内外压加载管材试验机控制系统研究

发布时间：2018-05-22 08:35

本文选题：材料试验机 + 复合加载　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：管材液压成形是一种实现结构轻量化的塑性加工技术,管材屈服行为的研究有助于预测材料成形的过程,分析缺陷产生的原因,对于液压成形工艺的改进具有指导性意义。为研究管材屈服行为,需要进行大量的管材试验,因此开发专用试验设备很有必要。针对适用于液压成形的合金管材,本课题开发内外压复合加载试验机控制系统,实现管材轴向压力和内外壁表面压力的同步复合加载,进行复杂三维应力状态下的管材屈服试验。在轴向力以及内外压力的复合作用下,管材负载受力情况复杂,对此进行了应力和应变分析,建立管材中部位置的各向应力与外界加载量的关系和各向应变与管材形状参数的联系,并根据应力应变分析确定了需要采集的物理量,提出了具体的应力加载方案。加载量的控制效果直接影响管材的试验效果,因此对试验机控制系统进行了分析。首先建立了轴向推力缸和内外增压缸的数学模型,并进行了单通道的仿真分析;然后根据加载原理搭建了多通道复合加载的试验机系统,通过仿真分析得到了加载量之间的影响规律。针对复合加载的影响和管材负载的特性分析了试验机的控制策略。为消除复合加载时各加载量之间的相互影响,采用引入补偿回路的方式改善了管材轴向压力和内外壁表面压力的控制效果。对于管材在加载过程中刚度变化的问题,设计了传统PID和模糊理论结合的模糊PID控制器。根据试验需求和系统硬件参数,编写试验机控制程序,实现信号读取、模式切换和数据保存。在完成系统单通道调试后,进行了复合加载实验,实验结果表明本试验机能够稳定的进行复合加载,揭示了管材在内外压加载情况下的部分变形规律。
[Abstract]:Tube hydroforming is a light weight plastic processing technology. The study of tube yield behavior is helpful to predict the process of material forming and analyze the causes of defects. It is of guiding significance for the improvement of hydroforming process. In order to study the yield behavior of pipes, a large number of pipe tests are needed, so it is necessary to develop special test equipment. Aiming at the alloy pipe which is suitable for hydroforming, the control system of internal and external pressure compound loading testing machine is developed in this paper, which realizes the synchronous composite loading of tube axial pressure and inner and outer wall surface pressure. The tube yield test under complex three-dimensional stress state was carried out. Under the combined action of axial force and internal and external pressure, the load of pipe is complicated, so the stress and strain are analyzed. The relationship between the stress in the middle position of the pipe and the external loading quantity and the relation between the strain in each direction and the shape parameters of the pipe are established. According to the stress-strain analysis, the physical quantities that need to be collected are determined, and the concrete stress loading scheme is put forward. The control effect of loading quantity directly affects the test effect of pipe, so the control system of test machine is analyzed. Firstly, the mathematical models of axial thrust cylinder and internal and external pressurized cylinder are established, and the simulation analysis of single channel is carried out, and then the multi-channel composite loading testing machine system is built according to the loading principle. Through the simulation analysis, the influence law of the loading amount is obtained. The control strategy of the testing machine is analyzed according to the influence of composite loading and the characteristics of pipe load. In order to eliminate the interaction between the loading quantities during the composite loading, the axial pressure of the pipe and the surface pressure of the inner and outer wall were improved by introducing the compensation loop. A fuzzy PID controller based on traditional PID and fuzzy theory is designed to solve the problem of stiffness change in the course of loading. According to the test requirements and system hardware parameters, the control program of the test machine is written to realize signal reading, mode switching and data saving. After the single channel debugging of the system was completed, the compound loading experiment was carried out. The experimental results show that the test machine can carry out the composite loading stably, and reveal the partial deformation law of the pipe under the condition of internal and external pressure loading.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH87;TP273

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