Fig. 2. The longitudinal stress-strain behavior of a wool fiber in water at 20°C at 0.1% strain min^-1; six cycles at a maximum strain of 20% (modelled after fig. 3.19a in Feughelman, 1997). The area denoted with an `A' exists to about 2% strain and is termed the Hookean region due to its linear elastic behavior. Area `B' exists from about 3% strain to as much as 30% strain and is termed the `yield' region because it follows an apparent yield point where the Hookean region and its respective modulus undergoes a reversible order-of-magnitude decrease in elastic modulus. For mechanical parameters, see Introduction.