复杂形体面片缠绕成型方法的分析与实现

通过对复杂形体缠绕成型方法的分析，提出了面片缠绕的思想；同时针对缠绕过程中可能存在的架空问题提出了一套可行的判定准则和解决方案。以面片缠绕理论为基础，针对飞机发动机进气道缠绕成型，编制缠绕控制程序并进行相应的实验，验证了面片缠绕方法的实用性，为航空航天高性能构件的缠绕成型探索了一条新的途径。     

凹回转曲面纤维缠绕架空分析及应用

针对诸如带喷管固体火箭发动机的凹曲面过渡段等负高斯曲率面的缠绕,应用微分几何曲面理论推导出了凹回转曲面的纤维缠绕架空条件及判据,并对不同的过渡段曲线进行了分析,分别给出了判别公式。通过缠绕实验验证了架空判据的正确性和实用性,表明采用单叶双曲面比采用凹圆曲线回转曲面具有更好的缠绕工艺性,且其直纹线的缠绕角恰好为不架空的临界缠绕角;缠绕时,为了保证运动的平稳性,需要剔除奇异点,进行平滑处理。     

宽马赫数范围高超声速进气道转动唇口变几何方案研究

结合简单一维流理论讨论了一种工作于Ma=4～7、采用可转动唇口的变几何二元高超声速进气道设计方案,并利用数值仿真手段对其Ma=4下的自起动性能及其他不同工作马赫数下的性能进行了研究.结果表明:所设计的变几何进气道必须辅以附面层排移措施才能在Ma=4下顺利实现自起动;该变几何方案Ma=4下的流量系数达0.7以上,这为飞行器加速提供了强有力保障;与定几何进气道相比,变几何进气道高低马赫数下的总体性能均得到显著提高;此外,转动唇口的铰接位置对自起动性能有重要影响.      

进口导叶可调的涡轴发动机性能寻优控制模式

根据变比热容原理建立了进口导叶可调的涡轴发动机部件级全包线数学模型;仿真研究了涡轴发动机的最大功率、最低油耗、最低涡轮前温度控制模式.仿真结果表明:建立的涡轴发动机数学模型具有较高的准确度;采用最大功率控制模式在整个包线范围内显著提高了涡轴发动机的功率;采用最低油耗控制模式保证功率基本不变,而耗油率明显降低;采用最低涡轮前温度控制模式,能够保证功率基本不变,动力涡轮前温度显著降低.      

纤维缠绕不等极孔椭球类容器的应力分析及优化

基于微分几何推导出了不等极孔椭球类容器纤维缠绕的非测地线稳定缠绕方程,并根据薄膜理 论、层合板理论、蔡-吴失效准则得到了赤道处纤维层的最小厚度1. 281 7 mm,计算出的纤维方向的应力小于 纤维的极限强度3. 92 GPa。发现纤维缠绕椭球容器的应力状态是赤道处最先发生破坏,且会出现局部失效现 象。以缠绕层最小质量M 为目标函数,蔡-吴失效准则为约束条件,在给定内压5 MPa 的情况下,得到了优化 后的容器质量为34. 072 kg。相比于等极孔的容器而言,非测地线缠绕具有高度非线性、不稳定性及精度难以 控制等问题。     

基于微分几何纤维缠绕回转壳封头的厚度计算

应用微分几何理论,建立了纤维复合材料在回转壳封头上稳定缠绕的数学模型,推导出了缠绕角、中心角与轴向坐标之间的微分方程。结合缠绕轨迹在封头上叠带的几何关系,给出了厚度的计算方法。算例表明该计算方法反映了纤维缠绕回转壳封头上厚度的分布规律,可直接应用于结构的初步设计。     

Dynamic analysis of the composite laminated repaired perforated plates by using multi-patch IGA method

The bonded repair techniques seem to be the most frequent procedures in the aviation maintenance. The achieved composite repaired perforated thin-walled plate is a complex geometry with high numerical analysis cost. The NURBS-based Isogeometric Analysis (IGA) proposes a sensible and affordable tool to carry out such geometry analysis. In this context, a well-known technique is to divide the original geometry assembly into number of simple neighbors connected geometries. In the present study the free vibration analysis of the perforated plates repaired on one side with an external bonded composite laminated patch is investigated. A multi-patch geometry modeling approach is implemented in line with the first order shear deformation theory of plates. In order to hold the geometry integrity and uniformity, all the degrees of freedom between adjacent geometry patches are completely tied through implementing a Nitsche method. To show the effectiveness and accuracy of the developed formulation, some representative results are extracted and compared with those from literature. The effects of geometrical as well as material parameters including boundary condition, cutout shape, and repair layup on the dynamic response of the repaired perforated plates are then investigated.     

Winding Pattern Design and Simulation of S-elbow

Aimed at the S-elbow composed of two elbows with different radii, this article proposes a winding pattern design method combined with patch winding method and traditional winding method. It proposes an optimal combination of calculating the tangential point amount and skip point amount to make the pattern distribution even and keep the minimal adjusting angle. The S-elbow overall winding pattern plan and simulation module are designed to verify the combined winding pattern design method and the calculation algorithm of the tangential point amount and skip point amount. From the pattern distribution and the simulation effect analysis, it shows that this combined winding pattern design method is a good solution to the S-elbow combined winding pattern design. Aimed at the S-elbow winding pattern based on the patch winding method, it carries out the precision error analysis and points out the correspondence between the error and mesh size. Generally speaking, the bigger the mesh size is, the quicker the program calculation speed is; the smaller the mesh size is, the smaller the winding pattern error is.     

纤维缠绕复合材料圆环壳线型设计与优化

由微分几何理论，导出了纤维缠绕圆环壳曲面的滑移和架空判据。基于薄膜理论和网格理论，结合圆环壳几何特征，得到了内压作用下纤维螺旋加环向缠绕圆环壳的平衡方程组，给出了均衡缠绕线型的确定方法。以稳定缠绕条件和壳体强度要求为约束，缠绕层最小质量为优化目标，利用收敛效率较高的序列二次规划算法（SQP）求得了不同爆破压强下的各项最优均衡缠绕参数。文中的设计方法真实反映了环壳结构特征和实际工程设计要求，算例表明可直接应用于纤维缠绕环壳的初步设计。     

纤维缠绕的曲面架空分析及其应用

针对诸如壳体－喷嘴一体化的固体火箭发动机过渡段、环壳燃料箱等复杂型面的缠绕，应用曲面理论和力学分析方法，研究了纤维缠绕的成型压力与曲面几何的关系，进而确定了一般曲面、负荷斯曲面、环壳以及过渡段缠绕过程的纤维架空条件与判据，为复杂型面的缠绕成形奠定基础。     

复合材料缠绕后置处理方法研究

利用芯模表面的离散落纱点,依据空间几何和微分几何理论,针对纤维缠绕过程提出纤维缠绕出纱点轨迹的网格后置处理方法。该方法首先通过纤维缠绕轨迹的落纱点,以及缠绕过程中等悬纱长约束条件来求取出纱点,然后通过计算相邻出纱点的各坐标差得到机床运动轨迹,最后分别通过对三通管和组合回转体的缠绕成型实验,来验证该网格后置处理方法在处理非回转体和回转体缠绕出纱点轨迹的可行性和准确性。     

Integrated optimization on aerodynamics-structure coupling and flight stability of a large airplane in preliminary design

The preliminary phase is significant during the whole design process of a large airplane because of its enormous potential in enhancing the overall performance. However, classical sequential designs can hardly adapt to modern airplanes, due to their repeated iterations, long periods, and massive computational burdens. Multidisciplinary analysis and optimization demonstrates the capability to tackle such complex design issues. In this paper, an integrated optimization method for the preliminary design of a large airplane is proposed, accounting for aerodynamics, structure, and stability. Aeroelastic responses are computed by a rapid three-dimensional flight load analysis method combining the high-order panel method and the structural elasticity correction. The flow field is determined by the viscous/inviscid iteration method, and the cruise stability is evaluated by the linear small-disturbance theory. Parametric optimization is carried out using genetic algorithm to seek the minimal weight of a simplified plate-beam wing structure in the cruise trim condition subject to aeroelastic, aerodynamic, and stability constraints, and the optimal wing geometry shape, front/rear spar positions, and structural sizes are obtained simultaneously. To reduce the computational burden of the static aeroelasticity analysis in the optimization process, the Kriging method is employed to predict aerodynamic influence coefficient matrices of different aerodynamic shapes. The multidisciplinary analyses guarantee computational accuracy and efficiency, and the integrated optimization considers the coupling effect sufficiently between different disciplines to improve the overall performance, avoiding the limitations of sequential approaches utilized currently.     

一种组合发动机变几何进气道流场特性研究

对一种组合发动机变几何进气道各马赫数下不同几何形状的三维流场进行了数值模拟.研究了不同马赫数时进气道的流场特征及气动性能.结果表明:随着来流马赫数的减小,外压段的超声溢流不断增大,进气道的流量系数不断减小;第一道内压缩波及其反射点位置对组织管道内的流场有着非常重要的作用;当有反压作用时,会在扩张段内形成激波串,激波串的形状和位置与来流马赫数、反压大小及管道内的流动有关.研究结果对类似进气道的几何调节方式有一定的指导意义.      

固体火箭发动机喷管燃气舵铰链力矩参变分析

以固体火箭发动机喷管燃气舵绕流流场为研究对象,采用数值模拟技术,通过离散求解流动方程及相关湍流模型方程,对包含舵基、舵片和发动机喷管在内的复杂流场进行了变参数分析,获得并揭示了舵基、舵片附近的流动现象和流动特点.验证了所引入的数值模拟方法的有效性,分析结果对舵基、舵片的结构安装以及控制机构的设计具有借鉴意义.     

二维超音速进气道性能实验研究

介绍几何喉道上游具有不同进口侧板、不同槽宽的附面层吸除槽和槽腔出口不同放气孔面积的二维超音速进气道,在自由流马赫数:Ma_∞=1.793,2.037,2.292,2.557;攻角:α=0°,3°,6°,10°,-6°条件下的实验研究结果。讨论了零攻角下,有无吸除时进气道的流型、性能和不同侧板、吸除槽宽、放气孔面积对进气道性能的影响。分析了二维超音速进气道的攻角特性;描述了进气道结尾波系随下游反压增高时的波系演变图案,录相显示了具有一定槽宽、一定吸除量的实验模型具有连续的气动特征,如同全外压式进气道那样,结尾波系从超临界连续地通过槽区到达亚临界。     

Research of Optical Fiber Coil Winding Model Based on Large-deformation Theory of Elasticity and Its Application

Optical fiber coil winding model is used to guide proper and high precision coil winding for fiber optic gyroscope (FOG) application. Based on the large-deformation theory of elasticity, stress analysis of optical fiber free end has been made and balance equation of infinitesimal fiber is deduced, then deformation equation is derived by substituting terminal conditions. On condition that only axial tensile force exists, approximate curve equation has been built in small angle deformation scope. The comparison of tangent point longitudinal coordinate result between theory and approximation gives constant of integration, and expression with tangent point as origin of coordinate is readjusted. Analyzing the winding parameters of an example, it is clear that the horizontal distance from the highest point of wheel to fiber tangent point has millimeter order of magnitude and significant difference with fiber tension variation, and maintains invariant when wheel radius changes. The height of tension and accurate position of tangent point are defined for proper fiber guide. For application to fiber optic gyroscope, spiral-disc winding method and nonideal deformation of straddle section are analyzed, and then spiral-disc quadrupole pattern winding method has been introduced and realized by winding system. The winding results approve that the winding model is applicable.     

不同进气状态对矩形大S弯扩压器流动特性的影响

通过亚音扩压器内壁面流谱图、有关截面的总压恢复分布图、速度矢量图以及各壁面沿程静压恢复系数分布分析对比了四种进气状态下矩形大Ｓ弯扩压器流动特性。试验表明不同进气状态对矩形大Ｓ弯扩压器性能有很大影响，其中均匀核心流进气条件下的流动代表了大Ｓ弯扩压器流动的一般特征，其出口平均总压恢复系数最高，周向总压畸变指数不大，旋流很弱。研究腹部或两侧进气道地面起飞进气状态下矩形大Ｓ弯扩压器的流动特性更具有实际意义。试验表明其出口平均总压恢复系数较低，周向总压畸变指数较大，旋流较强且很不规则。     

锥柱面螺旋线短程线与网格缠绕成型技术

针对复合材料网格结构筋条及蒙皮缠绕成型的需求,运用微分几何方法,对柱圆锥面螺旋线短程线进行了探讨。解决了复合材料网格结构筋条及蒙皮的缠绕成型问题。结果表明圆柱和锥段螺旋线的弧长和曲率计算方法,可用于圆柱段和圆锥段复合材料网格结构成型装置的设计生产和纤维缠绕。对数螺线和阿基米德螺线的弧长和曲率计算方法,可用于锥段复合材料网格结构软模成型装置的设计生产和纤维缠绕,为复合材料网格结构自动化制造创造了条件,同时针对工程需要,对不同的网格结构选择不同的加工成型方式,可大大降低加工难度,实现低成本快速批量生产。     

圆筒纤维缠绕变张力神经网络动态控制

 缠绕张力作为纤维缠绕成型中的关键影响因素,其波动直接影响缠绕精度和制品的性能。针对缠绕张力的动态变化,且保证制品等环向残余应力,提出神经网络动态控制缠绕变张力方法。考虑芯模变形影响,基于各向异性缠绕层弹性变形及各向同性内衬厚壁筒理论,给出外压作用下缠绕层的径向应力及环向应力;在弹性范围内采用应力叠加原理建立剩余张力与缠绕张力之间的解析算法。基于制品环向残余应力叠加特点,采用给定输出层权值的神经网络算法,通过误差反向传播及放大方法,对等环向残余应力制品纤维缠绕过程中的缠绕变张力进行动态更新。仿真与实验结果表明:该控制方法对纤维缠绕变张力起到动态优化作用,可以达到预期要求,且更符合实际缠绕过程。     

二元高超声速变几何进气道气动特性研究

设计了一种唇罩可沿来流方向平移的二元高超声速变几何进气道,对进气道开展了三维数值仿真研究,就气动特性与相应定几何进气道进行了对比.结果表明:通过迎着来流方向平移唇罩,进气道内收缩比由1.80下降至1.57,自起动马赫数由4.9下降至3.4.在来流马赫数为4.0~7.0范围内,变几何进气道与定几何进气道隔离段出口马赫数和增压比相差不大,变几何进气道流量系数和总压恢复系数可实现提升最大值分别为21%和9%.二元高超声速变几何进气道综合气动性能明显高于定几何进气道.