Note: Dynamic strain field mapping with synchrotron X-ray digital image correlation

PurposeThe purpose of this paper is to develop a methodology for in situ stress intensity factor (SIF) determination that can be used for the analysis of cracked structures. The technique is based on digital image correlation (DIC) combined with an overdetermined algorithm.Design/methodology/approachThe linear overdeterministic algorithm for calculating the SIF based on stress values around the crack tip is applied to a strain field obtained by DIC.FindingsAs long as the image quality is sufficiently high, a good accuracy can be obtained for the measured SIF. The crack tip can be automatically detected based on the same strain field. The use of the strain field instead of the displacement field, eliminates problems related to the rigid body motion of the analysed structure.Practical implicationsIn future works, based on the applied techniques, the SIF of complex cracked plane stress structures can be accurately determined in real engineering applications.Originality/valueThe paper demonstrates application of known techniques, refined for other applications, also the use of stress field for SIF overdeterministic calculations.

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A study of the progression of damage in an axially loaded Branta leucopsis femur using X-ray computed tomography and digital image correlation

PeerJ ◽

10.7717/peerj.3416 ◽

2017 ◽

Vol 5 ◽

pp. e3416 ◽

Cited By ~ 2

Author(s):

Zartasha Mustansar ◽

Samuel A. McDonald ◽

William Irvin Sellers ◽

Phillip Lars Manning ◽

Tristan Lowe ◽

...

Keyword(s):

Computed Tomography ◽

Digital Image Correlation ◽

Digital Image ◽

Time Lapse ◽

Image Correlation ◽

Long Bone ◽

Barnacle Goose ◽

3D Images ◽

X Ray ◽

X Ray Computed

This paper uses X-ray computed tomography to track the mechanical response of a vertebrate (Barnacle goose) long bone subjected to an axial compressive load, which is increased gradually until failure. A loading rig was mounted in an X-ray computed tomography system so that a time-lapse sequence of three-dimensional (3D) images of the bone’s internal (cancellous or trabecular) structure could be recorded during loading. Five distinct types of deformation mechanism were observed in the cancellous part of the bone. These were (i) cracking, (ii) thinning (iii) tearing of cell walls and struts, (iv) notch formation, (v) necking and (vi) buckling. The results highlight that bone experiences brittle (notch formation and cracking), ductile (thinning, tearing and necking) and elastic (buckling) modes of deformation. Progressive deformation, leading to cracking was studied in detail using digital image correlation. The resulting strain maps were consistent with mechanisms occurring at a finer-length scale. This paper is the first to capture time-lapse 3D images of a whole long bone subject to loading until failure. The results serve as a unique reference for researchers interested in how bone responds to loading. For those using computer modelling, the study not only provides qualitative information for verification and validation of their simulations but also highlights that constitutive models for bone need to take into account a number of different deformation mechanisms.

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A new methodology to identify minimum strain anatomical lines based on 3-D digital image correlation

Mechanical Sciences ◽

10.5194/ms-8-337-2017 ◽

2017 ◽

Vol 8 (2) ◽

pp. 337-347 ◽

Cited By ~ 2

Author(s):

Jorge Barrios-Muriel ◽

Francisco Javier Alonso Sánchez ◽

David Rodríguez Salgado ◽

Francisco Romero-Sánchez

Keyword(s):

Digital Image Correlation ◽

Digital Image ◽

Strain Field ◽

Three Dimensional ◽

Wearable Devices ◽

Plane Motion ◽

Human Motion ◽

The Body ◽

Image Correlation ◽

Minimum Deformation

Abstract. Today there is continuous development of wearable devices in various fields such as sportswear, orthotics and personal gadgets, among others. The design of these devices involves the human body as a support environment. Based on this premise, the development of wearable devices requires an improved understanding of the skin strain field of the body segment during human motion. This paper presents a methodology based on a three dimensional digital image correlation (3D-DIC) system to measure the skin strain field and to estimate anatomical lines with minimum deformation as design criteria for the aforementioned wearable devices. The errors of displacement and strain measurement related to 3-D reconstruction and out-of-plane motion are investigated and the results are acceptable in the case of large deformation. This approach can be an effective tool to improve the design of wearable devices in the clinical orthopaedics and ergonomics fields, where comfort plays a key role in supporting the rehabilitation process.

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