基于新的场强法模型的抽油机关键部件疲劳寿命预测研究

发布时间：2017-12-27 04:17

本文关键词：基于新的场强法模型的抽油机关键部件疲劳寿命预测研究　出处：《西南石油大学》2017年硕士论文　论文类型：学位论文

【摘要】：游梁式抽油机是将原油从地下提升到地面的主要设备,是大型可修复的复杂机械系统。由于其工作时主要承受高幅值、高频率的循环交变载荷,因此机械疲劳是抽油机的主要失效形式。抽油机常年工作在野外,工作环境恶劣,零部件疲劳断裂失效时有发生,某些关键部件的失效可能导致整机失效,不仅造成油井停产,甚至可能危及周围工作人员,造成人员伤亡,给油田带来巨大经济损失。因此预测抽油机关键部件的疲劳寿命,为抽油机部件的更换提供参考是很有必要的。此外疲劳寿命预测过程复杂,油田工作人员学习难度较大,因此开发一款疲劳寿命预测软件,简化过程操作,提高疲劳寿命预测效率是具有实际意义的。为此本文围绕抽油机关键部件的疲劳寿命预测研究这—主题,主要工作内容和结论如下:(])总结传统的疲劳寿命分析方法的特点。通过对名义应力法、局部应力应变法、能量法、体积法等常用的疲劳寿命分析方法进行分析总结,得到结论:传统的疲劳寿命分析方法存在较多人为假设,与疲劳机理不符,对影响疲劳寿命的因素考虑不周全,导致其预测精度不高,使用条件苛刻,不适用于抽油机疲劳寿命预测。(2)分析研究应力场强法。总结应力场强法的基本原理,对比传统的疲劳寿命分析方法,确定应力场强法为本文预测抽油机疲劳寿命的方法,理由是:应力场强法考虑因素全面,与疲劳机理吻合,适用于抽油机的高周疲劳。此外对应力场强法中场径的确定方法和数值计算方法进行了深入研究。(3)提出新的应力场强法模型。指出原有场强法中存在的问题,并提出新的应力场强法模型。新模型中以应力等值线作为损伤区的边界并考虑了载荷幅值对损伤区的影响,结合新的损伤区提出新的应力梯度数学模型,给出方向角的确定方法,算例验证的结果表明:新的场强法模型更贴近真实的损伤区形状和大小,权函数更准确的反映了损伤区内各点对疲劳损伤的贡献,可用于构件的疲劳寿命预测。(4)提出基于Qt的ANSYS二次开发新技术,并开发了抽油机疲劳寿命预测软件。开发了基于Qt的核心接口技术和辅助数据技术,解决了 Qt与ANSYS的接口问题,实现了对ANSYS的调用和数据传输,并且设计了友好的人机交互界面。将ANSYS和应力场强法的复杂性封装起来,开发了抽油机疲劳寿命预测软件。(5)用应力场强法预测抽油机关键部件的疲劳寿命。分别采用原有场强法和改进的场强法预测抽油机关键部件的疲劳寿命,并与油田现场统计寿命进行对比,结果表明:新的应力场强法的预测精度高于原有场强法,预测结果稳定,可用于抽油机的疲劳寿命预测。演示了软件中预测抽油机疲劳寿命的操作流程,结果表明:抽油机疲劳寿命预测软件人机界面友好,操作简单,预测效率高。
[Abstract]:The beam pumping unit is the main equipment to lift crude oil from the ground to the ground, and it is a large and repairable complex mechanical system. Because of its high amplitude and high frequency cyclic alternating load, mechanical fatigue is the main failure mode of the pumping unit. The perennial work in the field of oil pumping machine, working environment, failure components of fatigue fracture occurs, the failure of some key components may lead to failure, not only caused the production stop, and may even endanger the surrounding personnel casualties, bring huge economic losses to the oil. Therefore, it is necessary to predict the fatigue life of the key components of the pumping unit and provide reference for the replacement of the components of the pumping unit. In addition, the fatigue life prediction process is complex, so the oilfield workers are very difficult to learn. Therefore, developing a fatigue life prediction software, simplifying process operation and improving the efficiency of fatigue life prediction is of practical significance. For this reason, this paper focuses on the fatigue life prediction of the key components of pumping units. The main contents and conclusions are as follows:] the characteristics of traditional fatigue life analysis methods are summarized. By law, the local stress fatigue life method, energy method and volume method commonly used analysis methods are analyzed and summarized, obtained the conclusion: nominal stress on the fatigue life of the traditional analysis method has many artificial assumptions inconsistent with the mechanism of fatigue, impact on the fatigue life of the factors considered, the prediction accuracy is not high, the use of harsh conditions, not suitable for oil pumping machine fatigue life prediction. (2) the stress field strength method is analyzed and studied. The basic principle of the stress field strength method is summarized, and the traditional fatigue life analysis method is compared. The stress field strength method is used to predict the fatigue life of the pumping unit. The reason is that the stress field strength method is considered in a comprehensive way, which is consistent with the fatigue mechanism and suitable for the high cycle fatigue of pumping units. In addition, the method of determining the midfield diameter of the force field strength method and the numerical calculation method are further studied. (3) a new stress field strength method is proposed. The existing problems in the original field strength method are pointed out, and a new stress field strength method is proposed. In the new model to stress isoline as the damage zone and the influence of load amplitude of damage zone, combined with the damage zone and puts forward a new stress gradient, a new mathematical model and method are given to determine the direction angle of the example verification results show that the new model is more close to the field of damage zone size and shape true, the right to function more accurately reflect the damage zone of each point in the fatigue damage of the contribution can be used to predict the fatigue life of the components. (4) a new ANSYS development technology based on Qt is proposed, and the software for predicting fatigue life of the pumping unit is developed. The core interface technology and auxiliary data technology based on Qt were developed, which solved the interface problem between Qt and ANSYS, realized the call and data transmission to ANSYS, and designed friendly man-machine interaction interface. The software of fatigue life prediction for pumping unit is developed by encapsulating the complexity of ANSYS and stress field strength method. (5) the fatigue life of the key components of the pumping unit is predicted by the stress field strength method. Respectively using the method of field intensity of original method and improved the fatigue life prediction of key components of the oil pumping machine, and compared with the field life statistical results show that the new method of stress field prediction accuracy should be higher than the original field method, the forecasting results are stable and can be used to predict the fatigue life of the pumping unit. The operation process of predicting the fatigue life of pumping unit is demonstrated. The result shows that the fatigue life prediction software of pumping unit is friendly, simple and efficient.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE933.1

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