There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

As a practical and effective tool for quantitative in-plane deformation measurement of a planar object surface, two-dimensional digital image correlation (2D DIC) is now widely accepted and commonly used in the field of experimental mechanics. It directly provides full-field displacements to sub-pixel accuracy and full-field strains by comparing the digital images of a test object surface acquired before and after deformation. In this review, methodologies of the 2D DIC technique for displacement field measurement and strain field estimation are systematically reviewed and discussed. Detailed analyses of the measurement accuracy considering the influences of both experimental conditions and algorithm details are provided. Measures for achieving high accuracy deformation measurement using the 2D DIC technique are also recommended. Since microscale and nanoscale deformation measurement can easily be realized by combining the 2D DIC technique with high-spatial-resolution microscopes, the 2D DIC technique should find more applications in broad areas.

https://iopscience.iop.org/article/10.1088/0957-0233/20/6/062001/pdf

Two-dimensional digital image correlation for in-plane displacement and strain measurement: a review

Basic biomechanical measurements of bone: a tutorial.

Mathematical Handbook for Scientists and Engineers

The following paper summarises a number of international research projects being undertaken to understand the mechanical properties of natural cellulose fibres and composite materials. In particular the use of novel techniques, such as Raman spectroscopy, synchrotron x-ray and half-fringe photoelastic methods of measuring the physical and micromechanical properties of cellulose fibres is reported. Current single fibre testing procedures are also reviewed with emphasis on the end-use in papermaking. The techniques involved in chemically modifying fibres to improve interfacial adhesion in composites are also reviewed, and the use of novel fibre sources such as bacterial and animal cellulose. It is found that there is overlap in current international research into this area, and that there are complementary approaches and therefore further combining of these may make further progress possible. In particular a need to measure locally the adhesion properties and deformation processes of fibres in composites, with different chemical treatments, ought to be a focus of future research.

/pdf/review-current-international-research-into-cellulosic-fibres-3qgs4az0ct.pdf

Review: Current international research into cellulosic fibres and composites

This work is concerned with a new method for testing material properties under uniform plane-stress conditions by means of a specially designed plane specimen. Photoelastic analysis showed that in the significant section of the specimen it is possible to produce uniform plane stress, with high accuracy, subject to the limitation that the principal stresses are of different signs. An important special case of loading produces pure shear on the significant section. The specimen is of particular importance for fiber-composite testing. The experimental results presented are encouraging.

A method to produce uniform plane-stress states with applications to fiber-reinforced materials

Shock absorption of meniscectomized and painful knees: a comparative in vivo study.

An in vivo study of low back pain and shock absorption in the human locomotor system.

This paper presents a "fast and simple" (FAS) detection algorithm based on the digital image correlation for measurement of the surface deformation of planar objects. The proposed algorithm uses only fine search at the pixel level resolution and surface fitting for sub-pixel level. Two different specimens are investigated to explore the feasibility of this proposed algorithm. The displacements calculated by the FAS algorithm are compared with the ones obtained from Newton-Raphson method (N-R) and Enhanced Sequential Similarity Detection Algorithm (ESSDA). The results show that the experimental data are in good agreement with the theoretical solution. The proposed algorithm is found to be much faster than Newton-Raphson method with inferior, yet reasonable, accuracy for displacement and strain evaluation in the cases of uniaxial tension and disk under diametrical compression tests.

/pdf/in-plane-strain-measurement-by-digital-image-correlation-3nrydia9ub.pdf

Arkady Voloshin

Papers

A method to produce uniform plane-stress states with applications to fiber-reinforced materials

Shock absorption of meniscectomized and painful knees: a comparative in vivo study.

An in vivo study of low back pain and shock absorption in the human locomotor system.

In-plane strain measurement by digital image correlation

Wave attenuation in skeletons of young healthy persons.