Identification of Out-of-Plane Material Characteristics through Sheet-Metal Blanking

Abstract

The mechanical characteristics of sheet metals are typically identified in the in-plane direction, although the sheet-metal forming processes (e.g., blanking, deep-drawing) are normally applied in the out-of-plane direction. As the mechanical characteristics are not necessarily constant, their direct experimental evaluation through the forming process would enable material monitoring and process optimization, and, additionally, material characterization in the out-of-plane direction. Full, partial (to a certain depth) and sequential (consecutive partial steps to full penetration) blanking experiments are performed on a laboratory blanking apparatus to correlate the out-of-plane material characteristics with the in-plane ones. The well-established in-plane approach to damage is introduced for the out-of-plane direction to determine the isotropic Lemaitre damage variable. Furthermore, yield and ultimate shear stresses are determined and correlated to their respective in-plane counterparts, offering a new insight in the sheet-metal blanking process. Keywords: cutting and forming, constitutive behavior, elastic-plastic material, mechanical testing, ductile damage, out-of-plane experiment Highlights • Experimental out-of-plane sheet-metal material characterization. • Use of in-plane approach for out-of-plane characterization. • Direct material characterization and correlation to in-plane parameters. • Experimental Lemaitre damage characterization in the out-of-plane direction. • Full, partial and sequential blanking experiments on laboratory blanking apparatus.

Computational and Numerical Analysis of Ductile Damage Evolution under Load-Unload Tensile Test in Dual Phase Steel

“…Taking Eqs. (13), (17) and 22, we obtained the next expression that leads to a second-order equation with respect to Δγ,…”

“…Traditionally, the methods used to predict failure have been based on systematic and expensive testing of real models under laboratory conditions [12]. However, with the progressively growing knowledge about ductile failure mechanisms in steels, along with the development of computational power, it is becoming possible to define constitutive models that describe the internal behaviour in materials [13] and [14].…”

The Effect of the Thickness-to-Die Diameter Ratio on the Sheet Metal Blanking Process

“…Wang et al [8] also tried to observe the different wear characteristics of different die materials in high strength steel blanking. Bolka et al [9] studied the identification of the material characteristics and damage correlation through in and out-of-plane direction for blanking with experimental methods. Subramonian et al attempted to determine the interaction between the punch, stripper plate and sheet material under various speeds in blanking; furthermore, the effect of punch velocity on the blanking load was investigated in this study [10] and in another [11].…”