Prediction of Fracture Strains for DP980 Steel Sheets Using a Modified Lou–Huh Ductile Fracture Criterion

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This paper is concerned with the prediction of fracture strains for DP980 steel sheets using a modified Lou–Huh ductile fracture criterion. The usage of DP980 steel is significantly increasing in the automotive industry for weight reduction, enhancement of crashworthiness and safety of car body. The material behavior of AHSS show unpredictable and sudden fracture during sheet metal forming process. A modified Lou–Huh ductile fracture criterion is utilized to predict the formability of AHSS because the conventional FLD constructed based on necking is unable to evaluate the formability of AHSS. Fracture loci were extracted from 3D fracture envelopes by assuming the plane stress condition to evaluate equivalent plastic strain up to the point of fracture at a wide range of loading paths. Three different types of specimens such as pure shear, dog-bone and plane strain grooved specimens were used for tensile tests to construct 3D fracture envelopes of DP980. Fracture strain of each loading path was evaluated to show that there is little deviation between predicted fracture strains and experimentally acquired ones. From the comparison, it is concluded that the 3D fracture envelopes can accurately predict the onset of the fracture of DP980 steel sheets in complicated loading conditions including the pure shear condition.

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Edited by:

Yeong-Maw Hwang and Cho-Pei Jiang

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347-352

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N. Park and H. Huh, "Prediction of Fracture Strains for DP980 Steel Sheets Using a Modified Lou–Huh Ductile Fracture Criterion", Key Engineering Materials, Vol. 626, pp. 347-352, 2015

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August 2014

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[1] Keeler, S.P., Backofen, W.A., Plastic instability and fracture in sheets stretched over rigid punches. Transactions of American Society for Metals 56 (1963) 25-48.

[2] Cockcroft, M.G., Latham, D.J., Ductility and the workability of metals, Journal of the Institue of Metals 96 (1968) 33-39.

[3] Brozzo, P., Deluca, B., Rendina, R., A new method for the prediction of formability in metal sheets. In: Proceedings of the 7th Biennial Conference of the International Deep Drawing Research Group on Sheet Metal Froming and Formability, (1972).

[4] Oh, S.I., Chen, C.C., Kobayashi, S., Ductile fracture in axisymmetric extrusion and drawing: Part 2, workability in extrusion and drawing, ASME Journal of Engineering for Industry 101 (1979) 36-44.

DOI: https://doi.org/10.1115/1.3439471

[5] Oyane, M., Sato, T., Okimoto, L., Shima, S., Criteria for ductile fracutre and their applications, Journal of Mechanical Working Technology 4 (1980) 65-81.

DOI: https://doi.org/10.1016/0378-3804(80)90006-6

[6] Clift, S.E., Hartley, P., Sturgess, C.E.N., Rowe, G.W., Fracture prediction in plastic deformation processes, International Journal of Mechanical Science 32 (1990) 1-17.

DOI: https://doi.org/10.1016/0020-7403(90)90148-c

[7] Bai, Y., Wierzbicki, T., Application of extended Mohr–Coulomb criterion to ductile fracture, International Journal of Fracture 161 (2010) 1-20.

DOI: https://doi.org/10.1007/s10704-009-9422-8

[8] Lou, Y., J. H. Yoon and H. Huh, Modeling of shear ductile fracture considering a changeable cut-off value for stress triaxiality, International Journal of plasticity 54 (2014) 56-80.

DOI: https://doi.org/10.1016/j.ijplas.2013.08.006