Spatial-Temporal Characteristics Analysis and Vibration Measurement of Cargo Hold in Bulk Carrier for Cargo Performance

The main reason for the frequent accidents of bulk carriers with cargoes that may liquefy is that the cargo liquefaction due to many internal and external interference factors. The performance of cargo during marine transportation is significantly affected by the intensity and duration of vibration in the cargo holds in particular. Therefore, it is necessary to find out the relationship between the performance of cargo and the vibration characteristics of the hull. Firstly, the acceleration sensor was arranged at the characteristic position of the whole ship, based on the vibration simultaneous measurement and transmission system, and the vibration data acquisition experiment was carried out by multiple operating modes and ship maneuvering in different marine environments. Next, the vibration data of the internal space of ship hull under different loading conditions were obtained from the simultaneous measurement system, and the time-frequency domain analysis method was used to deal with the instantaneous frequency and amplitude under the time sequence, and an approach to anomaly discernment and risk judgment was proposed. Then, based on the energy transfer function, a method for analyzing the spatial-temporal characteristics of the vibration transfer in the cargo spaces was proposed to carry out the correlation inference between ship operation quality and cargo performance and provide the vibration signal input for the subsequent model experiment of cargoes that may liquefy. The real ship experiment shows that the excitation source and frequency response eigenvalue of the cargo space vibration can be focused, and the spatial and temporal distribution of the vibration response was found. This research has important experimental significance in revealing the coupling effect between cargo performance and ship vibration. It can also provide technical support for cargo performance monitoring and liquefaction situation judgment in the hold of autonomous cargo ships.