Mechanics of Elastic Solids
After conducting the associated activity, students are introduced to the material behavior of elastic solids. Engineering stress and strain are defined and their importance in designing devices and systems is explained. How engineers measure, calculate and interpret properties of elastic materials is addressed. Students calculate stress, strain and modulus of elasticity, and learn about the typical engineering stress-strain diagram (graph) of an elastic material.
Solid mechanics are important for engineers who design many different structures including bridges, biological implants and skyscrapers.Copyright (top left, bottom left, right) tomruen, wikimedia.org; Glenn Research Center, NASA; NOAA http://sv.wikipedia.org/wiki/Fil:I-35W_bridge_collapse_TLR1.jpg http://www.nasa.gov/centers/glenn/moonandmars/med_topic_atomic_oxygen.html http://www.photolib.noaa.gov/htmls/corp2239.htm
During the design process, engineers select materials to use in their designs. These materials must be able to withstand the forces that the device or structure is expected to experience and must be compatible in the environment that the device or structure will operate in. If a device is designed to function in the human body, then it must be biocompatible, survive any forces or chemicals that the body may impose on it, and not harm any part of the body. The materials that engineers select are key to the success or failure of designs. To ensure correct functioning, engineers must understand the properties of the materials selected for the device as well as the properties of the surrounding materials that the device will be interacting with.
After this lesson, students should be able to:
- Describe the importance of understanding solid mechanics during device design.
- Calculate stress, strain and modulus of elasticity.
- Explain how engineers measure and calculate elastic material properties such as elastic modulus.
- Explain a typical engineering stress-strain diagram of an elastic material and its important features.