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Relationship between second- and third-order acoustic nonlinear parameters in relative measurement
Gang Ren1, Jongboem Kim1, Kyung-Young Jhang2
1Department of Mechanical Convergence Engineering, Hanyang University, Seoul 133-791, Republic of Korea.
Ultrasonics
|December 3, 2014
Summary
This study clarifies relative nonlinear parameters for nondestructive evaluation (NDE). A new relationship between simplified parameters was derived and validated, improving damage assessment in materials like Al 6061-T6.
Area of Science:
- Materials Science
- Acoustics
- Nondestructive Evaluation (NDE)
Background:
- Higher-order acoustic nonlinear parameters are crucial damage indices in NDE.
- Absolute nonlinear parameters rely on displacement amplitudes, which are difficult to measure for high harmonics.
- Relative nonlinear parameters, using detected wave signal amplitudes, offer a practical alternative but have limitations.
Purpose of the Study:
- To elucidate the concept of relative nonlinear parameters in NDE.
- To establish the equivalence between relative and absolute nonlinear parameter ratios under linear signal amplitude conditions.
- To derive and validate a new relationship between simplified second- and third-order nonlinear parameters.
Main Methods:
- Theoretical derivation of the relationship between relative ratios of simplified nonlinear parameters.
- Experimental verification using Aluminum 6061-T6 (Al 6061-T6) with varying heat treatment.
- Confirmation of linear proportionality between PZT detection signal amplitudes and displacement amplitudes for fundamental and harmonic frequencies.
Main Results:
- Demonstrated that the ratio of simplified nonlinear parameters equals the ratio of absolute nonlinear parameters when signal amplitudes are linearly proportional to displacement amplitudes.
- Derived a novel relationship between the relative ratio of simplified second-order and third-order nonlinear parameters.
- Successfully validated this new relationship using experimental data from heat-treated Al 6061-T6.
Conclusions:
- The study clarifies the theoretical basis and practical application of relative nonlinear parameters in NDE.
- The derived relationship offers a new tool for damage assessment, extending the utility of simplified nonlinear parameters.
- Experimental validation confirms the applicability of the findings to materials like Al 6061-T6, enhancing NDE capabilities.
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