On the Poisson's Ratio of the Nucleus Pulposus

2013 ◽  
Vol 135 (10) ◽  
Author(s):  
M. D. Farrell ◽  
P. E. Riches
Keyword(s):  
Strain Rate ◽  
Nucleus Pulposus ◽  
Poisson’S Ratio ◽  
Solid Phase ◽  
Axial Strain ◽  
Intervertebral Disk ◽  
Poisson's Ratio ◽  
Solid Matrix ◽  
Rate Dependency ◽  
Rate Dependent

Existing experimental data on the Poisson's ratio of nucleus pulposus (NP) tissue is limited. This study aims to determine whether the Poisson's ratio of NP tissue is strain-dependent, strain-rate-dependent, or varies with axial location in the disk. Thirty-two cylindrical plugs of bovine tail NP tissue were subjected to ramp-hold unconfined compression to 20% axial strain in 5% increments, at either 30 μm/s or 0.3 μm/s ramp speeds and the radial displacement determined using biaxial video extensometry. Following radial recoil, the true Poisson's ratio of the solid phase of NP tissue increased linearly with increasing strain and demonstrated strain-rate dependency. The latter finding suggests that the solid matrix undergoes stress relaxation during the test. For small strains, we suggest a Poisson's ratio of 0.125 to be used in biphasic models of the intervertebral disk.

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.

Strain-Rate-Dependent Poisson’s Ratio and Stress of Polymer Gels in Solvents Revealed by Ultraslow Stretching

2011 ◽  
Vol 44 (8) ◽  
pp. 3000-3006 ◽  
Author(s):  
Akihiro Konda ◽  
Kenji Urayama ◽  
Toshikazu Takigawa
Keyword(s):  
Strain Rate ◽  
Poisson’S Ratio ◽  
Polymer Gels ◽  
Poisson's Ratio ◽  
Rate Dependent

scholarly journals Dynamic Deformation Behaviour of Chiral Auxetic Lattices at Low and High Strain-Rates

Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 52
Author(s):  
Anja Mauko ◽  
Tomáš Fíla ◽  
Jan Falta ◽  
Petr Koudelka ◽  
Václav Rada ◽  
...  
Keyword(s):  
Strain Rate ◽  
Poisson’S Ratio ◽  
Deformation Process ◽  
Split Hopkinson Pressure Bar ◽  
Impact Testing ◽  
Image Correlation ◽  
Poisson's Ratio ◽  
Rate Dependency ◽  
Strain Rate Dependency ◽  
The Impact

The mechanical behaviour of three different auxetic cellular structures, hexa-chiral 2D, tetra-chiral 2D and tetra-chiral 3D, was experimentally investigated in this study. The structures were produced with the powder bed fusion method (PBF) from an austenitic stainless steel alloy. The fundamental material mechanical properties of the sample structures were determined with classic quasi-static compressive tests, where the deformation process was captured by a high-resolution digital camera. The Split Hopkinson Pressure Bar (SHPB) apparatus was used for dynamic impact testing at two impact velocities to study the strain-rate dependency of the structures. Two synchronised high-speed cameras were used to observe the impact tests. The captured images from both quasi-static and dynamic experiments were processed using a custom digital image correlation (DIC) algorithm to evaluate the displacement/strain fields and the Poisson’s ratio. Predominant auxetic behaviour was observed in all three structures throughout most of the deformation process both under quasi-static and impact loading regimes. The tetra-chiral 2D structure showed the most significant auxetic behaviour. Significant stress enhancement in all tested structures was observed in dynamic testing. The Poisson’s ratio strain-rate dependency was confirmed for all three auxetic structures.

Poisson’s Ratio and Strain Rate Dependency of the Constitutive Behavior of Spinal Dura Mater

2010 ◽  
Vol 38 (3) ◽  
pp. 975-983 ◽  
Author(s):  
Cecilia Persson ◽  
Sam Evans ◽  
Rainy Marsh ◽  
Jon L. Summers ◽  
Richard M. Hall
Keyword(s):  
Strain Rate ◽  
Dura Mater ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Constitutive Behavior ◽  
Rate Dependency ◽  
Strain Rate Dependency

Strain Rate Effect on Shear Behavior of Open-Graded Aggregates

2017 ◽  
Vol 2655 (1) ◽  
pp. 64-70 ◽  
Author(s):  
Thomas Gebrenegus ◽  
Jennifer E. Nicks ◽  
Michael T. Adams
Keyword(s):  
Strain Rate ◽  
Axial Strain ◽  
Shear Behavior ◽  
Strain Rate Effect ◽  
Rate Effect ◽  
Strength Parameter ◽  
Strain Rates ◽  
Rate Dependency ◽  
Confining Stress ◽  
Dilation Angle

Despite their wide application as construction materials in various earthworks built by state and local transportation agencies, the role of physical and mechanical factors in the strength and deformation behavior of crushed, manufactured open-graded aggregates (OGAs) is not well studied. In this investigation, the strain rate dependency of strength–deformation behaviors of two commonly employed crushed aggregates with small (12.7 mm) and large (38.1 mm) sizes is investigated. A 150-mm diameter triaxial testing device was used to conduct a drained compression test at five strain rates, ranging from 0.000083%/s to 0.0083%/s. To evaluate the significance of confining stress and density on the effect of strain rates, the shear tests were conducted at 34 kPa and 207 kPa effective confining stress levels, with the samples compacted at loose (30%) and dense (95%) relative densities. The peak friction angle, maximum dilation angle, secant modulus, and axial strain at which the aggregates started to dilate were determined to evaluate the strain rate effect on the shear behavior of OGAs. The results demonstrate that within the imposed quasistatic strain rate ranges, only the dilation angle showed an increasing trend with the increase in strain rate, whereas other extracted strength parameters were less sensitive to strain rate for both OGAs tested. Hence, the selection of strain rates according to ASTM specifications is appropriate for conducting strength parameter tests, used by practitioners for the design of geotechnical structures, on OGAs under quasistatic conditions.

Characterization of the Mechanical Properties of Monolayer Molybdenum Disulfide Nanosheets Using First Principles

2013 ◽  
Vol 4 (3) ◽  
Author(s):  
R. Ansari ◽  
S. Malakpour ◽  
M. Faghihnasiri ◽  
S. Ajori
Keyword(s):  
Mechanical Properties ◽  
Molybdenum Disulfide ◽  
Poisson’S Ratio ◽  
Density Functional ◽  
Hexagonal Boron Nitride ◽  
Axial Strain ◽  
Poisson's Ratio ◽  
Generalized Gradient ◽  
Shear Moduli ◽  
Molybdenum Disulfide Nanosheets

Recently, synthesized inorganic two-dimensional monolayer nanostructures are very promising to be applied in electronic devices. This article explores the mechanical properties of a monolayer molybdenum disulfide (MoS2) including Young's bulk and shear moduli and Poisson's ratio by applying density functional theory (DFT) calculation based on the generalized gradient approximation (GGA). The results demonstrate that the elastic properties of MoS2 nanosheets are less than those of graphene and hexagonal boron-nitride (h-BN) nanosheets. However, their Poisson's ratio is found to be higher than that of graphene and h-BN nanosheet. It is also observed that due to the special structure of MoS2, the thickness of nanosheet changes when the axial strain is applied.

Strain rate dependence of stiffness and Poisson's ratio of auxetic open cell PU foams

2007 ◽  
Vol 244 (3) ◽  
pp. 955-965 ◽  
Author(s):  
P. Pastorino ◽  
F. Scarpa ◽  
S. Patsias ◽  
J. R. Yates ◽  
S. J. Haake ◽  
...  
Keyword(s):  
Strain Rate ◽  
Poisson’S Ratio ◽  
Rate Dependence ◽  
Strain Rate Dependence ◽  
Poisson's Ratio ◽  
Open Cell ◽  
Pu Foams

The Effects of Temperature, Strain Rate, and Aging on the Poisson’s Ratio of SAC Lead Free Solders

2018 ◽  
Author(s):  
K. M. Rafidh Hassan ◽  
Mohammad S. Alam ◽  
Munshi Basit ◽  
Jeffrey C. Suhling ◽  
Pradeep Lall
Keyword(s):  
Finite Element ◽  
Strain Rate ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Lead Free ◽  
Uniaxial Tensile ◽  
Automatic Data ◽  
Effects Of Temperature ◽  
Lead Free Solders ◽  
Temperature Strain

In this study, we have conducted a combined numerical and experimental study on the Poisson’s ratio of SAC lead free solders. The Poisson’s ratio (PR) is one of the basic mechanical properties used in many material constitutive models. Although often not measured, it is important property in many finite element method (FEM) calculations. The value of the Poisson’s ratio of SAC lead free solders is relatively unexplored compared to other material properties, and for FEA simulations it is typically assumed to be v = 0.3. In the current work, we have shown the effects of the chosen value of the solder joint Poisson’s ratio on the finite element results for BGA components subjected to thermal cycling. In the finite element models, the reliability predictions were based on the Morrow-Darveaux energy-based fatigue model. Several sizes (5, 10, 15 mm) of PBGA components with SAC305 solder joints with 0.4 and 0.8 mm spacing were modeled. The packages were subjected to a time dependent cyclic temperature distribution from −40 to 125 °C. The package assemblies were assumed to be in a stress-free state at 25 °C (room temperature), with no residual stresses induced in the manufacturing process. The simulation results have demonstrated that for specified range of Poisson’s ratio values of 0.15 < v < 0.40, the solder Plastic Work varied over 20% and the Predicted Reliability Varied over 50%. To determine the actual Poisson’s ratio experimentally, uniaxial tensile stress-strain tests were carried out on SAC305 (96.5Sn3.0Ag0.5Cu) specimens using a micro tension/torsion testing machine with two strain rates (0.0001, and 0.00001 (sec−1)), four testing temperatures (T = 25, 50, 75, 100 °C), and several durations of prior aging at T = 125 °C. Deformations and strains in axial and transverse directions were measured using strain gages with automatic data acquisition from LabVIEW software. The recorded transverse strain vs. axial strain data were then fit with a linear regression analysis to determine the Poisson’s ratio values. A test matrix of experiments was developed to study the effects of temperature, strain rate, alloy composition, and solidification cooling profile on the value of solder Poisson’s ratio. The Poisson’s ratio was found to increase with increasing temperature, and decrease with increasing strain rate. Using a slower solidification cooling profile led to an increase in the solder Poisson’s ratio value. Finally, the microstructural coarsening that occurs during isothermal aging lead to an increase in the Poisson’s ratio.

EFFECTS OF STRAIN RATE DEPENDENCY OF MATERIAL PROPERTIES IN LOW VELOCITY IMPACT

2008 ◽  
Vol 22 (09n11) ◽  
pp. 1165-1170 ◽  
Author(s):  
HIROFUMI MINAMOTO ◽  
ROBERT SEIFRIED ◽  
PETER EBERHARD ◽  
SHOZO KAWAMURA
Keyword(s):  
Finite Element ◽  
Strain Rate ◽  
Yield Stress ◽  
Coefficient Of Restitution ◽  
Finite Element Simulations ◽  
Material Behavior ◽  
Rate Dependency ◽  
Rate Dependent ◽  
Strain Rate Dependency ◽  
The Impact

Impact processes are often analyzed using the coefficient of restitution which represents the kinetic energy loss during impact. In this paper the effect of strain rate dependency of the yield stress on the coefficient of restitution is investigated experimentally and numerically for the impact of a steel sphere against a steel rod. Finite Element simulations using strain-rate dependent material behavior are carried out. In addition, Finite Element simulations with elastic-plastic material behavior, which ignore the strain rate dependency, are carried out as well as elastic material behavior. Comparisons between the experiments and the simulations using strain-rate dependent material behavior show good agreement, and also prove the strong dependency of the coefficient of restitution on the strain rate dependency of the yield stress for steel. The results from both, the experiments and the simulations show also the strong influence of the wave propagation in the rod on the coefficient of restitution.

Sign in / Sign up

Export Citation Format

Share Document