含螺栓连接复杂结构的冲击响应与破坏研究

发布时间：2018-03-14 08:37

本文选题：复杂结构　切入点：数值分析　出处：《中国工程物理研究院》2015年博士论文　论文类型：学位论文

【摘要】：本文针对武器装药结构、航空航天结构等含螺栓连接复杂结构在撞击、跌落等载荷环境下的冲击响应与破坏问题,开展了数值建模、扩展有限元应用和实验技术研究,提出了螺栓连接结构的精细有限元建模技术及复杂结构冲击破坏的数值模拟技术。在此基础上,开展了某典型装药结构跌落条件下的冲击响应及破坏效应研究,研究方法和技术途径的合理性,保证了可靠的结构应力响应及破坏规律的获得。本文的研究,可为含螺栓连接复杂结构冲击响应与破坏研究提供数值手段和重要参考。针对含螺栓连接复杂结构冲击动力学响应研究的重要问题之一—高精度几何数值模型,开展了螺栓连接结构冲击响应的精细有限元建模技术研究。基于有限元前处理软件Patran的基本建模技术,提出了考虑螺纹连接几何特征的双导线建模方法,与已有的建模技术相比,该方法具有无需在螺杆上人为设置小孔或建立复杂的截面数学模型等优点,方法简单易于实施,能获得合理规整的有限元网格；采用对称罚函数方法处理螺纹的连接接触,应用指数型接触压力-过盈关系并结合数值试验确定相关接触参数,解决了螺纹连接类齿合性接触的计算收敛问题；采用直接在螺母一组相对的侧面上施加分布预紧力的方法模拟预紧力载荷的加载,与传统预紧力施加方法相比,本方法不仅简单易于实施,而且更与实际的预紧力施加方式相符合；针对含螺栓连接结构预紧力载荷与结构冲击载荷的静、动耦合问题,提出了结构的静动耦合计算方法。在精细有限元建模的基础上,开展了螺栓连接结构静力响应和冲击响应的数值模拟研究。首先设计了简单的口型螺栓连接结构,开展了预紧力矩为10N.m～70N.m七种工况下的静力响应数值模拟,以及小球3m和5.5m高度跌落撞击螺栓连接结构的冲击响应数值模拟,获得了螺牙及螺栓中的应力分布；与此同时,开展了相同加载条件下的实验研究。结果表明,在静力响应研究中,计算结果与试验结果的最小相对误差为0.5%,最大相对误差为4.8%。小球3m跌落撞击时,螺杆中部单元应力时程曲线,计算值与实验值相比,二者波形基本一致,幅值的最大相对误差为16.18%,脉宽的最大相对误差为16.36%。小球5.5m跌落撞击时,二者波形也基本一致,幅值的最大相对误差为19.79%,脉宽的最大相对误差为8.46%。由此可知,数值计算结果与实验结果吻合较好。针对含螺栓连接复杂结构冲击响应研究的另一重要问题—结构冲击破坏问题,开展了结构冲击破坏的扩展有限元建模技术研究。基于黏聚裂纹模型,应用扩展有限元及虚拟节点方法,结合有限元软件所具备的扩展有限元功能,研究并提出了结构冲击破坏响应的扩展有限元建模技术及实施方法。在此基础上,开展了含螺栓连接结构准静态拉伸断裂过程的数值模拟,获得了与实验相一致的破坏图像,实现了对初始无初始缺陷结构的裂纹起裂及破坏过程的数值模拟。此外,设计了三点弯曲实验,开展了不同子弹撞击速度下三点弯曲实验研究,获得了实验件的冲击破坏图像。并对子弹打击速度分别为12.2m/s、15.1m/s和26.3m/s时结构的冲击破坏进行了数值模拟研究,再现了结构的冲击破坏过程,分析了结构的冲击破坏规律,模拟结果与实验数据基本一致,实现了对含初始裂纹结构冲击破坏过程的数值模拟。最后,针对某典型含螺栓连接复杂结构,开展了跌落条件下冲击响应及破坏过程的数值模拟研究,计算获得了结构的冲击响应规律,以及与试验相接近的冲击破坏模式,表明本文的方法可实现对含螺栓连接复杂结构冲击响应及冲击破坏过程的研究。本文研究结果表明,通过建立螺栓连接结构的精细有限元模型,并采用扩展有限元方法模拟冲击载荷下结构的冲击破坏,能够实现对含螺栓连接复杂结构冲击响应的数值分析,并获得合理的结果。
[Abstract]:The weapons charge structure, aerospace structure with bolt connection structure in the complex impact load drop impact response and failure problems, to carry out the numerical modeling, the extended finite element application and experimental technology research, put forward the numerical simulation technology of impact damage finite element modeling technology of bolt connection structure and complex structure. On this basis, to carry out research and destructive effects of a typical charge structure condition of drop impact response, the rationality of research methods and technical means, which can get the stress response and failure law of reliable structure. This study can provide response and numerical methods and important reference for research on failure with bolt with complex structure impact. For complex structures containing bolts one of important problems in the study of the impact dynamic response of the high precision geometric numerical model is carried out. Study on the fine finite element modeling of shock response. Bolt connection structure of the basic modeling technology of finite element pre-processing software Patran based on the proposed modeling method of double wire connection geometry with thread, compared with the existing modeling techniques, this method has no advantage on the screw holes or the establishment of artificial section complex mathematical model so, the method is simple and easy to implement, the finite element mesh to obtain the reasonable regular contact; connected by symmetric penalty function method to deal with the thread, application of exponential contact pressure - interference relationship and numerical test to determine the relevant contact parameters, solve the convergence problem of threaded connection type tooth contact; the method applied directly the distribution of pre tightening force in a nut group on an opposite side of the simulation preload load, compared with the traditional preload method, this method is not only simple Easy to implement, and more with the actual preload applied to conform with bolt connection structure; preload load and impact load of static structure, dynamic coupling problem, put forward the calculation method of static and dynamic coupling structure. Based on finite element modeling, numerical simulation research was carried out a bolt connection structure the static response and impulse response. The first design of simple die bolt connection structure, the tightening torque for the numerical simulation of static 70N.m seven under the conditions of 10N.m and 3M in response to the ball and 5.5m height drop impact bolt connecting structure of the shock response of numerical simulation, the stress distribution of the thread and the bolt is obtained; at the same time, the experiment study is carried out under the same loading condition. The results showed that in the study of the static response, the minimum relative error of calculation results and test results is 0.5%, the maximum relative error of 4.8%. 3M ball screw unit drop impact, the central stress time curves, calculated values are compared with experimental values, the two are basically the same waveform, the maximum relative error of amplitude is 16.18%, the maximum relative error of pulse width is 16.36%. 5.5m ball drop impact, the two waveforms are basically the same, the maximum relative error of amplitude is 19.79%. The maximum relative error of pulse width is 8.46%. which shows that the numerical results are in good agreement with the experimental results. The bolt response containing another important problem of the structural impact damage problem of complex structures impact connection, carry out structural impact damage extended finite element modeling technology. Research on cohesive crack model based on extended finite element method and virtual node method, extended finite element method combined with finite element software with the extended finite element modeling technology research and puts forward the structure and implementation method of the impact damage response. On this basis, to carry out the numerical simulation of bolt connection structure containing quasi-static tensile fracture process, destruction of the image is consistent with the experimental obtained and achieved initial crack defect free structure on the initial crack and failure process of numerical simulation. In addition, the design of the three point bending test, the different impact velocities of bullets experimental study on three point bending experiments, obtained the impact damage image. And the velocity of the projectile were 12.2m/s, 15.1m/s and 26.3m/s structure impact damage were studied by numerical simulation, the structure of the reproduction impact failure process, analyzed the impact of structural failure law, simulation results agree with the experimental data, implementation the numerical simulation of failure process of structures with initial cracks impact. Finally, a typical bolt containing complex structure, carry out the condition of drop impact response and failure process Research on numerical simulation, obtained the impact of structural response, and close to test the impact of failure mode, show that this method can realize the study on failure process of complex structure including bolts impact response and impact connection. The results of this study indicate that the finite element model is built of bolt connection structure, and simulated the impact of failure impact load structure of the extended finite element method can realize the numerical analysis of complex structure with bolt connection of shock response, and get a reasonable result.

【学位授予单位】：中国工程物理研究院
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TH131.3

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