1 / 40

Continuum Biomechanics of Soft Tissue: Successes and Challenges

Continuum Biomechanics of Soft Tissue: Successes and Challenges. J. D. Humphrey Department of Biomedical Engineering and M.E DeBakey Institute Texas A&M University, College Station TX 77843-3120 U.S.A. Biomechanics - A Long History of Past Successes. Leonardo (1452-1519) Galileo (1564-1642)

ronan-mejia
Download Presentation

Continuum Biomechanics of Soft Tissue: Successes and Challenges

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Continuum Biomechanics of SoftTissue: Successes and Challenges J. D. Humphrey Department of Biomedical Engineering and M.E DeBakey Institute Texas A&M University, College Station TX 77843-3120 U.S.A.

  2. Biomechanics - A Long History of Past Successes Leonardo (1452-1519) Galileo (1564-1642) W. Harvey (1578-1657) R. Descartes (1596-1650) G. Borelli (1608-1679) L. Euler (1707-1783) … and many others

  3. Biomechanics comes of age ~ 1965 • Renaissance in continuum mechanics (1948-1965) • Structural biology (1951, 1954) • Digital computer (late 1950s - mid 1960s) • Finite element methods (1956) • Space race (1957-1969) Note: L. Pauling (1995) attributes the birth of modern biology to the methods of theoretical physics / mathematics

  4. Constitutive Relations - The Key to Success “we see that the greatest need lies in the direction of collecting data in multiaxial loading conditions and formulating a theory for the general rheological behavior of living tissues when stresses and strains vary with time in an arbitrary manner.” Y.C. Fung (1973)

  5. An Example - Vascular Mechanics

  6. Early Stress Analyses (~1979)

  7. Importance of Residual Stress (~1986)

  8. Importance of Smooth Muscle (~1999)

  9. From Complexity Comes Simplicity • Nonlinear Material Properties and Large Strain • Anisotropy (circumferential muscle, axial collagen) • Residual Stresses • Smooth Muscle Activation • Heterogeneity (functionally graded) Question – what optimization rules govern the development and adaptation of vessels?

  10. Future Challenges & Promises “There are however innumerable other local motions which on account of the minuteness of the moving particles cannot be detected, such as the motions of the particles in hot bodies, fermenting bodies, in putrescent bodies, growing bodies, in the organs of sensation and so forth. If any one shall have the good fortune to discover all these, I might almost say that he will have laid bare the whole nature of bodies so far as the mechanical causes of things are concerned.” Sir I. Newton (1642-1727)

  11. ECM Synthesis Receptor Binding Cell Traction Growth MMP’s Balance Cell Factors TIMP’s Cycle Relations Modeling in Mechanobiology Cytokines Cross-linking Constitutive Relations Cell Migration Integrins Mechanical Loads

  12. Developmental Biomechanics “Here and elsewhere we shall not obtain the best insights into things until we actually see them growing from the beginning” Aristotle (384-322 B.C.) “without the aid of mechanicians, and others skilled in simulation and modelling, developmental biology will remain a prisoner of our inadequate and conflicting physical intuitions and methaphors.” A.K Harris (1994) See: LA Taber (1995) Appl Mech Rev 48:487-545.

  13. Growth & Remodeling Growth - an increase in mass that is achieved locally via an increase in the number (hyperplasia, migration) or size (hypertrophy) of cells and via a synthesis of extracellular matrix that exceeds removal. Remodeling - a change in structure that is achieved by reorganizing existing constituents (cross-links) or by producing new constituents having a different organization.

  14. Regulators of Vascular G&R

  15. Conceptually - G&R

  16. Constrained mixture stress-response

  17. Stretches for a constrained mixture

  18. Kinetics of production and removal

  19. Solid-Fluid Coupling - Aneurysms

  20. Linearization – Stability in the Small

  21. Elastodynamics of Aneurysms

  22. Phase Plane – Time Plot

  23. Denaturation of Collagen

  24. Thermomechanical Testing of Collagenous Membranes

  25. Heat-induced Changes in Mechanical Properties

  26. In Summary, the Need… “The success of reductionist and molecular approaches in modern medical science has led to an explosion of information, but progress in integrating information has lagged… Mathematical models provide a rational approach for integrating this ocean of data, as well as providing deep insight into biological processes.” 1998 BECON Report

  27. Molecular & Cellular Biomechanics Developmental Biomechanics Growth & Remodeling Injury & Rehab Functional Tissue Engineering Muscle Mechanics Solid-Fluid Interactions Biothermomechanics The Promise...

  28. The Bioengineer’s Bookshelf • Alberts et al. (2002) Molecular Biology of the Cell. Garland Publishers. • Fawcett DW (1986) A Textbook of Histology. W.B. Saunders. • Medical Dictionary (e.g., Dorland’s) • and a good “system-specific” text on physiology, e.g., Milnor (1990) Cardiovascular Physiology, Oxford.

  29. Acknowledgments Funding by the NIH, NSF, Texas-ATP, and Whitaker Foundation References • Humphrey JD (2002) Cardiovascular Solid Mechanics: Cells, Tissues, and Organs, Springer-Verlag, NY • Humphrey JD (2003) Continuum biomechanics of soft biological tissues. Proc R Soc Lond A 459: 3-46 • Humphrey JD (2003) Continuum thermomechanics and the clinical treatment of disease and injury. Appl Mech Rev 56: 231-260. • Biomechanics and Modeling in Mechanobiology http://link.springer.de

More Related