Propagation of discontinuity waves of any order through an elastic solid saturated with an inviscid fluid

1984 ◽  
Vol 35 (3) ◽  
pp. 373-386 ◽  
Author(s):  
Alessandra Borrelli ◽  
Maria Cristina Patria
Keyword(s):  
Elastic Solid ◽  
Inviscid Fluid ◽  
Discontinuity Waves

scholarly journals A Special Theory of Biphasic Mixtures and Experimental Results for Human Annulus Fibrosus Tested in Confined Compression

1999 ◽  
Vol 122 (2) ◽  
pp. 180-188 ◽  
Author(s):  
Stephen M. Klisch ◽  
Jeffrey C. Lotz
Keyword(s):  
Experimental Data ◽  
Annulus Fibrosus ◽  
Experimental Studies ◽  
Time History ◽  
Elastic Solid ◽  
Special Theory ◽  
Intervertebral Discs ◽  
Inviscid Fluid ◽  
Confined Compression ◽  
Material Constants

A finite deformation mixture theory is used to quantify the mechanical properties of the annulus fibrosus using experimental data obtained from a confined compression protocol. Certain constitutive assumptions are introduced to derive a special mixture of an elastic solid and an inviscid fluid, and the constraint of intrinsic incompressibility is introduced in a manner that is consistent with results obtained for the special theory. Thirty-two annulus fibrosus specimens oriented in axial n=16 and radial n=16 directions were obtained from the middle-lateral portion of intact intervertebral discs from human lumbar spines and tested in a stress-relaxation protocol. Material constants are determined by fitting the theory to experimental data representing the equilibrium stress versus stretch and the surface stress time history curves. No significant differences in material constants due to orientation existed, but significant differences existed due to the choice of theory used to fit the data. In comparison with earlier studies with healthy annular tissue, we report a lower aggregate modulus and a higher initial permeability constant. These differences are explained by the choice of reference configuration for the experimental studies. [S0148-0731(00)01002-5]

Effects of Inserting a Pressensor Film Into Articular Joints on the Actual Contact Mechanics

1998 ◽  
Vol 120 (5) ◽  
pp. 655-659 ◽  
Author(s):  
J. Z. Wu ◽  
W. Herzog ◽  
M. Epstein
Keyword(s):  
Contact Mechanics ◽  
Solid Phase ◽  
Elastic Solid ◽  
Fluid Phase ◽  
Measurement Precision ◽  
Inviscid Fluid ◽  
Articular Joint ◽  
Joint Contact ◽  
Contact Pressures ◽  
Fuji Film

Fuji film has been widely used in studies aimed at obtaining the contact mechanics of articular joints. Once sealed for practical use in biological joints, Fuji Pressensor film has a total effective thickness of 0.30 mm, which is comparable to the cartilage thickness in the joints of many small animals. The average effective elastic modulus of Fuji film is approximately 100 MPa in compression, which is larger by a factor of 100–300 compared to that of normal articular cartilage. Therefore, inserting a Pressensor film into an articular joint will change the contact mechanics of the joint. The measurement precision of the Pressensor film has been determined systematically; however, the changes in contact mechanics associated with inserting the film into joints have not been investigated. This study was aimed at quantifying the changes in the contact mechanics associated with inserting sealed Fuji Pressensor film into joints. Spherical and cylindrical articular joint contact mechanics with and without Pressensor film and for varying degrees of surface congruency were analyzed and compared by using finite element models. The Pressensor film was taken as linearly elastic and the cartilage was assumed to be biphasic, composed of a linear elastic solid phase and an inviscid fluid phase. The present analyses showed that measurements of the joint contact pressures with Fuji Pressensor film will change the maximum true contact pressures by 10–26 percent depending on the loading, geometry of the joints, and the mechanical properties of cartilage. Considering this effect plus the measurement precision of the film (approximately 10 percent), the measured joint contact pressures in a joint may contain errors as large as 14–28 percent.

Material Constants for Human Annulus Fibrosus Depend on Water Content and Reference Configuration

1999 ◽  
Author(s):  
Stephen M. Klisch ◽  
Jeffrey C. Lotz
Keyword(s):  
Water Content ◽  
Annulus Fibrosus ◽  
Elastic Solid ◽  
Special Theory ◽  
Initial Water Content ◽  
Inviscid Fluid ◽  
Confined Compression ◽  
Healthy Human ◽  
Initial Water ◽  
Material Constants

Abstract We apply a special theory of an incompressible mixture of an elastic solid and an inviscid fluid (Klisch and Lotz, 1998) to experimental data for healthy human annulus fibrosus tested in a stress-relaxation confined compression protocol. The material constants revealed no significant differences due to orientation (i.e., axial vs. radial, n = 16). The aggregate modulus and initial permeability constants were significantly different (n = 32) due to the choice of theory used to fit the data (i.e., that of Klisch and Lotz (1998) vs. that of Holmes and Mow (1990)) and were significantly correlated with initial water content.

Mathematical Model of Wave Propagation in Thermo-Magneto-Piezoelectric Elastic Solid Bar Immersed in an Inviscid Fluid

2017 ◽  
Vol 14 (8) ◽  
pp. 3764-3771
Author(s):  
S. R Mahmoud ◽  
E. O Alzahrani ◽  
A. K Alzahrani ◽  
E Ghandourah ◽  
Shafeek A Ghaleb
Keyword(s):  
Mathematical Model ◽  
Wave Propagation ◽  
Elastic Solid ◽  
Inviscid Fluid

scholarly journals Thin plate effects in the Rayleigh–Taylor instability of elastic solids

2006 ◽  
Vol 24 (2) ◽  
pp. 275-282 ◽  
Author(s):  
A. R. PIRIZ ◽  
J. J. LÓPEZ CELA ◽  
M. C. SERNA MORENO ◽  
N. A. TAHIR ◽  
D. H. H. HOFFMANN
Keyword(s):  
Growth Rate ◽  
Initial Conditions ◽  
Elastic Solid ◽  
Taylor Instability ◽  
Inviscid Fluid ◽  
Fluid Interfaces ◽  
Elastic Solids ◽  
Vacuum Interface ◽  
Rayleigh Taylor Instability ◽  
Asymptotic Growth Rate

We perform the analysis of the Rayleigh–Taylor instability of thin perfectly elastic solid plates using the analytical approach recently developed by Piriz and coworkers. The model describes the evolution of the perturbation amplitude from the initial conditions and at relatively long times it yields the asymptotic growth rate. It applies to solid/inviscid fluid interfaces. For the particular case of solid/vacuum interface, the model has been compared with the exact results by Plohr and Sharp and an excellent agreement has been found. In general, thinner plates are found to be more unstable and, in the presence of a fluid below the elastic plate, the growth rate is reduced.

The internal stability of an elastic solid

2000 ◽  
Vol 80 (12) ◽  
pp. 2827-2840 ◽  
Author(s):  
J. W. Morris Jr, C. R. K Renn
Keyword(s):  
Elastic Solid ◽  
Internal Stability
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