A Finite Element Model of Skin Subjected to a Flash Fire

1994 ◽  
Vol 116 (3) ◽  
pp. 250-255 ◽  
Author(s):  
D. A. Torvi ◽  
J. D. Dale
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Closed Form Solution ◽  
Blood Perfusion ◽  
Element Model ◽  
Form Solution ◽  
Bioheat Transfer ◽  
Multiple Layer ◽  
Degree Burn ◽  
Flash Fire

A variable property, multiple layer finite element model was developed to predict skin temperatures and times to second and third degree burns under simulated flash fire conditions. A sensitivity study of burn predictions to variations in thermal physical properties of skin was undertaken using this model. It was found that variations in these properties over the ranges used in multiple layer skin models had minimal effects on second degree burn predictions, but large effects on third degree burn predictions. It was also found that the blood perfusion source term in Pennes’ bioheat transfer equation could be neglected in predicting second and third degree burns due to flash fires. The predictions from this model were also compared with those from the closed form solution of this equation, which has been used in the literature for making burn predictions from accidents similar to flash fires.

Identification of cracks in an Euler–Bernoulli beam using Bayesian inference and closed-form solution of vibration modes

2020 ◽  
pp. 146442072096971
Author(s):  
Tianyu Wang ◽  
Mohammad Noori ◽  
Wael A. Altabey
Keyword(s):  
Finite Element ◽  
Bayesian Inference ◽  
Finite Element Model ◽  
Crack Detection ◽  
Closed Form Solution ◽  
Element Model ◽  
Form Solution ◽  
Vibration Modes ◽  
Vibration Data ◽  
The Finite Element Model

Over the past two decades, extensive research has been carried out in the field of structural health monitoring for damage detection in structural systems. Some crack detection methods are based on the finite element model of a beam and use vibration data are developed. These methods identify the crack by updating of the finite element model according to the vibration data of structure. This paper proposes a novel method for crack detection in Euler–Bernoulli beams based on the closed-form solution of mode shapes using Bayesian inference. The expression of vibration modes is derived analytically with the crack parameters as unknown variables. Subsequently, the Bayesian inference is used to obtain the probability density function of crack parameters and to evaluate the uncertainty of the modes. Finally, the method is applied to a series of numerical examples, including a beam with a single-crack and multi-cracks, to verify the effectiveness of this method.

Parametric Identification of a Vibratory System With a Clearance

1993 ◽  
Vol 115 (1) ◽  
pp. 25-32 ◽  
Author(s):  
R. M. Alexander ◽  
S. T. Noah ◽  
C. G. Franck
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Closed Form ◽  
Piecewise Linear ◽  
Closed Form Solution ◽  
Element Model ◽  
Form Solution ◽  
Degree Of Freedom ◽  
Vibratory System ◽  
Experimental Structure

An analytical and experimental investigation of a vibratory system with a clearance was conducted. A finite element model and an equivalent single-degree-of-freedom closed-form solution were used to determine the dynamic parameters and response of an experimental structure interacting with a gap. The closed-form solution is obtained by taking advantage of the piecewise linearity of the system. Results from these solution methods are in agreement with experimental data. The results also suggest that the closed-form solution approximates the response of the experimental structure with accuracy greater than that of the finite element model. The closed-form solution was also used to determine the gap size of the structure. The parameter identification procedure utilized in this study appears to be simple to use and can be readily extended to other types of piecewise-linear multi-degree-of-freedom systems.

Parametric Identification of a Vibratory System With a Clearance

1991 ◽  
Author(s):  
Richard M. Alexander ◽  
Sherif T. Noah ◽  
Charles G. Franck
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Closed Form ◽  
Piecewise Linear ◽  
Closed Form Solution ◽  
Parametric Identification ◽  
Element Model ◽  
Form Solution ◽  
Vibratory System ◽  
Experimental Structure

Abstract An analytical and experimental investigation of a vibratory system with a clearance was conducted. A finite element model and an equivalent single degree of freedom closed-form solution were used to determine the dynamic parameters and response of an experimental structure interacting with a gap. The closed-form solution is obtained by taking advantage of the piecewise linearity of the system. Results from these solution methods are in agreement with experimental data. The results also suggest that the closed-form solution approximates the response of the experimental structure with accuracy greater than that of the finite element model. The closed-form solution was also used to determine the gap size of the structure. The parameter identification procedure utilized in this study appears to be simple to use and can be readily extended to other types of piecewise-linear multidegree of freedom systems.

Temperature Profiles in a Finite Element Thermal Model of the Prostate Region Under Hyperthermia Treatment

1990 ◽  
Vol 189 ◽  
Author(s):  
Indira Chatterjee ◽  
Roy E. Adams ◽  
Namdar Saniei
Keyword(s):  
Finite Element ◽  
Phased Array ◽  
Blood Perfusion ◽  
Element Model ◽  
Bioheat Transfer ◽  
Transient Temperature ◽  
Temperature Profiles ◽  
Hyperthermia Treatment ◽  
Finite Element Software ◽  
Transient Temperature Distribution

ABSTRACTThe detailed transient temperature distribution in an inhomogeneous model of a cross section through the prostate region of the human body undergoing hyperthermia treatment forcancer has been calculated. The finite element method has been used to solve the bioheattransfer equation. A commercially available finite element software package called ANSYS® has been adapted to the present problem.The model consists of 523 triangular elements and incorporates a tumor in the prostate.The hyperthermia device under test is an Annular Phased Array consisting of dipole antennas. The model is surrounded by a bolus of deionized water. The calculated electromagnetic energy distribution is input into the bioheat transfer equation and the resulting temperature distributions calculated.The increase in blood perfusion rates due to heating is incorporated into the model. Detailed transient temperature profiles in the finite element model are presented for various values of blood perfusion rates in the tumor and surrounding tissues. It is observed that the Annular Phased Array is effective in raising the temperature of the tumor to therapeutic values.

scholarly journals A multiple-layer finite-element model of the surface EMG signal

2002 ◽  
Vol 49 (5) ◽  
pp. 446-454 ◽  
Author(s):  
M.M. Lowery ◽  
N.S. Stoykov ◽  
A. Taflove ◽  
T.A. Kuiken
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Surface Emg ◽  
Emg Signal ◽  
Multiple Layer ◽  
Surface Emg Signal

scholarly journals On the Convergence of Nonlinear Modes of a Finite Element Model

2008 ◽  
Vol 15 (6) ◽  
pp. 655-664
Author(s):  
Ramesh Balagangadhar ◽  
Joseph C. Slater
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Modal Analysis ◽  
Complex Geometry ◽  
Linear Part ◽  
Mesh Refinement ◽  
Closed Form Solution ◽  
Element Model ◽  
Mesh Independence ◽  
Nonlinear Modal Analysis

Convergence of finite element models is generally realized via observation of mesh independence. In linear systems invariance of linear modes to further mesh refinement is often used to assess mesh independence. These linear models are, however, often coupled with nonlinear elements such as CFD models, nonlinear control systems, or joint dynamics. The introduction of a single nonlinear element can significantly alter the degree of mesh refinement necessary for sufficient model accuracy. Application of nonlinear modal analysis [1,2] illustrates that using linear modal convergence as a measure of mesh quality in the presence of nonlinearities is inadequate. The convergence of the nonlinear normal modes of a simply supported beam modeled using finite elements is examined. A comparison is made to the solution of Boivin, Pierre, and Shaw [3]. Both methods suffer from the need for convergence in power series approximations. However, the finite element modeling method introduces the additional concern of mesh independence, even when the meshing the linear part of the model unless p-type elements are used [4]. The importance of moving to a finite element approach for nonlinear modal analysis is the ability to solve problems of a more complex geometry for which no closed form solution exists. This case study demonstrates that a finite element model solution converges nearly as well as a continuous solution, and presents rough guidelines for the number of expansion terms and elements needed for various levels of solution accuracy. It also demonstrates that modal convergence occurs significantly more slowly in the nonlinear model than in the corresponding linear model. This illustrates that convergence of linear modes may be an inadequate measure of mesh independence when even a small part of a model is nonlinear.

scholarly journals Analysis of the effect of external heating in the human tissue: A finite element approach

2020 ◽  
Vol 26 (4) ◽  
pp. 251-262
Author(s):  
Mridul Sannyal ◽  
Abul Mukid Mohammad Mukaddes ◽  
Md. Matiar Rahman ◽  
M. A. H. Mithu
Keyword(s):  
Finite Element ◽  
Human Tissue ◽  
Transfer Problem ◽  
Thermal Response ◽  
Blood Perfusion ◽  
Element Model ◽  
Bioheat Transfer ◽  
Tissue Temperature ◽  
Blood Temperature ◽  
External Heating

AbstractThermal therapy which involves either raising or lowering tissue temperature to treat malignant cells needs precise acknowledgment of thermal history inside the biological system to ensure effective treatment. For this purpose, this study presents a two-dimensional unsteady finite element model (FEM) of the bioheat transfer problem based on Pennes bio-heat equation to analyze the thermal response of tissue subject to external heating. Crank-Nikolson scheme was used for the unsteady solution. A finite element code was developed using C language to calculate results. The obtained numerical result was compared with the analytical and other numerical results available in the literature. A good agreement was found from the comparison. Temperature distribution inside the human body due to constant and sinusoidal spatial and surface heating were analyzed. Response to point heating was also investigated. Moreover, a sensitivity analysis was carried out to know the effect of various parameters, i.e. blood temperature, thermal conductivity, and blood perfusion rate on tissue temperature. The outcome of this study will be helpful for the researchers and physicians involved in the thermal treatment of human tissue.

TWO-DIMENSIONAL FINITE ELEMENT MODEL OF TEMPERATURE DISTRIBUTION IN DERMAL TISSUES OF EXTENDED SPHERICAL ORGANS OF A HUMAN BODY

2013 ◽  
Vol 06 (01) ◽  
pp. 1250065 ◽  
Author(s):  
AKSHARA MAKRARIYA ◽  
NEERU ADLAKHA
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Blood Perfusion ◽  
Element Model ◽  
The Body ◽  
Two Dimensional ◽  
Human Breast ◽  
Physical Conditions ◽  
Dimensional Finite Element ◽  
Body Core

In the present study the thermal model of skin and subdermal tissues (SST) of human breast have been developed. The human breast is assumed to be spherical in shape with upper hemisphere projecting out from the trunk of the body and lower hemisphere is considered to be a part of the body core. The upper hemisphere represents the breast and its SST region is divided into three layers namely epidermis, dermis and subdermal tissues. The inner part of the breast represents the core/shell of the breast. The outer surface of the breast is assumed to be exposed to the environment from where the heat loss takes place by conduction, convection, radiation and evaporation. The heat transfer from core to the surface takes place by thermal conduction and blood perfusion. Also metabolic activity takes place at different rates in different SST layers of the breast. Boundary conditions have been framed on the basis of physical conditions. A finite element model has been developed for a two-dimensional steady state case.

Finite-element simulation of blood perfusion in muscle tissue during compression and sustained contraction

1997 ◽  
Vol 273 (3) ◽  
pp. H1587-H1594 ◽  
Author(s):  
W. J. Vankan ◽  
J. M. Huyghe ◽  
D. W. Slaaf ◽  
C. C. van Donkelaar ◽  
M. R. Drost ◽  
...  
Keyword(s):  
Finite Element ◽  
Blood Flow ◽  
Finite Element Model ◽  
Muscle Tissue ◽  
Three Dimensional ◽  
Blood Perfusion ◽  
Element Model ◽  
Loading Conditions ◽  
Sustained Contraction ◽  
Dimensional Finite Element

Mechanical interaction between tissue stress and blood perfusion in skeletal muscles plays an important role in blood flow impediment during sustained contraction. The exact mechanism of this interaction is not clear, and experimental investigation of this mechanism is difficult. We developed a finite-element model of the mechanical behavior of blood-perfused muscle tissue, which accounts for mechanical blood-tissue interaction in maximally vasodilated vasculature. Verification of the model was performed by comparing finite-element results of blood pressure and flow with experimental measurements in a muscle that is subject to well-controlled mechanical loading conditions. In addition, we performed simulations of blood perfusion during tetanic, isometric contraction and maximal vasodilation in a simplified, two-dimensional finite-element model of a rat calf muscle. A vascular waterfall in the venous compartment was identified as the main cause for blood flow impediment both in the experiment and in the finite-element simulations. The validated finite-element model offers possibilities for detailed analysis of blood perfusion in three-dimensional muscle models under complicated loading conditions.

A Finite Element Model for General Thick-Walled Shell Structures

1985 ◽  
Vol 107 (2) ◽  
pp. 126-133 ◽  
Author(s):  
A. M. Khaskia ◽  
A. I. Soler
Keyword(s):  
Finite Element ◽  
Closed Form Solution ◽  
Element Model ◽  
Order Theory ◽  
Form Solution ◽  
Test Problems ◽  
Legendre Series ◽  
Structure Thickness ◽  
Higher Order Theory ◽  
Nonlinear Distribution

A finite element for general thick-walled structures is presented. The general theory leading to this element is reviewed. A superparametric formulation is adapted. Legendre series expansions of all field variables through the structure thickness are key features in this formulation. “The General Higher Order Theory”—GENHOT element, as we call our element, presented here is capable of predicting the nonlinear distribution, through the thickness, of all stresses and displacements. Test problems with known closed form solution are modeled in order to assess the GENHOT performance. Also, a true thick-walled shell is modeled in order to demonstrate the power and capabilities of this element against a 3-D finite element.

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