Multi-line spectrum feedback control algorithm for active vibration isolation

ZHANG Qingwei;YU Xiang;YANG Lihua

Chinese Journal of Ship Research,2021,No. 06

[Objectives] Considering the poor control effect of the traditional adaptive filtering algorithm for multi-frequency excitation in vibration control and the engineering problems that difficult sensor installation and channel coupling cause reference signal mismatch, this paper proposes a multi-line spectrum feedback control algorithm. [Methods] First, the error signal passes through the cascaded adaptive notch filters, and the notch filter parameters are updated according to the adaptive algorithm to estimate multiple signal frequencies. Next, each reference signal is synthesized, phase compensation is performed, and another reference signal is obtained through the Hilbert transform. Finally, the signals enter parallel controllers to complete the amplitude update and thereby achieve vibration control. [Results] Through simulation and experimental verification, the results show that the proposed algorithm can accurately estimate frequency information, synthesize reliable reference signals, and achieve 20–40 dB energy attenuation for 30, 37, 60, and 110 Hz line spectra. [Conclusions] This algorithm provides a better solution to the problems of reference signal mismatch and multi-line spectrum vibration in vibration control and effectively reduces and suppresses low-frequency vibration energy transmission.

Sea states effects on fatigue damage of large ship prone to springing effect

HUA Kang;ZHAO Wenbin;WU Dingfan

Chinese Journal of Ship Research,2021,No. 06

[Objectives] This paper aims to study the fatigue damage problem of large ships prone to the springing effect. [Methods] The tested fatigue damage of two-generation 400 000 DWT very large ore carriers (VLOCs) is compared by the ship model test method, and the relationships of sea states and fatigue under the springing of hull girders are analyzed. According to the recursion method, a classical sea state is selected from a series of model test sea states. [Results] The results show that the fatigue damage magnification effect has trend relationships with significant wave height and encounter period. The concept of “dominant sea state” is proposed by the inductive recursion method, and the formula of the fatigue damage magnification factor is improved. The springing effect varies significantly according to different sea states, and the fatigue damage magnification effect of wave-induced loads increases very rapidly as significant wave height and encounter period decrease. [Conclusions] Replacing multiple typical sea states with a dominant sea state could allow a relatively accurate fatigue damage magnification factor to be ascertained rapidly. As such, this paper can provide references during the initial design period.

Optimal design of internal pressure-resistant square compartment based on strength analysis

GUO Yu;YUAN Yuchao;TANG Wenyong

Chinese Journal of Ship Research,2021,No. 06

Experimental study on wheel load distribution characteristics of truck tires

HE Shiwei;LIU Hui;ZHANG Genglin;WANG Deyu

Chinese Journal of Ship Research,2021,No. 06