Identification of the Local Elasto-Plastic Behavior of FSW Welds Using the Virtual Fields Method

Louëdec, G. Le; Pierron, Fabrice; Sutton, Michael A.; Reynolds, Anthony P.

doi:10.1007/s11340-012-9679-0

Cited by 38 publications

(34 citation statements)

References 32 publications

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“…Noise was directly applied as a random number to the strain field. For the higher noise condition, temporal smoothing (Le Louëdec et al, 2013) was introduced to reduce the noise effect, as illustrated in Figure 14.…”

Section: Numerical Validationmentioning

confidence: 99%

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Application of the virtual fields method to large strain anisotropic plasticity

Rossi

Pierron

Štamborská

2016

International Journal of Solids and Structures

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The identification of the plastic behaviour of sheet metals at severe deformation is extremely important for many industrial application such as metal forming, crashworthiness, automotive, aerospace, piping, etc. In this paper, the virtual fields method (VFM) was employed to identify the constitutive parameters of anisotropic plasticity models. The method was applied using the finite deformation theory in order to account for large strains. First the theoretical principles to implement the method are described in details, especially how to derive the stress field from the strain field. Afterwards a numerical validation was performed using the Hill48 model. Several aspects were studied with the numerical model: the effect of the used virtual fields, the minimum number of specimens required to identify the parameters, the stress distribution obtained from the specimen and its influence in the identification performance. A brief analysis on the influence of noise is also conducted. Finally a series of experiments was conducted on notched specimens of stainless steel, cut along different anisotropic directions. The displacement and strain fields were obtained by digital image correlation. Afterwards, the VFM was used to identify the parameters of the Hill48 model and the Yld2000-2D model. In this case, the Hill48 model was not able to correctly describe the material behaviour, while a rather good agreement was found with the Yld2000-2D model. The potential and the limitation of the proposed method are finally discussed.

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Section: Numerical Validationmentioning

confidence: 99%

“…Then many other applications have been presented, for instance Le Louëdec et al (2013) applied the VFM to the elasto-plastic behaviour of welded materials, Pierron et al (2010) investigated cyclic loads and kinematic hardening, Kim et al (2013) look at the post-necking strain hardening behaviour.…”

Section: Introductionmentioning

confidence: 99%

Application of the virtual fields method to large strain anisotropic plasticity

Rossi

Pierron

Štamborská

2016

International Journal of Solids and Structures

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“…The damping parameter is denoted η in Table 2. It corresponds to the parameter m j in equation (14)(15)(16)(17)(18)(19)(20)(21)(22) from the theory reference of ANSYS [28]. From the numerical results, the data have been retrieved in the same region as the deflectometry results.…”

Section: Finite Element Modelmentioning

confidence: 99%

“…However, its displacement resolution is not sufficient for the current application. If one considers a correlation resolution of 0.01 pixels [16] and an sensor array of 1000 × 1000 pixels, one can therefore detect displacements of 0.01/1000 = 1×10 −5 of the field of view. For a field of view of 60 mm × 60 mm as is the case here, one has a resolution in out-ofplane displacements of 600 nm, about 3 times larger than the maximum amplitudes measured in this work.…”

Section: Introductionmentioning

confidence: 99%

Time-resolved full-field imaging of ultrasonic Lamb waves using deflectometry

et al. 2015

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This pioneering experimental work is a proof of concept in which ultrasonic flexural waves have been imaged in a spatially and temporally resolved manner. Thin vibrating plates made of mirror glass and carbon/epoxy composite have been used in the experiments. Results obtained via a standard approach (scanning laser Doppler vibrometry) and the novel methodology based on deflectometry have been compared with a multi-physics finite element simulation. There is a very good correlation between the two experimental techniques. The numerical model provides insight into the experiments, but differs in its detailed structure due to uncertainties over material properties. The extreme slope resolution of deflectometry allows the measurement of peak-to-peak deflections of a few tens of nanometres in one shot. The use of an ultra-high speed camera allows for both space and time resolved measurements of Lamb waves which, to the best knowledge of the authors, has never been reported before. The limitations of the technique arise from the need for a flat specularly reflective surface. However, coating is possible for non-reflective materials and extension to moderately curved surfaces is possible in the future.

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“…Dierent strategies have been devised in the past to parameterize this variation: identify distinct zones based on strain localization (or microstructure), as in [29] or consider the properties constant over a certain transverse slice of the weld, as in [53]. This is the approach used here.…”

Section: Virtual Fields In Plasticity For Heterogeneous Materialsmentioning

confidence: 99%

Identification of the Dynamic Properties of Al 5456 FSW Welds Using the Virtual Fields Method

Louëdec

Pierron

Sutton

et al. 2015

J. dynamic behavior mater.

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The present study focuses on the identication of the evolution of the dynamic elasto-plastic properties of Al 5456 FSW welds. An innovative method is proposed to make best use of the data collected with full-eld measurements during dynamic experiments, and achieve identication of the mechanical properties of heterogeneous materials without requiring measurement of the load. Compressive specimens have been submitted to high strain-rate loading through a Split Hopkinson Pressure Bar (SHPB) device while displacement elds were measured using full-eld measurement techniques. Two sets of experiments have been performed using two dierent methods: the Grid Method and Digital Image Correlation. Afterwards, the identication of the elastic and plastic properties of the material was carried out using the Virtual Fields Method. Finally, identication of the evolution of the yield stress throughout the weld has been achieved for strain-rates of the order of 10 3 s −1 .

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Identification of the Local Elasto-Plastic Behavior of FSW Welds Using the Virtual Fields Method

Cited by 38 publications

References 32 publications

Application of the virtual fields method to large strain anisotropic plasticity

Application of the virtual fields method to large strain anisotropic plasticity

Time-resolved full-field imaging of ultrasonic Lamb waves using deflectometry

Identification of the Dynamic Properties of Al 5456 FSW Welds Using the Virtual Fields Method

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