An investigation into hyper-elastic behavior of BR/epoxy-polyester hybrid/nanoclay nanocomposites

2017 ◽  
Vol 39 (S4) ◽  
pp. E2028-E2035 ◽  
Author(s):  
Sepideh Zoghi ◽  
Ghasem Naderi ◽  
Shirin Shokoohi
Keyword(s):  
Elastic Behavior ◽  
Hyper Elastic

Fluid–Structure Interaction Models of Bicuspid Aortic Valves: The Effects of Nonfused Cusp Angles

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Karin Lavon ◽  
Rotem Halevi ◽  
Gil Marom ◽  
Sagit Ben Zekry ◽  
Ashraf Hamdan ◽  
...  
Keyword(s):  
Flow Direction ◽  
Fluid Dynamic ◽  
Fluid Structure Interaction ◽  
Jet Flow ◽  
Elastic Behavior ◽  
Principal Stresses ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Biomechanical Models ◽  
Hyper Elastic

Bicuspid aortic valve (BAV) is the most common type of congenital heart disease, occurring in 0.5–2% of the population, where the valve has only two rather than the three normal cusps. Valvular pathologies, such as aortic regurgitation and aortic stenosis, are associated with BAVs, thereby increasing the need for a better understanding of BAV kinematics and geometrical characteristics. The aim of this study is to investigate the influence of the nonfused cusp (NFC) angle in BAV type-1 configuration on the valve's structural and hemodynamic performance. Toward that goal, a parametric fluid–structure interaction (FSI) modeling approach of BAVs is presented. Four FSI models were generated with varying NFC angles between 120 deg and 180 deg. The FSI simulations were based on fully coupled structural and fluid dynamic solvers and corresponded to physiologic values, including the anisotropic hyper-elastic behavior of the tissue. The simulated angles led to different mechanical behavior, such as eccentric jet flow direction with a wider opening shape that was found for the smaller NFC angles, while a narrower opening orifice followed by increased jet flow velocity was observed for the larger NFC angles. Smaller NFC angles led to higher concentrated flow shear stress (FSS) on the NFC during peak systole, while higher maximal principal stresses were found in the raphe region during diastole. The proposed biomechanical models could explain the early failure of BAVs with decreased NFC angles, and suggests that a larger NFC angle is preferable in suture annuloplasty BAV repair surgery.

HYPER-ELASTIC PARAMETER ESTIMATION OF HUMAN HEEL-PAD: A FINITE ELEMENT AND EVOLUTIONARY BASED ALGORITHM

2012 ◽  
Vol 12 (03) ◽  
pp. 1250034 ◽  
Author(s):  
M. M. KHANI ◽  
H. KATOOZIAN ◽  
K. AZMA ◽  
I. NASEH ◽  
A. H. SALIMI
Keyword(s):  
Experimental Data ◽  
Genetic Algorithm ◽  
Finite Element ◽  
Nonlinear Material ◽  
Elastic Behavior ◽  
Diabetic Patients ◽  
Initial Contact ◽  
Heel Pad ◽  
Hyper Elastic ◽  
The Impact

The heel-pad as a biological shock absorber has an important role in the initial contact phase of gait cycle dissipating the impact forces resulted in locomotion. An axisymmetric finite element model of human heel-pad has been generated and the heel-pad experimental data deduced from a published force-deflection graph of the same specimen (Iain R. Spears, Janice E. Miller-Young), Iterative identification task has been used to extract nonlinear material properties describing hyper-elastic behavior of heel-pad. The genetic algorithm was incorporated into estimation process using an interface program. Two parameters of hyper-elastic materials potential energy function represented by Mooney–Rivlin were determined by using the genetic algorithm technique to minimize the displacement error between the experimental data and the corresponding finite element results after a considerable number of iterations. The result can be used for design and construction of synthetic heel-pad and therapeutic foot wear as well as insoles, especially for diabetic patients.

scholarly journals The Role of Pre-Conditioning Frequency in the Experimental Characterization of Hyper-Elastic Materials as Models for Soft Tissue Applications

2016 ◽  
Vol 08 (05) ◽  
pp. 1650066 ◽  
Author(s):  
Serena de Gelidi ◽  
Gianluca Tozzi ◽  
Andrea Bucchi
Keyword(s):  
Experimental Data ◽  
Biological Tissues ◽  
Experimental Simulation ◽  
Elastic Behavior ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Elastic Materials ◽  
Hyper Elastic ◽  
The Impact

Rubber-like materials as many soft tissues can be described as incompressible and hyper-elastic materials. Their comparable elastic behavior, up to a certain extent, has been exploited to develop and test experimental methodologies to be then applied to soft biological tissues such as aortic wall. Hence, theoretical and experimental simulation of aortic tissue, and more generally blood vessel tissue, has been often conducted using rubbers. Despite all the efforts in characterizing such materials, a clear and comprehensive testing procedure is still missing. In particular, the influence of pre-conditioning in the mechanical response of hyper-elastic materials has been often neglected. In this paper, the importance of pre-conditioning is demonstrated by: (i) exploring the effect of stretching frequency applied before the uniaxial tensile test; (ii) recognizing the role of specimen geometry and strain amplitude; (iii) verifying the impact of experimental data acquisition on finite element predictions. It was found that stress–strain relationship shows a statistical difference between some frequencies of pre-conditioning and its absence. Only certain pre-conditioning frequencies were able to generate repeatable experimental data for strip or dumb-bell shapes. This feature corresponds to a consistent reduction in the scatter of critical pressures obtained by numerical simulations.

Parallel Singularities for the Design of Softening Springs Using Compliant Mechanisms

2015 ◽  
Author(s):  
Quentin Boehler ◽  
Marc Vedrines ◽  
Salih Abdelaziz ◽  
Philippe Poignet ◽  
Pierre Renaud
Keyword(s):  
Additive Manufacturing ◽  
Material Properties ◽  
Compliant Mechanisms ◽  
Elastic Behavior ◽  
Necessary Condition ◽  
Hyper Elastic

In this paper, the design of nonlinear softening springs using compliant mechanisms is investigated. The use of compliant structures is of great interest, because of the resulting absence of backlash and friction. We demonstrate that the existence of parallel singularities is a necessary condition for the architecture of a compliant softening spring. From this result, two original arrangements of softening springs are derived, with the introduction of traction and torsion softening springs. A synthesis is performed and the traction spring is numerically and experimentally assessed. As nonlinearity can also be obtained from material properties, the interest of using additive manufacturing with multi-material capability is investigated. Rubber-like materials exhibit a hyper-elastic behavior. Their integration in the proposed compliant architecture is shown to be of interest to customize the geometry of a softening spring according to the designer requirements.

Analysis of Liner Deformation Behaviour in Transtibial Prosthesis

2020 ◽  
Author(s):  
Srinivasa Prakash Regalla ◽  
Kirange Piyush Prashant ◽  
Harshal Vinayak Dhake ◽  
Prakash Narayan Shrivastava
Keyword(s):  
Shear Deformation ◽  
Knee Prosthesis ◽  
Shear Loading ◽  
Elastic Behavior ◽  
Deformation Model ◽  
Elastic Model ◽  
Liner Material ◽  
Prosthetic Socket ◽  
Shear Loads ◽  
Hyper Elastic

Abstract The problems associated with the prostheses for transtibial amputees are related mainly to the fit and comfort. There has been a steady effort to improve the wearability, stability, and durability of the below-knee prosthesis. The liner in the below-knee prosthesis plays a crucial role in ensuring these quality characteristics. Isotropic liner material either acts hard and hence result in discomfort or deforms too much and results in eventual loosening of the prosthetic socket. The material hyper-elastic behavior and thickness are both critical in the design of the liner with optimum comfort. A generalized deformation model taking into account the interaction of the socket, liner, muscle, and tissue becomes cumbersome. In the literature, numerous hyper-elastic models have been applied. Studies on suitability and application of hyper-elastic materials for liner material has not been sufficiently carried out. In this paper, the suitability of liner materials in terms of their ability to allow sufficient elastic deformation in the normal direction for the cushioning effect while undergoing limited shear deformation has been investigated. The hyper-elastic liner and rigid socket pair have been idealized as adhesively bonded flat layers of suitable thicknesses subjected to various combinations of normal and shear loads. The deformations for a normal load and varied range of shear loads have been compared to conclude on the best-suited material model. The low shear deformation observed for all three liner materials implies that the shear loading will not affect the adhesive bond between the liner and socket and hence will not cause loosening with prolonged usage of the prosthetics. The deformation observed was maximum with Ogden 3-parameter hyper-elastic model, whereas it was least in the case when Mooney Rivlin 3-parameter hyper-elastic model. The results obtained for the Mooney-Rivlin 3-parameter model and Neo-Hookean model are very close to each other.

The Mechanical Properties of Mimic Skin

2020 ◽  
Vol 899 ◽  
pp. 73-80
Author(s):  
Nur Nabila Mohd Nazali ◽  
Nur Ani Aniqah Anirad ◽  
Nor Fazli Adull Manan
Keyword(s):  
Mechanical Properties ◽  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Bovine Serum ◽  
Numerical Approach ◽  
Skin Layer ◽  
Elastic Behavior ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Hyper Elastic

This paper focuses on the characterized of the mechanical properties and hyper elastic behavior of lab made skin. Bovine Serum Albumin (BSA) combined with gelatin as a base. BSA is a plasma lead concentrations or heparin plasma which is separated from blood sample and it is not associated with significant changes in iron or hemoglobin concentrations. In general, the gelatin is widely used as the best material for skin substitution since it exhibits the characteristic of human skin. However, the lab made skin layer was made of non-halal type gelatin (Type B). The methodology process started by adding the BSA and using the type A gelatin to carry out the mechanical properties and hy-per elastic behavior of halal lab made skin layer. A uniaxial tensile test standard that being used in this study is ASTM D412. The raw data (Load-Extension) from computational was plotted on graph stress-strain. The numerical approach such as Mooney-Rivlin model and Yeoh’s model were selected to analyze a stress-stretch of composition gelatin and BSA. From the results Mooney-Rivlin model, the con-stant, C1 is in the range of (0.0187-0.0658) MPa and C2 is in the range of (0.0628-0.0737) MPa. Meanwhile the constant, CP for Yeoh model is in the range of (0.0748-0.0861) MPa. As a conclusion, the composition of gelatin and Bovine Serum Albumin is a best combina-tion as it increases the strength of the lab made skin layer. Therefore, the most suitable composition is 10 wt.% of gelatin and Bovine Serum Albumin.

scholarly journals Life Prediction of Rubber Automotive Components Using Finite Element Method

2011 ◽  
Vol 462-463 ◽  
pp. 535-540
Author(s):  
M.S.A. Samad ◽  
Aidy Ali ◽  
Mohd Khairol A. Arifin
Keyword(s):  
Finite Element ◽  
Life Prediction ◽  
Large Strain ◽  
Elastic Behavior ◽  
Element Analysis ◽  
Automotive Components ◽  
The Finite Element Analysis ◽  
Hyper Elastic ◽  
Engine Mount ◽  
Failure Location

The usage of rubbers has always been so important, especially in automotive industries. Rubbers have a hyper elastic behavior which is the ability to withstand very large strain without failure. The normal applications for rubbers are used for shock absorption, sound isolation and mounting. In this study, the predictions of fatigue life of an engine mount of rubber automotive components were presented. The finite element analysis was performed to predict the critical part and the strain output were incorporated into fatigue model for prediction. The predicted result shows agreement in term of failure location of rubber mount.

Electron Microscopy of Metal-Matrix Composites

1970 ◽  
Vol 28 ◽  
pp. 404-405
Author(s):  
A. Lawley ◽  
M. R. Pinnel ◽  
A. Pattnaik
Keyword(s):  
Electron Microscopy ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Critical Evaluation ◽  
Elastic Behavior ◽  
Matrix Composites ◽  
Directionally Solidified ◽  
Fracture Characteristics ◽  
Broad Program

As part of a broad program on composite materials, the role of the interface on the micromechanics of deformation of metal-matrix composites is being studied. The approach is to correlate elastic behavior, micro and macroyielding, flow, and fracture behavior with associated structural detail (dislocation substructure, fracture characteristics) and stress-state. This provides an understanding of the mode of deformation from an atomistic viewpoint; a critical evaluation can then be made of existing models of composite behavior based on continuum mechanics. This paper covers the electron microscopy (transmission, fractography, scanning microscopy) of two distinct forms of composite material: conventional fiber-reinforced (aluminum-stainless steel) and directionally solidified eutectic alloys (aluminum-copper). In the former, the interface is in the form of a compound and/or solid solution whereas in directionally solidified alloys, the interface consists of a precise crystallographic boundary between the two constituents of the eutectic.

Dynamics of Nanoparticle Chain Aggregates of Carbon Under Tension

2003 ◽  
Vol 778 ◽  
Author(s):  
Rajdip Bandyopadhyaya ◽  
Weizhi Rong ◽  
Yong J. Suh ◽  
Sheldon K. Friedlander
Keyword(s):  
Mechanical Properties ◽  
Carbon Black ◽  
Polymer Film ◽  
Elastic Behavior ◽  
Small Strains ◽  
Transmission Electron ◽  
Chain Aggregates ◽  
Nanoparticle Chains ◽  
Reinforcing Filler

AbstractCarbon black in the form of nanoparticle chains is used as a reinforcing filler in elastomers. However, the dynamics of the filler particles under tension and their role in the improvement of the mechanical properties of rubber are not well understood. We have studied experimentally the dynamics of isolated nanoparticle chain aggregates (NCAs) of carbon made by laser ablation, and also that of carbon black embedded in a polymer film. In situ studies of stretching and contraction of such chains in the transmission electron microscope (TEM) were conducted under different maximum values of strain. Stretching causes initially folded NCA to reorganize into a straight, taut configuration. Further stretching leads to either plastic deformation and breakage (at 37.4% strain) or to a partial elastic behavior of the chain at small strains (e.g. 2.3% strain). For all cases the chains were very flexible under tension. Similar reorientation and stretching was observed for carbon black chains embedded in a polymer film. Such flexible and elastic nature of NCAs point towards a possible mechanism of reinforcement of rubber by carbon black fillers.

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