Osmo-inelastic response of the intervertebral disc annulus fibrosus tissue

2020 ◽  
Vol 234 (9) ◽  
pp. 1000-1010
Author(s):  
Amil Derrouiche ◽  
Ameni Zaouali ◽  
Fahmi Zaïri ◽  
Jewan Ismail ◽  
Zhengwei Qu ◽  
...  
Keyword(s):  
Intervertebral Disc ◽  
Annulus Fibrosus ◽  
Mechanical Response ◽  
Rate Sensitivity ◽  
Image Correlation ◽  
Inelastic Response ◽  
Full Field ◽  
Osmotic Effect ◽  
Rate Dependent ◽  
Optical Strain

The aim of this article is to provide some insights on the osmo-inelastic response under stretching of annulus fibrosus of the intervertebral disc. Circumferentially oriented specimens of square cross section, extracted from different regions of bovine cervical discs (ventral-lateral and dorsal-lateral), are tested under different strain-rates and saline concentrations within normal range of strains. An accurate optical strain measuring technique, based upon digital image correlation, is used in order to determine the full-field displacements in the lamellae and fibers planes of the layered soft tissue. Annulus stress–stretch relationships are measured along with full-field transversal strains in the two planes. The mechanical response is found hysteretic, rate-dependent and osmolarity-dependent with a Poisson’s ratio higher than 0.5 in the fibers plane and negative (auxeticity) in the lamellae plane. While the stiffness presents a regional-dependency due to variations in collagen fibers content/orientation, the strain-rate sensitivity of the response is found independent on the region. A significant osmotic effect is found on both the auxetic response in the lamellae plane and the stiffness rate-sensitivity. These local experimental observations will result in more accurate chemo-mechanical modeling of the disc annulus and a clearer multi-scale understanding of the disc intervertebral function.

Digital Image Correlation Method in Measuring the Out of Plane Displacement: A Case Study on an Artificial Intervertebral Disc

2020 ◽  
Author(s):  
Hassan M. Raheem ◽  
Willie “Skip” E. Rochefort ◽  
Brian K. Bay
Keyword(s):  
Digital Image Correlation ◽  
Intervertebral Disc ◽  
Digital Image ◽  
Annulus Fibrosus ◽  
Mechanical Response ◽  
Spinal Column ◽  
Correlation Method ◽  
Image Correlation ◽  
Therapeutic Interventions ◽  
Compression Tests

Abstract We have developed a simple, low-cost, and innovative design — known as a “disc emulator” to mimic the mechanical response of a motion segment (vertebra - intervertebral disc-vertebra) of the human spinal column under axial compression loads. The disc emulator consists of upper and lower components that mimic the human vertebrae and a middle component that represents the annulus fibrosus (AF). This study aims to investigate the effects of changing the stiffness of artificial annulus fibrosus of the disc emulator on the bulging measurements while performing compression tests on the disc emulator. A non-contact measurement — digital image correlation (DIC) — was used for the bulging measurements. The results show that the bulging at the posterior region for the discs without nucleus pulposus (NP) bulged inwards, but the bulging at the posterolateral region was outwards, which accords with the reported behavior of the human disc, for the disc without and with NP regardless of the stiffness of the discs. Changing the stiffness of the artificial annulus fibrosus (AAF) alters the bulging magnitudes in the disc, which shows similar responses with respect to the available data on the human disc. The emulator provides a convenient experimental platform for evaluating normal and pathological disc states and assessing the biomechanics of potential therapeutic interventions.

scholarly journals Multi-Scale Structural and Tensile Mechanical Response of Annulus Fibrosus to Osmotic Loading

2012 ◽  
Author(s):  
Woojin M. Han ◽  
Nandan L. Nerurkar ◽  
Lachlan J. Smith ◽  
Nathan T. Jacobs ◽  
Robert L. Mauck ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Intervertebral Disc ◽  
Mechanical Testing ◽  
Biochemical Composition ◽  
Annulus Fibrosus ◽  
Mechanical Response ◽  
Tissue Level ◽  
Multi Scale ◽  
Osmotic Loading

The annulus fibrosus (AF) is a multi-lamellar fibrocartilagenous ring in the intervertebral disc. The variation of biochemical composition from the outer to the inner AF is largely responsible for the heterogeneous mechanical properties. In vitro tissue-level studies require mechanical testing in aqueous buffers to avoid tissue dehydration. The varying glycosaminoglycan (GAG) contents from outer to inner AF suggest that the response to high and low PBS osmolarity may also be different with radial position. Previous studies in tendon and ligament have been conflicting: soaking tendon fascicles in PBS decreased tensile modulus1 and treating ligament in buffer had no effect on modulus.2

scholarly journals A novel apparatus and methodology for the high frequency mechanical characterisation of ultrasoft materials

2021 ◽  
Vol 250 ◽  
pp. 01033
Author(s):  
Aaron Graham ◽  
Clive R Siviour
Keyword(s):  
Mechanical Response ◽  
Soft Materials ◽  
Biological Tissues ◽  
Image Correlation ◽  
Full Field ◽  
Mechanical Characterisation ◽  
Wide Range ◽  
Experimental Apparatus ◽  
Low Modulus ◽  
Elastic Shear

Characterising the mechanical response of ultra-soft materials is challenging, particularly at high strain rates and frequencies [1]. Time Temperature Superposition (TTS) can sometimes be used to mitigate these limitations [2], however not all materials are suitable for TTS. Biological tissues are particularly difficult to test: in addition to the extreme softness, challenges arise due to specimen inhomogeneity, sensitivity to boundary conditions, natural biological variability, and complex post-mortem changes. In the current study, a novel experimental apparatus and methodology was developed and validated using low modulus silicone elastomers as model materials. The full field visco-elastic shear response was characterised over a wide range of deformation frequencies (100-1000+ Hz) and amplitudes using Digital Image Correlation (DIC) and the Virtual Fields Method (VFM). This methodology allows for the extraction of fullfield material properties that would be difficult or impossible to obtain using traditional engineering techniques.

scholarly journals Nanomechanical Characterization of Canine Femur Bone for Strain Rate Sensitivity in the Quasistatic Range under Dry versus Wet Conditions

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Kun-Lin Lee ◽  
Marta Baldassarri ◽  
Nikhil Gupta ◽  
Dinesh Pinisetty ◽  
Malvin N. Janal ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Strain Rate ◽  
Cross Sections ◽  
Mechanical Response ◽  
Peak Load ◽  
Rate Sensitivity ◽  
Rate Dependent ◽  
Dry Conditions ◽  
Unloading Rate

As a strain rate-dependent material, bone has a different mechanical response to various loads. Our aim was to evaluate the effect of water and different loading/unloading rates on the nanomechanical properties of canine femur cortical bone. Six cross-sections were cut from the diaphysis of six dog femurs and were nanoindented in their cortical area. Both dry and wet conditions were taken into account for three quasistatic trapezoid profiles with a maximum force of 2000 μN (holding time = 30 s) at loading/unloading rates of 10, 100, and 1000 μN/s, respectively. For each specimen,254±9(mean ± SD) indentations were performed under different loading conditions. Significant differences were found for the elastic modulus and hardness between wet and dry conditions (P<0.001). No influence of the loading/unloading rates was observed between groups except for the elastic modulus measured at 1000 μN/s rate under dry conditions (P<0.001) and for the hardness measured at a rate of 10 μN/s under wet conditions (P<0.001). Therefore, for a quasistatic test with peak load of 2000 μN held for 30 s, it is recommended to nanoindent under wet conditions at a loading/unloading rate of 100–1000 μN/s, so the reduced creep effect allows for a more accurate computation of mechanical properties.

Recent Developments in ARCMAC and Related Creep Strain Monitoring Techniques

2011 ◽  
Author(s):  
Aditya Narayanan ◽  
Andy Morris ◽  
Catrin Mair Davies ◽  
John Dear
Keyword(s):  
High Temperature ◽  
Creep Strain ◽  
High Temperatures ◽  
Strain Measurement ◽  
Measurement Techniques ◽  
Image Correlation ◽  
Camera System ◽  
Full Field ◽  
Optical Strain Measurement ◽  
Optical Strain

Developments have been made to E.ON’s Auto-Reference Creep Management and Control (ARCMAC) system to measure strain at high temperature using both Digital Image Correlation (DIC) and conventional ARCMAC techniques. These techniques are aimed at measuring creep strain rate in power plant steam pipes and associated weldments operating at high temperatures and pressures for the purposes of estimation of remaining life of such components. The ARCMAC optical strain measurement system is used to measure point to point strain through the capture and analysis of images of a pair of Inconel gauges, with Silicon Nitride spheres, welded to steam pipe and other components. A modified ARCMAC image capture system has been developed using a DSLR camera, with higher resolution offering the potential to capture DIC images suitable for measuring strain accurately. Development of the system to measure strain using both ARCMAC gauges and DIC at high temperature offers the potential to obtain full-field strain measurement across features such as welds, giving a useful improved research tool for creep evaluation. The recently developed DSLR-ARCMAC camera system has been optimised to measure strain using a number of optical strain measurement techniques, including the ARCMAC strain measurement procedure and DIC. These techniques have been used to measure strain during room temperature tensile tests prior to their use at high temperatures. Following these experiments, creep testing of CMV steel specimens is planned paying particular attention to the evaluation of the ARCMAC system at high temperatures.

On the Calibration of Optical Full-Field Strain Measurement Systems

2006 ◽  
Vol 3-4 ◽  
pp. 397-402 ◽  
Author(s):  
Maurice P. Whelan ◽  
Erwin Hack ◽  
Thorsten Siebert ◽  
Richard L. Burguete ◽  
E.A. Patterson ◽  
...  
Keyword(s):  
Strain Measurement ◽  
Parametric Design ◽  
Image Correlation ◽  
Standard Reference Materials ◽  
Full Field ◽  
Measurement Systems ◽  
Measurement Protocol ◽  
Optical Strain Measurement ◽  
Optical Strain ◽  
Point Bend

There are no standard reference materials suitable for the calibration of full-field optical strain measurement systems. This is hindering the uptake of the technology by industrial end-users since optical metrology instrumentation and procedures cannot be easily integrated into quality assurance systems. The EU-funded SPOTS project is developing a physical reference material (PRM) and measurement protocol that should provide the basis of a calibration standard for establishing the traceability of strain values obtained with optical devices. This paper describes a PRM based on a parametric design of monolithic four-point bend test that can reliably generate a known strain field over a range of specimen sizes. Measurements acquired from strain gauges and LVDTs compared well with data obtained from ESPI, digital image correlation, photoelasticity and thermoelasticity studies, demonstrating excellent repeatability and inter-laboratory reproducibility.

Condition Monitoring of Textiles Using Optical Techniques

2009 ◽  
Vol 413-414 ◽  
pp. 447-454 ◽  
Author(s):  
C.C. Ye ◽  
Janice M. Dulieu-Barton ◽  
A.R. Chambers ◽  
F.J. Lennard ◽  
D.D. Eastop
Keyword(s):  
Mechanical Response ◽  
Adhesive System ◽  
Epoxy Adhesive ◽  
Image Correlation ◽  
Fibre Bragg Grating ◽  
Transfer Coefficients ◽  
Full Field ◽  
Strain Transfer ◽  
Fbg Sensors ◽  
Static Conditions

In the paper it is proposed to use fibre Bragg grating (FBG) sensors to monitor the deformation and strain in a woven textile. Non-contact digital image correlation (DIC) is used to validate the results. The principal objective of the work in this paper is to identify a suitable adhesive for attaching the FBG sensors to tapestries and textiles. To do this, the interfacial interactions of the optical fibre, the textile material and the necessary adhesive must be considered. The performance of two types of adhesive are studied: a PVA conservation adhesive and a two-part epoxy adhesive Araldite 2015. The effect of the application of the adhesives on the mechanical response of the textile is investigated. Full-field stain maps are obtained from the DIC and are used as the basis to characterise the behaviour of the FBG sensors/adhesive system. The strain transfer coefficients and a reinforcement factor are determined under quasi-static conditions. It is shown that the local reinforcement introduced is more significant in the specimen with the FBG bonded using the Araldite adhesive than those with conservation adhesives. Nevertheless, the Araldite adhesive has a better strain transfer coefficient than the conservation adhesive, although not as high as that expect with conventional engineering materials.

Mechanical Response of Aluminium Alloy AA6061 Butt-Welded Joints Subjected to Two Initial Tempers and Different Heat Treatments

2015 ◽  
Vol 752-753 ◽  
pp. 51-54
Author(s):  
A. Alisibramulisi ◽  
Odd Geir Lademo ◽  
Ole Runar Myhr ◽  
Per Kristian Larsen
Keyword(s):  
Aluminium Alloy ◽  
Strain Measurement ◽  
Mechanical Response ◽  
Experimental Studies ◽  
Heat Treatments ◽  
Post Weld Heat Treatment ◽  
Image Correlation ◽  
Response Curves ◽  
Full Field ◽  
Dic Technique

Experimental studies have been carried out on butt-welded specimens of aluminium alloy AA6061. Two tempers; T4 and T6 prior to welding were investigated and the subsequent effects of natural ageing (NA) and post weld heat treatment (PWHT) were assessed. Digital image correlation (DIC) technique was used to obtain full field strain measurement on the transversely loaded tensile specimens. The tensile properties of these specimens are presented in terms of response curves. In addition, hardness profiles were also obtained. Both initial tempers and heat treatments were shown to give a significant effect on the mechanical response of the welded specimens tested.

Use of three-dimensional digital image correlation to evaluate mechanical response of prosthetic systems

2016 ◽  
Vol 41 (1) ◽  
pp. 101-105
Author(s):  
Michelin Alvarez-Camacho ◽  
Victor Alvarez-Guevara ◽  
Carlos Galvan Duque Gastelum ◽  
Daniel Flores Vazquez ◽  
Gerardo Rodriguez-Reyes ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Technical Note ◽  
Image Correlation ◽  
Patient Specific ◽  
Real Patient ◽  
Full Field ◽  
Measurement Protocol

Background and aim:The need of comfortable and safe prosthetic systems is an important challenge for both prosthetists and engineers. The aim of this technical note is to demonstrate the use of three-dimensional digital image correlation to evaluate mechanical response of two prosthetic systems under real patient dynamic loads.Technique:This note describes the use of three-dimensional digital image correlation method to obtain full-field strain and displacement measurements on the surface of two lower limb prostheses for Chopart amputation. It outlines key points of the measurement protocol and illustrates the analysis of critical regions using data obtained on specific points of interest.Discussion:The results show that the use of three-dimensional digital image correlation can be a tool for the prosthetist to optimize the prosthesis considering features related to the material and design, in order to bear with real patient-specific load conditions.Clinical relevanceThree-dimensional digital image correlation can support decision-making on new designs and materials for prosthetics based on quantitative data. Better understanding of mechanical response could also assist prescription for appropriate prosthetic systems.

Validation of Impact Simulations of a Car Bonnet by Full-Field Optical Measurements

2011 ◽  
Vol 70 ◽  
pp. 57-62
Author(s):  
George Lampeas ◽  
Vasilis Pasialis ◽  
Thorsten Siebert ◽  
Mara Feligiotti ◽  
Andrea Pipino
Keyword(s):  
Displacement Field ◽  
High Speed ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Quantitative Information ◽  
Image Correlation ◽  
Optical Measurements ◽  
Optical Techniques ◽  
Full Field ◽  
Dynamic Events

Innovative designs of transport vehicles need to be validated in order to demonstrate reliability and provide confidence. The most common approaches to such designs involve simulations based on Finite Element (FE) analysis, used to study the mechanical response of the structural elements during critical events. These simulations need reliable validation techniques, especially if anisotropic materials, such as fibre reinforced polymers, or complex designs, such as automotive components are considered. It is normal practice to assess the accuracy of numerical results by comparing the predicted values to corresponding experimental data. In this frame, the use of whole field optical techniques has been proven successful in the validation of deformation, strain, or vibration modes [1]. The strength of full-field optical techniques is that the whole displacement field can be visualized and analyzed. By using High Speed cameras, the Digital Image Correlation (DIC) method can be applied to highly non-linear dynamic events and deliver quantitative information about the three-dimensional displacement field [2].

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