A new approach to damage modelling and fracture analysis for metal bar with V-shaped notch

Variant-frequency vibration cropping is a new approach of low-stress manufacturing technology, which utilizes the stress concentration effect of V-shaped notch to realize the regular fracture of metal bar under conditions of low cycle fatigue. The material fracture process has a great effect on the manufacturing quality obtained by this cropping method. Aiming at the geometric shape of fracture surface and the initial cracked angle, a new approach to the damage modelling is proposed for the metal bar with V-shaped notch. Based on the relationship of stress-field components for different loads derived from the solid mechanics and the Von-Mises yield criterion under conditions of low cycle fatigue, the stress state is determined for the damage modelling. Through the definition of the damage variable and the damage coefficient, the damage modelling process is discussed according to the numerical analysis results, and the plastic slip zone is obtained near the V-shape notch. Finally, the geometric shape of fracture surface and the initial cracked angle are analysed in terms of the damage model. To verify the analysis result, experiments on the material of steel C45e are conducted, and the initial cracked angle is measured.