航空发动机中纤维增强型复合薄壁构件的非线性振动特性研究

Fiber-reinforced composite has excellent mechanical properties and capability on weight reduction, it is an inevitable trend that fiber/metal, fiber/ceramic and other fiber composite and their structures will be gradually utilized to replace traditional thin-walled structures in the aircraft engine, such as blade, compressor disk and drum, so as to meet the increasing demanding on fatigue resistance, vibration reduction, high temperature tolerance and other stringent requirements in aircraft industry. However, due to the fact that their nonlinear vibration mechanism is not well known, the corresponding applications of the above composite structures have currently been restricted and suppressed. In this project, thin composite plate and cylindrical shell of fiber-reinforced metal materials are taken as study objects, and their nonlinear vibration characteristics as well as the related test and analysis method will be studied. The study contents include characterization testing on nonlinear damping parameters which is dependent on excitation amplitude and frequency, identifying mechanics parameters of fiber-reinforced composite with anisotropic property, creating analytical model and finite element model which can be used to describe nonlinear vibration phenomenon, optimization study and comprehensive evaluation on vibration characteristics of composite structures and etc. Ultimately, the study of this project will reveal the nonlinear vibration mechanism of composite thin-walled structure strengthened by fiber composite, provide theory and practice reference on building the corresponding test and analysis methodology, and make positive contribution to the application of such composite structure in our own aeroengine in China.

纤维增强型复合材料具有优异的力学性能和减重效果，随着航空工业对功能部件的抗疲劳、抗振性、耐高温等性能要求越来越高，在航空发动机中逐步使用纤维/金属、纤维/陶瓷等复合材料构件，以取代叶片、轮盘、鼓筒等传统薄壁构件，是一种必然的技术发展趋势。但对其非线性振动机理认识不清，已严重限制了该类型复合薄壁构件的推广应用。本项目将以纤维增强型复合薄板及圆柱壳为研究对象，并围绕其非线性振动特性及相关测试、分析方法开展研究，具体包括：具有振幅及频率依赖性的非线性阻尼表征测试、具有各向异性特点的复合材料力学特性参数辨识、可描述非线性振动现象的解析及有限元模型的创建、该类型复合薄壁结构振动特性的优化及综合评价等研究内容。通过本项目的研究，可以进一步揭示纤维增强型复合薄壁构件的非线性振动机理，为建立该类型复合结构振动测试与分析的方法体系提供理论与实践的参考，为其在我国航空发动机的推广应用做出最积极的努力。

随着航空发动机不断追求推重比，使用以纤维增强复合材料薄壁构件，以取代金属叶片、轮盘、鼓筒等传统薄壁构件，是一种必然的技术发展趋势。但对其非线性振动机理认识不清，已严重限制了该类型复合薄壁构件的推广应用。本项目针对上述工程迫切需求，以纤维增强复合材料薄板及圆柱壳为研究对象，从该类型复合薄壁结构线性/非线性振动问题出发，开展了系统性的研究工作。首先，利用了激光扫描测振技术的优势，自主设计并开发了一套新型纤维增强复合薄板非线性振动测试平台，通过客观、高效地表征该类型结构的振动特性，提出了具有振幅依赖性的纤维增强复合结构非线性刚度及阻尼、非线性内共振等测试新方法；进一步，研制了一套基于激光无损扫描技术的纤维增强复合材料参数测试仪，并提出了基于频响函数测试、基于非接触激振-测振一体化技术的该类型复合材料弹性模量、损耗因子等力学参数的高效辨识方法，还考虑了温度效应的影响，利用激光扫描法实现了热环境下复合材料力学参数的辨识；然后，基于经典层合板理论、板壳理论、改进的Jones-Nelson复合材料非线性理论、复模量法、应变能法、能量法等相关理论与技术，创建了适合纤维增强复合材料梁、板、壳的线性/非线性振动特性分析的解析模型，确立了高效、准确分析结构系统线性/非线性固有频率、模态振型、振动响应和阻尼性能的方法及流程，并基于MATLAB研发了多套软件算法及程序。最后，依托所建立的分析模型，确立了应变能指标，提出了相应的优化设计流程，研究了纤维增强复合薄壁结构振动性能，特别是阻尼性能的优化及综合评价方法。通过上述研究，对该类型复合薄壁结构，已初步建立了一套完整的测试、建模、分析、辨识、优化设计方法与体系，较好地完成了预先设定的各项研究目标。