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Title: Possibilities And Influencing Parameters For The Early Detection Of Sheet Metal Failure In Press Shop Operations

Abstract

The concept of forming limit curves (FLC) is widely used in industrial practice. The required data should be delivered for typical material properties (measured on coils with properties in a range of +/- of the standard deviation from the mean production values) by the material suppliers. In particular it should be noted that its use for the validation of forming robustness providing forming limit curves for the variety of scattering in the mechanical properties is impossible. Therefore a forecast of the expected limit strains without expensive cost and time-consuming experiments is necessary. In the paper the quality of a regression analysis for determining forming limit curves based on tensile test results is presented and discussed.Owing to the specific definition of limit strains with FLCs following linear strain paths, the significance of this failure definition is limited. To consider nonlinear strain path effects, different methods are given in literature. One simple method is the concept of limit stresses. It should be noted that the determined value of the critical stress is dependent on the extrapolation of the tensile test curve. When the yield curve extrapolation is very similar to an exponential function, the definition of the critical stress value is verymore » complicated due to the low slope of the hardening function at large strains.A new method to determine general failure behavior in sheet metal forming is the common use and interpretation of three criteria: onset on material instability (comparable with FLC concept), value of critical shear fracture and the value of ductile fracture. This method seems to be particularly successful for newly developed high strength steel grades in connection with more complex strain paths for some specific material elements. Nevertheless the identification of the different failure material parameters or functions will increase and the user has to learn with the interpretation of the numerical results.« less

Authors:
; ; ;  [1]
  1. ThyssenKrupp Steel AG, Sales/Engineering - Auto Division, Kaiser-Wilhelm Strasse 100, 47166 Duisburg (Germany)
Publication Date:
OSTI Identifier:
21061788
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 908; Journal Issue: 1; Conference: NUMIFORM 2007: 9. international conference on numerical methods in industrial forming processes, Porto (Portugal), 17-21 Jun 2007; Other Information: DOI: 10.1063/1.2740795; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; DIAGRAMS; EXTRAPOLATION; FRACTURES; HARDENING; JOINTS; MECHANICAL PROPERTIES; METALS; NONLINEAR PROBLEMS; PRESSING; REGRESSION ANALYSIS; SHEAR; SHEETS; STEELS; STRAINS; STRESSES; VALIDATION

Citation Formats

Gerlach, Joerg, Kessler, Lutz, Paul, Udo, and Roesen, Hartwig. Possibilities And Influencing Parameters For The Early Detection Of Sheet Metal Failure In Press Shop Operations. United States: N. p., 2007. Web. doi:10.1063/1.2740795.
Gerlach, Joerg, Kessler, Lutz, Paul, Udo, & Roesen, Hartwig. Possibilities And Influencing Parameters For The Early Detection Of Sheet Metal Failure In Press Shop Operations. United States. doi:10.1063/1.2740795.
Gerlach, Joerg, Kessler, Lutz, Paul, Udo, and Roesen, Hartwig. Thu . "Possibilities And Influencing Parameters For The Early Detection Of Sheet Metal Failure In Press Shop Operations". United States. doi:10.1063/1.2740795.
@article{osti_21061788,
title = {Possibilities And Influencing Parameters For The Early Detection Of Sheet Metal Failure In Press Shop Operations},
author = {Gerlach, Joerg and Kessler, Lutz and Paul, Udo and Roesen, Hartwig},
abstractNote = {The concept of forming limit curves (FLC) is widely used in industrial practice. The required data should be delivered for typical material properties (measured on coils with properties in a range of +/- of the standard deviation from the mean production values) by the material suppliers. In particular it should be noted that its use for the validation of forming robustness providing forming limit curves for the variety of scattering in the mechanical properties is impossible. Therefore a forecast of the expected limit strains without expensive cost and time-consuming experiments is necessary. In the paper the quality of a regression analysis for determining forming limit curves based on tensile test results is presented and discussed.Owing to the specific definition of limit strains with FLCs following linear strain paths, the significance of this failure definition is limited. To consider nonlinear strain path effects, different methods are given in literature. One simple method is the concept of limit stresses. It should be noted that the determined value of the critical stress is dependent on the extrapolation of the tensile test curve. When the yield curve extrapolation is very similar to an exponential function, the definition of the critical stress value is very complicated due to the low slope of the hardening function at large strains.A new method to determine general failure behavior in sheet metal forming is the common use and interpretation of three criteria: onset on material instability (comparable with FLC concept), value of critical shear fracture and the value of ductile fracture. This method seems to be particularly successful for newly developed high strength steel grades in connection with more complex strain paths for some specific material elements. Nevertheless the identification of the different failure material parameters or functions will increase and the user has to learn with the interpretation of the numerical results.},
doi = {10.1063/1.2740795},
journal = {AIP Conference Proceedings},
number = 1,
volume = 908,
place = {United States},
year = {Thu May 17 00:00:00 EDT 2007},
month = {Thu May 17 00:00:00 EDT 2007}
}