scholarly journals Permanent set and stress-softening constitutive equation applied to rubber-like materials and soft tissues

2013 ◽  
Vol 225 (6) ◽  
pp. 1685-1698 ◽  
Author(s):  
M. Rebouah ◽  
G. Chagnon
Keyword(s):  
Constitutive Equation ◽  
Soft Tissues ◽  
Stress Softening ◽  
Permanent Set

scholarly journals Effect of sample preservation on stress softening and permanent set of porcine skin

2015 ◽  
Vol 48 (12) ◽  
pp. 3135-3141 ◽  
Author(s):  
A.S. Caro-Bretelle ◽  
P.N. Gountsop ◽  
P. Ienny ◽  
R. Leger ◽  
S. Corn ◽  
...  
Keyword(s):  
Porcine Skin ◽  
Sample Preservation ◽  
Stress Softening ◽  
Permanent Set

STUDY ON MECHANICAL CHARACTERIZATION OF LIVER TISSUE BASED ON HAPTIC DEVICES FOR VIRTUAL SURGICAL SIMULATION

2016 ◽  
Vol 16 (08) ◽  
pp. 1640016 ◽  
Author(s):  
JING YANG ◽  
LINGTAO YU ◽  
LAN WANG ◽  
HONGYANG LI ◽  
QI AN
Keyword(s):  
Soft Tissue ◽  
Constitutive Equation ◽  
Soft Tissues ◽  
Mechanical Characterization ◽  
Surgical Simulation ◽  
Surgical Instruments ◽  
Compression Tests ◽  
Haptic Devices ◽  
Liver Tissues

In recent years, virtual surgical simulation has been one of the hot direction of digital medical research, it is mainly used in teaching, training, diagnosis, preoperative planning, rehabilitation and modeling and analysis of surgical instruments. The modeling of soft tissue of human organs is the basis to realize the virtual surgical simulation. The quasi-linear viscoelastic (QLV) theory has been proposed by Fung, and it was widely used for modeling the constitutive equation of soft tissues. The purpose of this study is to determine the mechanical characterization of the liver soft tissue based on the PHANTOM Omni Haptic devices. Five parameters are included in the constitutive equation with QLV theory, which must be determined experimentally. The specimens were obtained from fresh porcine liver tissues in vitro. The liver tissues were cut into 14[Formula: see text]mm[Formula: see text][Formula: see text][Formula: see text]14[Formula: see text]mm[Formula: see text][Formula: see text][Formula: see text]14[Formula: see text]mm cubes. Two types of unconfined compression tests were performed on cube liver specimens. Puncture tests were performed on the complete liver. The material parameters of the QLV constitutive equation were obtained by fitting the experimental data. These parameters will provide the references for the computational modeling of the liver in the virtual surgical simulation.

scholarly journals Characterisation of Skin Biomechanical Properties via Experiment-Numerical Integration

2018 ◽  
Vol 7 (4.26) ◽  
pp. 205
Author(s):  
Nor Fazli Adull Manan ◽  
Linasuriani Muhamad ◽  
Zurri Adam Mohd Adnan ◽  
Mohd Azman Yahaya ◽  
Jamaluddin Mahmud
Keyword(s):  
Mechanical Properties ◽  
Constitutive Equation ◽  
Numerical Integration ◽  
Soft Tissues ◽  
Biomechanical Properties ◽  
Test Machine ◽  
Medical Sciences ◽  
Ogden Model ◽  
Hyperelastic Model ◽  
Load Displacement

By having specific mechanical properties of skin, computational program and analysis become more reliable by showing the real skin behaviour. Up to date, mechanical properties of biological soft tissues (skin) haven’t been accepted solely for official usage. Therefore, characterisation of the skin biomechanical properties might contribute a new knowledge to the engineering and medical sciences societies. This paper highlights the success in characterising the hyperelastic parameters of leporine (rabbit) skin via experimental-numerical integration. A set of five sample of leporine skin were stretched using the conventional tensile test machine to generate the load-displacement graphs. Based on the Ogden’s constitutive equation and Mooney-Rivlin hyperelastic model, a stress-stretch equation was developed and a programme was written using Matlab. By varying the Ogden’s and Mooney-Rivlin’s parameters, the programme was capable of plotting stress-stretch and load-displacement graphs. The graphs that best match the experimental results will constitut to the corresponding coefficient, µ, and α for Ogden Model and C1 and C2 material parameter for Mooney-Rivlin Model that will best describe the behaviour of the leporine skin. The current results show that the Ogden’s coefficient and exponent for the subject was estimated to be (μ = 0.048MPa, α = 7.073) & (μ = 0.020MPa, α = 9.249) for Anterior-Posterior (AP) and Dorsal-Ventral (DV) respectively for Ogden Model. Meanwhile the value for Mooney-Rivlin Model were estimated to be (C1 = 1.271, C2 = 1.868) & (C1 = 1.128, C2 = 1.537) for AP and DV respectively, which is in close agreement to results found by other researchers. Further analyses for comparison could be carried out by developing mathematical model based on other constitutive equation such as Arruda-Boyce and Neo-Hookean. Nevertheless, this study has contributed to the knowledge about skin behaviour and the results are useful for references.  

scholarly journals Constitutive modeling of stress softening and permanent set in a porcine skin tissue: Impact of the storage preservation

2016 ◽  
Vol 49 (13) ◽  
pp. 2863-2869 ◽  
Author(s):  
A.S Caro-Bretelle ◽  
P. Ienny ◽  
R. Leger ◽  
S. Corn ◽  
I. Bazin ◽  
...  
Keyword(s):  
Constitutive Modeling ◽  
Skin Tissue ◽  
Porcine Skin ◽  
Stress Softening ◽  
Permanent Set

Stress Softening in Natural Rubber Vulcanizates III. Carbon Black Filled Vulcanizates

1966 ◽  
Vol 39 (5) ◽  
pp. 1544-1552 ◽  
Author(s):  
J. A. C. Harwood ◽  
A. R. Payne
Keyword(s):  
Carbon Black ◽  
Amplification Factor ◽  
Mullins Effect ◽  
Factor X ◽  
Stress Strain ◽  
Stress Softening ◽  
Permanent Set ◽  
Different Types ◽  
Hydrodynamic Effects ◽  
Natural Rubber Vulcanizates

Abstract This paper has confirmed the conclusions of the previous paper that the stress softening (Mullins effect) of a black-loaded vulcanizate is similar in magnitude to the stress softening of a gum rubber if the two vulcanizates are stretched initially to the same stress. The initial stress used in the present work was 180 kg/cm2, which is very near to the breaking stress of these vulcanizates. The similarity of the normalized stress-strain curves for all the vulcanizates, both gum and loaded with 60 phr of different types of black, suggests that the main difference between the stress-strain characteristics of a filled and a pure gum rubber, after the initial stressing cycle, can be accounted for by the strain amplification factor X. The more reinforcing blacks possess the higher X factors, i.e., they stiffen the rubber more than, for example, a fine thermal black. It is concluded that the black is acting mainly in a stiffening capacity due to the hydrodynamic effects of the degenerate carbon black networks. For sulfur crosslinked pure gum vulcanizates, in which the crosslinks are polysulfidic, the stress softening is partly associated with the breakage of polysulfide linkages. These reform in the extended condition and produce a real permanent set, but the major stress softening is attributed to the incomplete recovery of the crosslinked network to its initial random state due to network junctions or similar associations being displaced in a nonaffine way during extension. For example, junctions at the ends of chains which become fully extended at relatively low extensions will be displaced in this way. Thus when the rubber is subsequently strained, the network is already in a preferred disposition.

Inflation of a Thick-Walled Shell Which Exhibits Stress Softening

1998 ◽  
Vol 65 (1) ◽  
pp. 46-50 ◽  
Author(s):  
J. B. Haddow ◽  
J. L. Wegner
Keyword(s):  
Internal Pressure ◽  
Strain Softening ◽  
Complete Removal ◽  
Mullins Effect ◽  
Stress Softening ◽  
Permanent Set ◽  
Virgin State ◽  
Rubberlike Material ◽  
As Stress

The Mullins effect (Mullins, 1947), also known as stress softening, is exhibited by certain rubberlike materials and refers to changes of the mechanical properties, due to prior deformation. Johnson and Beatty (1995) have investigated the Mullins effect in equibiaxial tension by performing cycles of static inflation and deflation experiments on latex balloons. These experiments show that stress softening results in a decrease in the pressure necessary to inflate a balloon, and in addition, indicate inelastic effects of hysteresis and permanent set. The objective of this paper is to investigate the finite deformation static inflation from the virgin state, followed by quasi-static removal of the internal pressure, of a thick-walled homogeneous spherical shell composed of an incompressible isotropic rubberlike material which exhibits stress softening and permanent set. Since the initial inflation of the shell, due to application of an internal pressure, does not result in a homogeneous deformation, a state of residual stress is present after complete removal of the internal pressure. A procedure is presented for the determination of the response of the shell for the first cycle of inflation and deflation from the virgin state, and the analysis includes strain softening and the inelastic effects of hysteresis and permanent set. It is assumed that, for the initial static inflation of the shell from the virgin state, the internal pressure and stress distribution for a monotonically increasing internal or external radius are the same as for a hyperelastic shell, and also that the magnitude of the permanent set of an element of the material is related monotonically to the deformation at the end of the inflation.

Physical Invariant Constitutive Equation for Soft Tissues

2013 ◽  
Vol 432 ◽  
pp. 196-201 ◽  
Author(s):  
M.H.B.M. Shariff
Keyword(s):  
Constitutive Equation ◽  
Principal Axis ◽  
Soft Tissues ◽  
Strain Energy Function ◽  
Transversely Isotropic ◽  
General Function ◽  
Anisotropic Problems ◽  
Isotropic Elasticity ◽  
Transversely Isotropic Solids ◽  
Isotropic Solids

Principal axis formulations are regularly used in isotropic elasticity but they are not often used in dealing with anisotropic problems. In this paper, based on a principal axis technique, we develop a physical invariant constitutive equation for incompressible transversely isotropic solids, where it contains only a one variable (general) function. The corresponding strain energy function depends on four invariants that have immediate physical interpretation. These invariants are useful in facilitating an experiment to obtain a specific constitutive equation for a particular type of materials. The explicit appearance of the classical ground state constants in the constitutive equation simplifies the calculation for their admissible values. A specific constitutive model is proposed for soft tissues and the model fits reasonably well with existing experimental data; it is also able to accurately predict experiment data.

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