【作者】 潘萍萍；

【导师】 陈长征；

【作者基本信息】 沈阳工业大学 ， 机械设计及理论， 2013， 博士

【摘要】 大型风力发电机塔架是重要的承载部件，塔架的性能直接影响了风力发电机运行的稳定性和可靠性，随着风力发电机单机容量不断加大，风力机结构整体的强度、振动、稳定性问题日益突出。本文以国家自然科学基金项目为背景，以MW级风力发电机塔架为主要研究对象，结合工程规范、有限元分析方法、实验方法，对大型风力机塔架的动力学进行分析，并对塔架的两个主要连接失效方式，螺栓连接和焊接进行研究，给出塔架螺栓连接失效的主要评估参数和影响焊缝疲劳寿命的几何参数。首先分别采用工程算法和有限元分析方法对塔架的自振频率进行计算。采用有限元分析方法计算塔架自振频率时分别考虑了机舱叶轮质量、塔门、叶轮的工作载荷、作用在塔架上的随机风载荷对其的影响。采用流固耦合方法，在复杂多变的随机风载荷作用下，计算塔架表面在风场中受到的风载荷，计入其对结构刚度的影响，得到风力机塔架的自振频率，并且与实测的风力机塔架自振频率进行对比，采用风机标准对其进行校核。给出一种合理的风力机塔架有限元分析模型，用于塔架自振频率的计算。塔架动力学响应分析中，得到风力机塔架顺风向和横风向响应。在顺风向响应分析中，对风力机塔架顶端的最大位移量进行校核。在横风向响应分析中，主要对塔架尾流的脱涡情况进行分析，得到在极限风速下，塔架不同高度处横截面的涡脱落频率。在塔架的振动分析中，本文将叶轮旋转产生的激振力频率与塔架自振频率避开，在达到风机标准要求后，计算塔架尾流的脱涡频率，并且与塔架的自振频率相比较，对风机标准中塔架的振动校核进行补充，给出一种塔架振动校核的新方法。其次，在风力机塔架满足强度和振动要求的前提下，计算风力机塔架的疲劳寿命，工程算法只能得到指定位置的疲劳寿命值，本文通过BLADE软件得到时程疲劳载荷谱，采用有限元分析软件得到塔架在六个载荷分量下的应力分布，结合风机设计标准得到塔架材料的应力-寿命曲线，在疲劳分析中考虑材料的表面加工质量和平均应力的影响，采用局部应力应变法计算塔架结构的疲劳寿命分布。可以得到塔架各个位置的疲劳寿命值，给出通过商业软件进行塔架疲劳寿命计算的建模方法。塔架疲劳分析计算后得到塔门附近的疲劳寿命较低，为后续塔架疲劳寿命优化提供依据和计算手段。当塔架满足强度、振动、疲劳要求后，以大型风力机塔架为研究对象，进行塔架失效机理研究，塔架失效形式有多种，本文分析其连接部位的失效形式，即螺栓连接和焊接。对塔架的螺栓连接建立有限元分析模型，螺栓的强度和疲劳完全满足使用要求的前提下，将螺栓松动做为螺栓连接失效的主要形式进行实验研究和数值计算，得到螺栓连接结构的自振频率对螺栓松动损伤比较敏感，双螺栓试件的损伤实验结果与有限元分析数据吻合，验证有限元方法的可行性。给出塔架连接螺栓自振频率计算的有限元建模方法，得到自振频率可以做为螺栓松动的判定参数。最后对塔架焊接的失效机理进行分析，在随机交变风载荷的作用下，由于焊缝的承载能力一般高于母材，其主要失效形式为疲劳。焊缝的疲劳分析采用结构应力法，此方法可得到焊趾处的应力集中，建立平板对接焊焊缝模型，采用疲劳分析软件FE-SAFE得到板厚和焊缝余高与焊缝疲劳寿命的关系曲线。以塔架焊缝模型为对象，利用结构应力法计算得到塔架焊缝的疲劳寿命分布，为塔架的焊缝的疲劳设计及优化提供一种仿真建模方法。更多还原

【Abstract】 The Large-scale wind turbine tower is an important part, the capacity of the toweraffects the stability and reliability of the wind turbine, with the wind turbine capacityincreasing, the wind turbine structure strength, vibration and stability of the whole problemhave become increasingly prominent. Based on the national natural science fundation, theMW wind turbine tower is chosen as the research object. Based on the engineeringstandard, finite element analysis method, experimental method, the dynamic characteristicsand fatigue of large wind turbine tower are analyzed. The two main connection failuremode of tower, bolt connection and weld connection failure are analyzed and get mainparameters, the tower bolt connection failure and the weld fatigue are affected by the mainparameters. A checking method of tower is given.Firstly, the natural vibration frequency of tower are calculated by the engineeringstandard and finite element analysis method, Considering the mass of cabin and blades, thetower door, the working load of blade, and the random wind load. Got a suitablecalculation method for wind turbine tower vibration frequency, and compared results to theexperiment, using the standard to check it. During the analysis on the vibration frequencyof tower, the fluid-solid coupling method is used, the wind pressure on the surface of toweris calculated. Including its influence on the structure stiffness, get more reasonable towervibration frequency. In tower of dynamic analysis, the wind turbine wind vertical directionand horizontal direction response analysis are carried. In the horizontal direction responseanalysis, the maximum displacement at the top of wind turbine tower is calculated andcheck. In vertical wind response analysis, the tower to wake of vortex is analyzed, andunder the Extreme wind speed, tower at different height of cross section of the vortexshedding frequency is calculated. In tower vibration analysis, the natural vibrationfrequency of tower should be avoided blade rotation excitation frequency and tower vortexshedding frequency. Secondly, the wind turbine tower comply with the requirements of strength andvibration, the fatigue life is analysed. The fatigue load spectrum is from BLADE software,and stress distribution is calculated by the finite element analysis software, the tower underthe six load components of wind turbines blade, stress-life curve of materials is fromcertification of wind turbine standard, the local stress strain fatigue analysis of towerstructure is applied. The material surface machining quality, the average stress and theexternal load are taken into account in the fatigue analysis of tower. After fatigue analysis,the distribution of fatigue life found near the door is low, for fatigue life of toweroptimization provides a kind of analysis method.The large-scale wind turbine tower as the research object, after meet the requirementsof static strength, dynamic analysis and fatigue analysis. The main tower failure in theconnection parts, including bolts connection and weld connections. Tower bolt connectionanalysis model is set up, and get the bolt strength and fatigue are completely meet therequirements, will the bolt looseness as the main reason. The bolt looseness is analysedusing the experiment and simulation method. The natural vibration frequency of thestructure is the most sensitive. The experiments data and the analysis date of the doublebolt specimens is similar. The finite element method is feasibility, and then using thismethod to the natural vibration frequency of tower structure bolt connection analysis. Theparameters can serve as a judge for bolt looseness, for after the bolt looseness faultdiagnosis to provide technical foundation.Finally, tower welding connection failure is analysed. Welding line strength isgenerally higher than the base. The main failure of welding line is fatigue. Weld fatiguestructure stress method is adopted, which can analyse the stress concentration at weld toe.The finite element analysis software to establish model of butt welding seam, the fatigueanalysis software to calculate the thickness and the weld residual high impact on weldfatigue life. Get the relationship between the two main parameters and weld fatigue lifecurve. The tower weld model as the object, use structure stress method calculated thefatigue life of tower weld distribution, provide tower weld fatigue design and optimizationof a simulation method.更多还原