Characterizing chaotic dynamics from simulations of large strain behavior of a granular material under biaxial compression

2013 ◽  
Vol 23 (1) ◽  
pp. 013113 ◽  
Author(s):  
Michael Small ◽  
David M. Walker ◽  
Antoinette Tordesillas ◽  
Chi K. Tse
Keyword(s):  
Granular Material ◽  
Chaotic Dynamics ◽  
Large Strain ◽  
Biaxial Compression ◽  
Strain Behavior

Continuum Description of the Time- and Strain-Dependent Poisson’s Ratio of Ligament Under Finite Deformation

2013 ◽  
Author(s):  
Aaron M. Swedberg ◽  
Shawn P. Reese ◽  
Steve A. Maas ◽  
Benjamin J. Ellis ◽  
Jeffrey A. Weiss
Keyword(s):  
Large Scale ◽  
Mechanical Response ◽  
Tensile Deformation ◽  
Large Strain ◽  
Fiber Direction ◽  
Strain Behavior ◽  
Nonlinear Stress ◽  
Poisson's Ratios ◽  
Poisson’S Ratios ◽  
Strain Dependent

Ligament volumetric behavior controls fluid and thus nutrient movement as well as the mechanical response of the tissue to applied loads. The reported Poisson’s ratios for tendon and ligament subjected to tensile deformation loading along the fiber direction are large, ranging from 0.8 ± 0.3 in rat tail tendon fascicles [1] to 2.98 ± 2.59 in bovine flexor tendon [2]. These Poisson’s ratios are indicative of volume loss and thus fluid exudation [3,4]. We have developed micromechanical finite element models that can reproduce both the characteristic nonlinear stress-strain behavior and large, strain-dependent Poisson’s ratios seen in tendons and ligaments [5], but these models are computationally expensive and unfeasible for large scale, whole joint models. The objectives of this research were to develop an anisotropic, continuum based constitutive model for ligaments and tendons that can describe strain-dependent Poisson’s ratios much larger than the isotropic limit of 0.5. Further, we sought to demonstrate the ability of the model to describe experimental data, and to show that the model can be combined with biphasic theory to describe the rate- and time-dependent behavior of ligament and tendon.

The Strength of Thick-Walled Cylinders

1959 ◽  
Vol 81 (2) ◽  
pp. 95-111 ◽  
Author(s):  
B. Crossland ◽  
S. M. Jorgensen ◽  
J. A. Bones
Keyword(s):  
Shear Stress ◽  
Mild Steel ◽  
Close Agreement ◽  
Large Strain ◽  
Tension Test ◽  
Experimental Results ◽  
Maximum Pressure ◽  
Strain Behavior ◽  
Pressure Tests ◽  
Strain Data

Comprehensive pressure tests have been carried out on thick-walled, closed-ended cylinders made from a mild steel and a hardened and tempered steel, the maximum pressure reached being 94,000 lb/in.2 The complete theoretical behavior of the cylinders is computed from shear stress-strain data obtained from torsion tests and is shown to be in very close agreement with the experimental results. In addition, a method is given for deriving the large strain behavior of the cylinders from tension test data. When compared with the experimental results this approach gives larger errors, the theoretical values of pressure being consistently high. Finally, ultimate pressures have been calculated from two empirical expressions.

scholarly journals Analysis of Reversed Torsion of FCC Metals Using Polycrystal Plasticity Models

2015 ◽  
Vol 07 (03) ◽  
pp. 1550033 ◽  
Author(s):  
X. Q. Guo ◽  
H. Wang ◽  
P. D. Wu ◽  
X. B. Mao
Keyword(s):  
Large Strain ◽  
Texture Evolution ◽  
Constitutive Models ◽  
Stress And Strain ◽  
Fcc Metals ◽  
Strain Behavior ◽  
Polycrystal Plasticity ◽  
Self Consistent ◽  
Overall Performance ◽  
Fixed End

Large strain behavior of FCC polycrystals during reversed torsion are investigated through the special purpose finite element based on the classical Taylor model and the elastic-viscoplastic self-consistent (EVPSC) model with various Self-Consistent Schemes (SCSs). It is found that the response of both the fixed-end and free-end torsion is very sensitive to the constitutive models. The models are assessed through comparing their predictions to the corresponding experiments in terms of the stress and strain curves, the Swift effect and texture evolution. It is demonstrated that none of the models examined can precisely predict all the experimental results. However, more careful observation reveals that, among the models considered, the tangent model gives the worst overall performance. It is also demonstrated that the intensity of residual texture during reverse twisting is dependent on the amounts of pre-shear strain during forward twisting and the model used.

Stress-Strain Behavior of Randomly Crosslinked Polydimethylsiloxane Networks

1982 ◽  
Vol 55 (4) ◽  
pp. 1108-1122
Author(s):  
M. Gottlieb ◽  
C. W. Macosko ◽  
T. C. Lepsch
Keyword(s):  
Large Strain ◽  
Strain Energy Function ◽  
Small Strain ◽  
Careful Analysis ◽  
Relative Magnitude ◽  
Polymer Backbone ◽  
Strain Behavior ◽  
Strain Data ◽  
Crosslinked Networks ◽  
Good Agreement

Abstract We have demonstrated by means of our small-strain data that suppression of junction fluctuations cannot solely account for the discrepancy between experimental modulus values and the predictions of the phantom-network theory. The good agreement between the intercepts in Figures 3 and 4 and the value of GN0 leaves little doubt regarding the relation between the two and the validity of the model represented by Equation (12). Further experiments should be carried out on materials with higher GN0 values than the PDMS chains used here. This will magnify the contribution of trapped entanglements and will demonstrate more clearly the effects discussed here. Further study is also required in order to understand the role played by the polymer backbone on the amount of junction suppression. The question raised by Dossin and Graessley as to whether differences in h values for different networks are due to differences in structure between randomly crosslinked and end-linked networks or to differences in the relative magnitude of topological contributions for different polymers was answered by this work. The agreement of the h value obtained here with those obtained for endlinked PDMS networks indicates that no inherent differences in structure exist between endlinked and crosslinked networks and that differences in polymer backbone are responsible for the values of h obtained. Objections that radiation crosslinked networks are somehow not suitable for testing rubber elasticity theories should also be laid to rest by the good agreement of our results with those of Langley and Polmanteer. The large-strain data obtained here show the ability of Flory's strain energy function to correctly model tension-compression data over the range of crosslink densities covered by this work. Edwards' model did not agree well with our data for low degree of crosslinking samples. Further work is still required since our data exhibited relatively small deviations from Mooney-Rivlin behavior. Finally, the extreme importance of the careful analysis of the materials used, the reaction employed, and the resulting networks was demonstrated. The simplest available method for the verification of the network structure is by the determination of the sol fraction. The extraction of solubles in the case of highly crosslinked networks was found to be susceptible to weighing uncertainty and the presence of unreactive material. The former can be avoided by the use of larger samples, while the latter could be removed by vacuum stripping for our material.

Strain Softening of Aluminum in Shear at Elevated Temperature

2018 ◽  
Vol 941 ◽  
pp. 1490-1494
Author(s):  
Michael E. Kassner ◽  
Roya Ermagan
Keyword(s):  
Elevated Temperature ◽  
Flow Stress ◽  
Single Crystals ◽  
Strain Softening ◽  
Large Strain ◽  
Dislocation Climb ◽  
Taylor Factor ◽  
Shear Texture ◽  
Strain Behavior ◽  
Versus Strain

Large-strain deformation of aluminum in shear consistently evinces strain softening of roughly 15-20%. Most researchers have suggested that this flow stress decrease is a consequence of a decrease in the average Taylor factor as a consequence of a shear-texture. The authors also consider, now, the possibility that changes in the dislocation climb stress induced by the texture could rationalize the softening. This work reports on an analysis of large strain deformation of aluminum single crystals in the softest orientation {111} <110>. Here softening is not observed. However, this result and other in earlier publications are consistent with dislocation climb being the rate-controlling process that also explains the observed stress versus strain behavior.

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