Example of Brittle Materials: Glass, Ceramics
Example of Flexible Materials: Rubber, Carbon Fiber
Looking at the example stress-strain curves below, the main distinction between brittle and flexible materials is the duration at which they can endure plastic deformation. Brittle materials, think like of a ceramic bowls, tolerate little-to-no deformation. Hence, this is why the x-duration (strain) on the stress-strain curve is only within the elastic region.
A great way to think about stress-strain curves for flexible materials is looking at the strain equation. They can tolerate greater changes in total elongation, hence why the curve extends further along the x-axis!
Example Stress Strain Curves for Brittle vs. Strong Materials:
Another Visual Representation:
