Dynamic parametric modeling-based model updating strategy of aeroengine casings

For accurate Finite Element (FE) modeling for the structural dynamics of aeroengine casings, Parametric Modeling-based Model Updating Strategy (PM-MUS) is proposed based on efficient FE parametric modeling and model updating techniques regarding uncorrelated/correlated mode shapes. Casings structure is parametrically modeled by simplifying initial structural FE model and equivalently simulating mechanical characteristics. Uncorrelated modes between FE model and experiment are reasonably handled by adopting an objective function to recognize correct correlated modes pairs. The parametrized FE model is updated to effectively describe structural dynamic characteristics in respect of testing data. The model updating technology is firstly validated by the detailed FE model updating of one fixed–fixed beam structure in light of correlated/uncorrelated mode shapes and measured mode data. The PM-MUS is applied to the FE parametrized model updating of an aeroengine stator system (casings) which is constructed by the proposed parametric modeling approach. As revealed in this study, (A) the updated models by the proposed updating strategy and dynamic test data is accurate, and (B) the uncorrelated modes like close modes can be effectively handled and precisely identify the FE model mode associated the corresponding experimental mode, and (C) parametric modeling can enhance the dynamic modeling updating of complex structure in the accuracy of mode matching. The efforts of this study provide an efficient dynamic model updating strategy (PM-MUS) for aeroengine casings by parametric modeling and experimental test data regarding uncorrelated modes.     

某型起动机起动故障的分析与研究

主要针对某型发动机地面起动时提前中止的状况进行理论分析,通过定位、排查,确定了故障原因,也为此类故障的排除提供了可行的方法。     

材料切除对机匣铣削动力学与稳定性的影响

在薄壁零件加工过程中,工件材料的连续切除会造成工艺系统动力学特性的不断变化,并对工艺系统的颤振稳定性产生显著影响。以航空发动机机匣为对象,研究了其铣削过程中工件材料切除以及切削位置变化对工件动力学特性与颤振稳定性的影响规律。首先,根据机匣的几何结构与铣削工艺特点,提出了按切削行及切削段进行材料切除过程细分的方法。其次,建立了工艺系统动力学特性演化的快速计算方法和颤振稳定性极限的频域预测方法,并在单个切削行内和不同切削行间分析了材料切除过程对工艺系统的影响。结果显示,在单个切削行内工艺系统的动力学特性会小幅度减小,稳定性极限图会向左下方小幅度偏移;在不同切削行间工艺系统的动力学特性变化幅度较大,稳定性极限图呈现出交错排列现象,难以针对整个铣削过程进行切削参数优选,因此提出了基于单行刀位轨迹的切削参数优选方法,保证了整个材料切除过程的稳定切削。最后,进行了机匣铣削与模态试验,验证了所提方法的正确性与有效性。     

带有安装边螺栓连接结构的机匣包容能力研究

为了研究带有安装边螺栓连接结构的机匣对断裂叶片的包容能力,截取环形机匣中的安装边螺栓连接结构,开展有限元仿真和冲击试验。首先,使用LS-DYNA软件建立有限元模型,研究撞击角度、撞击位置、定距套和止口对机匣安装边螺栓连接结构抗冲击能力的影响。仿真结果表明：撞击位置、撞击角度、定距套和止口都对结构的抗冲击能力有显著的影响,当叶片撞击在单侧机匣的安装边位置时结构的抗冲击能力最弱,定距套和合理的止口设计都能够有效提高结构的抗冲击能力。然后,通过机匣安装边螺栓连接结构的抗冲击试验,验证了数值仿真方法的准确性和可靠性,为数值仿真结论的有效性提供了依据。最后,通过数值仿真分析了螺栓断裂过程,并结合试验分析揭示了螺栓发生剪切断裂和拉伸断裂的原因。     

Hierarchical model updating strategy of complex assembled structures with uncorrelated dynamic modes

In structural simulation and design, an accurate computational model directly determines the effectiveness of performance evaluation. To establish a high-fidelity dynamic model of a complex assembled structure, a Hierarchical Model Updating Strategy(HMUS) is developed for Finite Element(FE) model updating with regard to uncorrelated modes. The principle of HMUS is first elaborated by integrating hierarchical modeling concept, model updating technology with proper uncorrelated mode treatment, and...     

进、排气壳对全流道大膨胀比涡轮性能影响研究

进、排气系统对涡轮级的性能影响鲜有研究,本文针对增压器涡轮,采用数值方法对全流道大膨胀比跨声速涡轮与进、排气壳进行耦合计算,探索进、排气壳耦合对涡轮级的性能参数影响,结果显示进气壳主要影响静叶10%叶高与50%叶高前缘来流气流角周向分布,静叶排会减弱进气壳带来的参数周向不均匀性,排气壳主要影响动叶尾缘0°与180°周向位置总压与静压分布,进、排气壳耦合涡轮级总静效率比均匀边界涡轮级下降0.25%。