Detection and localization of fatigue crack using nonlinear ultrasonic three-wave mixing technique

Two-dimensional scattering features of the mixed second harmonic A0 mode Lamb waves for incipient damage localization.


 A guided wave based method for localization of breathing delamination is presented in this investigation. The proposed technique utilizes one-way mixing of a dual-frequency fundamental antisymmetric Lamb modes with judiciously selected central frequencies. The dual frequency interrogation signal, upon interacting with a breathing delamination, leads to additional frequency sidebands in the frequency response spectrum; strength of which is quantified in terms of the Combination Tone index. The numerical predictions of these sidebands are validated using an in-house experimentation. It is further exposited that the Combination Tone index depends strongly on the extent of the temporal overlap the two constituent wave-envelopes have as they propagate through the breathing delamination. Accordingly, for a synchronous passage (with 100% temporal overlap) the Combination Tone index is maximum while it reduces with the decreasing temporal overlap. By utilizing the dispersive nature of the chosen Lamb mode, a relation is then developed correlating the temporal separation of the wave-envelopes at the location of the actuator, the group speeds, and the distance between the actuator and the delamination. Based on these inferences, a technique for localizing a breathing delamination is proposed, which involves interrogating the component by systematically altering the temporal overlap in the input waveform and monitoring the Combination Tone index for its maxima. The efficacy of the localization technique (close to 90%) is demonstrated through an illustrative case analyzed numerically as well as experimentally.

Localization of a Breathing Delamination using Nonlinear Lamb Wave Mixing

Many engineering structural elements make use of adhesively bonded joints due to its lighter weight, load distribution and transmission mechanisms. The safety of the structure relies greatly on the condition of the adhesive joint. In this paper, the detection of debonding at the adhesive joint is investigated using a nonlinear Lamb wave mixing approach. The method relies on the presence of combined harmonics as indicative of material nonlinearity due to dislocations or anharmonicity in intact specimens or contact nonlinearity produced by the defects. In this study, experiments and three-dimensional finite element simulations were conducted and demonstrated that the presence of combined frequency wave due to contact acoustic nonlinearity is effective for indicating debonding. The effect of the debonding width was investigated and the debonding width was found to correlate well with the combined harmonic energy generated due to debonding. The findings presented in this study provides physical insights into the effect of debonding mechanisms at adhesive joints in related to the nonlinear Lamb wave mixing approach, and can be used to further develop the debonding detection techniques using wave mixing.

Debonding detection at adhesive joints using nonlinear Lamb waves mixing

The nonlinear ultrasonic Lamb wave has attracted great attention recently due to its likelihood for microcrack detection in plate-like structures. Wave mixing technique has shown advantages...

Numerical and Experimental Investigation of Nonlinear Lamb Wave Mixing at Low Frequency

This paper presents a numerical study on the performance of a PZT (lead zirconate titanate)-bonded aluminium cantilever beam for both sensor and actuator configurations. The effect of varying the dimensions of PZT for two different cases of polarization direction is considered in the study. In case-1, polarization is along the length of PZT, and in case-2, polarization is across the thickness of PZT. The study is also extended for different configurations, types and locations of PZT. The results show that for case-1, the transverse displacement of the aluminium beam increases as the length of PZT decreases. No significant variation in displacement is noted by varying the width of PZT. Under different piezoelectric materials considered, PZT-5H showed maximum displacement. PZT, when located close to the support, showed maximum displacement and voltage response. The numerical results are also compared with one-dimensional analytical solutions and are found to be in good agreement.

Numerical Studies on PZT-Bonded Aluminium Beam

Nonlinear wave mixing provides a potential method to evaluate localized micro‐damage in structures. The wave mixing technique has some unique advantages over the nonlinear ultrasonic technique based on the higher harmonic generation, such as frequency selectivity, which can separate harmonic components generated due to instrumentation. In this paper, we numerically studied the frequency mixing response induced by the nonlinear interaction of two primary Rayleigh waves in a concrete material. The nonlinearity considered in the present study is due to crack‐wave interaction, which is often called contact acoustic nonlinearity (CAN). A limited number of experimental studies were conducted on concrete prisms to evaluate surface cracks. Both numerical and experimental results illustrate the generation of the second‐ and third‐order combined harmonics, which can be utilized to detect and localize subsurface cracks in concrete structures. The newly discovered third‐order combined harmonics, which result from the mutual interaction between the primary Rayleigh waves and their induced second‐harmonic waves, can be exploited to characterize micro‐damage in various applications.

Nonlinear ultrasonic evaluation of damaged concrete based on mixed harmonic generation

https://iopscience.iop.org/article/10.1088/1757-899X/936/1/012033/pdf

Mini Remanan

Papers

Numerical and Experimental Investigation of Nonlinear Lamb Wave Mixing at Low Frequency

Numerical Studies on PZT-Bonded Aluminium Beam

Nonlinear ultrasonic evaluation of damaged concrete based on mixed harmonic generation

Utilisation of Ultra-High Performance Fiber Reinforced Concrete(UHPFRC) for Retroffiting ─ a Review

Dynamic response of piezoelectric smart beam with adhesive debonding