scholarly journals Significance of accurate diffraction corrections for the second harmonic wave in determining the acoustic nonlinearity parameter

AIP Advances ◽  
2015 ◽  
Vol 5 (9) ◽  
pp. 097179 ◽  
Author(s):  
Hyunjo Jeong ◽  
Shuzeng Zhang ◽  
Dan Barnard ◽  
Xiongbing Li
Keyword(s):  
Second Harmonic ◽  
Harmonic Wave ◽  
Nonlinearity Parameter ◽  
Acoustic Nonlinearity Parameter ◽  
Acoustic Nonlinearity

Decomposition Method to Detect Fatigue Damage Precursors in Thin Components Through Nonlinear Ultrasonic With Collinear Mixing Contributions

2020 ◽  
Vol 3 (2) ◽  
Author(s):  
Gheorghe Bunget ◽  
Stanley Henley ◽  
Chance Glass ◽  
James Rogers ◽  
Matthew Webster ◽  
...  
Keyword(s):  
Fatigue Damage ◽  
Crack Nucleation ◽  
Second Harmonic ◽  
Turbine Blades ◽  
Nonlinearity Parameter ◽  
Decomposition Technique ◽  
Acoustic Nonlinearity Parameter ◽  
Acoustic Nonlinearity ◽  
Nonlinear Ultrasonic ◽  
Short Time

Abstract Cyclic loading of mechanical components promotes the formation of dislocation substructures in metals as precursors to crack nucleation leading to final failure of the metallic components. It is well known within the ultrasonic community that the acoustic nonlinearity parameter is a meaningful indicator of the microstructural damage accumulation. However, current nonlinear ultrasonic techniques suffer from response saturation and limited resolution after 50% fatigue life of the metallic medium. The present study investigates the feasibility of incorporating collinear wave mixing interactions into second harmonic assessments to improve the sensitivity of the nonlinear parameter to a microstructural accumulation of damage precursors (DP). To this end, a decomposition technique was explored to obtain higher harmonics from short time-domain pulses propagating through thin metallic components such as jet engine turbine blades. The results demonstrate the effectiveness of the decomposition technique to measure the acoustic nonlinearity parameter as an early and continuous indicator of fatigue damage precursors throughout the service life of critical aircraft components. A micrographic study showed a strong correlation between the nonlinearity parameter and the increase in damage precursors throughout the life of the specimens.

scholarly journals Acoustic Nonlinearity Parameter B/A, Internal Pressure, and Acoustic Impedance Determined at Pressures up to 100 MPa for 1-Ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide

2016 ◽  
Vol 41 (1) ◽  
pp. 59-66 ◽  
Author(s):  
Edward Zorębski ◽  
Michał Zorębski ◽  
Marzena Dzida
Keyword(s):  
Ionic Liquid ◽  
Internal Pressure ◽  
Acoustic Impedance ◽  
Room Temperature ◽  
Room Temperature Ionic Liquid ◽  
Thermodynamic Method ◽  
Nonlinearity Parameter ◽  
Molecular Liquids ◽  
Acoustic Nonlinearity Parameter ◽  
Acoustic Nonlinearity

Abstract The nonlinearity parameter B/A, internal pressure, and acoustic impedance are calculated for a room temperature ionic liquid, i.e. for 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide for temperatures from (288.15 to 318.15) K and pressures up to 100 MPa. The B/A calculations are made by means of a thermodynamic method. The decrease of B/A values with the increasing pressure is observed. At the same time B/A is temperature independent in the range studied. The results are compared with corresponding data for organic molecular liquids. The isotherms of internal pressure cross at pressure in the vicinity of 70 MPa, i.e. in this range the internal pressure is temperature independent.

Early Fatigue Damage of Magnesium Alloy On-Line Monitoring by Nonlinear Ultrasonic

2010 ◽  
Vol 139-141 ◽  
pp. 194-197
Author(s):  
Bing Sheng Yan ◽  
Bin Wu ◽  
Cun Fu He ◽  
Jing Pin Jiao
Keyword(s):  
Fatigue Life ◽  
Magnesium Alloy ◽  
Yield Stress ◽  
Fatigue Damage ◽  
Stress Level ◽  
Second Harmonic ◽  
Experimental Results ◽  
Nonlinearity Parameter ◽  
Acoustic Nonlinearity Parameter ◽  
On Line

This research develops a robust experimental procedure to monitor the evolution of early fatigue damage in AZ31 magnesium alloy with the acoustic nonlinearity parameter , and demons- trats its reliability by measuring the linear relationship between amplitudes of the second-harmonic waves and fundamental waves squared. Using this system, of two sets of specimens with different stress level is measured. The experimental results show that there is a significant increase in linked to fatigue degree in the early stages of fatigue life and reaches the maximum about 55%of fatigue life, when the stress level is ±60%of the yield stress, can characterize the early fatigue damage of magnesium alloy. However, when the stress level is ±70%of the yield stress, there is a regular fluctuation in linked to fatigue degree, this experimental results can’t be explained.

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