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To quantitatively identify the transfer paths and evaluate path contributions of shell structures, an singular value decomposition- (SVD-) and principal component analysis- (PCA-) based operational transfer path analysis method is constructed and studied in this paper. Firstly, SVD is used to determine the contribution of each path and reduce crosstalk. Secondly, PCA is applied to reduce the influence of unwanted frequency components and thus reduce noises. This allows the presented OTPA to be more accurate than its traditional counterpart. Once the transmissibility function is obtained, the response synthesis is determined, and the transfer path analysis and path contribution evaluation can be effectively carried out. Numerical and experimental case studies are carried out to validate and test the performance of the presented method. Furthermore, a comprehensive observing the influences of correlation between sources and distance of sources and receiver is also provided. Generally, this paper provides accurate transfer path analysis and path contributions for mechanical systems, which can benefit vibration and noise monitoring and reduction through vibration reduction structure design for new equipment or vibration damping on the major vibration transfer paths for current equipment.

To improve the accuracy and reliability of operational transfer path analysis (OTPA) in transfer path identification and path contribution evaluation, Landweber-iterative-method-based OTPA is proposed in this paper. Firstly, the vibration data at the reference points and the target points in the operating conditions are obtained. Secondly, the appropriate iteration model and the iterative termination criterion of the Landweber iterative method are designed to improve the fitting degrees of the transmissibility function matrix. Thirdly, the transmissibility function matrix is obtained using the data in experimental operating conditions. Finally, transfer path identification and contribution evaluation are carried out in practical operating conditions, and the major transfer paths are identified. Furthermore, the accuracy, reliability and noise tolerance capability of the proposed method are comparatively studied with truncated singular value decomposition and Tikhonov-regularization-based OTPA, according to typical numerical case studies and experimental case studies on a cylindrical test bed. Generally, the proposed method can obviously improve the accuracy and reliability of transfer path identification and path contribution evaluation, and provide significant evidence for vibration reduction and the control of mechanical systems.