【作者】 聂旭涛；

【导师】 范大鹏；

【作者基本信息】 国防科学技术大学 ， 机械工程， 2008， 博士

【摘要】 导引头系统具有实现对目标的捕获、跟踪、瞄准和稳定等功能,在精确制导武器中得到广泛应用。导引头伺服机构用于为光电探测器提供惯性稳定的物理平台,是导引头系统的核心部件之一,其结构性能的优劣直接影响着导引头系统的整体性能。随着超音速末制导导弹对飞行速度、制导精度等要求的提高,导引头伺服机构的工作环境越来越严酷,这就对伺服机构的强度设计和动力学特性设计提出了更新的要求。深入研究伺服机构,特别是轻量化高精度伺服机构的强度计算方法和动力学特性的影响机理显得十分迫切。正是在这种背景下,本文从结构强度和动力学特性两个方面展开研究工作,主要目的是研究复杂动力载荷下结构强度设计的一般准则和高效计算方法,以及研究结构参数对动力学特性的影响规律,以为新型导引头伺服机构的机械和控制的综合优化设计提供理论依据。围绕导引头结构强度计算和动力学特性分析两个方面,论文所开展的具体研究内容为：1.在结构强度计算方面,传统设计方法分析过程复杂、求解效率差、计算误差大。为了提高结构强度设计的性能,论文采用并行计算技术,研究了结构强度并行分析的计算方法、软件实现和具体应用问题。首先基于有限元EBE(Element-By-Element)并行策略提出并实现了确定性载荷下结构响应分析的有限元N-EBE-PCG并行算法,同时结合虚拟激励法,进一步实现了随机载荷下结构响应分析的并行虚拟激励法PPEM(Parallel Pseudo Excitation Method)。结构响应并行算法的研究与实现,有利于提高复杂动力载荷下伺服机构的结构强度分析效率。采用结构强度并行算法,在网络集群并行环境下,基于MPI(Message Passing Interface)消息传递编程模式自主开发了强度并行分析程序,然后利用参数化设计语言APDL(ANSYS Parameter Design Language)将自主并行分析程序无缝集成到有限元分析软件ANSYS中,从而实现了结构强度的并行计算。详细分析了导引头伺服机构在服役期间所处的动力载荷环境,利用结构强度并行计算方法,分别分析了冲击、随机振动载荷作用下伺服机构内外框架的结构强度,以及结构设计参数对强度的灵敏度,为框架结构的轻量化设计提供了理论分析和计算依据。研究结果表明,文中实现的结构强度并行分析程序计算精度和效率较高,能够满足复杂工况环境下导引头结构强度计算与优化设计的需要。2.在动力学特性分析方面,传统的伺服机构动力学研究主要采用理想模型,较少考虑设计公差、制造误差、摩擦磨损等随机因素对系统动力学特性的影响,难以准确描述实际的动力学特性。为此,论文建立了伺服机构的动力学模型,分析了随机因素的影响,并运用基于概率统计的分析方法进行了随机动力学仿真。首先基于Hamilton力学原理建立了导引头伺服机构的动力学仿真模型,分析了摩擦非线性、框架间的非线性耦合以及能量耗散对动力学特性的影响。在该模型的基础上,结合相关试验结果,较全面地分析了伺服机构中存在的随机因素并且提出了相应的研究方法。为了准确分析评价随机激励下伺服机构的随机响应特性,研究了拟Hamilton系统的随机平均法,实现了求解随机动力学FPK (Fokker-Planck-Kolmogorov)方程的点插值无网格法。综合运用随机平均法和无网格法,计算得到了随机激励下伺服机构的随机响应并且研究了结构参数对随机响应统计特征的影响,为评价机构的动力学特性提供了理论依据。针对内部摩擦随机性的问题,基于滚动轴承的基本分析方法,研究了摩擦力矩的产生机理和计算方法。在伺服机构动力学模型的基础上,运用蒙特卡罗方法进行随机模拟试验,分析了结构参数的随机性对动力学特性的影响,为进一步研究伺服机构的动力行为演变规律打下了基础。论文所研究的结构强度并行分析方法和非线性随机动力学仿真技术,为开展伺服机构的结构与控制的综合优化设计提供理论分析和计算依据。更多还原

【Abstract】 Seeker system, which can possess some functions such as capture, tracking, aiming and stabilization, is applied to the precision guided weapon widely. As an important part of seeker system, seeker servo mechanism can provide inertia stabilized platform for photoelectric detector, and its structural performance has a direct effect on the performance of seeker system. With the improvement of the flight speed and guidance precision of the final guidance supersonic missile, operating condition in missile is worse and worse, and the newer demands is put forward for the strength design and the dynamics analysis of servo mechanism. So it is very urgent that the strength design methods and the influence mechanism of dynamics of the high precision lightweighting servo mechanism are researched in depth. Under this circumstance, this dissertation suggests two research aspects included strength and dynamics, namely study on the guide lines and the high performance calculation methods of strength design when complicated dynamic load and study on the influence of structural parameters on dynamics. These studies can provide the foundations for the optimum design of the structure and control of the new-style seeker servo mechanism.The detailed contents and innovative work are organized as follows:1. In the structural strength respect, the traditional design methods are complex and low performance. In order to improve the performance of the strength design, computing methods, software realization and technical application problems are researched with parallel computing.Firstly, on the basis of finite element EBE parallel policy, finite element N-EBE-PCG parallel algorithm is presented and realized to calculate the structural response when deterministic load. Ulteriorly, combining N-EBE-PCG algorithm with pseudo excitation method, parallel pseudo excitation method is presented to calculate the structural response when stochastic load. The research and realization of the strength parallel algorithms is of advantage to improve the efficiency of the structural strength analysis when complicated dynamic load.Under the cluster of workstation (COW) environment, the strength parallel algorithms are applied to develop the strength parallel computing home-code based on the parallel programming mode of Message Passing Interface (MPI). In order to make these parallel algorithms take the form of software, the strength parallel computing home-code is integrated into ANSYS software seamlessly with the use of ANSYS Parameter Design Language (APDL).The dynamic environments which seeker servo mechanism suffers in its enlistment are analyzed systematically. And then, the strength parallel computing program is applied to calculate the mechanical strength of the inner and outer framework of a typical servo mechanism respectively under the shock and random vibration environments. Also, the strength sensitivity of structural design parameters is analyzed. It shows by simulation that the strength parallel computing program proposed has a high calculation precision and efficiency, and is applicable for the structural strength optimum design of the seeker servo mechanism under the complicated dynamic environments.2. In the dynamics respect, the traditional research of servo dynamics uses the ideal model and seldom allows for the random factors such as design tolerance, mismatchining tolerance and wear. So it can not describe the actual dynamics correctly. Therefor, the dynamic models with random factors which can describe the influence mechanism of dynamics better are researched based on the stochastic analysis methods.Firstly, the dynamic simulation model of the seeker servo mechanism is established based on the Hamilton mechanics principles and the influences of friction, nonlinear coupling and energy dissipation on the servo dynamic characteristics are analyzed. On the basis of the dynamic model, the random factors which affect the driving moment and inner friction of the servo mechanism are illuminated in full length according to the correlative experimental results, and the processing methods for these random factors are proposed.In order to analyze and evaluate the random response characteristic of the servo mechanism affected by the random excitation, the stochastic averaging methods of quasi Hamiltonian systems are investigated, and the points interpolation meshless (PIM) methods are studied to solve the FPK (Fokker-Planck-Kolmogorov) equations of stochastic dynamics. Following that, the random response of the servo mechanism is solved by the stochastic averaging methods and the the PIM methods. And then, the influence of the structural parameters on the stochastic response characteristic is studied. This work can provide theory foundations for evulating the dynamics of the mechanism.Aiming at the problem of the random friction, the mechanism and the calculation methods of the friction torque are studied systematically based on the basic theory of rolling bearing. Using these methods, the influence of the structural parameters on the dynamics is investigated in the Monte Carlo simulation test. This work makes preparations for the farther study on the evolvement rules of the servo dynamics.In a word, the parallel analysis technique of structural strength and the simulation method of nonlinear stochastic dynamics which are studied in this dissertation can be applicable for the optimum design of the servo structure and control.更多还原