Stochastic dynamics and sensitivity analysis of a multistage marine shafting system with uncertainties

• Published in: Ocean engineering 2021-01, Vol.219, p.108388, Article 108388
• Main Authors: Zhang, Zhenguo, Ma, Xinxing, Yu, Haiting, Hua, Hongxing
• Format: Article
• Language: English
• Subjects: Global sensitivity analysis; Marine shafting system; Stochastic dynamics; Surrogate model; Transfer matrix method
• ISSN: 0029-8018; 1873-5258
• DOI: 10.1016/j.oceaneng.2020.108388

The presence of uncertainties is ineluctable in marine shafting systems due to installation errors and varying operation conditions, where failure in quantifying these effects may cause excessive vibrations and even reliability problems of such systems. This paper concerns with the fast uncertainty quantification and sensitivity analysis of the stochastic dynamics for the marine shafting systems suffered propeller excitation and parameter uncertainties in bearing stiffnesses. A statistical surrogate model issued from the associating of a transfer matrix model for describing the shafting system together with a sparse generalized polynomial chaos expansion (gPCE) formalism for propagating probabilistic uncertainties is developed for the first time. A variance-based global sensitivity analysis is performed by evaluating Sobol indices from gPCE to quantitatively distinguish the relative importance of individual uncertain parameters and their interactions on the random vibration responses. The effects of uncertainties on the stochastic dynamic properties of the shafting system are subsequently investigated through the analysis of the uncertainty envelopes and probability density functions (PDFs) of the frequency responses, along with the associated sensitivity indices. Numerical results are compared with those obtained from the MCS with a large number of realizations, demonstrating the accuracy and significant computational advantage of the proposed methodology. •A new stochastic dynamic model is proposed for marine shafting systems.•The surrogate model enables a fast uncertainty quantification of shafting responses.•Global sensitivity analysis is performed to quantify effects of inputs on responses.•Effects of random bearing stiffnesses on FRFs exhibit strong frequency dependence.