The impact value (AK) measured with classic impact experiment of mechanical properties is a normal index from the five important basic mechanical properties for engineering, but it still has no definite physical meani...The impact value (AK) measured with classic impact experiment of mechanical properties is a normal index from the five important basic mechanical properties for engineering, but it still has no definite physical meaning. By use of the advanced impact experimental machine, the load-deflection signals under impact loading have been measured. According to the load-deflection curve of 30CrMnSiA steel obtained by this method, the AK value could be divided into the elastic deformation work, the plastic deformation work, the crack forming work, the work of crack propagation and the work of unstable crack propagation. Therefore, we can obtain the expression for the continuous changing of stress and strain under impact load. In this experiment, specimens with three different breaches, U type, V type and linear grooving, are used and the dynamic fracture toughness value (KDIC) of 30CrMnSiA steel is treated and calculated which follows the measuring method of material static fracture toughness, as ASTM E399. The experimental results verify that these impact specimens with three different breaches are satisfactory for plane strain relation under impact load. For high strength 30CrMnSiA steel, the maximum load of load-deflection curve under impact load can represent the unstable propagation load of crack. The precision of the calculated fracture toughness (KDIC) meets the engineering requirement of materials.展开更多
文摘The impact value (AK) measured with classic impact experiment of mechanical properties is a normal index from the five important basic mechanical properties for engineering, but it still has no definite physical meaning. By use of the advanced impact experimental machine, the load-deflection signals under impact loading have been measured. According to the load-deflection curve of 30CrMnSiA steel obtained by this method, the AK value could be divided into the elastic deformation work, the plastic deformation work, the crack forming work, the work of crack propagation and the work of unstable crack propagation. Therefore, we can obtain the expression for the continuous changing of stress and strain under impact load. In this experiment, specimens with three different breaches, U type, V type and linear grooving, are used and the dynamic fracture toughness value (KDIC) of 30CrMnSiA steel is treated and calculated which follows the measuring method of material static fracture toughness, as ASTM E399. The experimental results verify that these impact specimens with three different breaches are satisfactory for plane strain relation under impact load. For high strength 30CrMnSiA steel, the maximum load of load-deflection curve under impact load can represent the unstable propagation load of crack. The precision of the calculated fracture toughness (KDIC) meets the engineering requirement of materials.
