculated crack tip stress intensity factor according to the least squares and used a simplified unit grid topology dynamic updating method in the whole calculation process.The propagation simulation examples of unilateral crack,unilateral center symmetric 90°,inclined crack,crack extension process center symmetric 45°proved the feasibility of VFIFE.(4)The pipe VFIFE model was set up by simplifying pipeline longitudinal tensile and longitudinal bending stress model.The effect of different stress on crack growth was analyzed by simulating the axial tensile crack propagation and the longitudinal bending crack propagation of cast iron pipe under longitudinal stiffness of different soils and under different hanging length.This article reflected the VFIFE in the collision and fracture analysis of the advantages and made a preliminary study on the crack propagation of the actual cast iron pipe.Based on the research results,the paper put forward the corresponding conclusions and given some suggestions for further study problem.