The Fracture Tests At Room And Low Temperature And The Numerical Analysis Of The Welding Under High Stress Triaxiality

A large number of steel collapsed due to fracture in Kobe earthquake happened in Japan and the Northridge earthquake happened in the United States. The current design of steel structure is even more powerless especially in the brittle fracture at low temperatures. Therefore, it is particularly necessary that proposing a reasonable suggestion on fracture design of steel structure is particularly necessary.Room and low temperature tensile tests were done on E43-and E50-type welding rod under the high stress triaxiality. The results were simulated and analyzed by the software ANSYS secondary developed by the metal stress-based yield model proposed by Wang Wanzhen. And the results of the tests were simulated and analyzed by equivalent strain fracture criterion proposed by Hancock and Wierzbicki in contrast to the metal stress-based yield model proposed by Wang Wanzhen. Ten points composed of plastic strain and stress triaxiality are extracted from the numerical simulation results of the E43 and E50-type room temperature tests. These ten points are the breaking point of the welding notched bars. This article fits the curve of ten breaking points by means of the software MATLAB. Eventually the E43-and E50-type fracture model of the welding notched bars were established. And the proposed crack models were used to simulate the experimental results again. Finally this article will give the reasonable suggestions on the design of the E43- type and E50-type welding notched bars under high stress triaxiality. And through the fracture model to simulate the testing data.The result is Consistent with the fracture model proposed by Wang Wanzhen.The results showed: The metal stress-based yield model proposed by Wang Wanzhen is more applicable in predicting fracture of welding than the equivalent strain fracture criterion proposed by Hancock and Wierzbicki. The fracture model fitted out is a depth correction to the metal stress-based yield model proposed by Wang Wanzhen in the welding fields.