Journal ArticleDOI
Fatigue damage characterization using surface acoustic wave nonlinearity in aluminum alloy AA7175-T7351
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TLDR
In this paper, a nonlinear ultrasonic (NLU) harmonic generation system was used to characterize the fatigue damage in a flat hourglass, high strength Al-Cu-Zn-Mg alloy, AA7175-T7351 specimens.Abstract:
Nonlinear ultrasonic (NLU) harmonic generation system was used to characterize the fatigue damage in a flat hour-glass, high strength Al–Cu–Zn–Mg alloy, AA7175-T7351 specimens. Experiments were carried out to introduce controlled levels of fatigue damage under constant amplitude loading to determine the NLU response using surface acoustic wave (or Rayleigh mode) at regular intervals of fatigue life. The NLU parameter (A2/A12) plotted as a function of percentage of fatigue life shows two peaks for all the samples tested, independent of the amplitude of fatigue loading. The first peak appeared between 40%–50% of fatigue life and the second peak between 80%–90% of fatigue life. Among the two flat surfaces of the specimen, a higher nonlinearity response was observed on the surface which had the first crack initiation. The appearance of two peaks in the nonlinear response during fatigue damage progression is explained based on the dislocation dynamics and dislocation-crack interaction present in the specimens ...read more
Citations
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Journal ArticleDOI
Review of Second Harmonic Generation Measurement Techniques for Material State Determination in Metals
TL;DR: In this article, the authors present a comprehensive review of the current state of knowledge of second harmonic generation (SHG) measurements, a subset of nonlinear ultrasonic non-destructive evaluation techniques.
Journal ArticleDOI
Creep damage characterization using non-linear ultrasonic techniques
TL;DR: In this article, the use of non-linear ultrasonic techniques for the characterization of material degradation in 99.98% pure copper due to high-temperature creep was described, where flat dog-bone-shaped specimens were subjected to constant load creep testing at different stress and temperature levels.
Journal ArticleDOI
Creep damage characterization using a low amplitude nonlinear ultrasonic technique
TL;DR: In this article, a new nonlinear ultrasonic (NLU) technique for creep damage characterization is described, where dislocations are constrained between two quiescent lattice planes as defined by Cantrell.
Journal ArticleDOI
Effect of precipitate-dislocation interactions on generation of nonlinear Lamb waves in creep-damaged metallic alloys
TL;DR: In this paper, an analytical model is presented for the effect of the interactions of dislocations with precipitate coherency strains on the generation of second-harmonic of Lamb waves in metallic alloys.
Journal ArticleDOI
Nonlinear ultrasonic characterization of precipitation in 17-4PH stainless steel
Kathryn H. Matlack,Harrison A. Bradley,Sebastian Thiele,Jin-Yeon Kim,James J. Wall,James J. Wall,Hee Joon Jung,Jianmin Qu,Laurence J. Jacobs +8 more
TL;DR: In this article, the effects of copper precipitates on the acoustic nonlinearity parameter of 17-4PH stainless steel were investigated using nonlinear ultrasonic measurements using Rayleigh waves, consistent with evidence of copper precipitation from hardness, thermo-electric power, transmission electron microscopy and atom probe tomography measurements.
References
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Book
Fatigue of materials
TL;DR: In this article, the cyclic deformation and fatigue crack initiation in polycrystalline ductile solids was studied and a total-life approach was proposed to deal with the problem.
Journal ArticleDOI
Dislocation wall and cell structures and long-range internal stresses in deformed metal crystals
TL;DR: In this article, a simple model for single-slip and multiple-slink deformation is proposed, in which the crystal is considered as a composite consisting of hard dislocation walls of high local dislocation density which are separated by soft regions of low local dislocations density.
Journal ArticleDOI
A model of extrusions and intrusions in fatigued metals I. Point-defect production and the growth of extrusions
TL;DR: In this paper, a realistic model of the evolution of the surface profile of persistent slip bands (PSBs) in fatigued metals is proposed based on recent experimental observations, and cracks initiate at the surface steps at the PSB-matrix interface and, at a later stage, also at the notch-peak profile from the random slip processes.
Journal ArticleDOI
Fatigue damage assessment by nonlinear ultrasonic materials characterization
TL;DR: In this article, the second-order acousto-elastic coefficient (SOC) was measured in a variety of materials including plastics, metals, composites and adhesives.
Journal ArticleDOI
Acoustic harmonic generation at unbonded interfaces and fatigue cracks
TL;DR: In this article, a second-harmonic signal at a flat unbonded interface between two solids has been observed, caused by passage of a longitudinal acoustic wave across the interface.
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