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

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.

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.

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

New method for measuring poisson's ratio in polymer gels

1993 ◽  
Vol 50 (6) ◽  
pp. 1107-1111 ◽  
Author(s):  
Yong Li ◽  
Zhibing Hu ◽  
Chunfang Li
Keyword(s):  
Poisson’S Ratio ◽  
Polymer Gels ◽  
New Method ◽  
Poisson's Ratio

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.

scholarly journals Strain Rate Effect on Mechanical Properties of the 3D-Printed Metamaterial Foams With Tunable Negative Poisson’s Ratio

2021 ◽  
Vol 8 ◽  
Author(s):  
Di Gao ◽  
Bin Wang ◽  
Haoqiang Gao ◽  
Fuguang Ren ◽  
Chunxia Guo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Biomedical Engineering ◽  
Poisson’S Ratio ◽  
Strain Rate Effect ◽  
Rate Effect ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Negative Poisson's Ratio ◽  
Deformation Patterns

As a kind of metamaterial, the negative Poisson’s ratio foams, which expand (shrink) in the transverse direction when stretched (compressed) in the longitudinal direction, have many potential applications in fields such as aerospace and mechanical and biomedical engineering. In this paper, the out-of-plane crushing behaviors of four types of the orthogonal isotropic NPR convex-concave foams (CCF) were extensively studied using an electronic universal testing machine and Instron machine at different strain rates where each test was conducted at a constant compressive velocity under uniaxial compression. Strain rate effect on mechanical properties of these foams is experimentally studied. When the strain rate increases, the compressive force enhancement of the foams is obvious and varies with different specimens. The difference in energy absorption and deformation patterns for these foams between quasi-static and dynamic loading conditions is also analyzed. We find that the deformation patterns for the specimens are not only related to the compressive velocities but also the topologies of the specimens. The research in this paper is expected to be meaningful for the optimization design of the foam structures/materials widely used in the fields of aerospace and mechanical and biomedical engineering.

scholarly journals 3D Printing of Auxetic Shape-Memory Metamaterial Towards Designable Buckling

2021 ◽  
Vol 13 (01) ◽  
pp. 2150011
Author(s):  
Zhenghong Li ◽  
Yuheng Liu ◽  
Yafei Wang ◽  
Haibao Lu ◽  
Ming Lei ◽  
...  
Keyword(s):  
Shape Memory ◽  
Poisson’S Ratio ◽  
Influence Factors ◽  
Maxwell Model ◽  
Thermomechanical Properties ◽  
Poisson's Ratio ◽  
Rate Dependent ◽  
Generalized Maxwell Model ◽  
3D Printed ◽  
Thermomechanical Processes

As one of the most popular 3D printed metamaterials, the auxetic structure with its tunable Poisson’s ratio has attracted huge amount of attention recently. In this study, we designed an auxetic shape-memory metamaterial, which showed designable buckling responses by using the thermomechanically coupled in-plane instability. The influence of viscoelasticity on in-plane moduli and Poisson’s ratios of shape-memory auxetic metamaterial was experimentally investigated. Based on the generalized Maxwell model and finite-element method, the buckling behaviors and their main influence factors were studied. The analytical results and experimental ones showed a good agreement. Thermomechanical properties of the printed metamaterials govern the temperature and strain rate-dependent buckling, and a controllable transition from the negative to positive Poisson’s ratio in the metamaterials can be achieved. Based on the shape memory effect, the buckled state and the Poisson’s ratio of the metamaterials can be tuned by programmed thermomechanical processes. This study provides a simple and efficient way to generate morphing structures using the designable buckling effect.

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