Experimental and numerical analysis of micromechanical damage in the punching process for High-Strength Low-Alloy steels

Abstract

is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. b s t r a c tSequential sheet metal forming processes can result in the accumulation of work hardening and damage effects in the workpiece material. The mechanical strength of the final component depends on the ''evolution'' of these two characteristics in the different production steps. The punching process, which is usually in the beginning of the production chain, has an important impact on the stress, strain and damage states in the punched zones. It is essential that the influence of these mechanical fields be taken into account in the simulation of the forming sequence. In order to evaluate the evolution of each phenomenon, and in particular damage accumulation in the forming process, it is essential to characterize the punching process. The objective of this work is to understand and identify the physical damage mechanisms that occur during the punching operation and to establish relevant numerical models to predict the fracture location. The effect of the punch-die clearance on mechanical fields distribution is also discussed in this work.

Experimental Examination of Effects of Punch Angle and Clearance on Shearing Force and Estimation of Shearing Force Using Fuzzy Logic

“…Mechanical conditions (such as tool clearance and feed velocity) of the shearing process were investigated in [26]. Achouri et al [27] looked into the physical damage mechanisms that occur during the punching operation and established relevant numerical models to predict the fracture location.…”

Ductile fracture and deformation behavior in progressive microforming

“…Mori et al [23] developed a slight clearance punching process using a small round edge to improve the quality of the sheared edge, and they found that the delayed fracture did not happen and the fatigue strength was enhanced due to the large compressive stress around the sheared edge in such punching process. In addition, Achouri et al [24] investigated the physical damage mechanisms in punching operation, and further established an improved numerical formula to predict the fracture location based on the micromechanical approach. Furthermore, Liu and Fu [25,26] proposed a modified ductile criterion for fracture prediction of sheet metal forming, and verified its validity by flexible die forming and hemispherical bulging.…”

Examining the microtexture evolution in a hole-edge punched into 780 MPa grade hot-rolled steel

“…ACCEPTED MANUSCRIPT 3 dealt with the effects that the punching-clearance [8], burr-direction [10,13], cracks, and micro-voids in the edge of a hole [14,16] exert on the stretch-flange formability. However, the effects of the microtexture evolution that develops at the edge of the punched hole on stretch-flange formability have not been properly examined.…”

“…FEA can use spatial distribution, crystallographic orientation and volume fraction of the real microstructure to simulate micromechanical deformation behaviors in the constituent phases during the expansion of a hole [16][17][18][19]. Most FEA has been limited to explaining the deformation and fracture behaviors in the edge of a punched hole, but the microtexture evolution that is induced by the punching of a hole has not been properly investigated [13,16,20,21,23]. An understanding of the microtexture evolution that is induced by the punching of a hole is required in order to perform a more accurate analysis of the HER.…”