scholarly journals Implementing a micromechanical model into a finite element code to simulate the mechanical and microstructural response of arteries

2020 ◽  
Vol 19 (6) ◽  
pp. 2553-2566
Author(s):  
Daniele Bianchi ◽  
Claire Morin ◽  
Pierre Badel
Keyword(s):  
Finite Element ◽  
Mechanical Response ◽  
Micromechanical Model ◽  
Mechanical Tests ◽  
Material Behavior ◽  
The Finite Element Method ◽  
Experimental Findings ◽  
Constitutive Formulation ◽  
Constitutive Parameters ◽  
Computational Strategy

Abstract A computational strategy based on the finite element method for simulating the mechanical response of arterial tissues is herein proposed. The adopted constitutive formulation accounts for rotations of the adventitial collagen fibers and introduces parameters which are directly measurable or well established. Moreover, the refined constitutive model is readily utilized in finite element analyses, enabling the simulation of mechanical tests to reveal the influence of microstructural and histological features on macroscopic material behavior. Employing constitutive parameters supported by histological examinations, the results herein validate the model’s ability to predict the micro- and macroscopic mechanical behavior, closely matching previously observed experimental findings. Finally, the capabilities of the adopted constitutive description are shown investigating the influence of some collagen disorders on the macroscopic mechanical response of the arterial tissues.

A New Micromechanical Model to Study Transformation Plasticity in High-Carbon Steels

2019 ◽  
Author(s):  
Rohit Voothaluru ◽  
Vikram Bedekar ◽  
Praveen Pauskar
Keyword(s):  
Finite Element ◽  
Micromechanical Model ◽  
Inelastic Strain ◽  
Material Model ◽  
Carbon Steels ◽  
Transformation Plasticity ◽  
Element Approach ◽  
In Situ Neutron Diffraction ◽  
Constitutive Formulation

Abstract Hardened steels in engineering applications tend to have gradient microstructures with varying amounts of retained austenite alongside harder phases such as martensite or bainite. However, the metastable austenite can transform into martensite under mechanical loads, resulting in an inelastic strain within the material from the volumetric mismatch between FCC austenite and BCT martensite. In this work, a new constitutive formulation based upon the critical driving force for austenite transformation is presented. The model was implemented into a crystal plasticity formulation, and empirical data from in-situ neutron diffraction was used to determine the local micro-plasticity and transformation plasticity parameters. The results from finite element modeling also show that using a homogenized finite element approach could help to establish a material model that can capture the transformation plasticity within these materials with good accuracy.

Simulation Research of a Type of Pressure Vessel under Complex Loading Part 1 Component Load of the Numerical Analysis

2013 ◽  
Vol 756-759 ◽  
pp. 4656-4661
Author(s):  
Yu Fu Zhang ◽  
Hui Xia Guo ◽  
Jun Chen Li ◽  
Gui Rong Yang ◽  
Ying Ma ◽  
...  
Keyword(s):  
Finite Element ◽  
Pressure Vessel ◽  
Geometric Modeling ◽  
Mechanical Response ◽  
Complex Loading ◽  
Strain Response ◽  
The Finite Element Method ◽  
Key Factors ◽  
Dead Weight ◽  
Simulation Research

Macroscopic mechanical response is one of the key factors in designing pressure vessel. A geometric modeling of pressure vessel was established and the mesh of this modeling then generated by using the finite element simulating methods in software ABAQUS. Loading and boundary conditions of dead weight, hydraulic and uniform internal pressure which often suffered pressure vessel were set and calculated by the finite element method. Stress/strain response of pressure vessel in all kinds of alone loading ways were obtained. The results of finite element simulating were in accordance with those of theoretical calculation which provided useful data for research on mechanical response of pressure vessel under complex loading conditions.

Finite Element Model for Investigating the Thermo-Electro-Mechanical Response of Inhomogeneously Deforming Dielectric Elastomer Actuators

2021 ◽  
Author(s):  
Atul Kumar Sharma ◽  
Aman Khurana ◽  
Manish M. Joglekar
Keyword(s):  
Finite Element ◽  
Mechanical Response ◽  
Element Model ◽  
Dielectric Elastomer ◽  
Material Behavior ◽  
Effect Of Temperature ◽  
Dielectric Elastomer Actuators ◽  
Bending Actuator ◽  
Electromechanical Responses ◽  
Electromechanical Performance

Among the available soft active materials, Dielectric elastomers (DEs) possess the capability of achieving the large actuation strain under the application of high electric field. The material behavior of such elastomers is affected significantly by the change in temperature. This paper reports a 3-D finite element framework based on the coupled nonlinear theory of thermo-electro-elasticity for investigating the thermal effects on the electromechanical performance of inhomogeneously deforming dielectric elastomer actuators (DEAs). The material behavior of the actuator is modeled using the neo-Hookean model of hyperelasticity with temperature dependent shear modulus. An in-house computational code is developed to implement the coupled finite element framework. Firstly, the accuracy of the developed FE code is verified by simulating the temperature effects on the actuation response and pull-in instability of the benchmark homogeneously deforming planar DE actuator. Further, the influence of temperature on the electromechanical responses of complex bi-layered bending actuator and buckling pump actuator involving inhomogeneous deformation is investigated. The numerical framework and the associated inferences can find their potential use in addressing the effect of temperature in the design of electro-active polymer based actuators.

A Finite Element Model for Direction-Dependent Mechanical Response to Nanoindentation of Cortical Bone Allowing for Anisotropic Post-Yield Behavior of the Tissue

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
D. Carnelli ◽  
D. Gastaldi ◽  
V. Sassi ◽  
R. Contro ◽  
C. Ortiz ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Cortical Bone ◽  
Yield Stress ◽  
Bone Tissue ◽  
Mechanical Response ◽  
Experimental Studies ◽  
Element Model ◽  
Yield Behavior ◽  
Constitutive Parameters

A finite element model was developed for numerical simulations of nanoindentation tests on cortical bone. The model allows for anisotropic elastic and post-yield behavior of the tissue. The material model for the post-yield behavior was obtained through a suitable linear transformation of the stress tensor components to define the properties of the real anisotropic material in terms of a fictitious isotropic solid. A tension-compression yield stress mismatch and a direction-dependent yield stress are allowed for. The constitutive parameters are determined on the basis of literature experimental data. Indentation experiments along the axial (the longitudinal direction of long bones) and transverse directions have been simulated with the purpose to calculate the indentation moduli and the tissue hardness in both the indentation directions. The results have shown that the transverse to axial mismatch of indentation moduli was correctly simulated regardless of the constitutive parameters used to describe the post-yield behavior. The axial to transverse hardness mismatch observed in experimental studies (see, for example, Rho et al. [1999, “Elastic Properties of Microstructural Components of Human Bone Tissue as Measured by Nanoindentation,” J. Biomed. Mater. Res., 45, pp. 48–54] for results on human tibial cortical bone) can be correctly simulated through an anisotropic yield constitutive model. Furthermore, previous experimental results have shown that cortical bone tissue subject to nanoindentation does not exhibit piling-up. The numerical model presented in this paper shows that the probe tip-tissue friction and the post-yield deformation modes play a relevant role in this respect; in particular, a small dilatation angle, ruling the volumetric inelastic strain, is required to approach the experimental findings.

Simulation of Asphalt Materials Using Finite Element Micromechanical Model with Damage Mechanics

2003 ◽  
Vol 1832 (1) ◽  
pp. 86-95 ◽  
Author(s):  
Martin H. Sadd ◽  
Qingli Dai ◽  
Venkit Parameswaran ◽  
Arun Shukla
Keyword(s):  
Finite Element ◽  
Damage Mechanics ◽  
Mechanical Load ◽  
Numerical Study ◽  
Micromechanical Model ◽  
Heterogeneous Material ◽  
Material Behavior ◽  
Inelastic Behavior ◽  
Load Carrying ◽  
Asphalt Materials

A theoretical and numerical study of the micromechanical behavior of asphalt concrete was undertaken. Asphalt is a heterogeneous material composed of aggregates, binder cement, and air voids. The load-carrying behavior of such a material is strongly related to the local load transfer between aggregate particles, and this is taken as the microstructural response. Numerical simulation of this material behavior was accomplished by developing a special finite element model that incorporated the mechanical load-carrying response between the aggregates. The finite element scheme incorporated a network of special frame elements, each with a stiffness matrix developed from an approximate elasticity solution of the stress and displacement field in a cementation layer between particle pairs. A damage mechanics approach was then incorporated within this solution, and this approach led to the construction of a softening model capable of predicting typical global inelastic behavior found in asphalt materials. This theory was then implemented within the ABAQUS finite element code to conduct simulations of particular laboratory specimens. A series of model simulations of indirect tension (IDT) tests were conducted to investigate the effect of variation of specimen microstructure on the sample response. Simulation results of the overall sample behavior compared favorably with experimental results. Additional comparisons were made of the evolving damage behavior within the IDT test samples, and numerical results gave reasonable predictions.

scholarly journals Microstructural Modeling of Rheological Mechanical Response for Asphalt Mixture Using an Image-Based Finite Element Approach

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2041 ◽  
Author(s):  
Wenke Huang ◽  
Hao Wang ◽  
Yingmei Yin ◽  
Xiaoning Zhang ◽  
Jie Yuan
Keyword(s):  
Finite Element ◽  
Mechanical Response ◽  
Micromechanical Model ◽  
Asphalt Mixture ◽  
Simulation Software ◽  
Fe Model ◽  
Finite Element Approach ◽  
X Ray ◽  
Element Approach ◽  
Asphalt Mortar

In this paper, an image-based micromechanical model for an asphalt mixture’s rheological mechanical response is introduced. Detailed information on finite element (FE) modeling based on X-ray computed tomography (X-ray CT) is presented. An improved morphological multiscale algorithm was developed to segment the adhesive coarse aggregate images. A classification method to recognize the different classifications of the elemental area for a confining pressure purpose is proposed in this study. Then, the numerical viscoelastic constitutive formulation of asphalt mortar in an FE code was implemented using the simulation software ABAQUS user material subroutine (UMAT). To avoid complex experiments in determining the time-dependent Poisson’s ratio directly, numerous attempts were made to indirectly obtain all material properties in the viscoelastic constitutive model. Finally, the image-based FE model incorporated with the viscoelastic asphalt mortar phase and elastic aggregates was used for triaxial compressive test simulations, and a triaxial creep experiment under different working conditions was conducted to identify and validate the proposed finite element approach. The numerical simulation and experimental results indicate that the three-dimensional microstructural numerical model established can effectively analyze the material’s rheological mechanical response under the effect of triaxial load within the linear viscoelastic range.

A New Framework for Myocardium Constitutive Parameters Estimation

2018 ◽  
Vol 876 ◽  
pp. 128-132
Author(s):  
Yi Qiang Li ◽  
Zhi Qiang Huang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Left Ventricle ◽  
Constitutive Model ◽  
Optimization Algorithm ◽  
Left Ventricular ◽  
Parameters Estimation ◽  
Material Behavior ◽  
Element Analysis ◽  
Constitutive Parameters

In this study, a new inverse analysis framework for estimation of myocardium constitutive parameters is established. In this framework, by using cardiac magnetic resonance image of realistic human left ventricular, a more realistic, finite element analysis model for analyzing the deformation of left ventricle during diastole is introduced. The anisotropic nonlinear Holzapfel-Ogden constitutive model is used to describe the material behavior of myocardium. Estimating the parameters as for the inverse problem of left ventricle deformation, a novel hybrid simplex and particle swarm optimization algorithm is proposed to estimate the parameters of myocardium’s constitutive model. Numerical examples presents that finite element analysis results and the estimated parameters are in good agreement with the experimental data reported in literature, comparing with current optimization algorithm, the presented hybrid optimal algorithm can estimate the constitutive parameters more efficient. The efficiency and validity of the proposed parameter estimation framework is demonstrated.

scholarly journals Finite Element Modeling of Stress Behavior of FGM Nanoplates

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Nguyen Thi Giang
Keyword(s):  
Finite Element ◽  
Mechanical Response ◽  
Shear Deformation Theory ◽  
Numerical Results ◽  
Engineering Practice ◽  
The Finite Element Method ◽  
Maximum Value ◽  
Stress Components ◽  
Distribution Of Stress ◽  
Finite Element Formulations

The mechanical response investigation of nanoplates especially the stress distribution plays a very important role in engineering practice, which is a condition to help test the durability as well as design and use the nanoplate structures most effectively. This pioneering paper uses the finite element method to simulate the stress field of FGM nanoplates based on the first-order shear deformation theory of Mindlin. The finite element formulations are derived by taking into account the effect of the nonlocal coefficient to analyze the mechanical response of nanometer-scale plates. This work presents the distribution of stress components in the xy-plane of plates with different boundary conditions. The numerical results also show clearly that the nonlocal coefficient has a significant influence on the deflection and stress of FGM nanoplates. These numerical results are very new and stunning which clearly show the position of the stress reaching the maximum value. This work is also the basis for scientists in testing the durability of FGM nanoplates.

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