Ratio of Decrement to Modulus Change for Amplitude-Dependent Internal Friction

Abstract
The ratio r of the amplitude-dependent decrement δ_h to the amplitude-dependent modulus defect ΔM/M has been analyzed within the framework of theories of dislocation hysteresis based on both the breakaway Granato-Lücke model and the symmetrical pointed loop frictional model. In the particular case of power laws with the same exponent n for both the decrement and modulus defect : δ_h=r(ΔM/M)α σoⁿ, analytical expressions for the relationship between r and n have been derived. The theoretical requirements have been compared with the available experimental data. The use of r for identifying the mechanism of dislocation hysteresis is demonstrated.