Experimental Study on Plastic Deformation of EH690 Steel with the V-Notch during Falling Weight Impact Based on DIC

Abstract

In this study, a falling weight impact test was conducted on EH690 steel specimens with V-notches using Digital Imaging Correlation (DIC). In conjunction with scanning electron microscopy (SEM), the plastic deformation and crack initiation processes were examined at the notch of the specimen under different impact energies (90 J, 120 J, 135 J and 150 J). ABAQUS was used to simulate the plastic deformation of an EH690 specimen. The results show that the strain at the notch tip experienced some elasticity and yielding as the load increased under different impact energies. The load remains unchanged or decreases slightly when a plastic hinge forms at the tip of the notch. According to the microscopic images, there are three areas on the fracture surface: a fiber area, a radiation area, and a shear lip area. With increasing deformation, a crack source forms in the middle of the V-shaped notch and propagates to the inside and outside surfaces of the sample. Cracks are primarily caused by ductile tears. The use of DIC to analyze the surface strain of EH690 steel specimens was verified by comparing DIC with finite element analysis. Both curves have the same trend and the maximum error in the load-time curve is 9.42%, the maximum error in the displacement–time curve is 5.61%, and the maximum error in the strain-time curve is 10.68%.