ANALYSIS OF VISCOELASTICITY OF HUMAN SKIN FOR PREVENTION OF PRESSURE ULCERS

2008 ◽  
Vol 08 (01) ◽  
pp. 33-43 ◽  
Author(s):  
YOKO AKIYAMA ◽  
YOSHIRO YAMAMOTO ◽  
YUSUKE DOI ◽  
YOSHINOBU IZUMI ◽  
SHIGEHIRO NISHIJIMA ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Elastic Modulus ◽  
Resonance Frequency ◽  
Human Skin ◽  
Strain Distribution ◽  
Pressure Ulcers ◽  
Subcutaneous Tissue ◽  
Frequency Change ◽  
The Finite Element Method ◽  
The Difference

Change in viscoelasticity of human skin with aging is evaluated by measurement of deformation under suction and of resonance frequency change under probe indentation. The elastic modulus of human skin measured by suction increases with aging, but that measured by resonance frequency change decreases; the difference is considered to be caused by the difference in measured depth region of the human skin. In order to clarify the depth region which can be measured by each technique, strain distribution is calculated by the finite element method (FEM). The results show that the epidermis is mainly deformed by the skin suction method, whereas the dermis and subcutaneous tissue are mainly deformed by measurement of resonance frequency change. For confirmation of FEM results, skin models made of silicone rubber are prepared and measured by the two methods. Viscoelasticity in the depth region from the surface to several hundred micrometers of the material is obtained by the skin suction method, while that in the region from several millimeters to several centimeters is obtained by the resonance frequency change. Based on these results, it is observed that the elastic modulus of epidermis tends to increase with aging while that of dermis and subcutaneous tissue tends to decrease, thus causing pressure ulcers.

Study and Simulate the Air Pollution Based on the Finite Difference Method

2012 ◽  
Vol 518-523 ◽  
pp. 2820-2824
Author(s):  
Yi Ni Guo ◽  
Yan Zhang ◽  
Jian Wang ◽  
Ye Huang
Keyword(s):  
Finite Element Method ◽  
Air Pollution ◽  
Finite Difference ◽  
Finite Difference Method ◽  
Difference Method ◽  
The Finite Element Method ◽  
Liquid Diffusion ◽  
Continuous Problems ◽  
The Finite Difference Method ◽  
The Difference

The finite difference method that is the finite element method is used to solve the plane continuous problems. In this article, the theory and method of the finite difference method, as well as the application on the boundary problem are introduced. By analyzing the potential flew field equation and liquid diffusion equation, they are discreted using the difference method and the numerical analysis under certain boundary condition is conducted. In air pollution, the smoke in the diffusion is typical planar continuous problems. In this paper, the finite difference method is used to analyse and simulate the spread of the smoke.

scholarly journals The Search of Spatial Functions of Pressure in Adjustable Hydrostaticradial Bearing

2015 ◽  
Vol 9 (1) ◽  
pp. 23-26 ◽  
Author(s):  
Dmytro Fedorynenko ◽  
Sergiy Boyko ◽  
Serhii Sapon
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Elastic Deformation ◽  
Tangential Direction ◽  
The Finite Element Method ◽  
Radial Bearing ◽  
Operational Characteristics ◽  
Service Conditions ◽  
The Difference ◽  
Element Method

Abstract The analysis of spatial functions of pressure considering the geometrical deviations and the elastic deformation of conjugate surace have been considered. The analysis of spatial functions of pressure is performed by the finite element method. The difference of the size of pressure in a tangential direction of a pocket of a support under various service conditions has been investigated. A recommendation for improving of operational characteristics in regulated hydrostatic radial bearing has been developed.

Analysis for Vehicle Interior Noise Using Helmholtz Resonator

2005 ◽  
Author(s):  
Wakae Kozukue ◽  
Ichiro Hagiwara ◽  
Yasuhiro Mohri
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Resonance Frequency ◽  
Sound Pressure ◽  
Helmholtz Resonator ◽  
The Finite Element Method ◽  
Vehicle Interior ◽  
Vehicle Cabin ◽  
Set Up ◽  
Element Method

In this paper the reduction analysis of the so-called ‘booming noise’, which occurs due to the resonance of a vehicle cabin, is tried to carry out by using the finite element method. For the reduction method a Helmholtz resonator, which is well known in the field of acoustics, is attached to a vehicle cabin. The resonance frequency of a Helmholtz resonator can be varied by adjusting the length of its throat. The simply shaped Helmholtz resonator is set up to the back of the cabin according to the resonance frequency of the cabin and the frequency response of the sound pressure at a driver’s ear position is calculated by using the finite element method. It is confirmed that the acoustical characteristics of the cabin is changed largely by attaching the resonator and the sound quality is quite varied. The resonance frequency of the resonator can be considered to follow the acoustical characteristics of the cabin by using an Origami structure as a throat. So, in the future the analysis by using an Origami structure Helmholtz resonator should be performed.

scholarly journals Integrating the Finite Element Method with a Data-Driven Approach for Dam Displacement Prediction

2020 ◽  
Vol 2020 ◽  
pp. 1-16 ◽  
Author(s):  
Chenfei Shao ◽  
Chongshi Gu ◽  
Zhenzhu Meng ◽  
Yating Hu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Elastic Modulus ◽  
Random Coefficient ◽  
Arch Dam ◽  
Data Driven ◽  
The Finite Element Method ◽  
Random Coefficient Model ◽  
Proposed Model ◽  
Element Method

Both numerical simulations and data-driven methods have been applied in dam’s displacement modeling. For monitored displacement data-driven methods, the physical mechanism and structural correlations were rarely discussed. In order to take the spatial and temporal correlations among all monitoring points into account, we took the first step toward integrating the finite element method into a data-driven model. As the data-driven method, we selected the random coefficient model, which can make each explanatory variable coefficient of all monitoring points following one or several normal distributions. In this way, explanatory variables are constrained. Another contribution of the proposed model is that the actual elastic modulus at each monitoring point can be back-calculated. Moreover, with a Lagrange polynomial interpolation, we can obtain the distribution field of elastic modulus, rather than gaining one value for the whole dam in previous studies. The proposed model was validated by a case study of the concrete arch dam in Jinping-I hydropower station. It has a better prediction precision than the random coefficient model without the finite element method.

Numeric Loading Simulation of Titanium Implant Manufactured Using 3D Printing

2018 ◽  
Vol 284 ◽  
pp. 380-385 ◽  
Author(s):  
Anton I. Golodnov ◽  
Yu.N. Loginov ◽  
Stepan I. Stepanov
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Titanium Alloy ◽  
Elastic Modulus ◽  
Titanium Implant ◽  
Finite Element Method Simulation ◽  
Medical Implants ◽  
The Finite Element Method ◽  
Simulation Data

The problem of medical implants honeycomb structures loading has been stated. The problem was solved using simulation by the finite element method. Simulation revealed that it is possible to change the elastic modulus of the material more than three times with respect to the bulk titanium alloy. The quality of the simulation was estimated based on the convergence of the simulation data.

Effects of Free Damping Layers on Harmonic Response of Rotating Blades

1989 ◽  
Author(s):  
T. H. Young ◽  
T. N. Shiau ◽  
S. H. Chiu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Elastic Modulus ◽  
Loss Factor ◽  
Harmonic Excitation ◽  
The Finite Element Method ◽  
Harmonic Response ◽  
Rotating Blades ◽  
Rotating Blade ◽  
Triangular Elements

This paper studies the forced vibration of a rotating blade with free damping layers to harmonic excitation by means of the finite element method. The damping layers are made of viscoelastic material with complex elastic modulus, and the excitation may be either distributed or concentrated. Triangular elements with totally 15 d.o.f. are used to allow for a great variety of shapes and boundary conditions. The effects of various parameters, such as loss factor, storage modulus and thickness of damping layers, are investigated. The results show that the vibration amplitudes near resonances can be significantly reduced by the free damping layers.

Analytic Calculation About the Strain Distribution of Any-Shaped Self-Organized Quantum Dot

2007 ◽  
Author(s):  
Yumin Liu ◽  
Zhongyuan Yu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Quantum Dot ◽  
Function Approximation ◽  
Strain Distribution ◽  
Function Technique ◽  
Plane Wave Expansion ◽  
The Finite Element Method ◽  
Self Organized ◽  
Element Method

The strain distribution of quantum dots is analytically calculated using the Green’s function technique; the general expressions for any shaped quantum dot are derived. As examples, this method is applied to cube, pyramid column, and taper-shaped quantum dot. Our expressions are correct comparing with the calculated results by finite element method and finite difference. This approach is very powerful and can be applied to any-shaped quantum dot, especially this method can directly used in the calculation of electronic structure of quantum dot by the envelop function approximation or plane wave expansion methods, because the analytic expression can exactly calculate the strain at any position. In the paper, we give the strain distribution of four types of shaped quantum dot, and some comparisons are given with the results calculated by the finite element method.

scholarly journals Application of a new vector mode solver to optical fiber-based plasmonic sensors

2016 ◽  
Vol 30 (07) ◽  
pp. 1650075 ◽  
Author(s):  
V. A. Popescu ◽  
N. N. Puscas ◽  
G. Perrone
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Analytical Method ◽  
Distilled Water ◽  
The Finite Element Method ◽  
Plasmonic Sensor ◽  
Plasmonic Sensors ◽  
Vector Mode ◽  
Hankel Functions ◽  
The Difference

Our analytical method uses a linear combination of the Hankel functions [Formula: see text] and [Formula: see text] to represent the field in the gold region of a fiber-based plasmonic sensor. This method is applied for different structures made from three, four and five layers. When the analyte is distilled water, the difference between the resonant wavelengths calculated with the finite element method and the analytical method is very small (0.00 nm for three layers, 0.19 nm for four layers and 0.07 nm for five layers with two gold layers). The important characteristics of the Bessel and Hankel functions at the loss matching point are analyzed.

Modelling of ballraceway contacts in a slewing bearing with non-linear springs

2011 ◽  
Vol 225 (4) ◽  
pp. 827-831 ◽  
Author(s):  
X H Gao ◽  
X D Huang ◽  
H Wang ◽  
J Chen
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Contact Area ◽  
The Finite Element Method ◽  
Simple Method ◽  
Slewing Bearing ◽  
Combined Loads ◽  
Non Linear ◽  
The Difference ◽  
Supporting Structures

During the operation, a slewing bearing is always subjected to a set of combined loads. It is the source of deformation of ballraceway contacts, rings, and even supporting structures. In practice, deformation of rings and supporting structures is often neglected for simplification, that is, they are supposed to be ideally stiff. To take elasticity of rings and supporting (fixed) structures into consideration, the finite-element method (FEM) is applied. Due to hundreds of contact pairs and the difference in the scale of contact area and rings or supporting structures, it is difficult to simultaneously model both local ballraceway contacts and the global slewing rings in a slewing bearing. The article developed a simple method to solve the problem, where the contacts are replaced by non-linear springs.

scholarly journals Comparative analysis of finite element formulations at plane loading of an elastic body

2020 ◽  
Vol 16 (2) ◽  
pp. 139-145
Author(s):  
Natalia A. Gureeva ◽  
Anatoly P. Nikolaev ◽  
Vladislav N. Yushkin
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Elastic Body ◽  
Stiffness Matrix ◽  
Strain State ◽  
Mixed Formulation ◽  
The Finite Element Method ◽  
Displacement Method ◽  
Internal Forces ◽  
The Difference

The aim of the work - comparison of the results of determining the parameters of the stress-strain state of plane-loaded elastic bodies based on the finite element method in the formulation of the displacement method and in the mixed formulation. Methods. Algorithms of the finite element method in various formulations have been developed and applied. Results. In the Cartesian coordinate system, to determine the stress-strain state of an elastic body under plane loading, a finite element of a quadrangular shape is used in two formulations: in the formulation of the method of displacements with nodal unknowns in the form of displacements and their derivatives, and in a mixed formulation with nodal unknowns in the form of displacements and stresses. The approximation of displacements through the nodal unknowns when obtaining the stiffness matrix of the finite element was carried out using the form function, whose elements were adopted Hermite polynomials of the third degree. Upon receipt of the deformation matrix, the displacements and stresses of the internal points of the finite element were approximated through nodal unknowns using bilinear functions. The stiffness matrix of the quadrangular finite element in the formulation of the displacement method is obtained on the basis of a functional based on the difference between the actual workings of external and internal forces under loading of a solid. The matrix of deformation of the finite element was formed on the basis of a mixed functional obtained from the proposed functional by repla-cing the actual work of internal forces with the difference between the total and additional work of internal forces when loading the body. The calculation example shows a significant advantage of using a finite element in a mixed formulation.

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