Abstract
Viscoelastic sandwich structure is widely used in mechanical equipment. However, therein viscoelastic material inevitably suffers from gradual aging. To keep equipment running safety, it is urgent to perform the aging state identification of viscoelastic sandwich structure by vibration response signal analysis. Nevertheless, the structural vibration response signal is non-stationary and its variation caused by the structural aging state change is very puny. The vibration-based structural aging state identification has become a challenging task. Therefore, a novel method based on variational mode decomposition (VMD) with parameter optimization by sparrow search algorithm (SSA), and deep belief network (DBN) is proposed for this task. To extract sensitive aging feature information, the structural vibration response signal is processed by optimized variational mode decomposition with sparrow search algorithm (SSA-VMD), and multiple permutation entropy (PE) features are extracted from the intrinsic mode functions (IMFs) for reflecting. To attain intelligent and desirable aging state identification, using the extracted PE features as input, DBN is introduced for identifying structural aging states. The proposed method is performed on a viscoelastic sandwich structure to validate its feasibility and efficiency, and is compared with the traditional methods. The results show that the proposed method can obtain a better aging state intelligent identification result and has a good application prospect.
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