近日，由张立军教授指导的硕士生杨宁的论文《Research on the deflection of metal bar with V-shaped notch in low-stress cropping process》被国际知名期刊“Theoretical and Applied Fracture Mechanics”正式录用。杨宁为第一作者，张立军教授为通信作者。《Theoretical and Applied Fracture Mechanics》最新影响因子3.021（中科院SCI分区最新版2区期刊），该期刊重点报道工程断裂力学理论改进和数值仿真以及实验等方面的最新研究成果。

  In view of the deflection of metal bars in low-stress cropping process, which leads toserious extrusion damageon the surface of bar and difficulty to apply loads effectively, a five-segment type discontinuous variable cross-section bar model is established in this paper.The strain energy method is developed to establish the influence of V-shaped notch parameterson the deflection, and its accuracy is elevated with XFEM method, which is used to quantify the influence of crack depth. Finally, the characterization formula of deflection in the low-stress cropping process is established theoretically. The dynamic and static strain-deflection test and analysis platform is built on the low-stress cropping machine.The experimental results of 45# steel barconfirm the validity of the formula. On this basis, the law of follow-up rotation angle of loading die is analyzed, and the effective method to apply desirable loads is obtained.The evaluation parameter wi (LB/2R0) of allowable value of deflection at crack initiation is proposed, and the allowable deflection range (w1, w2) = (0.02343mm, 0.15383mm) of 45# steel bar with a diameter of 15mm is given, which can be applied to low-stress cropping and meet the requirements of industrialization.