Determination and Application of Critical J-integral for C70S6 in Fracture Splitting Connecting Rod

摘要

The paper proposes to employ J-integral technique for studying crack initiation in fracture splitting of connecting rod with stress-raising groove based on the analysis of plastic region at crack tip and critical J-integral for C-70 micro-alloyed steel that is known as typical material for fracture split connecting rods is determined by combining experiment with numerical simulation.The FEM code Msc.Marc is applied to analyze the fracture splitting of connecting rod, the plane stress or strain state of upon/down section and the middle section of crack region before crack starting is characterized, the location of crack starting is determined and the curve between J-integral at crack tip in middle section and loading is established. Combining with the fracture splitting experiment of connecting rod, the critical J-integral value for C-70 steel is obtained. The critical J-integral, as a material constant independent of stress state, i.e. specimen geometry and loading condition-independent constant, can be used to estimate the fracture force of connecting rod with different size , to deduce the crack start state under variedly loading pattern,and also can be widely used to find out the rule of starting notch geometry parameter's influence on separating force,is potentially very useful in the production of fracture split connecting rods.