scholarly journals Optimization of a Cruciform Specimen Geometry for the Identification of Constitutive Parameters Based Upon Full-Field Measurements

Strain ◽  
2016 ◽  
Vol 52 (4) ◽  
pp. 307-323 ◽  
Author(s):  
M. B. R. Bertin ◽  
F. Hild ◽  
S. Roux
Keyword(s):  
Field Measurements ◽  
Specimen Geometry ◽  
Full Field ◽  
Cruciform Specimen ◽  
Constitutive Parameters

scholarly journals Reconstruction of constitutive parameters in isotropic linear elasticity from noisy full-field measurements

2014 ◽  
Vol 30 (12) ◽  
pp. 125004 ◽  
Author(s):  
Guillaume Bal ◽  
Cédric Bellis ◽  
Sébastien Imperiale ◽  
François Monard
Keyword(s):  
Linear Elasticity ◽  
Field Measurements ◽  
Full Field ◽  
Constitutive Parameters

scholarly journals The Virtual Fields Method for Extracting Constitutive Parameters From Full-Field Measurements: a Review

Strain ◽  
2008 ◽  
Vol 42 (4) ◽  
pp. 233-253 ◽  
Author(s):  
M. Grédiac ◽  
F. Pierron ◽  
S. Avril ◽  
E. Toussaint
Keyword(s):  
Field Measurements ◽  
Virtual Fields Method ◽  
Full Field ◽  
Constitutive Parameters

Stress Analysis and Identification with Full-Field Measurements

2006 ◽  
Vol 3-4 ◽  
pp. 9-16 ◽  
Author(s):  
M. Grédiac
Keyword(s):  
Model Updating ◽  
Measurement Techniques ◽  
Field Measurements ◽  
Element Model ◽  
Finite Element Model Updating ◽  
Strain Fields ◽  
Full Field ◽  
Full Field Measurement ◽  
Constitutive Parameters ◽  
The Finite Element Model

The wealth of information provided by full-field measurement techniques is very useful in experimental mechanics. Among different possible applications, full-field measurements can be used to identify parameters governing constitutive equations from heterogeneous strain fields. This keynote lecture first describes the different possible uses of such measurements. It then focuses on the virtual fields method which has been proposed to extract constitutive parameters from full-field measurements. Finally, the method is compared with the finite element model updating technique which is usually used for solving such a problem.

scholarly journals Identification of a macroscopic anisotropic damage model using digital image correlation and the equilibrium gap method

2010 ◽  
pp. 229-240
Author(s):  
Laurent Crouzeix ◽  
Jean-Noël Périé ◽  
Francis Collombet ◽  
Bernard Douchin
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Damage Model ◽  
Field Measurements ◽  
Image Correlation ◽  
Anisotropic Damage ◽  
Biaxial Test ◽  
Displacement Fields ◽  
Full Field ◽  
Constitutive Parameters

The aim of the work is to demonstrate how an anisotropic damage model may be identified from full field measurements retrieved during a heterogeneous test. The example of a biaxial test performed on a 3D C / C composite is used. In a first step, the displacement fields measured by classical Digital Image Correlation are used as input data of a finite difference version of the Equilibrium Gap Method. A benefit from unloadings (assumed to be elastic) is shown to retrieve a damage law. In a second step, inelastic strains can be assessed from the total measured strain and the elastic estimated strains. The constitutive parameters relative to the inelastic part of the model are then identified.

scholarly journals The Virtual Fields Method for Extracting Constitutive Parameters From Full-Field Measurements: a Review

Strain ◽  
2006 ◽  
Vol 42 (4) ◽  
pp. 233-253 ◽  
Author(s):  
M. Grédiac ◽  
F. Pierron ◽  
S. Avril ◽  
E. Toussaint
Keyword(s):  
Field Measurements ◽  
Virtual Fields Method ◽  
Full Field ◽  
Constitutive Parameters

scholarly journals A full-field image conversion method for the inverse conductivity problem with internal measurements

2016 ◽  
Vol 472 (2187) ◽  
pp. 20150488 ◽  
Author(s):  
Cédric Bellis ◽  
Hervé Moulinec
Keyword(s):  
Heterogeneous Material ◽  
Field Measurements ◽  
Direct Conversion ◽  
Full Field ◽  
Inverse Conductivity Problem ◽  
Approximation Quality ◽  
Image Conversion ◽  
Full Intensity ◽  
Fixed Point Iterations ◽  
Constitutive Parameters

This article investigates a Fourier-based algorithm for computing heterogeneous material parameter distributions from internal measurements of physical fields. Within the framework of the periodic scalar conductivity model, a pair of dual Lippmann–Schwinger integral equations is derived for the sought constitutive parameters based on full intensity or current density field measurements. A numerical method based on the fast Fourier transform and fixed-point iterations is proposed. Convergence, stability and approximation quality of the method are analysed. For materials with small contrast, a first-order Born-like approximation is also obtained. Overall, the proposed reconstruction approach enables a direct conversion of full-field measurement images, possibly noisy, into maps of material conductivity. A set of numerical results is presented to illustrate the performance of the method.

Improved infrared temperature mapping of elastohydrodynamic contacts

2009 ◽  
Vol 223 (8) ◽  
pp. 1165-1177 ◽  
Author(s):  
T Reddyhoff ◽  
H A Spikes ◽  
A V Olver
Keyword(s):  
Effective Means ◽  
Field Measurements ◽  
Operating Conditions ◽  
Mapping Technique ◽  
Shear Stresses ◽  
Measured Temperature ◽  
Ir Camera ◽  
Full Field ◽  
Group I ◽  
Increased Sensitivity

An effective means of studying lubricant rheology within elastohydrodynamic contacts is by detailed mapping of the temperature of the fluid and the bounding surfaces within the lubricated contact area. In the current work, the experimental approach initially developed by Sanborn and Winer and then by Spikes et al., has been advanced to include a high specification infrared (IR) camera and microscope. Besides the instantaneous capture of full field measurements, this has the advantage of increased sensitivity and higher spatial resolution than previous systems used. The increased sensitivity enables a much larger range of testable operating conditions: namely lower loads, speeds, and reduced sliding. In addition, the range of test lubricants can be extended beyond high shearing traction fluids. These new possibilities have been used to investigate and compare the rheological properties of a range of lubricants: namely a group I and group II mineral oil, a polyalphaolephin (group IV), the traction fluid Santotrac 50, and 5P4E, a five-ring polyphenyl-ether. As expected, contact temperatures increased with lubricant refinement, for the mineral base oils tested. Using moving heat source theory, the measured temperature distributions were converted into maps showing rate of heat input into each surface, from which shear stresses were calculated. The technique could therefore be validated by integrating these shear stress maps, and comparing them with traction values obtained by direct measurement. Generally there was good agreement between the two approaches, with the only significant differences occurring for 5P4E, where the traction that was deduced from the temperature over-predicted the traction by roughly 15 per cent. Of the lubricants tested, Santotrac 50 showed the highest average traction over the contact; however, 5P4E showed the highest maximum traction. This observation is only possible using the IR mapping technique, and is obscured when measuring the traction directly. Both techniques showed the effect of shear heating causing a reduction in traction.

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