Direct Measurement of the Poisson’s Ratio of Human Patella Cartilage in Tension

2002 ◽  
Vol 124 (2) ◽  
pp. 223-228 ◽  
Author(s):  
Dawn M. Elliott ◽  
Daria A. Narmoneva ◽  
Lori A. Setton
Keyword(s):  
Articular Cartilage ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Surface Zone ◽  
Middle Zone ◽  
Linear Region ◽  
Tension Tests ◽  
Simple Tension ◽  
Viscoelastic Effects ◽  
Direct Measures

Articular cartilage has been shown to exhibit large transverse contractions when loaded in tension, suggesting the existence of large values for the Poisson’s ratio. Previous studies have suggested that this effect is dependent on amplitude of applied strain, so that a single Poisson’s ratio may not be sufficient to describe cartilage behavior. In this study, the Poisson’s ratio (ν), toe region modulus Eo, and linear region modulus E of human patellar articular cartilage were calculated in simple tension tests from optical analysis of the two-dimensional strain fields at equilibrium. The Poisson’s ratio was found to be independent of strain due to the absence of viscoelastic effects during testing. The Poisson’s ratio was found to be significantly higher in the surface zone (1.87±1.11, p<0.01) than in the middle zone (0.62±0.23), with no significant correlation of ν with age of the cartilage. In general, values for Poisson’s ratio were greater than 0.5, suggesting cartilage behavior in tension deviates from isotropy. Reported values for the Poisson’s ratio of cartilage in compression have been much lower than values measured here in tension, reflecting a mechanical contribution of the collagen fibers to anisotropy in tension but not compression. The toe-region modulus Eo was significantly higher in the surface zone (4.51±2.78 MPa, n=8) compared to the middle zone (2.51±1.93 MPa, n=10). In addition, the linear-region modulus E in the surface zone, but not middle zone (3.42±2.17 MPa, n=10), was found to correlate with age R=0.97,p<0.02 with values of surface zone E equal to 23.92±12.29 MPa n=5 for subjects under 70 yr of age, and 4.27±2.89 MPa n=3 for subjects over 70 yr. Moduli values and trends with depth were consistent with previous studies of human and animal cartilage. From direct measures of two independent material properties, ν and E, we calculated a shear modulus, G, which had not been previously reported for cartilage from tensile testing. Calculated values for surface zone G were 3.64±1.80 MPa for subjects under 70 yr old and 0.96±0.69 MPa for subjects over 70 yr old, and were significantly higher in the surface zone than in the middle zone (1.10±0.78 MPa). This study provides an intrinsic measure for the Poisson’s ratio of articular cartilage and its dependence on depth which will be important in understanding the nonlinear tension-compression and anisotropic behaviors of articular cartilage.

Mechanical anisotropy of the human knee articular cartilage in compression

2003 ◽  
Vol 217 (3) ◽  
pp. 215-219 ◽  
Author(s):  
J S Jurvelin ◽  
M D Buschmann ◽  
E B Hunziker
Keyword(s):  
Articular Cartilage ◽  
Poisson’S Ratio ◽  
Articular Surface ◽  
Mechanical Anisotropy ◽  
Poisson's Ratio ◽  
Hydraulic Permeability ◽  
Compression Tests ◽  
Direction Parallel ◽  
Anisotropic Mechanical Properties ◽  
Femoral Groove

Articular cartilage exhibits anisotropic mechanical properties when subjected to tension. However, mechanical anisotropy of mature cartilage in compression is poorly known. In this study, both confined and unconfined compression tests of cylindrical cartilage discs, taken from the adult human patello-femoral groove and cut either perpendicular (normal disc) or parallel (tangential disc) to the articular surface, were utilized to determine possible anisotropy in Young's modulus, E, aggregate modulus, Ha, Poisson's ratio, v and hydraulic permeability, k, of articular cartilage. The results indicated that Ha was significantly higher in the direction parallel to the articular surface as compared with the direction perpendicular to the surface ( Ha = 1.237 ± 0.486 MPa versus Ha = 0.845 ± 0.383 MPa, p = 0.017, n = 10). The values of Poisson's ratio were similar, 0.158 ± 0.148 for normal discs compared with 0.180 ± 0.046 for tangential discs. Analysis using the linear biphasic model revealed that the decrease of permeability during the offset compression of 0–20 per cent was higher ( p = 0.015, n = 10) in normal (from 25.5 × 10− 15 to 1.8 × 10−15 m4/N s) than in tangential (from 12.3 × 10− 15 to 1.3 × 10− 15 m4/N s) discs. Based on the results, it is concluded that the mechanical characteristics of adult femoral groove articular cartilage are anisotropic also during compression. Anisotropy during compression may be essential for normal cartilage function. This property has to be considered when developing advanced theoretical models for cartilage biomechanics.

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.

Effect of Fiber Orientation and Strain Rate on the Nonlinear Uniaxial Tensile Material Properties of Tendon

2003 ◽  
Vol 125 (5) ◽  
pp. 726-731 ◽  
Author(s):  
Heather Anne Lynch ◽  
Wade Johannessen ◽  
Jeffrey P. Wu ◽  
Andrew Jawa ◽  
Dawn M. Elliott
Keyword(s):  
Stress Relaxation ◽  
Strain Rate ◽  
Material Properties ◽  
Poisson’S Ratio ◽  
Constant Strain Rate ◽  
Tensile Tests ◽  
Poisson's Ratio ◽  
Fiber Direction ◽  
Linear Region ◽  
Rate Dependent

Tendons are exposed to complex loading scenarios that can only be quantified by mathematical models, requiring a full knowledge of tendon mechanical properties. This study measured the anisotropic, nonlinear, elastic material properties of tendon. Previous studies have primarily used constant strain-rate tensile tests to determine elastic modulus in the fiber direction. Data for Poisson’s ratio aligned with the fiber direction and all material properties transverse to the fiber direction are sparse. Additionally, it is not known whether quasi-static constant strain-rate tests represent equilibrium elastic tissue behavior. Incremental stress-relaxation and constant strain-rate tensile tests were performed on sheep flexor tendon samples aligned with the tendon fiber direction or transverse to the fiber direction to determine the anisotropic properties of toe-region modulus E0, linear-region modulus (E), and Poisson’s ratio (ν). Among the modulus values calculated, only fiber-aligned linear-region modulus E1 was found to be strain-rate dependent. The E1 calculated from the constant strain-rate tests were significantly greater than the value calculated from incremental stress-relaxation testing. Fiber-aligned toe-region modulus E10=10.5±4.7 MPa and linear-region modulus E1=34.0±15.5 MPa were consistently 2 orders of magnitude greater than transverse moduli (E20=0.055±0.044 MPa,E2=0.157±0.154 MPa). Poisson’s ratio values were not found to be rate-dependent in either the fiber-aligned (ν12=2.98±2.59, n=24) or transverse (ν21=0.488±0.653, n=22) directions, and average Poisson’s ratio values in the fiber-aligned direction were six times greater than in the transverse direction. The lack of strain-rate dependence of transverse properties demonstrates that slow constant strain-rate tests represent elastic properties in the transverse direction. However, the strain-rate dependence demonstrated by the fiber-aligned linear-region modulus suggests that incremental stress-relaxation tests are necessary to determine the equilibrium elastic properties of tendon, and may be more appropriate for determining the properties to be used in elastic mathematical models.

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.

Poisson's ratio of plywood measured by tension test

Holzforschung ◽  
2009 ◽  
Vol 63 (5) ◽  
Author(s):  
Hiroshi Yoshihara
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Poisson’S Ratio ◽  
Tension Test ◽  
Experimental Results ◽  
Poisson's Ratio ◽  
Element Analysis ◽  
Young’S Moduli ◽  
Tension Tests ◽  
Finite Element Calculations

Abstract In this research, Poisson's ratio of plywood as obtained by a tension test was examined by varying the width of the specimen. The tension tests were conducted on five-plywood of lauan (Shorea sp.) with various widths, and Young's moduli and Poisson's ratios of the specimens were measured. Finite element calculations were independently conducted. A comparison of the experimental results with those of finite element analysis revealed that Young's modulus could be obtained properly when the width of the plywood strip varied. In contrast, the width of the plywood strip should be large enough to determine Poisson's ratio properly.

Determination of Poisson’s Ratio of Articular Cartilage by Indentation Using Different-Sized Indenters

2004 ◽  
Vol 126 (2) ◽  
pp. 138-145 ◽  
Author(s):  
Hui Jin ◽  
Jack L. Lewis
Keyword(s):  
Finite Element ◽  
Articular Cartilage ◽  
Nonlinear Equation ◽  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
Young's Modulus ◽  
Indentation Test ◽  
Test Method ◽  
Poisson's Ratio ◽  
Unconfined Compression

Articular cartilage is often characterized as an isotropic elastic material with no interstitial fluid flow during instantaneous and equilibrium conditions, and indentation testing commonly used to deduce material properties of Young’s modulus and Poisson’s ratio. Since only one elastic parameter can be deduced from a single indentation test, some other test method is often used to allow separate measurement of both parameters. In this study, a new method is introduced by which the two material parameters can be obtained using indentation tests alone, without requiring a secondary different type of test. This feature makes the method more suitable for testing small samples in situ. The method takes advantages of the finite layer effect. By indenting the sample twice with different-sized indenters, a nonlinear equation with the Poisson’s ratio as the only unknown can be formed and Poisson’s ratio obtained by solving the nonlinear equation. The method was validated by comparing the predicted Poisson’s ratio for urethane rubber with the manufacturer’s supplied value, and comparing the predicted Young’s modulus for urethane rubber and an elastic foam material with modulii measured by unconfined compression. Anisotropic and nonhomogeneous finite-element (FE) models of the indentation were developed to aid in data interpretation. Applying the method to bovine patellar cartilage, the tissue’s Young’s modulus was found to be 1.79±0.59MPa in instantaneous response and 0.45±0.26MPa in equilibrium, and the Poisson’s ratio 0.503±0.028 and 0.463±0.073 in instantaneous and equilibrium, respectively. The equilibrium Poisson’s ratio obtained in our work was substantially higher than those derived from biphasic indentation theory and those optically measured in an unconfined compression test. The finite element model results and examination of viscoelastic-biphasic models suggest this could be due to viscoelastic, inhomogeneity, and anisotropy effects.

The influence of fibril organization on the mechanical behaviour of articular cartilage

2006 ◽  
Vol 462 (2075) ◽  
pp. 3301-3322 ◽  
Author(s):  
Fulin Lei ◽  
Andras Z Szeri
Keyword(s):  
Articular Cartilage ◽  
Mechanical Behaviour ◽  
Poisson’S Ratio ◽  
Three Dimensional ◽  
Tensile Modulus ◽  
Distribution Functions ◽  
Poisson's Ratio ◽  
Model Parameters ◽  
Microstructural Model ◽  
Single Set

The paper presents a three-dimensional microstructural model that was developed to study both equilibrium and time-dependent mechanical behaviour of articular cartilage. The model is based on consolidation theory and makes use of the structure and the mechanical properties of tissue components. Fibrils provide tensile stiffness in this model, whose geometric orientation is described by distribution functions that can be changed freely, making the model applicable to any particular fibril configuration. The model is capable of quantitatively predicting equilibrium properties of the different tests using a single set of model parameters, and explains the anomaly that small compressive modulus and small Poisson's ratio are observed in unconfined compression while tension is governed by large tensile modulus and large Poisson's ratio.

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