Biomechanics: Mechanical Properties of Living Tissues

Citation

Fung, Y. C. (1993). Biomechanics: Mechanical Properties of Living Tissues (2nd ed.). Springer.

Chapter Summary

The book is the first volume of a three-volume biomechanics set by its author; the other two are Biodynamics: Circulation and Biomechanics: Motion, Flow, Stress, and Growth. Its subject is the mechanical properties of living tissues, approached through the constitutive equation that links stress and strain for each material. The twelve chapters move from the history and the idea of a constitutive equation, through fluids and cells, to soft and hard tissues. The second edition runs to about 570 pages.

Chapter 1: Introduction: A Sketch of the History and Scope of the Field

Opens the volume with a sketch of the history and scope of the field.

Chapter 2: The Meaning of the Constitutive Equation

Explains what a constitutive equation is and why it is the starting point for describing a material. The remaining chapters take up one material after another in this light.

Chapter 3: The Flow Properties of Blood

Takes up the flow properties of blood, the first material examined in detail.

Chapter 4: Mechanics of Erythrocytes, Leukocytes, and Other Cells

Moves from blood as a bulk fluid to the mechanics of the individual cells within it and of other cells.

Chapter 5: Interaction of Red Blood Cells with Vessel Wall, and Wall Shear with Endothelium

Considers how blood cells interact with the vessel wall and how the shear exerted by flowing blood acts on the endothelium, linking the fluid and cell chapters to the vessel.

Chapters 6–7: Bioviscoelastic Fluids; Bioviscoelastic Solids

Two chapters on viscoelastic behaviour, first of biological fluids and then of biological solids. Together they extend the constitutive discussion to time-dependent behaviour.

Chapter 8: Mechanical Properties and Active Remodeling of Blood Vessels

Treats the mechanical properties of blood vessels together with their active remodeling.

Chapters 9–11: Skeletal Muscle; Heart Muscle; Smooth Muscles

Three chapters on the three muscle types.

Chapter 12: Bone and Cartilage

Closes the volume with bone and cartilage.

Key Concepts

Chapters 1–2: Scope and Constitutive Equations

• Constitutive equation: the relation between stress and strain (and, for fluids, rates of deformation) that characterises a material.
• Three-volume programme: this volume covers material properties; circulation and the broader problems of motion, flow, stress and growth are treated in the author's other volumes.

Chapters 3–5: Blood and Cells

• Flow properties of blood: the rheology of blood as a fluid.
• Cell mechanics: erythrocytes, leukocytes and other cells considered as deformable bodies.
• Wall shear and endothelium: the interaction between flowing blood and the vessel lining.

Chapters 6–8: Viscoelasticity and Vessels

• Bioviscoelasticity: time-dependent behaviour of biological fluids and solids.
• Active remodeling: change in blood-vessel properties in response to conditions.

Chapters 9–12: Muscle, Bone and Cartilage

• Muscle types: skeletal, heart and smooth muscle treated in separate chapters.
• Bone and cartilage: the final chapter, covering both tissues together.

Critical Analysis

Strengths

• A clear stated objective. The preface says the aim is a comprehensive perspective on biomechanics from the standpoint of bioengineering, physiology and medical science, developing the mechanics through a sequence of problems and examples.
• A single organising idea. The second chapter sets out the meaning of the constitutive equation, and the remaining chapters take blood, cells, vessels, muscle, bone and cartilage in turn, so the book reads as a consistent programme.
• Broad tissue coverage. The table of contents spans fluids, individual cells, vessels, three kinds of muscle, bone and cartilage in one volume.
• Revised for new work. The preface to the second edition says that advances of the 1980s affecting the understanding of tissue mechanical properties were described in detail and that the references were brought up to date.

Limitations

• Advanced mechanics assumed. The preface states that the mechanics prerequisite is the level of the author's A First Course in Continuum Mechanics (3rd edition, 1993). Readers need continuum mechanics before starting.
• One volume of three. Circulation and the problems of motion, flow, stress and growth are in other volumes, so this book alone is not a full biomechanics course.
• Dated. The second edition appeared in 1993 and its references stop there, so recent experimental and computational work is outside it.
• Organised by tissue. The chapters follow tissue types, so the book is most useful to a reader who already knows which material is needed; it is a monograph more than a first text.

Where It Fits in the Course

Within the biomechanics course, this is the monograph on tissue properties. Fundamentals of Biomechanics by Knudson centres on human movement and Fundamentals of Biomechanics: Equilibrium, Motion, and Deformation by Özkaya and colleagues teaches the mechanics needed to analyse the body at an introductory level; either is a natural first book. Introductory Biomechanics: From Cells to Organisms by Ethier and Simmons and An Introduction to Biomechanics: Solids and Fluids, Analysis and Design by Humphrey and O'Rourke are course textbooks that develop the continuum mechanics, and Biomechanics: Principles and Applications is a broad treatment of the field.

Fung's volume belongs after one of those. It is the place to go when the question is where a constitutive law for blood, a vessel wall, muscle or cartilage comes from and what evidence stands behind it.

How to Use This Book

The book is for graduate students and researchers in biomedical or mechanical engineering and physiology who already have continuum mechanics and some physiology. It is useful to anyone building models of tissue or organ behaviour who needs to trace the constitutive assumptions.

A practical plan:

• Core: Chapters 1 and 2 first, since they define the approach, then the chapters on the tissue of interest. A reader focused on cardiovascular mechanics would take Chapters 3 to 5 and 8; one focused on soft-tissue modelling would add Chapters 6 and 7.
• Muscle, bone and cartilage: Chapters 9 to 12 deal with separate tissues, so a reader can go directly to the one that matters for a project.
• Alongside: keep a continuum mechanics text at hand for notation and background, and work the problems as the preface intends. The other two volumes of the set cover circulation and the broader problems of motion, flow, stress and growth.

Read each chapter by asking the same three questions: what experiment is used, what constitutive form is proposed, and what limits the form's validity.