MICRO-CONSTITUENT BASED VISCOELASTIC FINITE ELEMENT ANALYSIS OF BIOLOGICAL CELLS

2010 ◽  
Vol 02 (02) ◽  
pp. 229-249 ◽  
Author(s):  
F. CHENG ◽  
G. U. UNNIKRISHNAN ◽  
J. N. REDDY
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Material Properties ◽  
Reaction Force ◽  
Experimental Studies ◽  
Viscoelastic Model ◽  
Material Model ◽  
Outer Cortex ◽  
Element Analysis ◽  
Actin Cortex

A viscoelastic analysis of the biological cell considering the microcellular material properties is carried out in this work. Three separate regions of the cell: the actin cortex, cytoplasm and nucleus are considered. The outer cortex and cytoplasm are modeled using standard linear viscoelastic model (SLS) and standard neo-Hookean viscoelastic solid, and a linear elastic material model is considered for the nucleus. The effect of the material properties of cytoplasm and actin cortex on the derivable parameters from three major experimental studies of magnetic twisting cytometry (MTC) and atomic force microscopy (AFM) and micropipette aspiration (MPA) are analyzed using the finite element method. The bead center displacement for the MTC, reaction force for AFM, and aspiration length ratio for the MPA are the major quantities derived from the finite element analysis. A number of parametric studies are also conducted and it is observed that SLS and SnHS models predict nearly identical results for the material constants.

scholarly journals Inverse Calculation of Timber-CFRP Composite Beams Using Finite Element Analysis

2020 ◽  
Author(s):  
Khaled Saad ◽  
András Lengyel
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Material Properties ◽  
Orthotropic Material ◽  
Material Model ◽  
Flexural Behavior ◽  
Fiber Reinforced Polymers ◽  
Element Analysis ◽  
Linear Elastic ◽  
Timber Beams

This study focuses on the flexural behavior of timber beams externally reinforced using carbon fiber-reinforced polymers (CFRP). Linear and non-linear finite element analysis were proposed and validated by experimental tests carried out on 44 timber beams to inversely determine the material properties of the timber and the CFRP. All the beams have the same geometrical properties and were loaded under four points bending. In this paper the general commercial software ANSYS was used, and three- and two-dimensional numerical models were evaluated for their ability to describe the behavior of the solid timber beams. The linear elastic orthotropic material model was assumed for the timber beams in the linear range and the 3D nonlinear rate-independent generalized anisotropic Hill potential model was assumed to describe the nonlinear behavior of the material. As for the CFRP, a linear elastic orthotropic material model was introduced for the fibers and a linear elastic isotropic model for the epoxy resin. No mechanical model was introduced to describe the interaction between the timber and the CFRP since failure occurred in the tensile zone of the wood. Simulated and measured load-mid-span deflection responses were compared and the material properties for timber-CFRP were numerically determined.

Lifetime Prediction of Tires with Regard to Oxidative Aging5

2008 ◽  
Vol 36 (1) ◽  
pp. 63-79 ◽  
Author(s):  
L. Nasdala ◽  
Y. Wei ◽  
H. Rothert ◽  
M. Kaliske
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Temperature Distribution ◽  
Superposition Principle ◽  
Accelerated Aging ◽  
Material Model ◽  
Aging Behavior ◽  
Element Analysis ◽  
Material Parameters ◽  
Reaction Processes

Abstract It is a challenging task in the design of automobile tires to predict lifetime and performance on the basis of numerical simulations. Several factors have to be taken into account to correctly estimate the aging behavior. This paper focuses on oxygen reaction processes which, apart from mechanical and thermal aspects, effect the tire durability. The material parameters needed to describe the temperature-dependent oxygen diffusion and reaction processes are derived by means of the time–temperature–superposition principle from modulus profiling tests. These experiments are designed to examine the diffusion-limited oxidation (DLO) effect which occurs when accelerated aging tests are performed. For the cord-reinforced rubber composites, homogenization techniques are adopted to obtain effective material parameters (diffusivities and reaction constants). The selection and arrangement of rubber components influence the temperature distribution and the oxygen penetration depth which impact tire durability. The goal of this paper is to establish a finite element analysis based criterion to predict lifetime with respect to oxidative aging. The finite element analysis is carried out in three stages. First the heat generation rate distribution is calculated using a viscoelastic material model. Then the temperature distribution can be determined. In the third step we evaluate the oxygen distribution or rather the oxygen consumption rate, which is a measure for the tire lifetime. Thus, the aging behavior of different kinds of tires can be compared. Numerical examples show how diffusivities, reaction coefficients, and temperature influence the durability of different tire parts. It is found that due to the DLO effect, some interior parts may age slower even if the temperature is increased.

scholarly journals 3D Finite Element Analysis of Rotary Instruments in Root Canal Dentine with Different Elastic Moduli

2021 ◽  
Vol 11 (6) ◽  
pp. 2547 ◽  
Author(s):  
Carlo Prati ◽  
João Paulo Mendes Tribst ◽  
Amanda Maria de Oliveira Dal Piva ◽  
Alexandre Luiz Souto Borges ◽  
Maurizio Ventre ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Root Canal ◽  
Elastic Moduli ◽  
Reaction Force ◽  
Von Mises Stress ◽  
Elastic Behavior ◽  
Element Analysis ◽  
Heat Treated ◽  
Von Mises

The aim of the present investigation was to calculate the stress distribution generated in the root dentine canal during mechanical rotation of five different NiTi endodontic instruments by means of a finite element analysis (FEA). Two conventional alloy NiTi instruments F360 25/04 and F6 Skytaper 25/06, in comparison to three heat treated alloys NiTI Hyflex CM 25/04, Protaper Next 25/06 and One Curve 25/06 were considered and analyzed. The instruments’ flexibility (reaction force) and geometrical features (cross section, conicity) were previously investigated. For each instrument, dentine root canals with two different elastic moduli(18 and 42 GPa) were simulated with defined apical ratios. Ten different CAD instrument models were created and their mechanical behaviors were analyzed by a 3D-FEA. Static structural analyses were performed with a non-failure condition, since a linear elastic behavior was assumed for all components. All the instruments generated a stress area concentration in correspondence to the root canal curvature at approx. 7 mm from the apex. The maximum values were found when instruments were analyzed in the highest elastic modulus dentine canal. Strain and von Mises stress patterns showed a higher concentration in the first part of curved radius of all the instruments. Conventional Ni-Ti endodontic instruments demonstrated higher stress magnitudes, regardless of the conicity of 4% and 6%, and they showed the highest von Mises stress values in sound, as well as in mineralized dentine canals. Heat-treated endodontic instruments with higher flexibility values showed a reduced stress concentration map. Hyflex CM 25/04 displayed the lowest von Mises stress values of, respectively, 35.73 and 44.30 GPa for sound and mineralized dentine. The mechanical behavior of all rotary endodontic instruments was influenced by the different elastic moduli and by the dentine canal rigidity.

scholarly journals On the Design of a Biodegradable POC-HA Polymeric Cardiovascular Stent

2012 ◽  
Author(s):  
Joonas Ponkala ◽  
Mohsin Rizwan ◽  
Panos S. Shiakolas
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Material Properties ◽  
Three Dimensional ◽  
Polymeric Composite ◽  
Coronary Stent ◽  
Element Analysis ◽  
Material Models ◽  
Solid Models ◽  
Biodegradable Stents

The current state of the art in coronary stent technology, tubular structures used to keep the lumen open, is mainly populated by metallic stents coated with certain drugs to increase biocompatibility, even though experimental biodegradable stents have appeared in the horizon. Biodegradable polymeric stent design necessitates accurate characterization of time dependent polymer material properties and mechanical behavior for analysis and optimization. This manuscript presents the process for evaluating material properties for biodegradable biocompatible polymeric composite poly(diol citrate) hydroxyapatite (POC-HA), approaches for identifying material models and three dimensional solid models for finite element analysis and fabrication of a stent. The developed material models were utilized in a nonlinear finite element analysis to evaluate the suitability of the POC-HA material for coronary stent application. In addition, the advantages of using femtosecond laser machining to fabricate the POC-HA stent are discussed showing a machined stent. The methodology presented with additional steps can be applied in the development of a biocompatible and biodegradable polymeric stents.

Strength-based design of a sunflower stalk cutter machine design using finite element analysis and experimental validation

2021 ◽  
pp. 095440622110597
Author(s):  
Gürkan İrsel
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Analysis ◽  
Strain Gage ◽  
Experimental Validation ◽  
Experimental Studies ◽  
Fatigue Analysis ◽  
Structural Stress ◽  
Element Analysis ◽  
Strength Based

In this study, the total algorithm of the strength-based design of the system for mass production has been developed. The proposed algorithm, which includes numerical, analytical, and experimental studies, was implemented through a case study on the strength-based structural design and fatigue analysis of a tractor-mounted sunflower stalk cutting machine (SSCM). The proposed algorithm consists of a systematic engineering approach, material selection and testing, design of the mass criteria suitability, structural stress analysis, computer-aided engineering (CAE), prototype production, experimental validation studies, fatigue calculation based on an FE model and experimental studies (CAE-based fatigue analysis), and an optimization process aimed at minimum weight. Approximately 85% of the system was designed using standard commercially available cross-section beams and elements using the proposed algorithm. The prototype was produced, and an HBM data acquisition system was used to collect the strain gage output. The prototype produced was successful in terms of functionality. Two- and three-dimensional mixed models were used in the structural analysis solution. The structural stress analysis and experimental results with a strain gage were 94.48% compatible in this study. It was determined using nCode DesignLife software that fatigue damage did not occur in the system using the finite element analysis (FEA) and experimental data. The SSCM design adopted a multi-objective genetic algorithm (MOGA) methodology for optimization with ANSYS. With the optimization solved from 422 iterations, a maximum stress value of 57.65 MPa was determined, and a 97.72 kg material was saved compared to the prototype. This study provides a useful methodology for experimental and advanced CAE techniques, especially for further study on complex stress, strain, and fatigue analysis of new systematic designs desired to have an optimum weight to strength ratio.

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