Research Of Numerical Simulation Of Crack Driving Force In Inhomogeneous Material Components

It is indicated that the adjacent region of inhomogeneous material is subject to fracture from many fracture accident analyses. For example, failure may often start from a micro-crack in welded joint region of welded constructions or in the vicinity of interface of bi-material. The inhomogeneous in material and mechanical properties would influence seriously the fracture behavior on the structures. The great efforts have been made to investigate the problem at home and abroad in recent years.The crack driving force parameter (J-integral) is calculated and analyzed using ANSYS software in this thesis. Furthermore, the numerical simulation and EPRI estimating method of J-integral are compared and analyzed by means of standard fracture mechanical samples. The results indicate that the result by numerical simulation in ANSYS approach that by EPRI estimating method, which prove that the numerical simulation of J-integral using the software is feasible.The inhomogeneous mechanical property of welded joint with longitudinal crack is analyzed and the effect of strength matching and weld width on J-integral is studied in this thesis. The results indicate that the crack driving force of the under-matching joint is higher than that of the even-matching joint, and that of the over-matching joint is lower than that of the even-matching joint for the same crack length and load. The crack driving force of the wide welded seam is higher than that of the narrow welded seam in the under-matching joint, and that of the wide welded seam is lower than that of the narrow welded seam in the over-matching joint.The crack driving force in the bi-material is analyzed and the variations of J-integral with the bi-material parameters and the distance between crack and interface are studied in this thesis. The results indicate that the crack driving force in harder medium is less than that in softer medium. The crack driving force of the crack far fromthe interface is higher than that close to the interface. When the crack is far from the interface, the material property of the other side has no influence on the crack driving force. When the crack is close to the interface, the crack driving force in harder medium will increase and that in softer medium will decrease.