Book contents
- Frontmatter
- Contents
- Preface
- 1 Introduction: Phenomena
- 2 Constitutive Relations
- 3 Dynamic Behavior
- 4 Conceptual Structure of Linear Viscoelasticity
- 5 Viscoelastic Stress and Deformation Analysis
- 6 Experimental Methods
- 7 Viscoelastic Properties of Materials
- 8 Causal Mechanisms
- 9 Viscoelastic Composite Materials
- 10 Applications and Case Studies
- A Appendix
- B Symbols
- Index
10 - Applications and Case Studies
Published online by Cambridge University Press: 21 January 2010
- Frontmatter
- Contents
- Preface
- 1 Introduction: Phenomena
- 2 Constitutive Relations
- 3 Dynamic Behavior
- 4 Conceptual Structure of Linear Viscoelasticity
- 5 Viscoelastic Stress and Deformation Analysis
- 6 Experimental Methods
- 7 Viscoelastic Properties of Materials
- 8 Causal Mechanisms
- 9 Viscoelastic Composite Materials
- 10 Applications and Case Studies
- A Appendix
- B Symbols
- Index
Summary
Introduction
Viscoelasticity can enter in the application of materials in many ways. In some applications one must deal with natural materials, such as stone, earth, or wood in the case of building construction, or bone and soft tissue in the case of biomedical engineering. In these cases, the viscoelastic behavior of the natural materials should be known. Artificial materials used in engineering applications may exhibit viscoelastic behavior as an unintentional side effect. Finally, one may deliberately use the viscoelasticity of certain materials in the design process, to achieve a particular goal.
A Viscoelastic Earplug: Use of Recovery
A foam earplug [1, 2] was designed to be easily fitted into the ear by making use of the controlled viscoelastic behavior of the polymer from which it is made. The earplug serves to attenuate sound entering the ear to protect the ear from damage from excessive noise, and also to alleviate suffering and reduce human fatigue.
To insert the earplug, the user rolls it into a narrow cylindrical shape, then inserts it into the ear canal. Insertion is easier if the outer ear is pulled outward and upward, since that straightens the ear canal. The earplug then gradually expands as a result of viscoelastic recovery to fill and contact the ear canal, and it then effectively blocks noise.
The earplug is [2] cylindrical, somewhat larger than the ear canal, and made of a foamed polymeric material with a recovery from 60 percent compression to 40 percent compression occurring in 1 to 60 seconds and an equilibrium stiffness at 40 percent compression from 0.2 to 1.3 p.s.i. (1.4 kPa to 9 kPa).
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- Information
- Viscoelastic Materials , pp. 377 - 440Publisher: Cambridge University PressPrint publication year: 2009