动载荷施加方式对船舶设备—基座系统建模方法的影响

The influence of dynamic loads on the FE model of the ship equipment-base system

船舶结构动力响应分析中,设备动载荷是通过基座传递到船体板架上的,构成了设备—基座系统。由于设备激振力较难测量,而设备传递到基座面板处的加速度容易测量,因此在实际工程中,按设备力载荷施加与按基座面板传递加速度载荷施加时,针对船体结构动力学响应的等效性研究,以及相关建模方法研究具有重要的应用价值。通过理论推导,分析2种动载荷施加方式对模型建立方法的影响;并针对某实船特定舱段,建立有限元模型,通过比较在设备—基座模型中施加激振力载荷与在单基座模型中施加加速度载荷2种情况下评价点的振动加速度级,验证结论的正确性。研究表明,在低频域内,载荷以加速度输入时,在设备—基座系统的有限元模型中无需考虑设备建模及其质量分布。

In ship dynamic response analysis, it is through the equipment base that the dynamic load of ship equipment passes onto the deck, which is called“equipment-base system”. Generally, since it is usually difficult to measure the equipment exciting force yet much easier in measuring the acceleration passed onto the base panel, the research about relevant model-building and the ship dynamic response equivalence of applying these two kinds of loads is of high application value for real projects. Firstly, based on theoretical derivation, the influence of these two kinds of dynamic loads on modelling is analyzed in the particle vibration system. Then, two FE models of a specific hull of an actual ship is established to confirm the validity of the conclusion by comparing the acceleration level of the check points in these two FE models,where one of which is an equipment-base model loaded with exciting force and the other is a single base model loaded with acceleration. The result shows that in the low frequency domain, when the type of dynamic load on the“equipment-base system”is acceleration, it is unnecessary to incorporate equipment or consider its mass in the FE model.