Design And Implementation Of High-Speed Measurement System For Electrical Plastic

In recent years, electric plastic effect has aroused worldwide attention. Many experiments are carried out to explore the mechanism of plastic effect and its application in the field of plastic forming. The more influenced by the current, the lower flow stress of the metal material and the higher the temperature, which leads to metal fatigue and improves the ductility. The complexity of the relation between current and metal plasticity makes the researches in this filed significative.Tensile test, whose two important variables are stress and temperature, is one of the most common methods to research on metal electrical plasticity. The stress-strain and temperature curves of the sample metal should be measured accurately during the tensile test in order to comprehensively analyze the electrical plasticity. Nowadays pulsed currents are usually used in tensile tests. However the low sampling frequency of the electronic material's stress sensor can not meet the need of the accuracy and narrows down the research and study. To compensate for this drawback, advanced high-speed stress measurement system is introduced in this paper and a high-speed Ethernet-based temperature acquisition system is designed while the rapid-changing temperature is taken into account.The 32-bit DSP TMS320F2812 is used as the core processor in this high-speed temperature acquisition system. Quick response thermocouple is applied and AD8495 is used for cold-junction compensation and signal amplification. DSP based TCP/IP protocol is realized to ensure fast data transmission and finally temperature curves will be displayed on PC.The working principle is also introduced in chapter?, which talks about the measurement system. Based on electronic testing machine, new high-speed stress sensor and high-precision integrated amplifier are applied in this system. High-speed acquisition card DAQ-2010-00B0 is used to realize fast data transmission and finally the stress curve will be displayed on PC, too.As the last part, a series of aluminum alloy tensile test are conducted in the research and the final results indicate that the objectives are achieved. Relation between the current pulse width, cycle and the flow stress of the aluminum, which is of some help to the research of electrical plasticity, is also studied.