【作者】 陈承皓；

【导师】 唐文勇；

【作者基本信息】 上海交通大学 ， 船舶与海洋结构物设计制造， 2012， 硕士

【摘要】 大深度潜水器的耐压壳体是保证潜水器正常作业的主要承力结构,其疲劳寿命及可靠性指标将直接影响潜水器的整体安全性能。本文基于断裂力学方法对大深度载人潜水器钛合金耐压球壳的疲劳寿命进行预测,并对其疲劳可靠性进行分析,为潜水器结构设计优化提供依据和参考。选用最大设计下潜深度为4500米的美国Alvin号潜水器的下潜历史数据作为参考,由此确定该深度级别潜水器的疲劳载荷谱。通过不同概率模型的对比研究,选择了Gumbel分布作为深潜器下潜深度的概率分布模型,并通过潜水器所受压力与下潜深度的关系得到了耐压球壳的疲劳载荷谱。分别基于板壳理论方法和有限元数值方法对耐压球壳的应力水平进行分析,通过计算,该耐压球壳满足潜水器建造规范中对于其静强度的要求。结合断裂力学对钛合金耐压球壳的疲劳寿命进行估算,分别采用基于Paris裂纹扩展模型和基于Brown-Hobson模型的疲劳全寿命裂纹扩展模型对裂纹扩展进行确定性分析,结果均满足设计要求。最后综合计算精度和计算效率选择不含交叉项的二次响应面法作为耐压球壳疲劳可靠性的计算方法,并且分别基于Paris模型和基于Brown-Hobson模型的全寿命模型进行了可靠度指标计算和参数敏感性分析,可为各参数数值的选取及下潜作业深度提供一定的参考。结合计算结果从模型分析,由于全寿命模型计及了短裂纹扩展阶段从而能更好的描述裂纹扩展的过程,比起Paris模型结果更为精确,更适合应用于潜水器耐压球壳。更多还原

【Abstract】 Pressure hull of deep submersible as a loading-bearing structure is the primary factor to ensure the normal work of the whole system, and the reliability of which is a direct impact on the performance of the submersible. In this paper, the author predicts the fatigue life of the pressure hull and then analyzes its reliability based on fracture mechanics, which could provide references for the structural design and optimization of the submersible.Dive data of Alvin is chosen as a reference to determine the fatigue load spectrum of the deep submersible because Alvin has the same design maximum dive depth of 4500 meters. Gumbel distribution is more suitable to be used to create the probability model for dive depth distribution of deep submersible compared with other distributions, and then the fatigue load spectrum of pressure hull could be concluded by the transformation between pressure on the submersible and the dive depth.Then the theory of plates and shells and the finite element method are used to analyze the stress level of the pressure hull which could be used to check the strength of the pressure hull. The result shows that the strength of the pressure hull meets the requirement to submersible.The author uses fracture mechanics to estimate the fatigue life of titanium pressure hull. Crack model based on the Paris model and Brown-Hobson model are used to do uncertainty analysis of the crack propagation. The results meet the design requirement of the pressure hull. At last, considering accuracy and efficiency quadratic response surface method without cross terms is chosen as the approximation method of fatigue reliability for the pressure hull. And then calculate the reliability index for the hull and analyze the parameter sensitivity in the two models, which could provide a reference for the selection of parameter values and dive depth. Compared with Paris model the total fatigue life model consider the stage of short crack propagation which could describe the full process of crack propagation more precisely, so the model is more suit for the analyzing of pressure hull.更多还原