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Stress gradients in circular membranous tissues with central fixations Daisuke Mori, Guido David, Jay D Humphrey, and Ja - PowerPoint PPT Presentation


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Transition of Mechanical Environment What is an Optimal Fixation Size? How do Cells Respond to Stress Gradients? Few Studies on Cellular Responses to Gradients of Solid Mechanical Stresses. Stretch. 5%. 10%. 15%. 20%. 25%. R i = r i = 1.0 R o = 2.0.

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Presentation Transcript
slide1

Transition of Mechanical Environment

  • What is an Optimal Fixation Size?
  • How do Cells Respond to Stress Gradients?
    • Few Studies on Cellular Responses toGradients of Solid Mechanical Stresses

Stretch

5%

10%

15%

20%

25%

Ri = ri = 1.0

Ro = 2.0

Skin Biopsy Arthroscopy Stent Deployment

Circumferentially Stiffer Case

Isotropic Case

Radially Stiffer Case

Procedural Failure

Wound Healing

Suture

Success?

Prolonged Hospital Stays

Finite DeformationModeling

PredictableStress Distributions

In VitroExperiments

Fixation (Zero-displacement)Sutures, Wound Healing,Apposition of Stent

Failure?

Ri, ri

0.001

0.5

1.0

1.5

Defect

Fixation

Ro = 2.0

Stretch: 10%

Defect (Traction-free)

Circumferentially Stiffer Case

Isotropic Case

Radially Stiffer Case

  • Theoretical Framework (David & Humphrey 2004)
    • Cauchy Stress
    • Fung-type Exponential Pseudostrain-energy Function
    • Equilibrium Equation
  • Boundary Conditions
    • Outer Boundar t0: Uniform Radial Stress
    • Inner Boundary (Zero-displacement)

lI: Principal Stretch ratio

Reference

EII: Green Strain

Ri

Ro

David, G., Humphrey, J. D., 2004. Redistribution of stress due to a circular hole in a nonlinear anisotropic membrane. Journal of Biomechanics 37, 1197-1203

c, ci: Material Parameters

Rectangular MembraneStretch Apparatus

Circular Membrane Stretch Apparatus

(R, Q)

(r, q)

ri

ro

Ro: Outer Radius

Ri: Inner Radius

ro: Outer Radius

ri: Inner Radius

Reference Configuration

Deformed Configuration

Elastic Response of Thin Circular Membrane

tqq

trr

Stress gradients in circular membranous tissues with central fixationsDaisuke Mori, Guido David, Jay D Humphrey, and James E Moore Jr.Texas A&M University, Department of Biomedical Engineering

Introduction

Results

Discussion

  • Medical Interventions Including Minimally Invasive Techniques
  • Effect of Stretch Ratio

Induce Changes in Mechanical Environment

Risk of:

  • How do Cells Respond to the Complex Stress EnvironmentsFollowing Interventional Procedures?
  • Stress Patterns Depend on a Defect or Fixation
  • Effect of Size of Fixation

Future Direction

Methods

  • Experiments of Cellular Reactions to StressGradients Following Interventional Procedures
  • Rigid Fixations Play an Important Role in the Distribution of Stress and Strain in a Manner Different From Tissue Defects.
  • Stress and its Gradients due to Interventional Treatments may Depend on the Size of Fixation, as well as the Material Behavior of the Tissue.
  • Material Parameters
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