A novel quadratic yield model to describe the feature of multi-yield-surface of rolled sheet metals

A review of some existing criteria for diffuse necking in sheet metals is given and their limitations are discussed. The introduction into production of new sheet materials whose plastic deformation is impossible to be modeled using Hill’s 1948 anisotropic yield function necessitates improvements of these existing criteria to accurately describe their necking behavior. In this paper, a generalization of the existing diffuse necking criteria for materials describable by Case IV of Hill’s 1979 anisotropic yield function is presented. The proposed criterion is consistent with the previous criteria. It predicts a significant effect of Hill’s 1979 yield surface shape factor on the critical principal strain in the range of negative minor strains while in the range of biaxial tension this influence is small.

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Modeling Induced Flow Anisotropy and Phase Transformations in Air Hardening Steels

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.504-506.443 ◽

2012 ◽

Vol 504-506 ◽

pp. 443-448

Author(s):

Clemens Barthel ◽

Benjamin Klusemann ◽

Ralf Denzer ◽

Till Clausmeyer ◽

Bob Svendsen

Keyword(s):

Phase Transformations ◽

Yield Surface ◽

Shear Test ◽

Current Model ◽

Material Model ◽

Loading Path ◽

Sheet Metals ◽

Surface Evolution ◽

Induced Flow ◽

Flow Anisotropy

In this work a material model for hardening development in sheet metals during forming processes involving loading path changes is formulated. In particular, such hardening development is due to the formation and interaction of dislocation microstructures in the material, resulting in an evolution in the size, center and shape of the yield surface. Such yield surface evolution is accounted for in the current model with the help of an evolving structure tensor. The model is intended for an air hardening steel and takes therefore thermomechanics into account in particular phase transformations from ferrite to austenite and from austenite to martensite. As numerical examples a tension shear test and a heating-cooling sequence are simulated.

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A Fourier series based generalized yield surface description for the efficient modelling of orthotropic sheet metals

Journal of Physics Conference Series ◽

10.1088/1742-6596/896/1/012016 ◽

2017 ◽

Vol 896 ◽

pp. 012016

Author(s):

C Raemy ◽

N Manopulo ◽

P Hora

Keyword(s):

Fourier Series ◽

Yield Surface ◽

Sheet Metals ◽

Surface Description

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Directionality of Fatigue Properties in Some Textured Sheet Metals

Journal of Basic Engineering ◽

10.1115/1.3424916 ◽

1970 ◽

Vol 92 (1) ◽

pp. 115-120 ◽

Cited By ~ 4

Author(s):

I. Le May ◽

K. D. Nair

Keyword(s):

Cold Rolling ◽

Sheet Metal ◽

Fatigue Properties ◽

Rolled Sheet ◽

Sheet Metals ◽

Rolled Material ◽

Pole Figures ◽

Cold Rolling And Annealing ◽

Cold Rolled

The fatigue properties of some face-centred cubic sheet metals with cold rolling and annealing textures are reported. The observed differences between fatigue properties measured in the transverse and longitudinal directions in cold-rolled material are discussed and are related to the pole figures for the material. The study emphasizes that considerable directionality of fatigue properties can occur in rolled sheet metal.

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Texture in Hot Extruded, Hot Rolled and Laser Welded Magnesium Base Alloys

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.105.23 ◽

2005 ◽

Vol 105 ◽

pp. 23-28 ◽

Cited By ~ 3

Author(s):

Robert A. Schwarzer

Keyword(s):

Laser Welding ◽

Grain Orientation ◽

Sheet Material ◽

Rolling Direction ◽

Fiber Texture ◽

Normal Direction ◽

Rolled Sheet ◽

Sheet Metals ◽

Orientation Measurement ◽

Hot Rolled

In this work the textures of MgAl9Zn1, MgAl6Zn1, MgAl3Zn1 and MgAl2Mn alloys have been studied, using individual grain orientation measurement (“ACOM”) in the SEM. Hot extruded billets, unidirectional, reverse and cross-rolled sheet metals as well as laser welding seams have been investigated. In the shaft of a partial extrudate through a circular die orifice, a <0001> ring fiber texture has formed which continuously changes into a spiral fiber texture in the bottom neck. The unidirectional and the reverse hot rolled MgAl2Mn specimens show an R type <0001> texture with a small asymmetrical split whereby the basal poles are tilted by about ±12° from the sheet normal direction to the rolling direction. In the hot cross rolled specimens, the basal poles are slightly spread both in the first and second rolling directions. Texture in the laser welding seams is weak and distinctly different from that of the sheet material. There is almost no heat affected zone at the margins of the welding seams.

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Anisotropic Distortional Yield Model

Journal of Applied Mechanics ◽

10.1115/1.2897056 ◽

1990 ◽

Vol 57 (3) ◽

pp. 537-547 ◽

Cited By ~ 57

Author(s):

George Z. Voyiadjis ◽

Mehrdad Foroozesh

Keyword(s):

Fourth Order ◽

Yield Surface ◽

Large Strain ◽

Small Strain ◽

Surface Model ◽

Yield Model ◽

Proposed Model ◽

Anisotropy Tensor ◽

Subsequent Yield Surface ◽

Uniform Expansion

A yield surface model is proposed in this work which may be adapted to both small strain and large strain offset definitions of yielding. The proposed anisotropic distortional yield model is capable of translation, uniform expansion or contraction, as well as distortion of the subsequent yield surface. Two versions of the proposed model are introduced through variations in fourth-order anisotropy tensor M of the yield surface. Experimental observations by Phillips and co-workers (1973, 1974, 1977, 1979, 1985), Helling et al. (1986), and Stout et al. (1985) are taken into consideration in the development of the proposed model. The corresponding fourth-order elastoplastic stiffness matrix is formulated and specific examples are given.

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