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

2012 ◽  
Vol 40 (7) ◽  
pp. 1610-1621 ◽  
Author(s):  
Woojin M. Han ◽  
Nandan L. Nerurkar ◽  
Lachlan J. Smith ◽  
Nathan T. Jacobs ◽  
Robert L. Mauck ◽  
...  
Keyword(s):  
Annulus Fibrosus ◽  
Mechanical Response ◽  
Multi Scale ◽  
Osmotic Loading

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

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.

Mesenchymal Stem Cell Seeded Nanofibrous Laminates Mimic the Multi-Scale Form and Function of the Annulus Fibrosus

2009 ◽  
Author(s):  
Nandan K. Nerurkar ◽  
Sounok Sen ◽  
Emily E. Wible ◽  
Jeffrey B. Stambough ◽  
Dawn M. Elliott ◽  
...  
Keyword(s):  
Annulus Fibrosus ◽  
Form And Function ◽  
Multi Scale ◽  
Aligned Arrays ◽  
Tensile Response ◽  
Nanofibrous Scaffolds ◽  
Multiple Length Scales ◽  
Spine Function ◽  
And Function ◽  
High Degree

The annulus fibrosus (AF) of the intervertebral disc is a multi-lamellar fibrocartilage that, together with the nucleus pulposus, confers mechanical support and flexibility to the spine. Function of the AF is predicated on a high degree of structural organization over multiple length scales: aligned collagen fibers reside within each lamella, and the direction of alignment alternates between adjacent lamellae from +30° to −30° with respect to the transverse axis of the spine. Electrospinning permits fabrication of scaffolds consisting of aligned arrays of nanofibers, and has proven effective for directing the alignment of both cells and extracellular matrix (ECM) deposition [1–3]. We recently employed electrospinning to engineer the primary functional unit of the AF, a single lamella [4]. However, it remains a challenge to engineer a multi-lamellar tissue that replicates the cross-ply fiber architecture of the native AF. Moreover, relatively few studies have considered functional properties of engineered AF, and, when measured, tensile properties of these constructs have been inferior to native AF [4]. In this study, mesenchymal stem cells (MSCs) were seeded onto aligned nanofibrous scaffolds organized into bi-lamellar constructs with opposing or parallel fiber orientations, and their functional maturation was evaluated with time. Additionally, we determined a novel role for inter-lamellar ECM in reinforcing the tensile response of bilayers, and confirmed this mechanism by testing acellular bilayers with controllable interface properties.

scholarly journals Multi-scale modelling of rubber-like materials and soft tissues: an appraisal

2016 ◽  
Vol 472 (2187) ◽  
pp. 20160060 ◽  
Author(s):  
G. Puglisi ◽  
G. Saccomandi
Keyword(s):  
Mathematical Models ◽  
Phenomenological Models ◽  
Mechanical Behaviour ◽  
Soft Tissues ◽  
Mechanical Response ◽  
Multi Scale ◽  
Bioinspired Materials ◽  
Macroscopic Properties ◽  
Network Scale ◽  
Scale Modelling

We survey, in a partial way, multi-scale approaches for the modelling of rubber-like and soft tissues and compare them with classical macroscopic phenomenological models. Our aim is to show how it is possible to obtain practical mathematical models for the mechanical behaviour of these materials incorporating mesoscopic (network scale) information. Multi-scale approaches are crucial for the theoretical comprehension and prediction of the complex mechanical response of these materials. Moreover, such models are fundamental in the perspective of the design, through manipulation at the micro- and nano-scales, of new polymeric and bioinspired materials with exceptional macroscopic properties.

scholarly journals Micro- and Nano-Scales Three-Dimensional Characterisation of Softwood

2021 ◽  
Vol 7 (12) ◽  
pp. 263
Author(s):  
Alessandra Patera ◽  
Anne Bonnin ◽  
Rajmund Mokso
Keyword(s):  
Mechanical Response ◽  
Three Dimensional ◽  
Deep Understanding ◽  
Swelling Behaviour ◽  
Multi Scale ◽  
Non Invasive ◽  
X Ray Imaging ◽  
New Findings ◽  
Bordered Pits ◽  
Paul Scherrer

Understanding the mechanical response of cellular biological materials to environmental stimuli is of fundamental importance from an engineering perspective in composites. To provide a deep understanding of their behaviour, an exhaustive analytical and experimental protocol is required. Attention is focused on softwood but the approach can be applied to a range of cellular materials. This work presents a new non-invasive multi-scale approach for the investigation of the hygro-mechanical behaviour of softwood. At the TOMCAT beamline of the Paul Scherrer Institute, in Switzerland, the swelling behaviour of softwood was probed at the cellular and sub-cellular scales by means of 3D high-resolution phase-contrast X-ray imaging. At the cellular scale, new findings in the anisotropic and reversible swelling behaviour of softwood and in the origin of swelling hysteresis of porous materials are explained from a mechanical perspective. However, the mechanical and moisture properties of wood highly depend on sub-cellular features of the wood cell wall, such as bordered pits, yielding local deformations during a full hygroscopic loading protocol.

A computational multi-scale approach for the stochastic mechanical response of foam-filled honeycomb cores

2012 ◽  
Vol 94 (5) ◽  
pp. 1861-1870 ◽  
Author(s):  
E.I. Saavedra Flores ◽  
F.A. DiazDelaO ◽  
M.I. Friswell ◽  
J. Sienz
Keyword(s):  
Mechanical Response ◽  
Multi Scale ◽  
Foam Filled ◽  
Honeycomb Cores

REORIENTATION OF FIBRES AND LOCAL MECHANISMS OF DEFORMATION IN A WOOD-INSPIRED COMPOSITE

2012 ◽  
Vol 04 (01) ◽  
pp. 1250003
Author(s):  
E. I. SAAVEDRA FLORES ◽  
M. S. MURUGAN ◽  
M. I. FRISWELL ◽  
E. A. DE SOUZA NETO
Keyword(s):  
Mechanical Response ◽  
Local Deformation ◽  
Simple Expression ◽  
Deformation And Failure ◽  
Multi Scale ◽  
Wide Range ◽  
Present Composite ◽  
Computational Homogenisation ◽  
Mechanisms Of Deformation ◽  
Good Agreement

This paper investigates the reorientation of fibres and local mechanisms of deformation in a composite material inspired by the mechanics and structure of wood cell-walls. The mechanical response of the material is calculated under tensile loading conditions by means of the computational homogenisation of a two-dimensional representative volume element (RVE) of material. Here, the fibres are represented by a periodic alternation of alumina and magnesium alloy fractions, embedded in a soft epoxy matrix. In order to validate the present multi-scale framework, we compare our numerical prediction for the reorientation of fibres in the wood cell-wall composite with experimental data, finding a good agreement for a wide range of strains. Numerical simulations show that the model is able to describe the reorientation of fibres and the different stages of local deformation and failure in the proposed wood-inspired material. Furthermore, we assess a simple expression to calculate the reorientation of fibres and the in-plane Poisson's ratio of the present composite.

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.

A Multi-Scale Modeling and Experimental Program for the Dynamic Mechanical Response of Tissue

2014 ◽  
Author(s):  
Jay Schieber ◽  
David Gidalevitz ◽  
Joseph Orgel ◽  
Victor Perez-Luna
Keyword(s):  
Mechanical Response ◽  
Experimental Program ◽  
Dynamic Mechanical ◽  
Multi Scale ◽  
Scale Modeling ◽  
Multi Scale Modeling
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