Volume Measurement of 3D displacement by Digital Volume Correlation (DVC)

Transcription

1 Displacement measurement Volume Measurement of 3D displacement by Digital Volume Correlation (DVC) Volume measurement Currently, most methods of strain measurement can determine only plane components of strain tensor on sample surface. DVC gives three components of displacement and the spatial variations in the bulk of a material and structure. The 3D displacement field allows us to calculate the full strain tensor at each measurement point.

2 Principle This technique uses the same principle than the one of 2D method of Digital Image Correlation (DIC) extended to 3D images obtained by tomography, for example optical or X-ray microtomography. It consists in matching two digital images showing the volume of the sample studied to two strain states. A natural and artificial volume speckle pattern showing sufficient greylevel gradients, must be visible in volume images in order to ensure the success of DVC process. Example of volume speckle pattern

3 References The feature of our technique are given in the next references. GERMANEAU A.; DOUMALIN P.; DUPRE J.C.; «3D strain field measurement by correlation of volume images using scaterred light: recording of images and choice of marks» Strain, 2007, Vol. 43; pp ;. GERMANEAU A.; DOUMALIN P.; DUPRE J.C.; «Full 3D Measurement of Strain Field by Scattered Light for Analysis of Structures» Experimental Mechanics, 47, 2007, pp GERMANEAU A.; DOUMALIN P.; DUPRE J.C.; «Comparison between X-ray micro-computed tomography and optical scanning tomography for full 3D strain measurement by digital volume correlation» NDT and E International, 41 (6), 2008, pp Software This DVC method is developped in a software named CorrelVol Performances Non-contact volume measurement Displacement range up 1µm to some centimeters (according to tomography setup used to record volume images) Strain range up 0.1% to some percent tens Devices Tomography setup (X-Ray laboratory system or Synchrotron, optical setup ) to record volume images Automatic analyse Software named CorrelVol Contacts : Pascal Doumalin : pascal.doumalin@univ-poitiers.fr Arnaud Germaneau : arnaud.germaneau@univ-poitiers.fr Jean-Christophe Dupré : jean.christophe.dupre@univ-poitiers.fr

4 Examples of applications Strain field in the vicinity of a localized flat contact in the bulk of epoxy block Experimental Eyy Eyy simulated by FEM GERMANEAU A.; «Développement de techniques de mesure dans le volume : photoélasticimétrie 3D par découpage optique et corrélation volumique par tomographie optique et rayons X. Application à l étude des effets mécaniques 3D dans les structures et les biomatériaux» Ph D thesis, University of Poitiers, Nov 2007

5 Strain field in the vicinity of a localized spherical contact in the bulk of epoxy block GERMANEAU A.; «Développement de techniques de mesure dans le volume : photoélasticimétrie 3D par découpage optique et corrélation volumique par tomographie optique et rayons X. Application à l étude des effets mécaniques 3D dans les structures et les biomatériaux» Ph D thesis, University of Poitiers, Nov 2007

6 Femoral head degenerated by arthritis Effort (N) Déplacement imposé (mm) E 1 eqn normalised equivalent Von Mises strain field (E eq /E eqmax ): GERMANEAU A.; «Développement de techniques de mesure dans le volume : photoélasticimétrie 3D par découpage optique et corrélation volumique par tomographie optique et rayons X. Application à l étude des effets mécaniques 3D dans les structures et les biomatériaux» Ph D thesis, University of Poitiers, Nov 2007

7 Aeronautical plain bearings GERMANEAU A., PEYRUSEIGT F., MISTOU S., DOUMALIN P.; DUPRE J.C.; «3D mechanical analysis of aeronautical plain bearings: validation of a finite element model from measurement of displacement fields by Digital Volume Correlation and Optical Scanning Tomography» Optics and Lasers in Engineering, 48, 2010, pp

8 SEN sample BARRANGER Y., DOUMALIN P., DUPRE J.C., GERMANEAU A., HEDAN S., VALLE, V. «Evaluation of three-dimensional and two-dimensional full displacement fields of a single edge notch fracture mechanics specimen, in light of experimental data using X-ray tomography» Engineering Fracture Mechanics, 76 (15), 2009, pp

9 Wood-based fibrous material Ezz 4,8% 9% 13,2% 16,9% 20,5% 23,7% 25,6% 28,4%

10 Study of transverse shear effects in UD composite