【作者】 丁志伟；

【导师】 吴荣仁； 宣海军；

【作者基本信息】 浙江大学 ， 化工过程机械， 2011， 硕士

【摘要】 航空发动机机匣需要要具有很好的包容能力,不能让转子碎片击穿机匣,造成飞机的二次损坏。航空大国在民用和军用航空发动机规范中都有专门条文对包容性做出严格规定,我国自行研制的大飞机涡扇发动机,要取得适航证,就必须通过包容性验证。为了研究航空发动机机匣的包容性问题,本文将航空发动机风扇叶片碎片和机匣包容区简化为平板条叶片和金属靶板,分别研究平板条叶片撞击金属等厚靶板过程及数值评定方法、平板条叶片撞击加筋结构金属靶板数值仿真方法及加强筋结构优化设计方法。结合打靶试验,通过建立平板条叶片撞击金属等厚靶板的计算模型,显式求解冲击过程,计算不同弹靶结构下金属靶板的弹道极限和残余速度,获得了与试验非常吻合的结果。由于弹体和塞柱之间多次撞击,靶板在冲击过程中多次回弹,靶板呈现多种破坏方式。靶板未击穿时,其变形挠度满足指数函数形式的经验公式；靶板被击穿时,残余速度和初速度关系满足Recht-Ipson公式。研究发现使用破坏势能法和K.A贝尔金公式用来计算靶板的弹道极限速度在工程上是可行的。为研究加强筋结构对包容能力的影响,建立了平板条叶片撞击加筋结构金属靶板的数值仿真模型,并且细化和修正了航空发动机机匣和叶片材料TC4的本构模型参数。仿真结果显示,加筋板的失效形式主要有局部剪切冲塞、整体弹塑性变形、背部花瓣形破坏、沿加强筋撕裂、靶板横向撕裂等。研究结果表明工程上将加强筋简化为等效厚度的计算方法是可行的,且相同质量的加筋板结构比等厚板抗冲击性能好,建议航空发动机机匣包容区域应尽量设计成带加强筋结构以增强包容能力。在平板条叶片撞击加筋结构靶板的数值仿真基础上,分析加强筋的布置对残余速度和弹道极限的影响,以期找到结构优化的途径。计算结果表明：叶片撞击区域布置加强筋数目越多,靶板抗冲击性能越好,为减轻重量,布置2～3条加强筋是合理的；而非撞击区域的加强筋影响不大,可以不设置。比较了相同质量情况下加强筋不同高度与厚度时的抗冲击性能,计算结果表明加强筋设置成细高型抗冲击性能更好,同等重量的“T”型加强筋比“|”型加强筋补强效果好。本文采用的数值仿真方法适用于不同材料、不同结构的撞击问题及包容性问题,研究成果对撞击问题和包容性问题的研究有一定的指导和借鉴意义。更多还原

【Abstract】 Aero-engine should have good tolerance ability to protect rotor debris from breaking the casing. Chinese large aircraft turbofan engine must be verified through inclusive to obtain airworthiness certificate. In order to study aero-engine casing inclusive problem, in this paper, fan debris and aero-engine fan casing tolerance zone is simplified as flat metal blade and metal target. Respectively, the process of flat blade impact the metal plate and the numerical evaluation method, the process of blade impact the stiffened plate and the optimal structure for stiffeners were detailed discussed in this paper.This paper calculate the ballistic limit and residual velocity by establishing numerical simulation model of different projectile and plate structures, the results obtained great agreement with the experimental datas. During the impact process, the projectle impact the plate several times, and the target presents multiple failure modes. When the plate not penetrated, its deflection can be approximation obtained by empirical formula, when projectile breakdown the target, the relationship between residual velocity and initial velocity meet the Recht-Ipson equation. Potential energy method and K.A.Belkin ballistic formula used in engineer were authenticated by numerical simulation and penetration experiments too.Paper also established numerical model to simulate the process of flat blade impact stiffened plate using a modified constitutive model parameters of material TC4. Simulation results show different failure modes of stiffened plates.The simplified method of equivalent thickness calculating is feasible, and the same quality stiffeners can promote the resistance ability of the plate.Based on the numerical simulation, this paper analysis the ballistic limit and residual velocity of different stiffened plates in order to find ways to structure optimization.The reults show that:increase the numbers of stiffeners in the impact area can promote resistance ability; the stiffeners in the non-impact region show small enhance. Stiffener set into a fine high-type, can obtain better impact resistance ability. Replace"|" type stiffener by "T" type stiffener, can improve the plate’s performance.更多还原