运用非线性多体动力学方法，建立某抛落式救生艇在主机怠速运转时推进系统的多体动力学模型，计算分析该救生艇落水时产生的冲击载荷对其推进系统主要轴承及艉轴的动态响应。结果表明：主轴承受力明显增大，轴心偏移增加6倍；艉轴承水平方向最大受力增大263%，垂直方向最大受力增大292%；艉轴水平方向弯曲振动偏移量增加190%，螺旋桨径向位移增大147%。曲轴和艉轴最大受力均在许用范围内，且有较大安全裕度，原来的设计方案不会对入水冲击带来不安全。这项研究为自由抛落式救生艇的可靠性设计提供了重要参考。%A multi-body dynamics model of propulsion system of the free-fall lifeboat, with idling engine working condition, is established based on multi-body dynamics. Dynamic response of propulsion system to the impact load from entry water is calculated and analyzed. The results show that the force acting on main bearing is increased significantly, and the displacement of axis center is increased by six times. Maximum force acting on stern tube bearing is increased by 263%in the horizontal direction and by 292%in the vertical direction. Displacement of flexural vibrations for the stern shaft is increased by 190%in the horizontal direction, and the radial displacement for the propeller is increased by 147%. Maximum stress of crank shaft and stern shaft is in allowable range with a greater safety margin, and the original design scheme would be safe for the impact of water entry. That provides a significant reference for reliability design of free-fall lifeboat.
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