【作者】 谭海涛；

【导师】 王善；

【作者基本信息】 哈尔滨工程大学 ， 固体力学， 2009， 博士

【摘要】 舰船在遭受水下武器攻击时,在非接触爆炸情况下,船体结构会受到水下爆炸冲击波以及气泡脉动载荷的破坏作用,船体结构的水下抗爆研究一直受到各海军强国的重视。本文首先介绍了结构可靠性的基本原理,在验算点法的基础上提出了一种结构可靠度计算的响应面法,随后研究了水下爆炸产生的冲击波超压峰值,分析了气泡的脉动以及气泡脉动时与结构的相互作用。在给出的可靠性方法的基础上,分别对爆炸冲击波和气泡脉动压力作用下的船体板架结构的冲击可靠性进行分析,并对爆炸载荷作用下的船体总纵极限强度进行可靠性分析。为满足工程实际中存在的高精度可靠性计算方法的需求,提出了将结构功能函数在设计验算点处进行一元分解高阶近似,得到一种用于可靠度计算的响应面法。算例计算结果表明,本文方法与直接Monte Carlo模拟法得出的结果很接近；在计算次数相当的情况下,本文方法所得结果比FORM法具有更高的精确度,说明本方法相对于FORM法而言,能更精确的逼近结构功能函数,具有较高的计算效率,可用于可靠性计算精度要求较高的工程问题。介绍了水下非接触爆炸引起冲击波以及气泡脉动相关的基本理论。利用已有的能流密度公式,推导出非接触爆炸时水中冲击波压力峰值的表达式。船体舷侧防护结构主要由板架等组成,研究板架结构在爆炸载荷下的响应一直是舰船抗爆研究的重要内容。本文建立了水下爆炸冲击波的简化数学模型,考虑水与板架间的流固耦合作用,给出了作用于板架上的冲击波载荷公式。并从理论方面对板架结构在水下非接触爆炸冲击波载荷作用下的动态响应进行分析,导出了舰船舷侧板架加筋板格在水下非接触爆炸冲击波载荷作用下响应的解析表达式。利用功能函数随机过程的极小化,将功能函数变为与时间无关的随机变量,分析了舰船舷侧板架加筋板格结构在冲击载荷作用下的冲击可靠性。以势流理论为基础,建立了水下爆炸气泡脉动的模型,并考虑了各次脉动之间的能量损失,对水下爆炸气泡脉动流场进行了数值计算。计算结果与实验值对比分析可知,理论公式所计算的气泡脉动的周期、速度等值与实际情况吻合良好,气泡脉动压力与实验值误差稍大,但仍在工程允许范围内,表明了本文建立的气泡脉动模型的正确性。随后分析了水下存在固支矩形板架的影响时,气泡的脉动特性以及在脉动的同时对于矩形板架所作的相对运动,推导出了气泡运动规律方程,并对板架在水下爆炸气泡脉动压力作用下的动态响应情况进行研究,分析了其可靠性。对于总纵强度研究,以往工作很少涉及到爆炸等极端载荷状态下舰船的总纵强度可靠性分析。研究船体结构受水下爆炸冲击波作用造成局部损伤后的剩余强度,应用基于验算点的一元分解响应面法,对受损船体结构在水下爆炸气泡附加载荷、波浪载荷及静水载荷共同作用下的船体总纵极限强度可靠性进行了计算和分析。并对多工况不同爆距下的总纵强度可靠性进行了计算,得出了相应结论：与常规载荷状态下的计算结果比较可知,水下爆炸载荷是影响其舰船总纵极限强度可靠度的主要载荷。在考虑水下爆炸冲击波造成的船体局部破坏后的三种工况计算结果表明,受水下爆炸气泡附加载荷作用的船体结构可靠指标均比不考虑气泡载荷时要低,且差别明显,表明气泡附加载荷在舰船的极端载荷状态下的结构设计中不可或缺。在计算水下爆炸气泡附加载荷作用下的船体总纵强度可靠性时,不能忽略波浪载荷的影响,必须考虑气泡附加载荷和波浪载荷的共同作用。更多还原

【Abstract】 At being attacked by the underwater weapons, in the non-contact explosion cases, the warships structure will be destructed by the explosion shock-wave as well as the bubble pulsating load. The research of hull structure’s ant detonation in the non-contact explosion situation has been of great importance to the countries that have power for navy. This paper first introduce the basic theory of structure reliability, developing a single variable decomposition method based on the design point to compute structural reliability, followed by study the shock-wave produced by underwater explosion, the bubble pulsation theory as well as the interaction of bubble and structure when the bubble pulsation and then analyzing the reliability of the warships structures under explosive loads based on the developed structure reliability method, and analyzing the reliability of the hull ultimate longitudinal strength under explosive loads also.In order to meet the demand for high accuracy reliability computational method in the actual project, a high accuracy reliability computational method is obtained by proposing higher order approximate through a single variable decomposition in the design point of the structure function. The results of examples calculations indicated that the results of the method developed in this paper and direct Monte Carlo simulation method are very close; the method developed in this paper has a higher precision compared to the FORM method in the situation of the approximately same number of computation times, explaining that the method developed in this paper relative to the FORM method can more precise approach the structure function with high efficiency, can be used to calculate the reliability of high precision engineering problems.The related elementary theory of shock-wave as well as the bubble pulsation caused by the underwater non-contact explosion is introduced. Expression of peak pressure of non-contact underwater explosion shock wave is derived using the energy density formula. The ships board protective structures are composed by the stiffened plates etc. The research of the response of stiffened plate structure under the explosion loads have been the important contents of the research of warships anti-detonation. This paper has established the simplification mathematical model of the underwater explosion shock wave. Considered the fluid-solid coupling between the water body and stiffened plates, the shock-wave load formula has been given. By the theoretical analysis of the dynamic response of the stiffened plate structure under the underwater non-contact explosion shock-wave load, the analytic expression of the dynamic response is obtained. Using the first time surmounting destruction model of the stochastic process level traversing theory, the dynamic reliability analysis of ships board stiffened plates under the explosion load is done.Taking the potential profile flow theory as the foundation, bubble pulsation model of underwater non-contact explosion has established, and the numerical simulation computation of underwater explosion bubble pulsating flow field had been carried on considered the energy loss between each pulsation. By the contrastive analysis of the computed result and the experimental data, we can see that the theoretical calculates for the calculation of the bubble pulsation’s cycle and the bubble pulsation’s speed are in good agreement with the actual situation, the error between the bubble pulsating pressure and the actual value is slightly big, but still in the project permission scope. The results had indicated that the model of bubble pulsation established in this paper is correct. From the view of conservation of momentum, the relative movement to the rectangular plate of the bubble at the same time of the pulsing has analyzed when existing clamped rectangular plate in water, deriving the law of relative movement equation, at the same time, the dynamic response of the stiffened plate structure under the underwater explosion bubble pulsating load is been researched, as well as its reliability.Regarding the overall longitudinal strength research, formerly literature did very little work on reliability analysis of ships overall longitudinal strength under extreme load status such as suffering explosion load. Considering the residual strength after partial injury of hull structure caused by the underwater explosion shock wave, applying the method developed in this paper, the reliability analysis of warships overall longitudinal strength under the underwater explosion bubble additional loads, the still water loads and wave loads has carried on. A variety of typical conditions according to different explosion distance is calculated, the corresponding conclusions were drawn:Compared with the normal loading states’computed results, we can see that the underwater explosion loads are the primary loads effected warships overall ultimate longitudinal strength reliability. The calculation results of three kinds working conditions considering the partial injury of hull structure caused by the underwater explosion shock wave show that, the reliable indicators of ship hull structures considering underwater explosion bubble additional loads are clear lower than the reliable indicators which not considering the bubble additional loads, indicating that the bubble additional loads must be in consideration for ship structural design in the extreme loading conditions. In the calculation of the reliability of overall ultimate longitudinal strength of warship subjected to the bubble additional loads, we must not ignore the impact of wave loads, considering the combined action of the bubble additional loads and the wave load.更多还原