【作者】 于浩洋；

【导师】 唐景林；

【作者基本信息】 燕山大学 ， 材料加工工程， 2014， 博士

【摘要】 大型模锻液压机是加工大型锻件产品，特别是大型航空锻件产品的重大技术装备，对国家经济、国防实力等具有重要意义，确保大型模锻液压机的运行可靠性及预测其疲劳寿命应给予高度重视。目前国内外对于疲劳可靠性的研究主要集中在元件级水平上，以机械系统作为疲劳可靠性研究对象的研究做的还很少。关于在预紧状态下的大型模锻液压机本体结构疲劳可靠性的研究成果尚未见报道。本文建立了一套完整的针对预紧状态下的大型液压机的强度及结构疲劳可靠性分析、寿命预测及监控的方法与手段。本论文基于疲劳可靠性分析理论，对预紧状态下的大型模锻液压机本体结构系统进行了研究，其中包括利用有限元软件和疲劳分析软件，对大型模锻液压机1：1模型进行了有限元分析得到了液压机整体及各个部件的应力应变结果，通过疲劳分析得到了各个部件的疲劳寿命，并且进行可靠性分析得到整体液压机的可靠性寿命；研究了大型模锻液压机结构预紧后在外载荷作用下的等效应力变化形态，从理论上证明了等效应力在随载荷变化的过程中存在最小极值点的可能性，给出了等效应力极小值点的位置及幅值的解析解，据此提出了预紧结构等效应力疲劳分析的算法；对载荷谱进行处理，通过在计数时附加一条件来避免非峰谷结点计入循环，该方法可以简化计数过程，并且使得改进后三峰谷计数模型不再需要进行数据压缩；提出采用现场作业调研的方法，采集在一段时间内对应不同载荷的工作循环次数簇，并基于人工神经网络技术获取压机的当量载荷谱，据此提出了基于BP神经网络的疲劳寿命估算模型。本文研制了一个能够进行加载、载荷、应力应变监测及数据处理的试验监测系统，该系统同时具备压机结构在线强度及疲劳寿命监测与预测功能，并进行了物理模拟实验；实验采用接近压机实际使用工况的按时间分段连续加载方式进行，通过随时监测各个测点的信号是否出现异常及定期检查测点附近是否出现裂纹的方法获取无故障加载次数，该系统达到使用要求，具有实用价值。更多还原

【Abstract】 Heavey die-forging hydraulic press is a very important technical equipment forprocessing large forgings, especially the aviation forging products, has the vitalsignificance to the national economy, national defense strength etc., and high attentionshould be payed on ensuring the operation reliability of large die-forging hydraulic pressand on predicting its failure life. Current researches on fatigue reliability in our countryand abroad are mainly focused on the element level, and the research on the system levelfor mechanical system is very seldom. Research results about fatigue reliability ofmachine body structure of die-forging hydraulic press on pre-tightening condition havenot been reported. In this paper the method and means for analysising the strength andpredicting and monitoring the structure fatigue life of the pre-tightened large hydraulicmachine are established.In this paper, based on fatigue reliability analysis theory, the hydraulic forgingmachine body structure system on pre tightening condition were studied, including the useof finite element software and fatigue analysis software, the large die forging hydraulicpress1:1model for finite element analysis of the hydraulic machine and the variouscomponents of the stress and strain results, the fatigue analysis of the fatigue life of eachpart, and reliability analysis reliability life of the whole hydraulic machine; the changeform equivalent stress under the action of external loading large die forging hydraulicpress structure after preloading, theoretically proved that the equivalent stress and there isa possibility of minimum in the process with the change of load in the analytical solution,its position and amplitude are obtained, and the equivalent preload stress fatigue analysisalgorithm; processing of load spectrum, to avoid peak valley node in non circulatingthrough the additional condition when the counting, the method can simplify the countingprocess, and the improved three peak valley count the model not to compress the data; themethod of field investigation, gathering in a period of time corresponding to different loadWorking cycle number cluster, and based on the equivalent load gets press of artificialneural network technology based on spectrum, the fatigue life prediction model based on BP neural network.This paper developed a capable of loading, stress and strain monitoring and dataprocessing of the test monitoring system, this system also has on-line compressorstructural static strength and fatigue life monitoring and prediction function, andconducted laboratory experiments; experiment using the actual use conditions close to thepress at the time of piecewise continuous loading mode, the signal at any time monitoringof each measuring point is abnormal and regularly check the measuring point whether nearcrack method to obtain the fault free loading times, the experimental results show that,using electrometric method detecting the working stress and strain state is feasible,reproduction can be achieved through press technology parameters of the real-time dataacquisition, the system to meet the use requirements, it has practical value.更多还原