Thermo-oxidative aging state detection of rubber sandwich structure using synchrosqueezing transform-assisted feature extraction and customized detection indicator

Rubber sandwich structures (RSSs) are used extensively in mechanical engineering. The aging state detection of such structures is urgently required to avoid disastrous accidents. However, this is still a challenging task owing to the weakness of the rubber layer aging feature information contained in the vibration signal of the RSS and the lack of effective aging feature information extraction techniques. Thus, an aging state detection method for the RSS using synchrosqueezing transform (SST)-assisted feature extraction and a customized detection indicator was proposed in this study. First, the SST was used to decompose the vibration signal of the RSS, and a time-frequency (TF) spectrum with an enhanced aging state feature was obtained. Second, a TF bandpass filter was constructed and used to filter the information unrelated to the aging state feature from the TF spectrum. Subsequently, a hard threshold denoising method was applied to reduce noise in the filtered TF spectrum. Then, the aging state signal was reconstructed using the inverse SST. Finally, a customized detection indicator was constructed and its value was calculated to detect the aging state of the RSS. A thermo-oxidative aging dataset of the RSS from Xi'an Jiaotong University was used to validate the proposed method. The experimental results showed that the proposed method was more effective than other methods.