MecMovies 4.0 : M3.2: The Stress-strain Diagram

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The graph plots stress in p s i versus strain in inch per inch. The horizontal axis ranges from 0 to 0.1 and the vertical axis ranges from 0 to 80,000. The graph starts at the bottom left of the viewing window at the origin, goes up and to the right with constant steepness till the point (0.050, 50,000). The graph then goes up and to the right with a reduced positive slope till (0.1, 60,000). A straight line is drawn passing through (0, 0) and (0.0040, 43,700) and it overlaps the linear portion of the curve. The slope of the line is marked E.

In practice, the best value for the elastic modulus $E$ is obtained from a least-squares fit of a line to the data between the origin and the proportional limit point. Using a least-squares analysis, the elastic modulus for this material is $E = 10, 750, 000 psi$ .