A New Experimental Technique for the Multi-axial Testing of Advanced High Strength Steel Sheets

Mohr, Dirk; Oswald, Markus

doi:10.1007/s11340-007-9053-9

Cited by 94 publications

(42 citation statements)

References 9 publications

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“…As for the uniaxial tension experiments, DIC is employed to determine the surface displacement field. The reader is referred to Mohr and Oswald (2008) for the determination of the true shear stress versus strain curve from MO experiments. The experimental results are only processed up to the point where small cracks become visible at the corners of the gage section boundaries.…”

Section: I11 Experimental Techniquesmentioning

confidence: 99%

Paint-bake effect on the plasticity and fracture of pre-strained aluminum 6451 sheets

Abi-Akl

Mohr

2017

International Journal of Mechanical Sciences

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In automotive engineering, sheet metal components are subject to a 20min heat treatment at 180C during paint baking. This process may significantly alter the mechanical properties of 6000-series aluminum alloys through artificial ageing. Here, a comprehensive experimental program is carried out to characterize the anisotropic plasticity and the fracture initiation in prestrained artificially-aged aluminum 6451 sheets. It is found that the combination of pre-straining up to 5% strain and heat treatment mainly changes the material's strain hardening behavior and the stress-state sensitivity of its fracture response. The material parameters of the Yld2000-2d plasticity model with combined Swift-Voce hardening are identified for four distinct materials from uniaxial tension and shear experiments. The corresponding Hosford-Coulomb fracture model parameters are determined from smiley shear, V-bending and punch experiments. As an important byproduct of the research, the Yld2000-2d and Hosford-Coulomb models are successfully validated for all four materials through notched and central hole tension experiments. Simple empirical expressions are also provided to estimate the material properties as a function of the prestrain in engineering practice.

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Section: I11 Experimental Techniquesmentioning

confidence: 99%

Paint-bake effect on the plasticity and fracture of pre-strained aluminum 6451 sheets

Abi-Akl

Mohr

2017

International Journal of Mechanical Sciences

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“…(g) Reverse shear plasticity experiments (MO): tangential loading is applied onto a rectangular specimen (Fig. 5), while keeping the vertical force zero (Mohr and Oswald 2008). The strains are measured within the 5 mm high and 50 mm long gage section using planar DIC.…”

Section: Specimensmentioning

confidence: 99%

“…The experiments are aborted as soon as small cracks become visible by eye in the gage section corners. The reader is referred to Mohr and Oswald (2008) for details on the stress-strain curve extraction. An example equivalent stress versus equivalent plastic strain curve for the DP780 material for an MO experiment with loading reversal at a strain of about 0.09 is shown in Fig.…”

Section: Reverse Shear Plasticity Experimentsmentioning

confidence: 99%

Critical hardening rate model for predicting path-dependent ductile fracture

Marcadet

Mohr

2016

Int J Fract

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A new phenomenological framework for predicting ductile fracture after non-proportional loading paths is proposed, implemented into FE software and validated experimentally for a limited set of monotonic and reverse loading conditions. Assuming that ductile fracture initiation is imminent with the formation of a shear band, a shear localization criterion in terms of the elastoplastic tangent matrix is sufficient from a theoretical point of view to predict ductile fracture after proportional and non-proportional loading. As a computationally efficient alternative to analyzing the acoustic tensor, a phenomenological criterion is proposed which expresses the equivalent hardening rate at the onset of fracture as a function of the stress triaxiality and the Lode angle parameter. The mathematical form of the criterion is chosen such that it reduces to the Hosford-Coulomb criterion for proportional loading. The proposed framework implies that the plasticity model is responsible for the effect of loading history on ductile fracture. Important non-isotropic hardening features such as the Bauschinger effect, transient softening and hardening stagnation must be taken into account by the plasticity model formulation to obtain reasonable fracture predictions after nonproportional loading histories. A new comprehensive plasticity model taking the above effects into account is thus an important byproduct of this work. In addition, compression-tension and reverse-shear experiments are performed on specimens extracted from dualphase steel sheets to validate the proposed plasticity and fracture model.

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“…The hydrostatic pressure parameter is important and in each step of the loading process the shape of fracture envelope is improved by the hydrostatic pressure parameter. Mohr et al (2008) presented a new experimental technique that can be used to investigate the large deformation behavior of advanced high strength steel sheets. Later they used this technique and studied experimentally and numerically the stress and strain histories at the point of fracture initiation in steel sheets tensile specimens with central holes and circular notches (Mohr et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Load Bearing Capacity of a Dented Aluminum Pipe Subjected to Internal Pressure Considering the Effect of Ductile Damage

Alashti

Jafari

Hosseinipour

2015

Lat. Am. j. solids struct.

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In this paper, the effect of ductile damage on the behavior of a dented Aluminum pipe subjected to internal pressure is investigated. The plastic behavior of pipes under indentation is studied using continuum damage mechanics theory and the elastic-plastic finite element analysis. Finite element calculations are carried out using the damage plasticity model proposed by Xue and Wierzbicki. The proposed damage plasticity model incorporates effects of both hydrostatic stress and the Lode angle to define the fracture envelope. Numerical calculations for different ranges of internal pressures and indenter diameters with and without damage effect are carried out and results are compared. It is shown that damage has a significant effect on the load bearing capacity of an indented pipe. Results of the present study confirm the credibility of the proposed model in predicting the ductile fracture under multi-axial state of stress loadings.

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A New Experimental Technique for the Multi-axial Testing of Advanced High Strength Steel Sheets

Cited by 94 publications

References 9 publications

Paint-bake effect on the plasticity and fracture of pre-strained aluminum 6451 sheets

Paint-bake effect on the plasticity and fracture of pre-strained aluminum 6451 sheets

Critical hardening rate model for predicting path-dependent ductile fracture

Load Bearing Capacity of a Dented Aluminum Pipe Subjected to Internal Pressure Considering the Effect of Ductile Damage

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