双S弯喷管的流固耦合特性研究

为了明晰S弯喷管的流固耦合特性,数值模拟了流固耦合作用下双S弯收敛喷管的结构变形特征及其内/外流特性。结果表明：S弯喷管的圆转方弯曲构型产生了非均匀的流场分布,并增强了结构的弹性特征,它们通过交换气动载荷与变形位移数据形成了S弯喷管流固耦合的作用机理。在气动载荷作用下,S弯喷管沿Y向的最大变形位移为25.3mm,它位于喷管出口上壁面的中心位置。当喷管的结构变形稳定时,第二弯转弯处下壁面的气流加速至局部超音速,壁面静压大幅降低;第一弯下游上壁面附近形成了气流分离区;喷管出口喷流沿轴向向上偏转。流固耦合作用导致S弯喷管的流量系数减小0.6%,推力系数降低1.8%。矩形截面与弯曲构型是影响S弯喷管流固耦合特性的主要几何特征,其中矩形截面能够显著增大喷管的变形位移;S形弯曲构型虽然能够有效抑制变形特征,但它导致喷管多个区域出现变形,喷管的结构变形分布变得更加复杂。     

计及摩擦的有限变形碟形弹簧薄膜解

应用Ｔｉｍｏｓｈｅｎｋｏ ＳＰ的刚性截面假设，分析了单片碟形弹簧在大变形情况下计及摩擦与滑动的载荷－位移关系，并对有导杆与无导杆，计摩擦与不计摩擦等不同情况下的载荷－位移曲线作了对比分析，在此基础上对重复加载时摩擦力的损耗（滞后功）进行了计算和讨论，这对连接件的抗疲劳设计将会起有益的作用。     

具有初始弯曲的转子系统的振动特性

具有初始弯曲的转子系统的振动特性与不平衡响应相比,既有相似之处,又存在独有的特点.从转子动力学理论出发,建立了适合工程应用的多自由度分析模型,给出了分析方法,并通过一实际转子系统的计算分析,阐述了其动力学特点.     

变形工艺对Ti-3Al-5Mo-5V动态压缩变形的影响

采用显微组织分析和工艺试验相结合的方法系统分析了变形工艺对Ti-3A l-5Mo-5V钛合金动态压缩变形行为的影响规律。结果表明,变形速率和变形量影响着合金动态变形局部化的程度(剪切带的宽度)和变形过程中出现的剪切带的类型,动态变形后剪切带区域的硬度与其他位置的硬度差异较大,这种差异可以通过变形后适当的后续退火处理来消除。     

Ti—10V—2Fe—3Al合金的应力诱发马氏体转变

研究了经不同固溶处理的Ti－1023合金在拉伸变形过程中的应力诱发马氏体转变特性，同时也测定了转变产物的晶体结构及激发应力。业已发现相变性质与固溶处理温度及冷却速率有密切关系。最后，讨论了应力诱发马氏体转变对合金拉伸性能的影响。     

固支边界的矩形板在横向载荷作用下弯曲问题的解及其应用

鉴于用文献方法求解固支矩形板横向弯曲问题时计算量大且难以理解,本文提出了一种以上述方法为基础,但较之简单的计算方法,在各向同性板中得到了文献相吻合的结果后,进一步应用到正交各向异性材料中,得到大量计算结果。另外,在各向同性介质中,平面热应力问题与弯曲问题是可以相互比拟的。将这种比拟推广到正交各向异性介质中去,可以由弯曲问题的解求得平面热应力问题的解。     

High Temperature Flow Stress Prediction of Nano-Al2O3/Cu Composite Using an Artificial Neural Network

Alumina dispersion strengthened copper composite （nano-Al2O3/Cu composite） was recently emerged as a kind of potentially viable and attractive engineering material for applications requiring high strength, high thermal and electrical conductivities and resistance to softening at elevated temperatures. The nano-Al2O3/Cu composite was produced by internal oxidation. The microstructures of the composite were analyzed by the TEM and its hot deformation behavior was investigated by means of continuous compression tests performed on a Gleeble 1500 thermo-simulator. Making use of the modified algorithm-Levenberg-Marquardt （L-M） algorithm BP neural network, a model for predicting the flow stresses during hot deformation was set up on the base of the experimental data. Results show that the microstructures of the composite are characterized by uniform distribution of nano-Al2O3 particles in Cu-matrix. The sliding of dislocations is the main deformation mechanism. The dynamic recovery is the main softening mode with the flow stress decreasing gently from 500℃ to 850 ~C. The recrystallization of Cu-matrix can be retarded late into as high as 850 ℃, when it happens only partially. The well-trained BP neural network model can accurately describe the influence of the temperature, strain rate, and true strain on the flow stresses, therefore, it can precisely predict the flow stresses of the composite under given deforming conditions and provide a new way to optimize hot deforming process parameters.     

橡胶大变形力学常数测试研究

 本文根据能量理论推导出了橡胶大变形力学常数计算公式,并根据该原理设计制做了试验测试装置,用两种方法进行了试验测试和分析,克服了时间和滞后的影响,试验方法是有效的,测试结果令人满意。     

GH169合金的本构关系研究

GH169合金主要是作为变形合金而得到广泛应用。因此,迫切需要明确其流动应力与变形条件的关系,即本构关系。文献[1]曾对GH169合金进行了这方面的研究,但所研究的结果只适用于预成形过程,而且所得到的本构关系与实测数据误差较大。近代航空发动机的涡轮盘广泛采用GH169合金制造,其锻造过程一般由预锻和终锻过程组成。     

The Effect of Composite Flexures on Aeroelastic Stability of a Hingeless Rotor Blade

The effects of ply orientation angle of composite flexures on stability of hingeless rotor blade system are studied.The composite hingeless rotor blade system is simplified as a hub,a flap flexure and a lag flexure.pitch bearing and main blade.The kinematics formulations are inferred by employing the moderate deflection beam theory.The shear deformation and warping related to torsion are considered.The quasi-steady strip theory with dynamic inflow effects is applied to obtain the aerodynamic loads acting on the blade.Based on these.the set of finite element formulations of a hingeless rotor blade system is worked out.The numerical results show that the ply angle of the composite flexures has great effects on the aeroelastic stability of rotor blade.