国内外航空发动机主轴轴承保持架材料的研究

用金相、透射电镜及光谱分析的方法，对国内外航空发动机２主轴承轴承保持架材料进行了研究。结果表明，国外保持架材料的质量优于我国。在高温、高速和重负荷条件下应选择钢制保持架。     

航空发动机用聚酰亚胺树脂基复合材料衬套研究进展

综述了航空发动机用聚酰亚胺树脂基复合材料衬套的特性及其研究进展与应用现状,重点介绍了石墨填充复合材料衬套、纤维编织增强复合材料衬套及短切纤维增强复合材料衬套的制备技术、性能特点与应用发展,指出低成本、连续化生产、耐高温及长使用寿命是未来航空发动机聚酰亚胺树脂基复合材料衬套及其材料体系的主要发展方向。     

纳米复合材料涂层提高航空发动机性能

位于赖特帕特森空军基地的美国空军实验室材料与制造处的科学家及工程师会同大学的研究人员，在超韧纳米复合材料涂层研究领域取得重大进展，这种涂层可提高先进喷气战斗机用发动机的性能，并改进耐久性。     

航空发动机多学科设计优化技术研究

多学科设计优化（MDO）是为实现复杂产品设计方法升级换代的最佳技术途径。针对先进航空发动 机设计面临的各学科间耦合关系复杂、指标冲突严重等困难,按零件、部件和总体方案设计３个阶段对MDO的 各项关键技术开展了研究、开发及应用工作,提出了基于MDO技术的航空发动机一体化设计方法。给出的５个 工程应用实例表明,该方法与传统设计方法相比,能大幅提高航空发动机设计水平,具有广泛的工程应用前景。     

商用航空发动机先进复合材料风扇叶片研究进展

<正>现代商用飞机"飞得更高、更快和更安静"的需求,对发动机的动力和效率提出了新的要求。在气动设计技术、结构设计技术和复合材料技术发展的基础上,大涵道比商用发动机应用复合材料风扇叶片,可以进一步提高商     

碳化硅陶瓷基复合材料在航空发动机上的应用需求及挑战

随着航空发动机推重比的不断提高,急需发展轻质、高强韧、耐高温、长寿命、抗烧蚀、抗氧化的碳化硅陶瓷基复合材料(SiC matrix ceramic composites,CMC-SiC),以满足航空发动机愈加苛刻的服役要求。本文简要介绍了CMC-SiC复合材料的特点和制备方法,综述了CMC-SiC复合材料在国外先进航空发动机热端部件上的应用进展及国内的研究现状。从工程化角度,指出了国内在高性能纤维、构件设计及制备、环境障涂层、无损检测技术、考核验证方法、修复技术等方面存在的差距及需突破的关键技术,指出了今后国内的研究目标与发展方向。     

航空发动机复合材料叶片用3D机织预制体研究进展

三维机织复合材料（3DWCs）因其高比强度、低密度、低热膨胀系数和良好的成型性等优点受到越来越多的青睐,已经成功运用到飞机和汽车工程等领域。随着航空发动机研发力度的加大,3DWCs也在飞机发动机零部件上有所应用。综述了航空发动机复合材料叶片用三维机织预制体（3DWPs）的研究进展及现状;对比了异形高厚度3DWPs的几种织造方法;基于试验测试和仿真模拟,介绍了国内外3DWPs变形性能的研究进展;分析了3DWPs结构对其复合材料性能的影响;最后,展望了3DWPs的发展方向,为航空发动机复合材料叶片的发展提供了参考依据。     

航空发动机复合材料的应用与研究

由于航空工业的迅猛发展,航空发动机复合材料应运而生,本文简单介绍了航空发动机复合材料的发展状况,以及主要的发展趋势,分析了发动机材料的各自独特的特性,并突显了复合材料在航空发动机发展中重要地位,为未来航空发动机的相关研究和研发奠定基础,使航空发动机相关制造工艺上再上一个新台阶。     

航空发动机高温材料的研究现状

概述了航空发动机高温材料的研究现状，指出在进一步挖掘传统高温合金潜力的基础上，应加快陶瓷基复合材料、碳／碳复合材料等新型高温材料的研究。     

碳纤维复合材料传动轴承扭性能优化设计

利用数值模拟分析的方法研究了铺层角度、厚度、顺序以及对称性对碳纤维复合材料传动轴抗扭性能的影响规律。研究发现结构抗扭截面系数在单向铺层方向为接近0°、45°及接近90°时较高,且随着铺层厚度增加而增大;扭转刚度则在40°～70°较好。在接近0°和接近90°铺层间铺设45°铺层能提高零件抗扭性能;与反对称铺层方案相比对称铺层方案更有利于零件承受扭矩。将优化铺层方案应用在某型号风机传动轴的设计中,试验证明能够满足使用要求并达到节约原材料的目的。     

基于渐进结构优化的取料梁腹板拓扑优化

为了实现圆形堆取料机取料梁的轻量化设计,采用渐进结构优化方法(ESO)研究取料梁腹板的拓扑优化问题.在有限元软件ANSYS平台上利用其APDL语言进行二次开发实现了基于应力水平的渐进结构优化法,并结合使用灵敏度再分配技术控制棋盘格式,使各单元对结构性能的贡献或影响实现平滑过渡.最后获得了较清晰的取料梁腹板拓扑优化构形,为实现取料梁下一步设计及优化提供参考模型.     

Discrete material optimization of general composite shell structures

A novel method for doing material optimization of general composite laminate shell structures is presented and its capabilities are illustrated with three examples. The method is labelled Discrete Material Optimization (DMO) but uses gradient information combined with mathematical programming to solve a discrete optimization problem. The method can be used to solve the orientation problem of orthotropic materials and the material selection problem as well as problems involving both. The method relies on ideas from multiphase topology optimization to achieve a parametrization which is very general and reduces the risk of obtaining a local optimum solution for the tested configurations. The applicability of the DMO method is demonstrated for fibre angle optimization of a cantilever beam and combined fibre angle and material selection optimization of a four‐point beam bending problem and a doubly curved laminated shell. Copyright © 2005 John Wiley & Sons, Ltd.     

旋转复合材料薄壁轴的不平衡非线性弯曲振动

研究几何非线性复合材料薄壁轴在偏心激励作用下的非线性振动特性。在轴的应变位移关系中引入Von Kármán几何非线性,基于Hamilton原理和变分渐进法(VAM)导出复合材料传动轴的拉-弯-扭耦合非线性振动偏微分方程组。为了着重研究轴的横向弯曲非线性振动特性,在上述模型中忽略轴向变形和扭转变形,得到轴的横向弯曲非线性振动偏微分方程,其中考虑了黏滞外阻和内阻的影响。采用Galerkin法,将偏微分方程转离散化为常微分方程,在此基础上利用四阶Runge-Kutta法对常微分方程组进行数值模拟,获得位移时间响应图、相平面图和功率谱图,研究了外阻、内组、偏心距和转速对非线性振动响应的影响,发现旋转复合材料薄壁轴存在混沌运动。     

基于多场耦合方法的厚截面复合材料固化过程的多目标优化

针对厚截面复合材料固化过程温度峰值过大所引起的材料力学性能降低及残余应力过大等问题,建立了基于多场耦合方法的复合材料固化过程多目标优化模型,用以降低固化温度峰值和缩短固化时间.首先建立包含热化学子模型、树脂黏度子模型和流动压实子模型的固化温度多场耦合模型,用以准确描述固化过程复合材料内部温度及构件厚度的演化规律.通过与...     

飞机总体设计中的一种多目标鲁棒优化方法

 提出一种基于灵敏度的多目标鲁棒优化方法。针对各维设计变量存在扰动的情况,在原约束多目标优化模型上,附加偏差目标函数,并采用最差估计法对约束条件进行鲁棒可行性调整。采用全局敏度方程方法来计算目标函数和约束函数对设计变量的敏度,进而采用Pareto遗传算法搜索约束多目标优化问题的非劣解集,设计者可以根据不同的设计准则从中选择合适的设计点。将上述方法用于飞机总体参数优化设计,并与采用常规优化方法所得的优化结果进行了分析和比较。     

Merits and limitations of optimality criteria method for structural optimization

The merits and limitations of the Optimality Criteria (OC) method for the minimum weight design of structures subjected to multiple load conditions under stress, displacement and frequency constraints were investigated by examining several numerical examples. The examples were solved utilizing the OC design code that was developed for this purpose at the NASA Lewis Research Center. This OC code incorporates OC methods available in the literature with generalizations for stress constraints, fully utilized design concepts, and hybrid methods that combine both techniques. It includes multiple choices for Lagrange multiplier and design variable update methods, design strategies for several constraint types, variable linking, displacement and integrated force method analysers, and analytical and numerical sensitivities. On the basis of the examples solved, the optimality criteria for general application were found to be satisfactory for problems with few active constraints or with small numbers of design variables. However, the OC method without stress constraints converged to optimum even for large structural systems. For problems with large numbers of behaviour constraints and design variables, the method appears to follow a subset of active constraints that can result in a heavier design. The computational efficiency of OC methods appears to be similar to some mathematical programming techniques.     

Particle swarm-based structural optimization of laminated composite hydrokinetic turbine blades

Composite blade manufacturing for hydrokinetic turbine application is quite complex and requires extensive optimization studies in terms of material selection, number of layers, stacking sequence, ply thickness and orientation. To avoid a repetitive trial-and-error method process, hydrokinetic turbine blade structural optimization using particle swarm optimization was proposed to perform detailed composite lay-up optimization. Layer numbers, ply thickness and ply orientations were optimized using standard particle swarm optimization to minimize the weight of the composite blade while satisfying failure evaluation. To address the discrete combinatorial optimization problem of blade stacking sequence, a novel permutation discrete particle swarm optimization model was also developed to maximize the out-of-plane load-carrying capability of the composite blade. A composite blade design with significant material saving and satisfactory performance was presented. The proposed methodology offers an alternative and efficient design solution to composite structural optimization which involves complex loading and multiple discrete and combinatorial design parameters.     

Automated structural optimization system for integrated topology and shape optimization

Abstract

This paper combines previously developed techniques for image‐preprocessing and characteristic image‐interpreting together with a newly proposed automated shape‐optimization modeling technique into an integrated topology‐optimization and shape‐optimization system. As a result, structure designers are provided with an efficient and reliable automated structural optimization system (ASOS). The automated shape‐optimization modeling technique, the key technique in ASOS, uses hole‐expanding strategy, interference analysis, and hole shape‐adjusting strategy to automatically define the design variables and side constraints needed for shape optimization. This technique not only eliminates the need to manually define design variables and side constraints for shape optimization, but during the process of shape optimization also prevents interference between the interior holes and the exterior boundary. The ASOS is tested in three different structural configuration design examples.     

Design of multifunctional structure with embedded electronic circuitry using composite laminate optimization techniques

This research investigates the optimization of a multifunctional structure with embedded electronic circuitry, following traditional composite laminate optimization methods. A heavily ‘de-featured’ finite element model provides thermal and mechanical analyses of the structure. The model places point heat sources at the surface component locations, and the optimization problem enforces strain constraints at these locations. A simple problem seeks the least-mass I-beam whose shear web contains a simple circuit, subject to strength and strain constraints. A second problem finds the lowest mass unmanned aerial vehicle (UAV) wing box configuration containing embedded circuitry subject to strength, deflection and strain constraints under two load cases. Sequential unconstrained minimization techniques and sequential quadratic programming perform the optimization; combinatorial methods are computationally impractical. Despite the model de-featuring and the use of calculus-based methods, the problem requires significant computational effort. The surface-component strain constraints result in structures with more mass than those without surface components.