【作者】 李正光；

【导师】 谭跃刚；

【作者基本信息】 武汉理工大学 ， 机械制造及其自动化， 2009， 硕士

【摘要】 本文主要通过对风扇叶片进行CAD逆向建模,然后将得到的模型导入有限元分析软件进行应力应变、裂纹扩展以及疲劳寿命的分析以及风扇叶片光栅测试的方法对叶片高速运转时的应力分布和疲劳特性进行研究。CAD逆向建模以实物测量图像数据为基础,通过把测量数据输入Pro/e进行重新造型,从而在CAD平台中还原“实物原貌”(再现实物的零件模型)。然后把Pro/e中生成的零件模型输入ANSYS,并严格按照叶片旋转时的边界条件对其进行应力应变、裂纹扩展以及疲劳寿命的分析。由此可以从理论上得到叶片的应力分布状况和疲劳裂纹易产生的部位,为下一步的光栅测试实验、光栅传感器的布置以及以后的优化设计提供了理论参考。首先,简要介绍了风扇叶片的主要研究方法以及课题的背景及其研究意义。其次,简单介绍了论文工作必须的有限元分析的理论知识和疲劳寿命分析的理论方法如名义应力法、局部应力应变法等,以及裂纹扩展的断裂力学的相关理论如YU裂纹模型。再者,对叶片进行逆向建模,并将其导入ANSYS进行了应力应变、疲劳寿命、裂纹扩展的分析:并依据分析结果画出叶片的疲劳寿命曲线S-N、裂纹扩展率与应力曲线da/dn-S曲线等。同时也进行实验研究,利用光栅传感器进行分布式测量,分析叶片在高速旋转时的应力大小、疲劳寿命。最后,将有限元分析的结果与实验测量的数据进行对比,从而确定叶片的危险部位,同时也证明了光栅测量旋转叶片应力应变的可靠性。通过光栅测试实验得到了叶片在实际运转情况下应力大小、裂纹扩展下的应力分布以及疲劳寿命。将有限元分析所得到的结果和光栅测试实验的数据对比分析,二者结果一致,尤其在应力大小和应力分布方面表现的更为吻合。从而确定了叶片高速旋转时的容易产生裂纹的危险部位以及叶片的疲劳寿命,并找出了影响叶片疲劳寿命的主要因素即局部应力集中部位,同时也验证了光栅测量方法的可行性和逆向建模的可靠性,并为以后的叶片的优化设计和在线监测提供了理论依据。更多还原

【Abstract】 In this paper,the writer mainly through building the model of electric fan blade backward by CAD software and then transport the model of the fan blades to finite element analysis software for stress and strain,growth of fatigue crack and the life of the fan blades.By contrast the test of high-speed operation of the fan blades for its stress distribution and Fatigue Characteristics by of the grating sensor.Building the CAD model reversely based on image data,the measurement data of the physical measurement which will be put through the pro/e for re-modeling,CAD platform in order to restore "physical appearance"(kind of reproduction parts model). Then the model generated by Pro/e the will be put into the ANSYS for analyzing their stress and strain,fatigue crack growth and life expectancy in strict accordance with the rotation fan blade the boundary conditions of.Thus the distribution of stress and fatigue crack of the fan will be clear which can provide a theoretical reference for the next step of the grating sensor testing laboratory after the layout and design optimization in future.First,it gave a briefing on research methods of the fan blade and talks about the background and significance of the subjects.Secondly,introduce the theoretical basis for finite element analysis,a brief introduction of the paper work must be finite element analysis of the theoretical knowledge and Fatigue life analysis of theoretical approaches such as nominal stress method,the local stress-strain law,as well as crack propagation in fracture mechanics such as the YU crack model.Thirdly,design the model of electric fan blade backward by CAD software which will be used for finite element analysis and analyze of the stress-strain and fatigue life,the crack growth of the fan blade by ANSYS10.0.Then the fatigue life curve(S-N curve),and crack growth rate and stress curves(da / dn-S curve) was painted in accordance with the results of the analysis of FEA.And the same time, make the experimental study,using the grating blade sensor in the high-speed rotation for test the size of the stress,fatigue life. Finally,the finite element analysis results and the results of experimental data were compared to determine the risk place of fan.if they are both agreed which will also prove the reliability of measuring the stress and strain rotating blades by the grating sensor.The third chapter,ChapterⅣandⅤ,is the focus of papers.By grating blade testing laboratory has been in the actual functioning under stress size,crack growth under the stress distribution and fatigue life.The results of finite element analysis and the results obtained by the grating testing laboratory are consistent with each other,particularly in the size and distribution of stress on the fan surface.So we get the risk place and fatigue life-span of a high-speed rotating fan blades which incline to have a fatigue crack.Further,we can identify the main factors which impacts most of fatigue life of a high-speed rotating blades that is local stress concentration,but also verify the feasibility of grating measurement and The reliability of reverse built.All this will provides a theoretical basis for the optimal design and on-line monitoring in some day.更多还原