大型压缩机转子疲劳损伤机理及再制造寿命预测基础研究

发布时间：2018-06-20 00:50

本文选题：转子 + 疲劳损伤　；参考：《燕山大学》2016年博士论文

【摘要】：大型压缩机属于重大装备机械,广泛应用于冶金、化工、电力等国家经济支柱产业及国防军工领域,是衡量着一个国家工业发展水平的标志性设备之一。压缩机转子由主轴和叶轮两部分组成,是保证压缩机组稳定运行的关键部件。目前制约我国再制造发展的核心问题是再制造基础研究不足,必须解决再制造对象的疲劳失效机理、寿命演变规律和寿命预测等专属问题才能高质量的实现再制造。本课题以高附加值的转子为研究对象,系统研究转子主轴和叶轮的疲劳失效机理,建立再制造寿命预测模型,对丰富转子疲劳基础研究和推动再制造产业的工业化发展具有重大意义。转子在服役过程中的疲劳损伤机理与寿命演变规律的研究是转子再制造的前提和基础。由于转子尺寸的限制和工况的复杂,使得常规试验方法很难准确的对实际工况下转子内部应变变化进行量化,从而分析研究其疲劳失效机理和寿命演变规律。本文利用有限元法,对转子的几何形状,边界条件、载荷条件进行合理简化,通过精确建模和网格划分技术对转子主轴和叶轮进行分析。分析了滚动接触下主轴内部的应力应变分布状态,确定了主轴的疲劳损伤机理;分析了特征载荷(离心力载荷、气流载荷、振动载荷等)非正常协同作用对叶轮疲劳损伤和寿命演变规律的影响,同时也对工艺载荷和极端工况载荷对转子寿命的影响进行了探讨和研究,这些研究为叶轮再制造提供了理论基础。以主轴的接触疲劳失效为主轴再制造主要研究方向,基于等离子喷涂技术的高效性和低成本性,采用超音速等离子喷涂技术为转子中主轴的关键再制造技术,通过正交法确定最优工艺参数,利用超音速等离子喷涂得到质量较好的主轴再制造涂层,利用课题组内的新型滚滑接触疲劳试验机得到了模拟工况下疲劳损伤试样形貌,利用SEM对不同失效形貌进行表征,以大样本统计方法对涂层的失效模式进行分类,系统研究不同接触应力水平下的涂层接触疲劳失效机理,通过P-S-N曲线建立了主轴再制造的接触疲劳寿命模型。针对叶轮复杂的尺寸和结构特点,对叶轮的危险结构部位进行力学和结构的相似简化处理,确定出能够代表叶轮危险结构的试件形式与尺寸,基于试件尺寸和形式研制和搭建了能够模拟叶轮实际工况条件的综合试验平台。研究了叶轮构件的疲劳失效机理并建立了叶轮构件的寿命预测模型。基于综合试验平台和叶轮材料试样,对模拟工况下的叶轮构件失效形式和机理进行分类和表征,并对预测叶轮构件疲劳极限的Soderberg曲线进行了修正和试验验证。以多轴疲劳模型为理论基础,对多轴疲劳寿命预测的经验和半经验公式方法:基于最大主应变的多轴等效应变疲劳寿命预测方法、基于等效应变的多轴等效应变疲劳寿命预测方法和基于最大剪切应变多轴等效应变疲劳寿命预测方法等方法进行了对比分析,建立起基于Von Mises屈服理论的叶轮构件的多轴等效应变疲劳寿命预测模型。研究了叶轮再制造构件的疲劳失效机理并建立了叶轮再制造构件的寿命预测模型。以叶轮疲劳失效为叶轮再制造的主要研究方向,以激光熔覆技术作为叶轮再制造的关键技术对叶轮进行修复,通过参数优化确定最优激光熔覆工艺,基于综合试验平台和再制造叶轮构件,对模拟工况下的再制造叶轮构件失效性形式和机理进行了分类和表征,并对修正的Soderberg曲线预测再制造叶轮构件疲劳极限准确性进行了验证。以修正的基于Von Mises等效应变屈服理论的叶轮多轴疲劳寿命预测模型为基础,引入再制造特征修正参数,得到了二次修正后Von Mises屈服理论的多轴等效应变疲劳寿命预测方法,获得了再制造叶轮构件的寿命预测模型。利用与新品叶轮相同的台架考核标准对激光再制造叶轮进行了强度考核,经传统无损检测方法和工业CT对考核后的叶轮进行检测和表征,未发现叶轮表面和内部有宏观和微观缺陷,再制造特征叶轮强度满足装机要求。
[Abstract]:Large compressor belongs to the major equipment machinery. It is widely used in the national economic pillar industries, such as metallurgy, chemical industry and electric power. It is one of the landmark equipment to measure the industrial development level of a country. The compressor rotor is composed of two parts of the spindle and the impeller. It is the key component to ensure the stable operation of the compressor unit. The core problem of remanufacturing development in China is the shortage of remanufacturing basic research. It is necessary to solve the fatigue failure mechanism of the remanufacturing object, the life evolution law and the life prediction, and so on. This subject takes the rotor of high added value as the research object, and studies the fatigue failure of the rotor spindle and the impeller system. The mechanism of the remanufacturing life prediction model is of great significance to the research of rich rotor fatigue foundation and the industrialization of remanufacturing industry. The research on the fatigue damage mechanism and life evolution law of the rotor in the service process is the prerequisite and foundation for the remanufacturing of the rotor. It is difficult to quantify the change of the internal strain of the rotor in the actual working condition, and then analyze the fatigue failure mechanism and the law of life evolution. In this paper, the finite element method is used to simplify the rotor's geometry, boundary conditions and load conditions, and the rotor spindle is modeled and meshed by precise modeling and mesh division. The stress and strain distribution in the spindle under rolling contact is analyzed, the fatigue damage mechanism of the spindle is determined, and the effect of abnormal synergy on the fatigue damage and life evolution of the impeller is analyzed, and the process load and the extreme work are also analyzed. The effect of the load on the life of the rotor is discussed and studied. These studies provide the theoretical basis for remanufacturing the impeller. The main research direction is the contact fatigue failure of the spindle. Based on the high efficiency and low cost of the plasma spraying technology, the key to the spindle in the rotor is the supersonic plasma spraying. The optimal process parameters are determined by orthogonal method. The high quality main shaft remanufacturing coating is obtained by supersonic plasma spraying. The fatigue damage specimen morphology is obtained by the new rolling contact fatigue test machine in the project group. The different failure morphology is characterized by SEM, and the statistical method of large sample is used. The failure mode of the coating is classified, and the contact fatigue failure mechanism of the coating under the different contact stress level is systematically studied. The contact fatigue life model of the spindle remanufacture is established through the P-S-N curve. The mechanical and structural similarity of the dangerous structure parts of the impeller is simplified and simplified to determine the complex size and structure characteristics of the impeller. The form and size of the specimen, which can represent the dangerous structure of the impeller, are developed and built on the basis of the size and form of the specimen. The fatigue failure mechanism of the impeller components is studied and the life prediction model of the impeller components is established. The failure modes and mechanisms of the impeller components under simulated working conditions are classified and characterized, and the Soderberg curves for predicting the fatigue limit of the impeller components are modified and tested. Based on the multi axis fatigue model, the empirical and semi empirical formula method for multi axis fatigue life prediction, based on the maximum principal strain of the multi axis effect, is made. The fatigue life prediction method is compared and analyzed based on the equivalent strain multi axis equivalent effect variable fatigue life prediction method and the maximum shear strain multi axis equal effect variable fatigue life prediction method. The multi axle equivalent effect fatigue life prediction model of the impeller components based on the Von Mises yield theory is established. The fatigue failure mechanism of the remanufactured component and the life prediction model of the remanufactured component of the impeller are established. The main research direction of the impeller remanufacture is the fatigue failure of the impeller. The laser cladding technology is used as the key technology for the remanufacturing of the impeller to repair the impeller, and the optimum laser cladding process is determined by the optimization of the parameters, based on the comprehensive test. The test platform and remanufactured impeller component are classified and characterized for the failure form and mechanism of remanufacturing impeller members under simulated working conditions, and the fatigue limit accuracy of the remanufactured impeller components is verified by the modified Soderberg curve. The modified multiaxial fatigue life of the impeller based on the Von Mises and other effect yield theory is modified. Based on the prediction model and introducing the remanufacturing feature correction parameters, the multi axis equivalent effect fatigue life prediction method of the Von Mises yield theory after two revisions is obtained. The life prediction model of the remanufactured impeller component is obtained. The strength assessment of the laser remanufacturing impeller is carried out by using the same bench test standard as the new impeller. The non destructive testing method and industrial CT are used to detect and characterize the impellers after examination. There are no macroscopic and microscopic defects on the surface and interior of the impeller, and the strength of the characteristic impeller meets the requirements of the loading.
【学位授予单位】：燕山大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TH45

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