Microscale parameters variation in biaxial tests

2010 ◽  
pp. 449-451
Author(s):  
Zhongwei Bi ◽  
Qicheng Sun ◽  
Jianguo Liu ◽  
Feng Jin
Keyword(s):  
Biaxial Tests

An octahedral stress-based fracture criterion for hyperelastic materials

2020 ◽  
pp. 095440622097213
Author(s):  
A Hamdi ◽  
A Boulenouar ◽  
N Benseddiq
Keyword(s):  
Pure Shear ◽  
Thermoplastic Elastomer ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Principal Stresses ◽  
Hyperelastic Materials ◽  
Biaxial Tests ◽  
Set Up ◽  
Loading Modes ◽  
Styrene Butadiene

No unified stress-based criterion exists, in the literature, for predicting the rupture of hyperelastic materials subjected to mutiaxial loading paths. This paper aims to establish a generalized rupture criterion under plane stress loading for elastomers. First, the experimental set up, at breaking, including various loading modes, is briefly described and commented. It consists of uniaxial tests, biaxial tests and pure shear tests, performed on different rubbers. The used vulcanizate and thermoplastic rubber materials are a Natural Rubber (NR), a Styrene Butadiene Rubber (SBR), a Polyurethane (PU) and a Thermoplastic elastomer (TPE). Then, we have investigated a new theoretical approach, based upon the principal stresses, to establish a failure criterion under quasi-static loadings. Thus, we have proposed a new analytical model expressed as a function of octahedral stresses. Quite good agreement is highlighted when comparing the ultimate stresses, at break, between the experimental data and the prediction of the proposed criteria using our rubber-like materials.

scholarly journals Study of biaxial mechanical properties of the passive pig heart: material characterisation and categorisation of regional differences

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Fulufhelo Nemavhola
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Computational Models ◽  
Heart Diseases ◽  
Interventricular Septum ◽  
Model Material ◽  
Biaxial Test ◽  
Material Behaviour ◽  
Material Parameters ◽  
Biaxial Tests

AbstractRegional mechanics of the heart is vital in the development of accurate computational models for the pursuit of relevant therapies. Challenges related to heart dysfunctioning are the most important sources of mortality in the world. For example, myocardial infarction (MI) is the foremost killer in sub-Saharan African countries. Mechanical characterisation plays an important role in achieving accurate material behaviour. Material behaviour and constitutive modelling are essential for accurate development of computational models. The biaxial test data was utilised to generated Fung constitutive model material parameters of specific region of the pig myocardium. Also, Choi-Vito constitutive model material parameters were also determined in various myocardia regions. In most cases previously, the mechanical properties of the heart myocardium were assumed to be homogeneous. Most of the computational models developed have assumed that the all three heart regions exhibit similar mechanical properties. Hence, the main objective of this paper is to determine the mechanical material properties of healthy porcine myocardium in three regions, namely left ventricle (LV), mid-wall/interventricular septum (MDW) and right ventricle (RV). The biomechanical properties of the pig heart RV, LV and MDW were characterised using biaxial testing. The biaxial tests show the pig heart myocardium behaves non-linearly, heterogeneously and anisotropically. In this study, it was shown that RV, LV and MDW may exhibit slightly different mechanical properties. Material parameters of two selected constitutive models here may be helpful in regional tissue mechanics, especially for the understanding of various heart diseases and development of new therapies.

Optimizing the Shape and Size of Cruciform Specimens Used for Biaxial Tensile Test

2014 ◽  
Vol 658 ◽  
pp. 167-172 ◽  
Author(s):  
Liviu Andrusca ◽  
Viorel Goanta ◽  
Paul Doru Barsanescu
Keyword(s):  
Mechanical Properties ◽  
Tensile Test ◽  
Continuous Monitoring ◽  
Biaxial Tension ◽  
Cruciform Specimen ◽  
Testing Method ◽  
Biaxial Tests ◽  
Properties Of Materials ◽  
Failure Theories ◽  
Shape And Size

Testing cruciform specimens subjected to biaxial tension is one of the most widely used experimental techniques and more accurate at this time to determine the mechanical properties of materials and to verify the failure theories. This type of experiment allows the continuous monitoring of behavior of materials from the beginning of deformation until fracture under different ratios of forces and directions of the deformation, which transforms it into a very versatile testing method. We have varied the number of parameters and their values in order to achieve a uniform distribution of biaxial state of stresses and strains in the area tested. In theory, any material can be tested by stretching a biaxial cruciform specimen, but must be investigated in what way the shape of the specimen influence the data obtained. In this paper are presented the requirements that must be fulfilled by the samples used for tensile / compression biaxial tests and the design of cruciform specimens through FEA that meet these demands.

scholarly journals Geomechanical modelling of sinkhole development using distinct elements: model verification for a single void space and application to the Dead Sea area

Solid Earth ◽  
2018 ◽  
Vol 9 (6) ◽  
pp. 1341-1373 ◽  
Author(s):  
Djamil Al-Halbouni ◽  
Eoghan P. Holohan ◽  
Abbas Taheri ◽  
Martin P. J. Schöpfer ◽  
Sacha Emam ◽  
...  
Keyword(s):  
Distinct Element ◽  
Cavity Growth ◽  
Dead Sea ◽  
Model Verification ◽  
Void Space ◽  
Ground Collapse ◽  
Biaxial Tests ◽  
Sinkhole Collapse ◽  
The Dead ◽  
Element Method

Abstract. Mechanical and/or chemical removal of material from the subsurface may generate large subsurface cavities, the destabilisation of which can lead to ground collapse and the formation of sinkholes. Numerical simulation of the interaction of cavity growth, host material deformation and overburden collapse is desirable to better understand the sinkhole hazard but is a challenging task due to the involved high strains and material discontinuities. Here, we present 2-D distinct element method numerical simulations of cavity growth and sinkhole development. Firstly, we simulate cavity formation by quasi-static, stepwise removal of material in a single growing zone of an arbitrary geometry and depth. We benchmark this approach against analytical and boundary element method models of a deep void space in a linear elastic material. Secondly, we explore the effects of properties of different uniform materials on cavity stability and sinkhole development. We perform simulated biaxial tests to calibrate macroscopic geotechnical parameters of three model materials representative of those in which sinkholes develop at the Dead Sea shoreline: mud, alluvium and salt. We show that weak materials do not support large cavities, leading to gradual sagging or suffusion-style subsidence. Strong materials support quasi-stable to stable cavities, the overburdens of which may fail suddenly in a caprock or bedrock collapse style. Thirdly, we examine the consequences of layered arrangements of weak and strong materials. We find that these are more susceptible to sinkhole collapse than uniform materials not only due to a lower integrated strength of the overburden but also due to an inhibition of stabilising stress arching. Finally, we compare our model sinkhole geometries to observations at the Ghor Al-Haditha sinkhole site in Jordan. Sinkhole depth ∕ diameter ratios of 0.15 in mud, 0.37 in alluvium and 0.33 in salt are reproduced successfully in the calibrated model materials. The model results suggest that the observed distribution of sinkhole depth ∕ diameter values in each material type may partly reflect sinkhole growth trends.

scholarly journals Large Deformation Characterization of Porcine Thoracic Aortas: Inverse Modeling Fitting of Uniaxial and Biaxial Tests

2015 ◽  
Vol 08 (10) ◽  
pp. 717-732 ◽  
Author(s):  
Jorge O. Virues Delgadillo ◽  
Sebastien Delorme ◽  
Francis Thibault ◽  
Robert DiRaddo ◽  
Savvas G. Hatzikiriakos
Keyword(s):  
Large Deformation ◽  
Inverse Modeling ◽  
Biaxial Tests

scholarly journals Strength characterization of glass/epoxy plain weave composite under different biaxial loading ratios

2020 ◽  
Vol 54 (19) ◽  
pp. 2549-2563
Author(s):  
A Kobeissi ◽  
P Rahme ◽  
L Leotoing ◽  
D Guines
Keyword(s):  
Biaxial Loading ◽  
Central Zone ◽  
Correlation Method ◽  
Axial Loading ◽  
Failure Criteria ◽  
Image Correlation ◽  
Biaxial Test ◽  
Cruciform Specimen ◽  
Plain Weave ◽  
Biaxial Tests

Over the past years, various studies have been investigated in order to characterize the behavior of composite materials under different multi-axial loading conditions. One of the most used biaxial techniques is the in-plane biaxial test on cruciform specimens. To achieve reliable biaxial failure results, the design of the cruciform specimen presents a crucial part. Previous studies show that there is no well-adapted cruciform geometry for the composite biaxial tests. In this paper, an optimal cruciform specimen has been defined numerically for the composite characterization test. The specimen is composed of two aluminum tabs glued on top and bottom side of the plain-weave glass/epoxy composite. Finite element simulations have been carried out in order to study the influence of the aluminum grade and thickness on the stress distribution in the composite. An experimental validation confirms the failure of the specimen in the central zone under three different biaxial tensile ratios. The experimental strains were evaluated using the digital image correlation method. The traction/traction quadrant of the failure envelop was obtained and compared with different failure criteria. The maximum strain criterion shows a good agreement with the experimental results.

Computational Modeling of Human Left Ventricle to Assess the Effects of Trabeculae Carneae on the Diastolic and Systolic Functions

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Fatemeh Fatemifar ◽  
Marc D. Feldman ◽  
Geoffrey D. Clarke ◽  
Ender A. Finol ◽  
Hai-Chao Han
Keyword(s):  
Left Ventricle ◽  
Systolic Function ◽  
Strain Energy Function ◽  
Patient Specific ◽  
Papillary Muscles ◽  
End Diastolic Volume ◽  
Wall Stiffness ◽  
Biaxial Tests ◽  
Cutting Model

Trabeculae carneae are irregular structures that cover the endocardial surfaces of both ventricles and account for a significant portion of human ventricular mass. The role of trabeculae carneae in diastolic and systolic functions of the left ventricle (LV) is not well understood. Thus, the objective of this study was to investigate the functional role of trabeculae carneae in the LV. Finite element (FE) analyses of ventricular functions were conducted for three different models of human LV derived from high-resolution magnetic resonance imaging (MRI). The first model comprised trabeculae carneae and papillary muscles, while the second model had papillary muscles and partial trabeculae carneae, and the third model had a smooth endocardial surface. We customized these patient-specific models with myofiber architecture generated with a rule-based algorithm, diastolic material parameters of Fung strain energy function derived from biaxial tests and adjusted with the empirical Klotz relationship, and myocardial contractility constants optimized for average normal ejection fraction (EF) of the human LV. Results showed that the partial trabeculae cutting model had enlarged end-diastolic volume (EDV), reduced wall stiffness, and even increased end-systolic function, indicating that the absence of trabeculae carneae increased the compliance of the LV during diastole, while maintaining systolic function.

scholarly journals A review and application of the failure criteria on a graphite epoxy under three-point bending test

2019 ◽  
Vol 286 ◽  
pp. 02007
Author(s):  
Y. Benbouras ◽  
M. Bellahkim ◽  
A. Maziri ◽  
E. Mallil ◽  
J. Echaabi
Keyword(s):  
Experimental Study ◽  
Analytical Modeling ◽  
Failure Criteria ◽  
Bending Test ◽  
Three Point Bending ◽  
Biaxial Tests ◽  
Software Program

The application of failure criteria are difficult partly because they are too various and must be validated by biaxial tests, which are expensive to be achieved. In this work, an analytical modeling based on a software program has been elaborated for application of the most general failure criteria and prediction of successive failure. Finally, the results obtained by this analytical modeling show a good correlation with those carried out by experimental study.

Bending Behavior of Plain-Woven Fabric Air Beams: Fluid-Structure Interaction Approach

2006 ◽  
Author(s):  
Paul V. Cavallaro ◽  
Ali M. Sadegh ◽  
Claudia J. Quigley
Keyword(s):  
Finite Element ◽  
Ideal Gas ◽  
Woven Fabric ◽  
Fluid Structure Interactions ◽  
Fluid Structure ◽  
Ideal Gas Law ◽  
Biaxial Tests ◽  
Structural Responses ◽  
Bending Behavior ◽  
Interaction Approach

A swatch of plain-woven fabric was subjected to biaxial tests and its material characterization was performed. The stress-strain relations of the fabric were determined and directly used in finite element models of an air beam, assumed constructed with the same fabric, subjected to inflation and bending events. The structural responses to these events were obtained using the ABAQUS-Explicit[1] finite element solver for a range of pressures including those considered typical in safe operations of air inflated structures. The models accounted for the fluid-structure interactions between the air and the fabric. The air was treated as a compressible fluid in accordance with the Ideal Gas Law and was subjected to adiabatic constraints during bending. The fabric was represented with membrane elements and several constitutive cases including linear elasticity and hyperelasticity were studied. The bending behavior for each constitutive case is presented and discussions for their use and limitations follow.

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