Relationship between Dislocation Density in P91 Steel and Its Nonlinear Ultrasonic Parameter

To describe the viscoplastic behavior of materials under cyclic loading, a dislocation density-based constitutive model is developed based on the unified constitutive theory in which both the creep and plastic strain are integrated into an inelastic strain tensor. The stress evolution during cyclic deformation is caused by the mutual competition and interaction between hardening and recovery. To incorporate the physical mechanisms of cyclic deformation, the change of mobile dislocation density is associated with inelastic stain in the proposed model. The evolution of immobile dislocation density induced by strain hardening, dynamic recovery, static recovery and strain-induced recovery are simulated separately. The deterioration of yield strength following the hardening in tension (or compression) and subsequently in compression (or tension) is described by the Bauschinger effect and reduction of immobile dislocation density, the latter is induced by static- and strain-induced recovery. A kinematic hardening law based on dislocation density is proposed, both isotropic hardening and softening are described by determining the evolution of hardening parameters. The experimental data of P91 steel under different strain rates and temperatures are adopted to verify the proposed model. In general, the numerical predictions agree well with the experimental results. It is demonstrated that the developed model can accurately describe the hardening rate change, the yield strength deterioration and the softening under cyclic loading.

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Monitoring damage in composite plates from crack initiation to macro-crack propagation combining linear and nonlinear ultrasonic techniques

Structural Health Monitoring ◽

10.1177/1475921720922922 ◽

2020 ◽

pp. 147592172092292

Author(s):

Hamad Alnuaimi ◽

Umar Amjad ◽

Pietro Russo ◽

Valentina Lopresto ◽

Tribikram Kundu

Keyword(s):

Composite Plates ◽

Fiber Reinforced Polymer ◽

Reinforced Polymer ◽

Damage Progression ◽

Nonlinear Ultrasonic ◽

Ultrasonic Techniques ◽

Linear And Nonlinear ◽

Ultrasonic Parameters ◽

Peak Count ◽

Ultrasonic Parameter

In this article, a holistic technique for sensing damage initiation, as well as damage progression in composite plates, is presented combining linear and nonlinear ultrasonic techniques. For this investigation, multiple sets of composite plate specimens made of two different composite materials were fabricated to check if the proposed technique works for different types of specimens. The specimens were damaged by impact loading and then inspected by propagating Lamb waves through them. Different failure mechanisms, such as fiber breaks, matrix cracking, debonding, and delamination, cause composite damage. Two groups of composite specimens that were fabricated and damaged were glass fiber–reinforced polymer composite and basalt fiber–reinforced polymer composite. A chirp signal excited by PZT (lead zirconate titanate) transducer was propagated through undamaged and damaged specimens to investigate the effects of varying degrees of damage on the recorded signals. Both linear and nonlinear ultrasonic parameters were extracted from the recorded signals and analyzed. The change in the linear ultrasonic parameters such as the wave speed and attenuation with damage progression were recorded. A new nonlinear ultrasonic parameter, the sideband peak count or sideband peak count-index, is also introduced and calculated from the recorded signals. It is observed that the nonlinear ultrasonic parameter can monitor the early stage of damage progression better than the linear ultrasonic parameters, while some linear ultrasonic parameters are more effective than the nonlinear ultrasonic parameter for monitoring the advanced stage of damage. Therefore, a combination of linear ultrasonic and nonlinear ultrasonic analyses is ideal for the holistic monitoring of the composite panels from the crack nucleation stage to the structural failure stage.

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Imaging the Nonlinear Ultrasonic Parameter of a Medium

Ultrasonic Imaging ◽

10.1177/016173468300500401 ◽

1983 ◽

Vol 5 (4) ◽

pp. 295-299 ◽

Cited By ~ 53

Author(s):

Nobuyuki Ichida ◽

Takuso Sato ◽

Melvin Linzer

Keyword(s):

Spatial Frequency ◽

Probe Beam ◽

Pump Wave ◽

Power Level ◽

Ultrasonic Waves ◽

Nonlinear Parameter ◽

Probe Wave ◽

Cross Sectional ◽

Nonlinear Ultrasonic ◽

Ultrasonic Parameter

A technique for imaging the nonlinear ultrasonic parameter B/A has been developed. The nonlinear parameter describes the dependence of ultrasonic velocity on pressure and may well provide a new and powerful tool for characterizing both biological and nonbiological media. Our approach is based on observing the interaction of two ultrasonic waves with different frequencies and power levels. A low frequency pump wave, with power level suitable for medical diagnosis (1 mW/cm2), is used to sinusoidally modulate the sound pressure over the region of interest. A much lower intensity high-frequency probe beam is propagated perpendicularly to the pump beam. The phase of the probe wave is modified in proportion to the integral of the product of the nonlinear parameter B/A and the pressure of the pump wave, which varies sinusoidally along the probe beam. This phase change provides a Fourier component of the distribution of the nonlinear parameter B/A for the spatial frequency corresponding to the inverse of the pump wavelength. By changing the frequency of the pump waves, the spatial frequency is changed and a set of spatial Fourier coefficients of the distribution of the nonlinear parameter B/A is obtained. An inverse operation then gives the one-dimensional image along the probe beam. If the probe beam is scanned mechanically, the entire cross-sectional image is obtained. Several images of the nonlinear parameter of biological objects were generated with our system. To our knowledge, these represent the first images of the nonlinear parameter to be reported in the literature. The nonlinear parameter of water was also measured and agreed well with values obtained by other techniques.

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Advanced Technologies for Estimation of Nonlinear Ultrasonic Parameter

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.326-328.673 ◽

2006 ◽

Vol 326-328 ◽

pp. 673-676

Author(s):

Kyung Young Jhang ◽

Kimio Sasaki ◽

Job Ha ◽

Hiroaki Tanaka

Keyword(s):

Processing Technique ◽

Acoustic Microscopy ◽

Signal Processing Technique ◽

Advanced Technologies ◽

Precise Estimation ◽

Power Spectral ◽

Bispectrum Estimation ◽

Nonlinear Ultrasonic ◽

Semiconductor Sample ◽

Ultrasonic Parameter

This paper proposes an advanced signal processing technique for the precise estimation of a nonlinear ultrasonic parameter, based on power spectral and bispectral analysis. The power spectrum and bispectrum estimation of the pulse-like ultrasonic signal used in the commercial SAM (scanning acoustic microscopy) equipment is especially considered in this study. The usefulness of the proposed estimation is confirmed by experiments for a Newton ring with a continuous air gap and a real semiconductor sample with local delaminations. The results show that the nonlinear parameter obtained by the proposed method had a good correlation with the delamination.

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A Comparison of Three Techniques to Determine the Nonlinear Ultrasonic Parameter β

Review of Progress in Quantitative Nondestructive Evaluation ◽

10.1007/978-1-4615-5947-4_180 ◽

1997 ◽

pp. 1383-1390 ◽

Cited By ~ 3

Author(s):

D. C. Hurley ◽

W. T. Yost ◽

E. S. Boltz ◽

C. M. Fortunko

Keyword(s):

Nonlinear Ultrasonic ◽

Ultrasonic Parameter

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Comparison of Linear and Nonlinear Ultrasonic Parameters in Characterizing Grain Size and Mechanical Properties of 304L Stainless Steel

Metals ◽

10.3390/met9121279 ◽

2019 ◽

Vol 9 (12) ◽

pp. 1279 ◽

Cited By ~ 1

Author(s):

Sungho Choi ◽

Juyoung Ryu ◽

Jae-Seung Kim ◽

Kyung-Young Jhang

Keyword(s):

Mechanical Properties ◽

Grain Size ◽

Attenuation Coefficient ◽

Ultrasonic Velocity ◽

Ultrasonic Attenuation ◽

304L Stainless Steel ◽

Ultrasonic Measurements ◽

Nonlinear Ultrasonic ◽

Ultrasonic Parameters ◽

Ultrasonic Parameter

Ultrasonic nondestructive techniques can be used to characterize grain size and to evaluate mechanical properties of metals more practically than conventional destructive optical metallography and tensile tests. Typical ultrasonic parameters that can be correlated with material properties include ultrasonic velocity, ultrasonic attenuation coefficient, and nonlinear ultrasonic parameters. In this work, the abilities of these ultrasonic parameters to characterize the grain size and the mechanical properties of 304L stainless steel were evaluated and compared. Heat-treated specimens with different grain sizes were prepared and tested, where grain size ranged from approximately 40 to 300 μm. The measurements of ultrasonic velocity and ultrasonic attenuation coefficient were based on a pulse-echo mode, and the nonlinear ultrasonic parameter was measured based on a through-transmission mode. Grain size, elastic modulus, yield strength, and hardness were measured using conventional destructive methods, and their results were correlated with the results of ultrasonic measurements. The experimental results showed that all the measured ultrasonic parameters correlated well with the average grain size and the mechanical properties of the specimens. The nonlinear ultrasonic parameter provided better sensitivity than the ultrasonic velocity and the ultrasonic attenuation coefficient, which suggests that the nonlinear ultrasonic measurement would be more effective in characterizing grain size and mechanical properties than linear ultrasonic measurements.

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