Quantification of fatigue damage accumulation using non-linear ultrasound measurements

On the feasibility of nonlinear assessment of fatigue damage in hardened IN718 specimens based on non-collinear shear wave mixing

“…Their results showed a significant increase of 100 % for QSPD, 50 % for LCF, and 30 % for HCF. Similar observations were made by Oruganti et al on DA718 that has the same chemical composition as our IN718 specimens [20]. Lo = -[3 + (2l + 4m + )], while nonlinear shear wave mixing is sensitive to m only.…”

Nondestructive assessment of tensile properties of cold worked AISI type 304 stainless steel using nonlinear ultrasonic technique

“…This was attributed to the increase in dislocation density and the dislocation dipole sub-structural development during fatigue loading. Oruganti et al (2007) studied the fatigue damage behavior of DA718 nickel-base super alloy using NLU technique and reported a 160% increase inˇparameter near the failure region of the fatigue specimen. Jeong et al (2003) reported that in heat-treated Cr-Mo-V steel a good correlation exists betweenp arameter and fracture appearance transition temperature (FATT) and they highlighted the possibility for using this correlation for nondestructive evaluation of fracture toughness (K IC ).…”

Ultrasonic quantification of high temperature cyclic damage in an advanced nickel based superalloy

“…Ultrasonic attenuation can be theoretically expressed as the reduction in linear density of acoustic phonons in material which largely depend on electron mean free path. Theoretical expression for ultrasonic attenuation as suggested by Pippard [17] is (10) Where N refers to electron density, m refers to electronic mass and e refers to electronic charge, ρ indicates metal's density, v s is the acoustic wave velocity and τ is the relaxation time for acoustic propagation in metals, k is the acoustic wavenumber (k=2π/λ) and l is the mean free path for electron. If the acoustic absorption can be accounted as an exponentially decaying process; relaxation time refers to the time at which the decay approaches to a steady state.…”

“…Ultrasonic response has a distinguished damping characteristic and this damping characteristic is not validated for each type of defects. Dislocation mediated plasticity and alteration of material's stress state due to fatigue cracking have been mechanistically elucidated and validated in literature [9,10,11]. Interaction of ultrasonic wave with material microstructure and defect structure has also been theoretically treated in a detailed manner but difference in opinion exists in their experimental determination.…”

“…Mi et al [9] developed a method for detecting crack initiation through measurement of elastic energy during interaction of crack and ultrasonic waves. Oruganti et al [10] applied non linear ultrasonic measurements for damage evaluation on the basis of Granato-Lucke theory that assumed the array of dislocations as elastic strings vibrating in accordance with fundamental frequency of the ultrasonic signal. Gupta et al [11] explained the effect of crack initiation and propagation on statistical pattern distribution of ultrasonic responses.…”