Modeling Passive Mechanical Interaction Between Aqueous Humor and Iris

2001 ◽  
Vol 123 (6) ◽  
pp. 540-547 ◽  
Author(s):  
Jeffrey J. Heys ◽  
Victor H. Barocas ◽  
Michael J. Taravella
Keyword(s):  
Aqueous Humor ◽  
Elastic Solid ◽  
Ultrasound Biomicroscopy ◽  
Mechanical Interaction ◽  
The Finite Element Method ◽  
Mesh Motion ◽  
Linear Elastic ◽  
Aqueous Humor Flow ◽  
Clinical Observations ◽  
Coupled Equation

Certain forms of glaucoma are associated with displacement of the iris from its normal contour. We present here a mathematical model of the coupled aqueous humor–iris system that accounts for the contribution of aqueous humor flow and passive iris deformability to the iris contour. The aqueous humor is modeled as a Newtonian fluid, and the iris is modeled as a linear elastic solid. The resulting coupled equation set is solved by the finite element method with mesh motion in response to iris displacement accomplished by tracking a pseudo-solid overlying the aqueous humor. The model is used to predict the iris contour in healthy and diseased eyes. The results compare favorably with clinical observations, supporting the hypothesis that passive iris deformation can produce the iris contours observed using ultrasound biomicroscopy.

A New Specimen for Measuring the Interfacial Toughness of Al-0.5%Cu Thin Film on Si Substrate

2005 ◽  
Vol 297-300 ◽  
pp. 521-526
Author(s):  
Insu Jeon ◽  
Masaki Omiya ◽  
Hirotsugu Inoue ◽  
Kikuo Kishimoto ◽  
Tadashi Asahina
Keyword(s):  
Thin Film ◽  
The Finite Element Method ◽  
Si Substrate ◽  
Detailed Structure ◽  
Micro Fabrication ◽  
Interfacial Toughness ◽  
Linear Elastic ◽  
Elastic Fracture ◽  
Cu Thin Film ◽  
Research Show

A new specimen is proposed to measure the interfacial toughness between the Al-0.5%Cu thin film and the Si substrate. The plain and general micro-fabrication processes are sufficient to fabricate the specimen. With the help of the finite element method and the concepts of the linear elastic fracture mechanics, the detailed structure for this specimen is modeled and evaluated. The results obtained from this research show that the proposed specimen provides efficient and convenient method to measure the interfacial toughness between the Al-Cu thin film and the Si substrate.

Crack-Path Effect on Material Toughness

1990 ◽  
Vol 57 (1) ◽  
pp. 97-103 ◽  
Author(s):  
Asher A. Rubinstein
Keyword(s):  
Crack Path ◽  
Numerical Procedure ◽  
Crack Tip ◽  
Elastic Solid ◽  
Singular Integral Equations ◽  
Length Change ◽  
Curvilinear Crack ◽  
Linear Elastic ◽  
System Of Cracks ◽  
Remote Stress

The material-toughening mechanism based on the crack-path deflection is studied. This investigation is based on a model which consists of a macrocrack (semi-infinite crack), with a curvilinear segment at the crack tip, situated in a brittle solid. The effect of material toughening is evaluated by comparison of the remote stress field parameters, such as the stress intensity factors (controlled by a loading on a macroscale), to effective values of these parameters acting in the vicinity of a crack tip (microscale). The effects of the curvilinear crack path are separated into three groups: crack-tip direction, crack-tip geometry pattern-shielding, and crack-path length change. These effects are analyzed by investigation of selected curvilinear crack patterns such as a macrocrack with simple crack-tip kink in the form of a circular arc and a macrocrack with a segment at the crack tip in the form of a sinusoidal wave. In conjunction with this investigation, a numerical procedure has been developed for the analysis of curvilinear cracks (or a system of cracks) in a two-dimensional linear elastic solid. The formulation is based on the solution of a system of singular integral equations. This numerical scheme was applied to the cases of finite and semi-infinite cracks.

Implementation of p and h-p Versions of the Finite Element Method

1992 ◽  
Author(s):  
Ye-Chen Lai ◽  
Timothy C. S. Liang ◽  
Zhenxue Jia
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Elastic Analysis ◽  
Two Dimensional ◽  
The Finite Element Method ◽  
Shape Functions ◽  
Linear Elastic ◽  
Finite Element Software ◽  
Analysis Process ◽  
Adaptive Analysis

Abstract Based on hierarchic shape functions and an effective convergence procedure, the p-version and h-p adaptive analysis capabilities were incorporated into a finite element software system, called COSMOS/M. The range of the polynomial orders can be varied from 1 to 10 for two dimensional linear elastic analysis. In the h-p adaptive analysis process, a refined mesh are first achieved via adaptive h-refinement. The p-refinement is then added on to the h-version designed mesh by uniformly increasing the degree of the polynomials. Some numerical results computed by COSMOS/M are presented to illustrate the performance of these p and h-p analysis capabilities.

Effect of Prostaglandin E2 on aqueous humor flow in the rabbit eye

1974 ◽  
Vol 190 (3) ◽  
pp. 221-227 ◽  
Author(s):  
Stephen Tak�ts ◽  
Casimir Jobst ◽  
Hilda Szilv�ssy
Keyword(s):  
Prostaglandin E2 ◽  
Aqueous Humor ◽  
Rabbit Eye ◽  
Aqueous Humor Flow

scholarly journals The influence of elastic deformations in high-strength structural materials on the hydrogen transport

2021 ◽  
Vol 225 ◽  
pp. 01010
Author(s):  
Polina Grigoreva ◽  
Elena Vilchevskaya ◽  
Vladimir Polyanskiy
Keyword(s):  
Chemical Potential ◽  
Potential Gradient ◽  
Elastic Solid ◽  
High Strength ◽  
Ideal Gas ◽  
Linear Elastic ◽  
Coupled Diffusion ◽  
Elastic Boundary ◽  
Linear Effects ◽  
Solid System

In this work, the diffusion equation for the gas-solid system is revised to describe the non-uniform distribution of hydrogen in steels. The first attempt to build a theoretical and general model and to describe the diffusion process as driven by a chemical potential gradient is made. A linear elastic solid body and ideal gas, diffusing into it, are considered. At this stage, we neglect any traps and non-linear effects. The coupled diffusion-elastic boundary problem is solved for the case of the cylinder under the tensile loads. The obtained results correspond to the experimental ones. Based on them, the assumptions about the correctness of the model and its further improvement are suggested.

Stiffness Model of the Armature Assembly in a Jet Pipe Pressure Servo Valve

2020 ◽  
Author(s):  
Yaobao Yin ◽  
Chengpeng He ◽  
Jing Li
Keyword(s):  
Finite Element ◽  
Complex Structure ◽  
Small Deformation ◽  
Element Model ◽  
Continuity Condition ◽  
The Finite Element Method ◽  
Servo Valve ◽  
Linear Elastic ◽  
Stiffness Model ◽  
Static Performance

Abstract The armature assembly of the jet pipe pressure servo valve plays an important role in connecting the torque motor and the jet pipe amplifier. A stiffness model of its complex structure is very necessary for analyzing the dynamic/static performance of the jet pipe pressure servo valve. At the present work, the component parts in the armature assembly are simplified into linear elastic beams. The simplified armature assembly is a fourfold statically indeterminate structure under the premise of small deformation. The unknown forces and moments are solved by using the section continuity condition as the additional supplement equation, and the functional relationship between the electromagnetic torque produced from the torque motor and the armature rotation angle /the nozzle displacement is derived based on the Castigliano's Theorem. The finite element model of the armature assembly is also established to calculate the deformation under different loads and different spring tube lengths. The simulated displacements with the finite element method are consistent with the theoretical results. The experimental results of the recovery pressure of the jet pipe valve verified the theoretical model. The proposed stiffness calculation method can be used as a reference for designing and optimizing the armature assembly in the jet pipe pressure servo valve.

Numerical simulation of the aqueous humor flow in the eye drainage system; a healthy and pathological condition comparison.

2020 ◽  
Vol 83 ◽  
pp. 82-92 ◽  
Author(s):  
G.J. Martínez Sánchez ◽  
C. Escobar del Pozo ◽  
J.A. Rocha Medina ◽  
J. Naude ◽  
A. Brambila Solorzano
Keyword(s):  
Numerical Simulation ◽  
Aqueous Humor ◽  
Pathological Condition ◽  
Drainage System ◽  
Aqueous Humor Flow ◽  
System A
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