【作者】 王平；

【导师】 徐兵；

【作者基本信息】 浙江大学 ， 机械工程， 2012， 硕士

【摘要】 伺服加载系统在工程领域通常也被称为负载模拟器,是在实验室条件下合理地模拟被试件所受真实载荷的加载试验装置,其具有高响应、高精度、高功率重量比和大功率输出等优点。电液伺服加载系统是伺服加载系统的一个重要组成部分,它是对结构件进行静力性能、疲劳性能、断裂韧度等试验的关键设备,能够为结构件设计提供充分的理论依据。本课题所研制的轴向伺服加载试验系统,是为立管疲劳试验而设计的。其功能是模拟输油管道在海底所受到的轴向力作用,从而检测被试件的各种机械性能指标,将经典的自破坏全实物试验转化为在实验室条件下的预测性试验,以达到缩短研制周期、节约研制经费、提高可靠性和成功率的目的。本轴向伺服加载试验系统属于典型的被动式电液力伺服系统。在试验过程中,立管试件会同时受到正弦变化的径向加载力作用,造成的弯曲变形会导致其两端头位置发生持续的移动,对施力系统来说这是一个扰动信号。本文从整体设计出发,通过对多个加载方案的详细仿真分析和比较,确立了采用伺服阀和蓄能器联合控制的加载方式；完成了电液系统的设计计算；完成了支架结构的布局分析；完成了控制策略的优化以及控制程序编制,控制软件采用功能强大的梯形图编程软件FPWIN GR,触摸屏软件采用简捷易懂的工程常用软件EasyBuilder,数据采集、存储及实时显示软件采用方便实用的图形化编程软件Labview,它们均具有良好的可读性和实时性；最后,完成了对实际立管被试件的加载试验,验证了试验结果的可靠性。本文各章节具体内容如下：第一章,主要介绍了各种伺服加载系统的原理和特点,总结了电液伺服加载系统的发展优势和难点,介绍了目前电液伺服加载系统在国内外研究和应用现状,并在此基础之上,提出了本课题的研究意义和主要研究内容。第二章,主要介绍了轴向伺服加载系统的设计任务,结合三种不同的加载方案,进行系统建模和仿真,对比分析各方案的优缺点,综合设计出符合任务要求的整体方案,并对轴向伺服加载试验系统的主要特点进行了归纳总结。第三章,在满足加载试验系统功能的前提下,基于系统紧凑化和操作便捷化的设计理念,分别对试验用液压系统各部分进行模块化设计,并对关键元件进行选型计算。对试验系统的支架结构布局进行详细的设计和受力分析,并且充分利用ANSYS软件的优势,对关键部分进行了有限元分析和强度校核,以保证实现其对整个系统稳定可靠的支撑作用。第四章,在满足加载试验系统功能的前提下,充分利用PLC和数据采集设备各自的优势对电控系统进行设计及软、硬件配置,并对关键元器件进行选型。以轴向伺服加载试验系统为基础,建立系统的数学模型,分析多余力的产生机理,建立多余力的数学模型,采用结构不变性补偿方法优化控制策略,并通过MATLAB/Simulink建模和动态仿真验证结构不变性补偿多余力的效果。最后,按照立管疲劳试验轴向加载的要求编写系统控制程序,并对加载试验流程进行合理规划。第五章,以轴向伺服加载试验系统为平台,对立管试件进行加载试验。主要是详细分析实现液压缸有杆腔压力和活塞杆输出加载力稳定的试验方法,结合本系统的特点,对试验结果进行研究分析和验证,从而为进一步研究如何提高伺服加载系统的稳态精度提供试验支撑。第六章,对全文的工作进行总结并作了下一步的展望。更多还原

【Abstract】 Servo loading system is also called load simulator in the field of engineering. It is to simulate different kinds of loads exerting on the sample under laboratory conditions and has the advantages of high response, high accuracy, high power weight ratio and high power output. Electro-hydraulic servo loading system is a important part of servo loading system. It is significant equipment on structure testing for static performance, fatigue performance, fracture toughness, and so on. These kinds of testings can provide theoretical basis for the design of structures.In this thesis, the axial servo loading test system is designed for the fatigue test of pipe which is used under the sea. Its function is to simulate the axial load exerting on the pipe subsea in order to check whether the performance of sample can meet the design requirement. Thus the classical all-objective experiment will be converted into half-objective forecasting experiment in laboratory to achieve the aims such as shorting developing time, saving developing funds, enhancing reliability and success proportion.The axial servo loading test system is a typical passive electro-hydraulic force servo system. During the test, the tested pipe is also exerted a radial force load. Because of the bending deformation which is caused by radial load, the axial position of pipe moves back and forth continuously and the movement is considered as interfering with the load system. In this dissertation, beginning with the overall design, the servo valve and accumulator united controlled load mode is established via the comparisons of three distinct load projects. The electro-hydraulic system and mechanical support are all designed. The control strategy is optimized and the program is prepared. The control software is organized by powerful Ladder-diagram software FPWIN GR, easy understanded Engineering software EasyBuilder and convenient graphical software Labview, all with well readability and real-time. The experiment on a tested pipe is conducted, and the reliability of experimental result is checked. Each chapter of this dissertation is introduced as follows:In chapter 1, the scheme and characteristics of each kind of servo loading system are introduced, and the advantages and difficulties of development are also summarized. The current situation of research and application on servo loading system is analyzed. Finally, the significance and main research subjects of this paper are presented.In chapter 2, the design tasks of the axial servo loading test system are introduced. The simulation models of three different kinds of load projects are built and the whole scheme of test system is proposed via the comparisons of their advantages and disadvantages. The main characteristics of the test system in this paper are inducted.In chapter 3, each module of hydraulic system is designed based upon compact design and convenient operation, under the context that the functions are fulfilled. the mechanical support of axial servo loading test system is also designed. The force analysis is carried out in details. Stress analysis and strength checkage on the key parts are made taking advantage of finite element analysis software ANSYS, in order to realize the function of stable and reliable support.In chapter 4, The software and hardware of electronic control system are configured taking advantages of programmed logic controller and data acquisition device. The mathematical model of this servo loading test system and the additional force are built. The causes of additional force is analyzed. The control strategy is optimized by using invariance theory. The effect of optimization is checked through the dynamic simulation of MATLAB/Simulink model. Finally, the control program is prepared and the process of axial loading testing is planned properly under the testing standard.In chapter 5, the experimental research on a certain tested pipe is carried out on the basis of the axial loading test system. The test items as well as their realization are analyzed in details. The test results are analyzed combining the characteristics of the system which can provide experimental support for the further research on improving the accuracy of servo loading system.In chapter 6, conclusions in this thesis are summarized and future research proposals are suggested.更多还原