Modelling of Strain-Path Transients in Commercially Pure Aluminium

2016 ◽  
Vol 877 ◽  
pp. 662-667
Author(s):  
Ji Sheng Qin ◽  
Bjørn Holmedal ◽  
Oddsture Hopperstad
Keyword(s):  
Bauschinger Effect ◽  
Quantitative Agreement ◽  
Pure Aluminium ◽  
Anisotropic Hardening ◽  
Hardening Rule ◽  
Commercially Pure ◽  
Reverse Loading ◽  
Strain Reversal ◽  
Transient Variations ◽  
Permanent Softening

In the current work, the recently proposed homogeneous anisotropic hardening (HAH) model, featuring a distorted yield surface, is applied to commercially pure aluminium. A dislocation-based hardening rule is incorporated into the HAH model to describe the transient stagnation of the hardening rate during strain reversal. A cast and homogenized material with random texture previously investigated by Mánik et al. [1] is selected. The material is prestrained either by compression or rolling, and then tested in uniaxial tension to acquire either reverse softening or orthogonal hardening. The Bauschinger effect, the permanent softening during reverse loading and the hardening in the course of orthogonal loading are captured by the model. However, the permanent softening during orthogonal loading cannot be predicted, and the transient variations of the R-value predicted by the HAH model are neither in qualitative nor quantitative agreement with the experimental data.

Effect of tensile prestrain on the yield locus of 1100-f aluminium

1970 ◽  
Vol 5 (2) ◽  
pp. 128-139 ◽  
Author(s):  
J F Williams ◽  
N L Svensson
Keyword(s):  
Bauschinger Effect ◽  
Yield Criterion ◽  
Significant Degree ◽  
Yield Locus ◽  
Statistical Reasoning ◽  
Pure Aluminium ◽  
Stress Tests ◽  
Commercially Pure ◽  
Rounded Corner ◽  
Yield Loci

A series of combined stress tests in torsion-tension space is carried out on thin-walled tubes of 1100-F commercially pure aluminium. One initial and four subsequent yield loci are established to a maximum prestrain level of 14 per cent tensile plastic strain. The results are analysed in terms of a proposed, rationally based, yield criterion constructed according to statistical reasoning. It is shown that during prestrain a significant degree of geometrical distortion is undergone by the yield loci, accompanied by a strong Bauschinger effect and a flattening of part of the locus opposite to the loading point. It is found that the yield locus does not rotate during prestrain and, contrary to the case for torsion prestrain, exhibits evidence of a sharply rounded corner developing at the loading point. The proposed criterion is shown to fit the experimental results extremely well and the mechanism of distortion is explained in terms of a statistical model for work-hardening materials.

Anisotropic hardening theory and the Bauschinger effect

1981 ◽  
Vol 16 (2) ◽  
pp. 85-95 ◽  
Author(s):  
D W A Rees
Keyword(s):  
Shear Strain ◽  
Bauschinger Effect ◽  
Published Data ◽  
Strain History ◽  
Pure Aluminium ◽  
Plastic Shear ◽  
Anisotropic Hardening ◽  
Plastic Shear Strain ◽  
Hardening Theory ◽  
Yield Loci

A review of anisotropic hardening theory is presented with particular reference to the Bauschinger effect in reversed torsion and anisotropic yield loci in σ, τ space associated with plastic shear strain history. The Bauschinger effect is obtained experimentally from a series of torsion tests on En3B steel tubes prestrained to a maximum of 10 per cent plastic shear strain. The effect, measured from the stress in reversed torsion at the proportionality limit, is analysed from the theory. It is shown to be consistent with experimental observations made on the translation and contraction of an initial yield locus, that are in marked contrast to the rigid translation of kinematic hardening rules. The degree of shear prestrain is shown to considerably influence the magnitude of the effect, an observation in full support of a theoretical Bauschinger parameter. The present test data together with existing published data for commercially pure aluminium 1100-F and the aluminium alloy Noral 19 S confirm that the controlling parameter is a scalar coefficient of plastic prestrain. The investigation supports a scalar function that is parabolic in the second invariant of plastic prestrain. The effect of yield point definition is examined and a comparison between theoretical and experimental yield loci is presented.

An Analysis of the Yield Criteria and the Stress-Strain Relationships of a Pre-Strained Commercially Pure Aluminium

1978 ◽  
Vol 20 (4) ◽  
pp. 169-175 ◽  
Author(s):  
G. H. Daneshi
Keyword(s):  
Yield Criterion ◽  
Stress Path ◽  
Isotropic Hardening ◽  
Pure Aluminium ◽  
Stress Strain ◽  
Yield Criteria ◽  
Hardening Rule ◽  
Commercially Pure ◽  
Deviatoric Plane ◽  
Strain Trajectory

An analysis of the stress path and the strain trajectory of a pre-strained engineering material in the deviatoric plane is presented. The deviatoric stress vector, which for a pre-strained material is initially at an angle to the strain trajectory, is shown to coincide with it after the ‘recoverable’ energy is consumed. Experimental work is carried out on the yield criteria and the stress—strain relationships of a pre-strained commercially pure aluminium. The significance of the isotropic hardening rule in relation to a metal's straining memory is demonstrated. It is shown that beyond a stress level associated with an isotropic hardening rule based on the Mises yield criterion, the representative stress—strain curves of a pre-strained specimen run parallel to that of an annealed material.

The Significance of the Isotropic Hardening Rule in Relation to the Stress-Strain Curves of a Pre-Strained Metal

1977 ◽  
Vol 19 (4) ◽  
pp. 157-162 ◽  
Author(s):  
G. H. Daneshi
Keyword(s):  
Yield Surface ◽  
Experimental Results ◽  
Isotropic Hardening ◽  
Pure Aluminium ◽  
Stress Strain ◽  
Hardening Rule ◽  
Commercially Pure ◽  
Flow Surface ◽  
Different Shapes

Defining yield in different ways leads to different shapes of yield surface. This is shown in connection with tests on commercially pure aluminium. Attention is drawn to a flow surface associated with the isotropic hardening rule. Experimental results suggest that, beyond this surface, the stress-strain curves of a pre-deformed specimen are parallel to similar curves for an annealed metal.

Application of the Radial Return Method to Compute Stress Increments From Mroz’s Hardening Rule

2000 ◽  
Vol 123 (4) ◽  
pp. 398-402 ◽  
Author(s):  
Sing C. Tang ◽  
Z. Cedric Xia ◽  
Feng Ren
Keyword(s):  
Metal Forming ◽  
Computing Time ◽  
Isotropic Hardening ◽  
Stress Increment ◽  
Anisotropic Hardening ◽  
Forming Process ◽  
Shell Elements ◽  
Hardening Rule ◽  
Metal Forming Process ◽  
Return Method

It is well known in the literature that the isotropic hardening rule in plasticity is not realistic for handling plastic deformation in a simulation of a full sheet-metal forming process including springback. An anisotropic hardening rule proposed by Mroz is more realistic. For an accurate computation of the stress increment for a given strain increment by using Mroz’s rule, the conventional subinterval integration takes excessive computing time. This paper proposes the radial return method to compute such stress increment for saving computing time. Two numerical examples show the efficiency of the proposed method. Even for a sheet model with more than 10,000 thin shell elements, the radial return method takes only 40 percent of the overall computing time by the subinterval integration.

scholarly journals Analysis of the Bauschinger Effect in Cold Drawn Pearlitic Steels

Metals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 114
Author(s):  
Jesús Toribio ◽  
Viktor Kharin ◽  
Francisco-Javier Ayaso ◽  
Miguel Lorenzo ◽  
Beatriz González ◽  
...  
Keyword(s):  
Mechanical Behaviour ◽  
Bauschinger Effect ◽  
High Strength ◽  
Pearlitic Steel ◽  
Internal Stresses ◽  
Compression Load ◽  
Prestressing Steel ◽  
Hardening Rule ◽  
Steel Wires ◽  
Cyclic Tension

Prestressing steel wires usually undergo cyclic loading in service. Therefore, it is of interest to analyse certain features of their mechanical behaviour under this type of loading, such as the Bauschinger effect (BE) or the hardening rule, that fit the real mechanical behaviour appropriately. In this study, different samples of high strength pearlitic steel wires were subjected to cyclic tension-compression load exceeding the material yield strength, thus generating plastic strains. From the experimental results, various parameters were obtained revealing that analysed steels exhibited the so-called Masing type BE. In addition, the variation of the BE characteristics (of the effective and internal stresses) with the applied plastic pre-strain indicated that the studied materials followed a mixed strain hardening rule with the domination of the kinematic component.

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