【作者】 尹群；

【导师】 胡海岩；

【作者基本信息】 南京航空航天大学 ， 工程力学， 2006， 博士

【摘要】 现代舰船在海战中必然会面临非接触爆炸引起的冲击破坏问题。随着导弹、激光炸弹和水中兵器的快速发展,爆炸当量和冲击持续时间明显增加,为保证舰船的安全和正常使用,提高舰船生命力和战斗力,应对舰船设备冲击环境与舰船结构、设备抗冲击性能进行详细深入的研究。舰船承受水下爆炸载荷是舰船结构在很短的时间内在巨大冲击载荷作用下的一种复杂的非线性动态响应过程,属大变形、强非线性问题。它涉及到水下爆炸冲击波和舰船结构的相互耦合作用,同时水下爆炸还包含很多不确定因素,如水下爆炸的炸药类型、药量大小、炸药到结构的距离、水下环境、舰船自身结构的特点等。由于水下爆炸的复杂性,对其进行详细的理论研究并企图通过建立一个精确的数学模型而使水下爆炸问题得到完全解析是十分困难的。水下爆炸试验固然可以获得准确可靠的结果,但它是一种极其昂贵的破坏性试验,对环境及舰员产生巨大的损伤,不可能经常性的采用,而且问题本身的强非线性特征和不确定性也使试验结果存在很大的局限性。随着计算机技术和数值计算技术的发展,使得计算机虚拟仿真试验的作用地位日益突出,以数值仿真试验为主,实验试验为辅的技术路线开始成为大多数国家海军舰船抗冲击研究的有效途径,同时也成为今后舰船抗冲击技术的发展方向。本文采用理论分析、数值仿真和试验验证相结合的研究方法,对舰船结构及设备的抗冲击性能进行了深入的研究。通过对显式非线性有限元求解技术的消化吸收,研究了适合船舶水下爆炸分析的数值仿真方法,实现了炸药爆轰、水下爆炸荷载在水中传播、舰艇结构在水下爆炸载荷作用下的动态响应的仿真过程。计算分析获得舰船典型设备冲击环境,建立典型水面舰船设备冲击环境仿真预报的理论和方法,对舰船设备的冲击环境进行了仿真预报,在此基础上提出了快速简便、准确可靠的舰船设备冲击环境的预报公式,实现对大、中、小三型典型水面舰船设备冲击环境快速、准确预报,为进一步开展舰船设备抗冲击设计与研究打下了坚实的基础。同时本文还对舰船结构的抗冲击性能进行了详细的研究,探讨了典型舰船在非接触水下爆炸载荷作用下结构的变形破坏模式及损伤机理,在此基础上对新型抗冲击结构形式进行了探索,提出了吸能效果较好的四种新型结构形式,并进行水下爆炸模型试验,对上述数值仿真结果进行验证。本文的主要研究工作如下:(1)对爆轰波理论和炸药爆轰冲击波理论进行了研究,建立炸药爆轰和水下爆炸荷载在水中传播的数值仿真方法。采用大型通用有限元程序MSC.DYTRAN对水下爆炸载荷进行了数值模拟和分析,实现了水下爆炸全过程数值仿真,获得了水下爆炸载荷特点及变化规律。对水下爆炸载荷数值仿真技术进行了研究,探讨了爆炸水域范围、网格划分大小、流场边界条件、炸药和水等参数的确定方法,引入无因数综合网格尺寸系数,获得最佳网格尺寸,解决数值仿真结果的精度问题。研究砂土、砂岩、岩石、绝对刚性等不同水底介质对水中冲击波的影响效果。试验比较研究表明,本文的数值仿真方法能较好的模拟水下爆炸的爆轰过程及冲击波的传播过程。(2)对舰船在水下爆炸载荷作用下的动态响应进行数值仿真计算,获得大、中、小三型典型舰船结构与设备动态响应特点。提出了炸药量、爆距等爆炸冲击特征参数对典型舰船冲击响应的影响趋势,总结出了影响的规律,获得舰船典型设备冲击环境,并分析了无限水深与刚性底面海底条件以及舷侧不同角度爆炸等因素对水面舰船设备冲击环境的影响规律。(3)在水下爆炸载荷作用下舰船动态响应研究的基础上,分析典型舰船各主要设备位置处的位移、速度、加速度响应特点,绘制其冲击环境图谱,建立爆炸冲击因子、设备位置参数与冲击环境之间的关系。在此基础上,建立大、中、小三型典型水面舰船设备冲击环境仿真预报的理论和方法,对舰船设备的冲击环境进行了仿真预报,提出快速简便、准确可靠的舰船设备冲击环境的预报公式,实现对典型水面舰船设备冲击环境快速、准确预报。实例计算表明,此方法快速简便、准确可靠。(4)对水下爆炸载荷作用下舰船结构损伤模式及构件塑性变形能吸收特性进行了深入的研究。在吸能理论研究的基础上,提出了吸能效果好、结构材料轻、制造工艺简单、符合舰船设计要求的舰船双层底新型抗冲击结构形式,计算其抗冲击性能。分析舰船双层底船底纵桁填充泡沫材料后的舰船抗冲击性能及单层隔冲器和双层隔冲系统的隔冲效果。(5)在水面舰船冲击环境和结构抗冲击性能理论及有限元数值仿真研究的基础上,进行了舰船结构及设备抗冲击模型试验研究,获得水下爆炸荷载实际分布规律,验证了帽形结构(CS)、半圆管结构(STS)等新型结构形式的吸能效果以及不锈钢钢丝绳隔冲系统的抗冲击性能。更多还原

【Abstract】 Modern warship inevitably encounters shock damage due to water explosion in a naval battle. With the quick development of guided missile, laser-bomb and weapon in water, and with the obviously increasing of mass and explosion time of bomb, shock environment for equipments, anti-shock characteristics of structures and equipments of warship should be deeply studied in detail, which will assure the safety and the normally work of ship structure and increase vital force and battle effectiveness of warship.However, it is a very complex nonlinear dynamic process that warship is shocked by underwater explosion. The process that the structure of warship is attacked by huge shock load within very short time belongs to big deformation and strong nonlinear problem due to interaction between the fluid and the hull. The underwater explosion includes many parameters, such as the type of detonator, the mass of detonator, the distance, the environment of underwater and the structural properties of the warship. For the complication of underwater explosion, it is very difficult to build an explicit numerical model for describe the problem of underwater explosion by using analytical method. In the same time experiments of underwater explosion are not often carried out for that it is a kind of very expensive devastating experiment. In addition, the experimental results are limited for generalization because there are some uncertainty and strongly nonlinear in the underwater explosion problem. Therefore, with the development of technology of nonlinear finite element (NFEM) method and the improvement of computer, the numerical simulation strategy will take on a more and more important role in dealing with the underwater explosion problem.The paper adopts a compositive research method including analytical method, numerical simulation strategy and model experiment method studying the shock environment of equipment on warship and the anti-shock properties of the warship structure. The paper presents a numerical simulation method applied to the problem of underwater explosion of ship on the basis of studying visualized NFEM. A serial of processes from detonator explosion, the spread of shock wave, to the dynamic response of the structure under shock wave are numerical simulated in the paper. Based on the simulation results, the paper concludes the structural damage deformation and mechanics of damage of the typical warship. The shock environment of equipment on the warship is predicted in the paper and the prediction equations of shock environment of equipments on surface ship are deduced. In addition, the paper discusses the new type shock resistance structures, and gives four new type shock resistance structures, which show favorable energy absorption behavior. Finally, the model experiment is carried out, and the experimental results validate the numerical simulation results.The main research contents of the paper are as follows:(1)The numerical simulation method of explosion of detonator and the spread of explosion load are built based on studying the theory of shock wave. The paper obtains the properties of underwater load and the spread rule by simulating the underwater loads with the MSC.DYTRAN software,and realize the simulation of the whole process of underwater explosion. In the same time, some key technologies in simulation are discussed including the reasonable determination the range of water, element size, the boundary condition of fluid, parameters of detonator and water,and adopts the parameter of element size which is dimensionless, to obtain the best element size in order to solve the problem about the explicit for simulation results. Simultaneously, the effects of different sea bottom which include soil, sandstone,rock, and rigid bottom to shock wave are studied in detail. The experimental results show that the presented method can preferably simulates the spread process of shock wave.(2)The paper calculates numerically the dynamic response of warship under explosion load, and concludes the properties of the dynamic response about structure and equipments. Furthermore the effect trend of mass of detonator and the distance of explosion to the dynamical response are given, and the effect rules are concluded. In addition, some factors such as bomb in different angle with the shipside and the different sea floor condition including infinite water depth and the rigid boundary are considered, and the effect principals are given.(3)The properties of the dynamic response of main equipments including displacement, velocity and acceleration are analyzed based on studying the dynamic response of the structure. And the shock spectrums of main equipments on the warship are plotted. The paper concludes the relationship among explosion shock factor, location parameters of equipment and shock environment of equipments. Finally, the prediction equations of shock environment of equipments on surface ship are deduced. The example results show that the predict method is convent, quick and correct.(4)The paper analyzes deeply the structural damage deformation and mechanics of damage of the typical warship. Furthermore, the paper presents new type double-bottom structures, which satisfy the requirement of warship design and have the excellence on energy absorption, the density of material, the technics of manufacture. The prosperities of shock resistance of new type double-bottom structures are simulated. The paper also analyzes the properties of shock resistance of the warship with the longitudinal flitch filled within foam and the effect of single floor shock isolator and double floors shock isolator. (5)The shock resistance model experiment of warship structure and equipment is carried out on basis of the numerical simulation about shock environment of surface ship and the theoretical research on structural anti-shock . Through analyzing the experimental results, the paper obtains the spread rule of underwater explosion load. In the same time the experiment results validate the effectiveness of shock resistance of cap-structure and semi-tube-structure. The stainless steel wire isolator shows favorable shock resistance property.更多还原