Interior 3D-Strain Mapping in Opaque Materials Using Digital Volumetric Speckle Photography and X-Ray Micro Computer Tomography

Abstract:

Developing a true 3D experimental stress analysis technique has been the holy grail of solid mechanics researchers since the genesis of the field. Combined the high-resolution x-ray computer tomography (Micro CT) with the 2D speckle photography technique developed by one of us (Chiang), we recently proposed a new 3D strain analysis technique called Digital Volumetric Speckle Photography (DVSP). The elements of DVSP technique are as follows. A reference volumetric image of the specimen is recorded by a Micro-CT scan and stored as a reference. Under load the deformed CT image of the specimen is also recorded. Both volume images are divided into subimages of certain voxel arrays. Each corresponding pair of the subimages are ‘compared’ via a two-step 3D Fourier Transform analysis. The result is a 3D map of displacement vectors representing the collective displacement experienced by all the speckles within the subset of voxels. Strain distribution of the entire specimen can then be calculated using appropriate displacement strain relations. Application of this technique to strain mapping of red sandstone and composite are presented.

• Periodical: Applied Mechanics and Materials (Volume 782)
• Pages: 345-348
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.782.345
• Online since: August 2015
• Authors: Ling Tao Mao, Qian Wen Sun, Fu Pen Chiang
• Keywords: 3D-strain Mapping, Composite, Digital Volumetric Speckle Photography, Red Sandstone, Spline Interpolation, Two-Step 3D Fourier Transform, X-Ray CT

References

[1] Bay B K， Smith T S， Fyhie D P， Saad M. Digital volume correlation: Three-dimensional. strain mapping using X-ray tomography. Experimental Mechanics, 39(3) (1999) 217-226.

DOI: 10.1007/bf02323555

[2] Lenoir N, Bornert M, Desrues J, Besuelle P, Viggiani G. Volumetric Digital Image Correlation Applied to X-ray Microtomography Images from Triaxial Compression Tests on Argillaceous Rock. Strain, 43(3) (2007) 193–205.

DOI: 10.1111/j.1475-1305.2007.00348.x

[3] Forsberg F., Sjodahl M., Mooser R., et al, Full three-dimensional strain measurements on wood exposed to three-point bending: analysis by use of digital volume correlation applied to synchrotron radiation micro-computed tomography image data, Strain, 46 (2010).

DOI: 10.1111/j.1475-1305.2009.00687.x

[4] Chen D.J., Chiang F.P., Tan Y.S., et al, Digital speckle-displacement measurement using a complex spectrum method, App. Opt., 32 (1993) 1839-1849.

DOI: 10.1364/ao.32.001839

[5] Chiang F. P., Mao L. T, Development of Interior Strain Measurement Techniques Using Random Speckle Patterns, Meccanica, 50 (2015) 401–410.

DOI: 10.1007/s11012-014-0048-1