A REVIEW OF THE MECHANICAL STRESSES PREDISPOSING ABDOMINAL AORTIC ANEURYSMAL RUPTURE: UNIAXIAL EXPERIMENTAL APPROACH

2020 ◽  
Vol 20 (08) ◽  
pp. 2030001
Author(s):  
MARIYA ANTONOVA ◽  
SOFIA ANTONOVA ◽  
LYUDMILA SHIKOVA ◽  
MARIA KANEVA ◽  
VALENTIN GOVEDARSKI ◽  
...  
Keyword(s):  
Strain Energy ◽  
Experimental Approach ◽  
Strain Energy Function ◽  
Ultimate Stress ◽  
Physical Parameters ◽  
Stress And Strain ◽  
Cauchy Stress ◽  
Biomechanical Behavior ◽  
Abdominal Aortic ◽  
Experimental Protocols

In this paper, problems concerning the uniaxial experimental investigation of the human abdominal aortic aneurysm (AAA) biomechanical characteristics, concomitant values of the associated Cauchy stress, failure (ultimate) stress in AAA, and the constitutive modeling of AAA are considered. The aim of this paper is to review and compare the disposable experimental data, to reveal the reasons for the high dissipation of the results between studies, and to propound some unification criteria. We examined 22 literature sources published between 1994 and 2017 and compared their results, including our own results. The experiments in the reviewed literature have been designed to obtain the stress–strain characteristics and the failure (ultimate) stress and strain of the aneurysmal tissue. A variety of forms of the strain–energy function (SEF) have been applied in the considered studies to model the biomechanical behavior of the aneurysmal wall. The specimen condition and physical parameters, the experimental protocols, the failure stress and strain, and SEFs differ between studies, contributing to the differences between the final results. We propound some criteria and suggestions for the unification of the experiments leading to the comparable results.

On the Ability of Structural and Phenomenological Hyperelastic Models to Predict the Mechanical Behavior of Biological Tissues Submitted to Multiaxial Loadings

2012 ◽  
Author(s):  
Mathieu Nierenberger ◽  
Yves Rémond ◽  
Saïd Ahzi
Keyword(s):  
Experimental Data ◽  
Mechanical Behavior ◽  
Strain Energy ◽  
Soft Tissues ◽  
Least Squares Method ◽  
Biological Tissues ◽  
Physical Parameters ◽  
Cauchy Stress ◽  
Specific Loading ◽  
Hyperelastic Models

Medical surgery is currently rapidly improving and requires modeling faithfully the mechanical behavior of soft tissues. Various models exist in literature; some of them created for the study of biological materials, and others coming from the field of rubber mechanics. Indeed biological tissues show a mechanical behavior close to the one of rubbers. But while building a model, one has to keep in mind that its parameters should be loading independent and that the model should be able to predict the behavior under complex loading conditions. In addition, keeping physical parameters seems interesting since it allows a bottom up approach taking into account the microstructure of the material. In this study, the authors consider different existing hyperelastic models based on strain energy functions and identify their coefficients successively on single loading stress-stretch curves. The experimental data used, come from a paper by Zemanek dated 2009 and concerning uniaxial, equibiaxial and plane tension tests on porcine arterial walls taken in identical experimental conditions. To achieve identification, the strain energy function of each model is derived differently to provide an expression of the Cauchy stress associated to each loading case. Firstly the parameters of each model are identified on the uniaxial tension curve using a least squares method. Then, keeping the obtained parameters, predictions are made for the two other loading cases (equibiaxial and plane tension) using the associated expressions of stresses. A comparison of these predictions with experimental data is done and allows evaluating the predictive capabilities of each model for the different loading cases. A similar approach is used after swapping the loading types. Since the predictive capabilities of the models are really dependent on the loading chosen to determine their parameters, another type of identification procedure is set up. It consists in adding the residues over the three loading cases during identification. This alternative identification method allows a better agreement between each model and the various types of experiments. This study evaluated the ability of some classical hyperelastic models to be used for a predictive scope after being identified on a specific loading type. Besides it brought to light some existing models which can describe at best the mechanical behavior of biological tissues submitted to various loadings.

Extended Two Compartmental Swelling Stress Model and Isotropic Cauchy Stress Equation for Articular Cartilage Proteoglycans

2007 ◽  
Author(s):  
Sevan R. Oungoulian ◽  
Silvia S. Chen ◽  
Andrew Davol ◽  
Robert L. Sah ◽  
Stephen M. Klisch
Keyword(s):  
Articular Cartilage ◽  
Strain Energy ◽  
Compartmental Model ◽  
Strain Energy Function ◽  
Extended Model ◽  
Cauchy Stress ◽  
Cartilaginous Tissues ◽  
Cartilage Proteoglycans ◽  
Tissue Models ◽  
Total Tissue

Proteoglycans (PGs), a constituent of cartilaginous tissues, have a negative fixed charge (FC) that causes an intratissue swelling stress [1]. This swelling stress is thought to balance tensile stress in the collagen network and contribute to the aggregate modulus of articular cartilage (AC) [1]. Stress constitutive equations that accurately characterize mechanical behavior of individual tissue constituents are crucial for the development of accurate total tissue models. The goal of this study is to extend the range of an existing two compartmental model for PG swelling stress by Basser et al. [1], and develop a continuum level equation for PG Cauchy stress. Specifically, the first aim is to increase the accuracy of the two compartmental model proposed in [1], to a lower range of FC density (FCD) typically found in bovine calf AC. The second aim is to use the extended model to develop a continuum level strain energy function and associated isotropic PG Cauchy stress constitutive equation.

Application and Research of Numerical Simulation for Rubber Like Material with MSC.Marc

2008 ◽  
Vol 575-578 ◽  
pp. 854-858
Author(s):  
Jian Bing Sang ◽  
Bo Liu ◽  
Zhi Liang Wang ◽  
Su Fang Xing ◽  
Jie Chen
Keyword(s):  
Numerical Simulation ◽  
Energy Function ◽  
Strain Energy ◽  
Strain Energy Function ◽  
Stress And Strain ◽  
Perfect Agreement ◽  
Energy Functions ◽  
Material Parameters ◽  
User Subroutine ◽  
Strain Energy Functions

This paper starts with a discussion on the theory of finite deformation and various types strain energy functions of rubber like material, the material parameter of elastic law of Gao[3] is estimated by experiment and numerical simulation. Because there are various types of strain energy functions, a user subroutine is programmed to implement the strain energy function of Gao[3] into the program of MSC.Marc, which offers a convenient method to analyze the stress and strain of rubber-like material with the strain energy function that is needed. Two examples will be presented in this paper to demonstrate the use of the framework for rubber like materials. One is to simulate a foam tube in compression. The other one is to simulate a rectangle board with a circular hole. After numerical analysis, it is proved the numerical results based on Gao model are in perfect agreement with the results based on Mooney model and the estimated material parameters are valid.

scholarly journals Dynamic Mechanical Response and Damage Mechanism of HTPB Propellant under Impact Loading

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3031 ◽  
Author(s):  
Hengning Zhang ◽  
Meng Liu ◽  
Yinggang Miao ◽  
Han Wang ◽  
Tao Chen ◽  
...  
Keyword(s):  
Strain Rate ◽  
Impact Loading ◽  
Strain Energy ◽  
High Speed ◽  
Split Hopkinson Pressure Bar ◽  
Ultimate Stress ◽  
Stress And Strain ◽  
Dynamic Mechanical ◽  
Time Deformation ◽  
Htpb Propellant

The dynamic mechanical behaviors of Hydroxyl-terminated polybutadiene (HTPB) propellant was studied by a split Hopkinson pressure bar apparatus (SHPB) at strain rates ranging from 103 to 104 s−1. The obtained stress–strain curves indicated that the mechanical features, such as ultimate stress and strain energy, were strongly dependent on the strain rate. The real time deformation and fracture evolution of HTPB propellant were captured by a high-speed digital camera accompanied with an SHPB setup. Furthermore, microscopic observation for the post-test specimen was conducted to explore the different damage mechanisms under various conditions of impact loading. The dominated damage characteristics of HTPB propellant were changed from debonding and matrix tearing to multiple cracking modes of ammonium perchlorate (AP) particles, along with the increase of the strain rate. For the first time, the influence of AP particle density on the dynamic response of HTPB propellant was studied by analyzing the strain-rate sensitivity (SRS) index of HTPB propellant with two different filler content (80 wt.% and 85 wt.%), which deduced from a power function of ultimate stress and strain energy density. The result of this study is of significance for evaluating the structural integrity and security of HTPB propellant.

Age Dependency of the Biaxial Biomechanical Behavior of Human Abdominal Aorta

2004 ◽  
Vol 126 (6) ◽  
pp. 815-822 ◽  
Author(s):  
Jonathan P. Vande Geest ◽  
Michael S. Sacks ◽  
David A. Vorp
Keyword(s):  
Experimental Data ◽  
Abdominal Aorta ◽  
Energy Function ◽  
Strain Energy ◽  
Strain Energy Function ◽  
Infrarenal Aorta ◽  
Biomechanical Behavior ◽  
Age Related ◽  
Human Abdominal Aorta ◽  
Group 1

Background: The biomechanical behavior of the human abdominal aorta has been studied with great interest primarily due to its propensity to develop such maladies as atherosclerotic occlusive disease, dissections, and aneurysms. The purpose of this study was to investigate the age-related biaxial biomechanical behavior of human infrarenal aortic tissue. Methods of Approach: A total of 18 samples (13 autopsy, 5 organ donor) were harvested from patients in each of three age groups: Group 1 (<30years old, n=5), Group 2 (between 30 and 60 years old, n=7), and Group 3 (>60years old, n=6). Each specimen was tested biaxially using a tension-controlled protocol which spanned a large portion of the strain plane. Response functions fit to experimental data were used as a tool to guide the appropriate choice of the strain energy function W. Results: Under an equibiaxial tension of 120 N/m, the average peak stretch values in the circumferential direction for Groups 1, 2, and 3 were mean±SD1.46±0.07,1.15±0.07, and 1.11±0.06, respectively, while the peak stretch values in the longitudinal direction were 1.41±0.03,1.19±0.11, and 1.10±0.04, respectively. There were no significant differences between the average longitudinal and circumferential peak stretch within each group p>0.1, but both of these values were significantly less p<0.001 for Groups 2 and 3 when compared to Group 1. Patients in Group 1 were modeled using a polynomial strain energy function W, while patients in Groups 2 and 3 were modeled using an exponential form of W, suggesting an age-dependent shift in the mechanical response of this tissue. Conclusion: The biaxial tensile testing results reported here are, to our knowledge, the first given for the human infrarenal aorta and reinforce the importance of determining the functional form of W from experimental data. Such information may be useful for the clinician or researcher in identifying key changes in the biomechanical response of abdominal aorta in the presence of an aneurysm.

Thermomechanical Fracture on a Pressurized Cylindrical Vessel Induced by a Localized Energy Source

1999 ◽  
Vol 121 (2) ◽  
pp. 160-169
Author(s):  
J. Beraun ◽  
J. K. Chen ◽  
D. Y. Tzou
Keyword(s):  
Energy Source ◽  
Strain Energy ◽  
Integral Transform ◽  
Axial Stress ◽  
Cylindrical Vessel ◽  
Physical Parameters ◽  
Stress And Strain ◽  
Thermally Induced ◽  
Thermally Driven ◽  
Elastic Fracture

Thermally induced elastic fracture around a localized energy source on a pressurized cylindrical vessel is studied in this work. Analytical solutions are obtained via the method of dual integral transform, with emphasis on the identification of the dominating parameters in thermal cracking. Directions for crack extension from the heat source are examined by the stress and strain-energy-based criteria, including the effects of internal pressure and axial stress. Special features include the intrinsic transition between the thermally driven and the mechanically driven fracture patterns. The physical parameters governing such transition are determined.

Mechanical power and hyperelasticity

2017 ◽  
Author(s):  
David J. Steigmann
Keyword(s):  
Energy Function ◽  
Strain Energy ◽  
Strain Energy Function ◽  
Mechanical Power ◽  
Elastic Materials ◽  
Cyclic Motion

This chapter covers the notion of hyperelasticity—the concept that stress is derived from a strain—energy function–by invoking an analogy between elastic materials and springs. Alternatively, it can be derived by invoking a work inequality; the notion that work is required to effect a cyclic motion of the material.

scholarly journals Modelling the Inflation and Elastic Instabilities of Rubber-Like Spherical and Cylindrical Shells Using a New Generalised Neo-Hookean Strain Energy Function

2021 ◽  
Author(s):  
Afshin Anssari-Benam ◽  
Andrea Bucchi ◽  
Giuseppe Saccomandi
Keyword(s):  
Experimental Data ◽  
Energy Function ◽  
Limit Point ◽  
Strain Energy ◽  
Cylindrical Shells ◽  
Strain Energy Function ◽  
Model Parameters ◽  
Wide Range ◽  
Cylindrical Tubes ◽  
Gent Model

AbstractThe application of a newly proposed generalised neo-Hookean strain energy function to the inflation of incompressible rubber-like spherical and cylindrical shells is demonstrated in this paper. The pressure ($P$ P ) – inflation ($\lambda $ λ or $v$ v ) relationships are derived and presented for four shells: thin- and thick-walled spherical balloons, and thin- and thick-walled cylindrical tubes. Characteristics of the inflation curves predicted by the model for the four considered shells are analysed and the critical values of the model parameters for exhibiting the limit-point instability are established. The application of the model to extant experimental datasets procured from studies across 19th to 21st century will be demonstrated, showing favourable agreement between the model and the experimental data. The capability of the model to capture the two characteristic instability phenomena in the inflation of rubber-like materials, namely the limit-point and inflation-jump instabilities, will be made evident from both the theoretical analysis and curve-fitting approaches presented in this study. A comparison with the predictions of the Gent model for the considered data is also demonstrated and is shown that our presented model provides improved fits. Given the simplicity of the model, its ability to fit a wide range of experimental data and capture both limit-point and inflation-jump instabilities, we propose the application of our model to the inflation of rubber-like materials.

Mechanical characterization of a woven multi-layered hyperelastic composite laminate under uniaxial loading

2021 ◽  
pp. 002199832110115
Author(s):  
Shaikbepari Mohmmed Khajamoinuddin ◽  
Aritra Chatterjee ◽  
MR Bhat ◽  
Dineshkumar Harursampath ◽  
Namrata Gundiah
Keyword(s):  
Composite Materials ◽  
Energy Function ◽  
Strain Energy ◽  
Strain Energy Function ◽  
Mechanical Tests ◽  
Stress Strain ◽  
Aerospace Applications ◽  
Envelope Material ◽  
The Individual ◽  
High Dielectric

We characterize the material properties of a woven, multi-layered, hyperelastic composite that is useful as an envelope material for high-altitude stratospheric airships and in the design of other large structures. The composite was fabricated by sandwiching a polyaramid Nomex® core, with good tensile strength, between polyimide Kapton® films with high dielectric constant, and cured with epoxy using a vacuum bagging technique. Uniaxial mechanical tests were used to stretch the individual materials and the composite to failure in the longitudinal and transverse directions respectively. The experimental data for Kapton® were fit to a five-parameter Yeoh form of nonlinear, hyperelastic and isotropic constitutive model. Image analysis of the Nomex® sheets, obtained using scanning electron microscopy, demonstrate two families of symmetrically oriented fibers at 69.3°± 7.4° and 129°± 5.3°. Stress-strain results for Nomex® were fit to a nonlinear and orthotropic Holzapfel-Gasser-Ogden (HGO) hyperelastic model with two fiber families. We used a linear decomposition of the strain energy function for the composite, based on the individual strain energy functions for Kapton® and Nomex®, obtained using experimental results. A rule of mixtures approach, using volume fractions of individual constituents present in the composite during specimen fabrication, was used to formulate the strain energy function for the composite. Model results for the composite were in good agreement with experimental stress-strain data. Constitutive properties for woven composite materials, combining nonlinear elastic properties within a composite materials framework, are required in the design of laminated pretensioned structures for civil engineering and in aerospace applications.

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