Abstract
The dual-tree quaternion wavelet transform (QWT) was used in conjunction with quaternion-based three-channel joint transmissibility (QTJT) for state inspection. Multiple QTJTs from the same structural state were used to construct a state matrix, which was considered as a feature image. Then QWT coefficients of the feature image were calculated. It supported one magnitude and three phases, in particular, the low-frequency magnitude-phase was set as state feature index. Ultimately, the difference of the state feature indexes were utilized as the state indicator. This method reduced the influence on state inspection caused by measurement uncertainty of single testing sample, because it took overall consideration of multiple testing samples and described the similarity from multiple directions. The availability of suggested method was demonstrated by a real experiment, in which the state changing was realized by loosening fasteners and altering the longitudinal force of rail. This method was also compared with method based on Karhunen-Loeve Transform (K-LT) and artificial neural network (ANN). Experimental result indicated that the suggested method was integrated optimal, moreover, the resolution of the longitudinal force of rail was less than 10 MPa which was equivalent to temperature change of 1.75 °C for full-lock rail.
Highlights
Structural state inspection based on response-only data has recently become a focused research topic, because it does not require a theoretical or numerical model of the measured structure and it is appropriate for structure motivated by unavailable or inaccessible excitation [1,2,3]
Based on the above analysis, a state inspection method using dual-tree quaternion wavelet transform (QWT) combined with quaternion-based three-channel joint transmissibility (QTJT) was described in this work
In order to test the performance of QWT-based state inspection method, it was compared with Karhunen-Loeve Transform (K-LT) method which was expounded in our previous work [10]
Summary
Structural state inspection based on response-only data has recently become a focused research topic, because it does not require a theoretical or numerical model of the measured structure and it is appropriate for structure motivated by unavailable or inaccessible excitation [1,2,3]. The transmissibility is known as a linear system concept only depended on the intrinsic characteristics of structure It defines how vibration (both amplitude and phase) is transmitted between two testing points, and provides complete information with respect to the dynamic behavior of the structure. Combined convex-optimization and permutation entropy, they improved tensor-based singular spectrum algorithm (TSSA) to map the vibration signal into a high-dimensional space, which further revealed the dynamic behavior of the original signals [12] Both two methods were used for fault diagnosis of rolling bearing and obtained good results. Another way to overcome the measurement uncertainty is to increase the testing sample capacity and utilize the statistical information. The availability of suggested method was demonstrated by an actual experiment
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