Investigation Into the Biphasic Properties of a Hydrogel for Use in a Cushion Form Replacement Joint

1998 ◽  
Vol 120 (3) ◽  
pp. 362-369 ◽  
Author(s):  
A. A. J. Goldsmith ◽  
S. E. Clift
Keyword(s):  
Articular Cartilage ◽  
Material Properties ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Biphasic Model ◽  
Aggregate Modulus ◽  
Curve Fit ◽  
Potential Applications

A hydrogel with potential applications in the role of a cushion form replacement joint bearing surface material has been investigated. The material properties are required for further development and design studies and have not previously been quantified. Creep indentation experiments were therefore performed on samples of the hydrogel. The biphasic model developed by Mow and co-workers (Mak et al., 1987; Mow et al., 1989a) was used to curve-fit the experimental data to theoretical solutions in order to extract the three intrinsic biphasic material properties of the hydrogel (aggregate modulus, HA, Poisson’s ratio, νs, and permeability, k). Ranges of material properties were determined: aggregate modulus was calculated to be between 18.4 and 27.5 MPa, Poisson’s ratio 0.0–0.307, and permeability 0.012–7.27 × 10−17 m4/Ns. The hydrogel thus had a higher aggregate modulus than values published for natural normal articular cartilage, the Poisson’s ratios were similar to articular cartilage, and finally the hydrogel was found to be less permeable than articular cartilage. The determination of these values will facilitate further numerical analysis of the stress distribution in a cushion form replacement joint.

On the Indentation Testing of Articular Cartilage: Determination of the Effective Poisson’s Ratio Using Two Different-Sized Punches

2008 ◽  
Author(s):  
Eugene T. Kepich ◽  
Roger C. Haut
Keyword(s):  
Articular Cartilage ◽  
Poisson’S Ratio ◽  
Direct Determination ◽  
Collagen Fibers ◽  
Poisson's Ratio ◽  
Compression Tests ◽  
Unconfined Compression ◽  
Collagen Network ◽  
Lateral Expansion

Effective Poisson’s ratio (EPR) of articular cartilage in compression is an important parameter, which is inversely correlated with stiffness of the collagen fibers [1]; and thus, if known, could provide valuable information about integrity of the collagen network in the tissue. Unfortunately, direct determination of the EPR by measuring lateral expansion during unconfined compression tests [2], while being effective, due to it’s destructive nature many times is not desired and/or hard to apply in practice. Optically-determined values of equilibrium EPR for bovine humeral articular cartilage using this method are reported to be in range 0.185±0.0065.

Morphological and Mechanical Property Correlations in Rabbit Tibial Plateau Cartilage Using a Fibril-Reinforced Biphasic Model

2008 ◽  
Author(s):  
Nurit Golenberg ◽  
Eugene Kepich ◽  
Roger C. Haut
Keyword(s):  
Mechanical Properties ◽  
Articular Cartilage ◽  
Poisson’S Ratio ◽  
Tibial Plateau ◽  
Rabbit Model ◽  
Model Analysis ◽  
Poisson's Ratio ◽  
Elastic Model ◽  
Biphasic Model ◽  
Linear Elastic

The rabbit model is often used for the study of the mechanical properties of articular cartilage. In numerous cases the authors are investigating the initiation and progression of osteoarthritis. The studies have shown that the mechanical properties of articular cartilage vary across the medial and lateral compartments of the tibial plateau. A review of these data indicates numerous inconsistencies in the location dependent mechanical properties and correlations with the macroscopic and microscopic characteristics of the tissue. For example, Hoch et al. [1] and Rasanen et al. [2] document a higher equilibrium tissue modulus in the medial than the lateral compartments of the tibial plateau, using a linear elastic model of the cartilage due to Hayes et al. [3]. In contrast, a recent study by Roemhildt el al. [4] documents a lower aggregate modulus in the medial versus the lateral compartments of the plateau, based on a linear biphasic model analysis. The study also documents a lower Poisson’s ratio in the medial than lateral facets, while more surface fissuring is noted in the medial compartment. While this surface morphology explains a higher permeability of the tissue in the medial than lateral compartments, the data are inconsistent with a notion set forth by Kiviranta et al. [5]. Using a fibril reinforced biphasic model analysis, this study would suggest a less structurally intact collagen network in the cartilage would yield a higher Poisson’s ratio in the medial than lateral compartments. These various inconsistencies in mechanical properties across the tibial plateau may be, in part, due to limitations of each computational model. The hypothesis of the current study is that a more structurally-based fibril-reinforced, biphasic model analysis of the rabbit cartilage will correlate better with the macroscopic and microscopic aspects of the tissue across the tibial plateau.

In Situ Measurement of Poisson’s Ratio of Steel Plates During Thermal Processes Using Resonant Modes

2021 ◽  
Author(s):  
Clemens Grünsteidl ◽  
Christian Kerschbaummayr ◽  
Edgar Scherleitner ◽  
Bernhard Reitinger ◽  
Georg Watzl ◽  
...  
Keyword(s):  
Poisson’S Ratio ◽  
Dual Phase Steel ◽  
Steel Plates ◽  
Poisson's Ratio ◽  
Austenitic Phase ◽  
Resonant Modes ◽  
Longitudinal Sound Velocity ◽  
Contact Free

Abstract We demonstrate the determination of the Poisson’s ratio of steel plates during thermal processing based on contact free laser ultrasound measurements. Our method utilizes resonant elastic waves sustained by the plate, provides high amplitudes, and requires only a moderate detection bandwidth. For the analysis, the thickness of the samples does not need to be known. The trend of the measured Poisson’s ratio reveals a phase transformation in dual-phase steel samples. While previous approaches based on the measurement of the longitudinal sound velocity cannot distinguish between the ferritic and austenitic phase above 770°C, the shown method can. If the thickness of the samples is known, the method also provides both sound velocities of the material. The gained complementary information could be used to analyze phase composition of steel from low temperatures up to its melting point.

Metamaterials with enhanced mechanical properties and tuneable Poisson’s ratio

2021 ◽  
Author(s):  
Amer Alomarah ◽  
Syed Masood ◽  
Dong Ruan
Keyword(s):  
Poisson’S Ratio ◽  
Structural Modification ◽  
Mechanical Response ◽  
Good Alternative ◽  
Poisson's Ratio ◽  
Polyamide 12 ◽  
Loading Direction ◽  
Wide Range ◽  
Potential Applications ◽  
Parametric Studies

Abstract This paper reports a structural modification of an auxetic metamaterial with a combination of representative re-entrant and chiral topologies, namely, a re-entrant chiral auxetic (RCA). The main driving force for the structural modification was to overcome the undesirable properties of the RCA metamaterial such as anisotropic mechanical response under uniaxial compression. Additively manufactured polyamide 12 specimens via Multi Jet Fusion (MJF) were quasi-statically compressed along the two in-plane directions. The experimental results confirmed that the modified structure was less sensitive to the loading direction and the deformation was more uniform. Moreover, similar energy absorptions were obtained when the modified metamaterial was crushed along the two in-plane directions. The energy absorptions were improved from 390 to 950 kJ/m³ and from 500 to 1000 kJ/m³ compared with the RCA when they were crushed along the X and Y directions, respectively. The absorbed energy per unit mass (SEA) also improved from 1.4 to 2.9 J/g and from 1.78 to 3.1 J/g compared with that of the RCA under the axial compression along the X and Y directions. Furthermore, parametric studies were performed and the effects of geometric parameters of the modified metamaterial were numerically investigated. Tuneable auxetic feature was obtained. The energy absorption and Poisson’s ratio of the modified metamaterial offer it a good alternative for a wide range of potential applications in the areas such as aerospace, automotive, and human protective equipment.

A Reexamination of the Extraction of Material Properties Using Nanoindentation

2008 ◽  
Author(s):  
B. Poon ◽  
D. Rittel ◽  
G. Ravichandran
Keyword(s):  
Contact Area ◽  
Material Properties ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Nanoindentation Test ◽  
Displacement Curve ◽  
Elastic Solids ◽  
Ratio Effect ◽  
Elastic Plastic ◽  
Tip Radius

The paper reexamines the extraction of material properties using nanoindentation for linearly elastic and elastic-plastic materials. The paper considers indentation performed using a rigid conical indenter, as follows. Linearly elastic solids: The reduction of nanoindentation test data of elastic solids is usually processed using Sneddon’s relation [1], which assumes a linearly elastic infinite half space and an infinitely sharp indenter tip. These assumptions are violated in practical indentation experiments. Since most of the research on the extraction of material properties relies heavily on numerical simulations, we used them to investigate the specimen dimensions required for it to qualify as an infinite body, and the indentation conditions for finite tip radius effect to be negligible. The outcome of this part is firstly, the definition of a “converged” 2D geometry so that additional magnification of the numerical model does not influence the load-displacement curve, and secondly, an explicit relationship between the measured load and displacement that takes into account the finite tip radius. Elastic-plastic solids: Here, the main data reduction technique was proposed by Pharr et al. [2], assuming elastic unloading of a plastic nanoindentation. We investigated the effects of finite tip radius in elastic-plastic indentations and found that the accuracy of the prediction is currently limited by the accurate determination of the projected contact area. This point will be discussed and a new experimental technique to measure the projected contact area will be proposed. The Poisson’s ratio effect in elastic-plastic indentations is found to be different from the linearly elastic case. This leads to the discussion on the applicability of the correction factor (for Poisson’s ratio effect) derived in linear elastic indentations, on elastic-plastic indentations. Finally, a technique to obtain an upper bound estimate of the yield stress for the indented elastic-plastic material (which is an exact estimation for non-hardening materials), will be presented.

Determination of poisson's ratio for polyimide films

1989 ◽  
Vol 29 (16) ◽  
pp. 1107-1110 ◽  
Author(s):  
C. L. Bauer ◽  
R. J. Farris
Keyword(s):  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Polyimide Films
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