What is the electronic tension testing machine measurement and control system?

1. The data acquisition rate of the electronic tensile testing machine is too low.

At present, data acquisition of analog signals is realized by an A/D converter. There are many types of A/D converters, but the ∑-Δ type A/D converter is used in the electronic tensile testing machine. These converters are flexible and can be dynamically adjusted at conversion rates for high-speed, low-accuracy conversion and low-speed, high-precision conversion. In the electronic tensile testing machine, since the data acquisition rate requirement is not too high, generally tens to hundreds of times per second can meet the demand, so generally lower conversion rate is adopted to achieve higher measurement accuracy. However, in some electronic tensile testing machines produced by some manufacturers, in order to pursue higher sampling resolution and extremely high data display stability, the sampling speed is lowered very low, which is not desirable. Because when the sampling speed is very low, the signal that changes at high speed cannot be accurately collected in real time. For example, in the performance test of metal materials, when the material yields and the force value fluctuates up and down, the signal changes so much that the upper and lower yield points cannot be accurately determined, resulting in failure of the test, resulting in the loss of watermelon and sesame seeds.

2. The improper use of the electronic tensile testing machine control method

The electronic tensile testing machine is designed for the relationship between stress and strain when the material yields. The control mode recommended by the national standard is constant strain control, and the elastic phase control mode before yielding is constant stress control, which is difficult to complete in most electronic tensile testing machines and in certain tests. Because it requires changing the control mode when the yielding phenomenon occurs, and the purpose of the test itself is to ask for the yield point. How can the unknown result be used as the control condition of the measurement and control link of the electronic tensile testing machine? Therefore, in reality, the same control mode is generally used to complete the whole test (even if different control modes are used, it is difficult to switch at the upper yield point, generally choose a point ahead). For the electronic tensile testing machine using constant displacement control (speed control), since the stress rate of the material in the elastic phase is proportional to the strain rate, as long as the appropriate test speed is selected, the speed control in the whole process can be compatible with the control characteristics of the two stages. Claim. However, for an electronic tensile testing machine that only controls one mode, if the response of the electronic tensile testing machine is particularly fast (this is the purpose that the automatic control effort wants to achieve), the process time of yielding will be very short, if data is collected. If the speed is not high enough, the yield value will be lost, and the excellent control performance will become the cause of the error. Therefore, when selecting the electronic tensile testing machine and control method, Zui should not choose a single load control mode.

Jiangsu Tianhui Testing Machinery Co., Ltd. is a professional service manufacturer engaged in material testing and testing equipment. It integrates R&D, design, production, sales and service, and provides solutions for material testing and finished product testing.