船舶气囊下水安全性评估方法研究

气囊下水是船舶下水的一种创新方式,但是气囊下水过程中船体强度和气囊的安全性还没有定量的计算方法.近年采用气囊下水的船舶重量不断增大,下水安全性问题日益突出.本文考虑气囊刚度的非线性、下水过程中船体的力平衡条件等,提出了一种基于全船结构有限元分析的船体结构和气囊安全性评估方法.研究的内容和结果是紧密结合工程实际的.(1)考虑气囊压缩变形的非线性,研究了一种预报气囊刚度的有效方法;(2)基于弹性下水理论,研究了一种考虑弹性基座刚度非线性变化的船体梁运动和受力的计算方法;(3)提出了直接采用全船结构有限元分析计算船体结构应力和气囊受力的方法;(4)对某型实船进行了气囊下水的安全性分析,并与文献的结果进行比较,验证了气囊下水工艺的优越性和本文建议方法的准确性.

Investigation on Safety Assessment of Ship Launching with Airbags

Launching based on airbags is new technology of ship launching. However, there is no feasible method for quantitative assessment of the strength of hull girder and safety of airbags during launching process. With increase in light weight of ships, the risk of launching becomes more severe. With the nonlinear rigidity of air-bags and forces equilibrium condition of hull girder being considered during launching, a method based on entire hull FEA is put forward to assess the strength of ship structure and the safety of airbags in this paper. The main contents are as follows. (1) Considering nonlinear rigidity of airbags, a calculation method of rigidity of airbags is studied. (2) A method of calculating ship motion and forces on ship hull is studied with the nonlinear rigidity of elastic foundation being considered. (3) The stress of hull structure and the forces on airbags are calculated by entire hull FEA. (4) Comparison with common assessment methods shows that the safety of ship launching by airbags is estimated better and that the reliability of the calculation method presented in this paper are verified.