Acoustic harmonic generation from fatigue-induced dislocation dipoles

Quantitative assessment of fatigue damage accumulation in wavy slip metals from acoustic harmonic generation

“…The elastic nonlinearity parameter β e is determined experimentally to be roughly 4.9 (Cantrell and Yost 1994) and N total ≈ 3.0 x 10 5 cycles.…”

Dependence of microelastic-plastic nonlinearity of martensitic stainless steel on fatigue damage accumulation

“…Nonlinear acoustical experiments [7][8][9][10] indicate that metal fatigue may be characterized by a unique nonlinear relationship between an impressed stress perturbation (e.g., a sound wave) and a microelastic-plastic straining of the material at each stage of the fatigue process from the virgin to fracture. The straining is quantified by an experimentally determined material (acoustic) nonlinearity parameter β that increases monotonically by several hundred percent over the fatigue life.…”

New Trends in Materials Nondestructive Characterization Using Surface Acoustic Wave Methodologies

“…The linear approximation allows the properties of the material that can be measured experimentally to two properties namely, the velocity of sound (elastic modulus) and attenuation (damping) in the material. However, it has been shown [53] that these parameters are not robust enough to describe the fatigue mechanism. Generally a solid possesses nonlinear elastic behavior, but for practical engineering applications and for the purpose of simplification it is ignored and treated as a linear material.…”

“…can affect the attenuation in a similar way. Studies [53] on nonlinear property of aluminium alloy and stainless steel have shown dramatic changes in the nonlinearity parameter by the time the material undergoes 30-40% of total fatigue life. However, this technique could not be applied, in real time, in test specimens during fatigue.…”