TY - JOUR AB - Purpose– The purpose of this paper is to demonstrate by experiments that non‐linear Lamb wave modulation spectrum (NLWMS) will be a good indicator of fatigue cracks in a metallic plate.Design/methodology/approach– A system composed of piezoelectric transducers, arbitrary waveform generator, power amplifier, laser vibrometer, digital oscilloscope and computer has been constructed, and using this system, three samples made of 7075‐T6 aluminium alloy plates are studied, respectively. One is with a fatigue crack, one is with a through hole and the other is intact.Findings– The experimental results show that there are no significant harmonics and sidebands in the intact sample, and there are no modulation frequencies in the drilled‐hole sample. On the contrary, in the cracked sample, there is an abundance of the harmonics and sidebands. Therefore, these new modulation frequency components can be used to indicate the presence of the fatigue crack.Practical implications– This paper will provide a method for detecting fatigue crack in metallic plates, especially aluminium alloy plates for aerospace applications.Originality/value– Under the excitation of two different frequency Lamb waves, experiments on 7075‐T6 alloy plates show that new rising modulation frequency components can be used to indicate the presence of the crack. So, the fatigue crack in metallic plates can be detected by NLWMS. VL - 82 IS - 5 SN - 0002-2667 DO - 10.1108/00022661011092910 UR - https://doi.org/10.1108/00022661011092910 AU - Guili Gao AU - Dayong Li AU - Dequan Shi AU - Jingwei Dong PY - 2010 Y1 - 2010/01/01 TI - Fatigue crack detection in metallic plates with non‐linear Lamb wave modulation spectrum T2 - Aircraft Engineering and Aerospace Technology PB - Emerald Group Publishing Limited SP - 279 EP - 283 Y2 - 2024/03/29 ER -