Combined Damage Index to Detect Plastic Deformation in Metals Using Acoustic Emission and Nonlinear Ultrasonics

Abstract

Understanding the amount of degradation using nondestructive evaluation (NDE) methods provides an effective way of determining the fitness to service and the residual life of structural components. Due to uncertainties introduced by the single NDE method, a combined damage index using multi-sensor data increases the reliability of damage assessment. In this paper, the outputs of three NDE methods including acoustic emission (AE), linear ultrasonics (LUT), and nonlinear ultrasonics (NLUT) are merged to identify the amount of plastic deformation in aluminum 1100. The sensitivities of individual and combined methods to microstructural changes are evaluated. The coupon samples are loaded up to different strain levels and then unloaded. AE data is recorded in real time and ultrasonic data is recorded from the unloaded samples. The major features combined in the damage index are cumulative AE absolute energy and nonlinear coefficient. The microstructural state is verified with microscopic analysis and hardness testing. The developed damage index can nondestructively assess the amount of plastic deformation with higher reliability.

Application of Odd Harmonic Resonances of a Single Crystal to Generation and Reception of Superharmonic Waves for Sensitive Monitoring of Heat-Treated Materials

“…The relative quintic nonlinearity parameter of each sample at a specific input power level was calculated using δ = A 5 /A 5 1 , where A 1 and A 5 are the spectral peak values at the fundamental and fifth harmonic frequencies, respectively. Figure 5a shows δ of seven samples measured at seven different input power levels.…”

“…Figure 5a shows 𝛿′ of seven samples measured at seven different input power levels. The calculation of these parameters is based on the relationship between 𝐴 1 5 and 𝐴 5 measured at seven different input power levels shown in Figure 5b. The results of 𝛿 ′ in Figure 5a are before the source nonlinearity correction was made.…”

“…Equation (7) indicates that a plot of U 5 1 vs. U 5 obtained experimentally at different input power levels should follow a straight line with zero y-intercept. However, the actual plot of A 5 1 vs. A 5 may not be linear across all input power levels used, as shown in Figure 5b. Furthermore, the y-intercept of the fitted line may not pass through the origin.…”

Characterization of mechanical deformation in aluminum by optical second harmonic generation

“…Because of these limitations, the earliest effects of stress on a material may not be detectable by many existing NDE techniques. Some of these issues can be mitigated by combining multiple techniques, but the capabilities and limitations of each method need to be well understood [9,10]. Ideally, an NDE method would utilize fast and simple instrumentation, be portable to allow for use in the field, and produce data that requires minimal interpretation by the operator.…”

Mechanical and Acoustic Emission Behavior of Gangue Concrete under Uniaxial Compression

“…At first, many researchers focused on microcracks development laws of concrete though the AE method, and analyzed the macro rupture of concrete by meso-mechanics [11,12,13]. Some scientists established the relationship between AE parameters and damage variable, and quantify the damage level of concrete by AE technology [10,14,15]. Colombo et al [16] introduced “b-value” from seismology, and quantify the damage to reinforced concrete by this parameter.…”