In MECHANICAL ENGINEERING, NOT JUST ABOUT GEARS, structural fatigue expert witness Philip J. O’Keefe, PE, MLE, writes:
Mechanical engineering is one of the oldest and broadest of engineering disciplines. It encompasses a broad number of disciplines, from physics to materials science, and includes:
Strength of Materials: The study of the properties of materials along with the geometry and sizing of structural components, structures, and machine parts to prevent failure.
Materials Science: The study of how metal alloys and polymers are formed to have specific properties.
Thermodynamics: The study of the properties of steam and other media used to absorb and transfer heat energy in power plants, engines, and refrigeration systems.
For more, see http://www.blogcatalog.com/blog/engineering-expert-witness-blog.