Estimation of the strain field from full-field displacement noisy data

Avril, Stéphane; Feissel, Pierre; Pierron, Fabrice; Villon, Pierre

doi:10.3166/remn.17.857-868

Cited by 53 publications

(29 citation statements)

References 14 publications

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“…The filtering procedure is a local fit of a second degree polynomial using a specific weighing function. This is referred to as diffuse approximation and details can be found in [12]. The strains are then obtained directly from the polynomial coefficients.…”

Section: Methodsmentioning

confidence: 99%

The virtual fields method applied to spalling tests on concrete

Pierron

Forquin

2012

EPJ Web of Conferences

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Abstract. For one decade spalling techniques based on the use of a metallic Hopkinson bar put in contact with a concrete sample have been widely employed to characterize the dynamic tensile strength of concrete at strain-rates ranging from a few tens to two hundreds of s −1 . However, the processing method mainly based on the use of the velocity profile measured on the rear free surface of the sample (Novikov formula) remains quite basic and an identification of the whole softening behaviour of the concrete is out of reach. In the present paper a new processing method is proposed based on the use of the Virtual Fields Method (VFM). First, a digital high speed camera is used to record the pictures of a grid glued on the specimen. Next, fullfield measurements are used to obtain the axial displacement field at the surface of the specimen. Finally, a specific virtual field has been defined in the VFM equation to use the acceleration map as an alternative 'load cell'. This method applied to three spalling tests allowed to identify Young's modulus during the test. It was shown that this modulus is constant during the initial compressive part of the test and decreases in the tensile part when micro-damage exists. It was also shown that in such a simple inertial test, it was possible to reconstruct average axial stress profiles using only the acceleration data. Then, it was possible to construct local stress-strain curves and derive a tensile strength value.

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Section: Methodsmentioning

confidence: 99%

The virtual fields method applied to spalling tests on concrete

Pierron

Forquin

2012

EPJ Web of Conferences

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“…By using an identical setup rotated by 90 • one obtains the other component of in-plane displacement. The displacement resolution is close to 0.1 m for a spatial resolution of about 16 m. Strains were obtained from displacements using a diffuse approximation filtering (radius = 20 pixels, 248 m resolution) that provides excellent reconstruction/filtering compromise as described in [16,17]. The strain resolution is 2 × 10 −5 .…”

Section: Mechanical Characterisationmentioning

confidence: 99%

Influence of the microstructural changes and induced residual stresses on tensile properties of wrought magnesium alloy friction stir welds

Commin¹,

Dumont²,

Rotinat³

et al. 2012

Materials Science and Engineering: A

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is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. a b s t r a c tFriction stir welding induces a microstructural evolution and residual stresses that will influence the resulting mechanical properties. Friction stir welds produced from magnesium alloy hot rolled plates were studied. Electron back scattered diffraction was used to determine the texture evolution, residual stresses were analysed using X ray diffraction and tensile tests coupled with speckle interferometry were performed. The residual stresses induced during friction stir welding present a major influence on the final mechanical properties.

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“…Here, polynomial basis of degree 2 is chosen, because, it appeared in [7] it was a good compromise between filtering and approximation error. With such a basis, the terms a 2 (x) and a 3 (x) represent the first order derivatives at point x in a diffuse way.…”

Section: The Diffuse Approximation (Da) As a Filtering Toolmentioning

confidence: 99%

“…It is reconstructed for the same filtering level, with both spatial Diffuse Approximation and Space-time Diffuse Approximation. One can note an improvement of the spatial resolution when using the Space-time 10005-p. 7 Diffuse Approximation. Furthermore, when comparing the strain field with the linear approximation of Figure 4(d), it seems the Space-time Diffuse Approximation yields a better spatial resolution.…”

Section: Comparing Spatial Diffuse Approximation and Space-time Diffumentioning

confidence: 99%

The Diffuse Approximation: a derivative tool dedicated to full-ﬁeld measurements

Feissel

Villon

2010

EPJ Web of Conferences

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Abstract. This study proposes a filtering tool based on the diffuse approximation, in order to reconstruct strain fields from full-field displacement measurements. The question of the filtering of the noise is adressed and an alternative approach based on space-time filtering is proposed. The methods are then applied to the detection of early damage detection on a tensile test on an interlock composite.

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Estimation of the strain field from full-field displacement noisy data

Abstract: RÉSUMÉ. Cette étude s'intéresse à la reconstruction de champs de déformation à partir de me-

Cited by 53 publications

References 14 publications

The virtual fields method applied to spalling tests on concrete

The virtual fields method applied to spalling tests on concrete

Influence of the microstructural changes and induced residual stresses on tensile properties of wrought magnesium alloy friction stir welds

The Diffuse Approximation: a derivative tool dedicated to full-ﬁeld measurements

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