【作者】 李磊；

【导师】 唐国金；

【作者基本信息】 国防科学技术大学 ， 航空宇航科学与技术， 2011， 博士

【摘要】 固体火箭发动机药柱设计是发动机设计的核心部分。药柱设计的目的是在选定固体推进剂之后设计出合理的药形,而药形设计往往以内弹道计算为主体,结构完整性分析只起到被动校核作用。实际上,内弹道性能优良的药柱一般体积装填分数较高,而较高的体积装填分数会导致药柱的结构响应较大,结构完整性难以满足要求。为了解决药形设计过程中这一突出矛盾,本文开展了相关的方法与应用研究,在系统总结发动机结构完整性分析流程的基础上,提出了发动机参数化建模方法并用于药形改进设计与几何参数灵敏度分析,进一步结合遗传算法进行了考虑结构完整性与体积装填分数的药形优化设计。主要研究内容如下:推导了一种基于Herrmann变分原理的粘弹性增量型有限元方法,适用于固体发动机药柱恒温过程和变温过程的结构分析,确定了发动机各部件的结构完整性判据,形式简洁且能够满足工程应用要求,为固体火箭发动机结构分析和完整性评估奠定了理论基础。总结了利用CAE软件进行固体火箭发动机结构完整性分析的方法与流程,对某型号发动机进行了结构完整性分析,研究了基于结构完整性分析的药形改进设计方法,得到了满足结构完整性要求的改进设计方案。应用表明,固体火箭发动机结构完整性分析和药形改进设计方法切实可行。提出了固体火箭发动机参数化建模方法,研究了利用MSC.Patran软件的二次开发工具PCL(Patran Command Language)实现固体火箭发动机参数化建模的相关技术,编制了星形发动机的PCL参数化建模程序,实现了根据几何参数自动建立有限元模型并进行分析计算和结果输出的功能。将其应用于星形发动机药形改进设计过程中,有效提高了结构完整性分析的建模与分析效率。实现了圆管伞盘形发动机、星形发动机和车轮形发动机的二维参数化建模,以及圆管星形发动机的三维参数化建模,结合使用中心差分法,对药柱几何参数进行了灵敏度分析,研究了药柱的最大Von Mises应变和体积装填分数随几何参数的变化规律,得到了它们对几何参数的灵敏度系数,确定了关键几何参数,为药形优化设计提供了重要依据。建立了固体火箭发动机药形优化设计的数学模型,讨论了遗传算法的基本实现技术,提出了将PCL参数化建模技术与遗传算法相结合的药形优化设计方法,将该方法应用于药形优化设计问题,同时考虑药柱结构完整性和体积装填分数要求,得到了圆管伞盘形药柱的最优纵截面形状、星形药柱和车轮形药柱的最优横截面形状以及圆管星形药柱的最优三维形状。总之,本文成功地实现了考虑结构完整性和体积装填分数要求的固体火箭发动机药形改进与优化设计,在应用上和方法上都取得了一定的进展,所得结果可为固体火箭发动机药柱设计提供更加全面的设计依据,所提出的方法对固体火箭发动机药形设计具有重要的应用价值,而且能够方便地应用于类似的复杂结构形状优化设计。更多还原

【Abstract】 During the Solid Rocket Motor (SRM) design, grain design is the core section. Theaim of grain design is to scheme out reasonable grain configuration after the suitablesolid propellant material is defined. However, in the design process of grainconfiguration, the interior ballistic performance is usually paid more attentions, and thestructural integrity of SRM is not given enough considering but only used to assess thedesign passively. In fact, the grains with excellent interior ballistics performance alwayshave high volumetric loading fraction, and this will lead to poor structural intergritybecause of high structural response. To resolve this confliction, correlative methods andapplications are studied in this dissertation. Based on summarizing the process of SRMstructural integrity analysis systematically, SRM parameterized modeling method isproposed and applied to the grain shape improvement and geometric parametersensitivity analysis. Moreover, combining this method with Genetic Algorithm (GA),the grain shape optimization is conducted taking structural integrity and volumetricloading fraction into account. The main work and achievements are summarized asfollows:Based on Herrmann variation principle, a viscoelastic incremental Finite ElementMethod (FEM) is developed, which is suitable for structural analysis of grain subjectedto variational temperature load. Structural integrity criterions of SRM are ascertained,which can satisfy the needs of engineering application. The research work provides thefoundation for structural analysis and integrity assessment of SRM.SRM structural integrity analysis method and general processes using CAEsoftware are summarized. The structural integrity analysis is completed for a certainSRM. Grain shape improvement method based on the structural integrity analysis isinvestigated and the improved project that fulfils structural integrity requirement isderived. The application shows that SRM structural integrity analysis and grain shapeimprovement method are practical and feasible.SRM parameterized modeling method is proposed. The specific techniques withsecondary development tool Patran Command Language (PCL) of MSC.Patran areresearched. Taking the star shape SRM for example, the finite element model can beautomatically established with geometric parameters and the processing of analysis andresult can also be controlled with corresponding parameters. The working efficiency isimproved obviously through the application for grain improvement of star shape SRM.The parameterizations for two-dimensional finite element model of conocyl SRM,star shape SRM, wheel shape SRM, and three-dimensional finite element model offinocyl SRM are realized. The sensitivity analysis of geometric parameters for the grain configuration is carried out with central difference method. The variations of grainmaximum Von Mises strain and volumetric loading fraction along with the geometricparameters are studied, and the sensitivity coefficients are obtained. At last, the keygeometric parameters are chosen for grain shape optimizations.Mathematical mode of the SRM grain shape optimization is established and theimplementation techniques of GA are discussed. The grain shape optimization methodis put forward by combining with GA and PCL parameterized modeling technique. Thegrain shape optimization with considering both of grain structure integrity andvolumetric loading fraction is completed and the optimum axial section shape ofconocyl grain, the optimum cross section shape of star shape grain and wheel shapegrain, and the optimum three-dimensional shape of finocyl grain are obtained.In conclusion, the SRM grain shape improvement and optimization consideringboth of the structural integrity and volumetric loading fraction are successfully executedin this dissertation, at the same time, some developments in applications and methodshave been attained. The acquired results can provide more comprehensive references forSRM grain design. The proposed methods possess great applicational value for SRMgrain configuration design and can be applied to similar complex sturcture shapeoptimization conveniently.更多还原