| Summary: | This study experimentally and numerically investigated the nonlinear behavior of the resonant bulk waves generated by the two-way collinear mixing method in 5052 aluminum alloy with micro-crack damage. When the primary longitudinal and transverse waves mixed in the micro-crack damage region, numerical and experimental results both verified the generation of resonant waves if the resonant condition <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mrow><mrow><msub><mi>ω</mi><mi>L</mi></msub></mrow><mo>/</mo><mrow><msub><mi>ω</mi><mi>T</mi></msub></mrow></mrow><mo>=</mo><mrow><mrow><mn>2</mn><mi>κ</mi></mrow><mo>/</mo><mrow><mo stretchy="false">(</mo><mi>κ</mi><mo>−</mo><mn>1</mn><mo stretchy="false">)</mo></mrow></mrow></mrow></semantics></math></inline-formula> was satisfied. Meanwhile, we found that the acoustic nonlinearity parameter (ANP) increases monotonously with increases in micro-crack density, the size of the micro-crack region, the frequency of resonant waves and friction coefficient of micro-crack surfaces. Furthermore, the micro-crack damage in a specimen generated by low-temperature fatigue experiment was employed. It was found that the micro-crack damage region can be located by scanning the specimen based on the two-way collinear mixing method.
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