Control system for multi-pulse width loading equipment based on dual-axis separated Hopkinson tension and compression rods

Abstract

The invention relates to a multi-pulse-width loading equipment control system based on a double-shaft split Hopkinson pressure / tensile bar. In a main capacitor charging loop, a charging voltage is accurately controlled by utilizing a PID loop, and a charging error is less than 1V, so that the control on the pulse amplitude of a stress wave is more accurate; in a main capacitor discharging loop, thyristors are used for replacing switches, so that the discharging loop can be more accurately triggered; in a capacitor discharging module, a digital pulse time delay generator is introduced, so thata discharging delay time error is controlled to be within 1 ns, and the synchronism of loading in a material testing process is ensured; in a capacitance adjusting unit, a mode that one switch corresponds to a capacitance value is used, so that the influence of interference between capacitors and excessive switches in one loop is avoided, the complexity of a circuit is reduced, and the capacitanceadjustment accuracy and the service lives of the capacitors are improved and prolonged; and in the main capacitor charging loop and the main capacitor discharging loop, all the switches adopt vacuumcontactors, so that high voltage and high current can be borne.

Description

technical field [0001] The invention belongs to the field of dynamic mechanical property testing of materials, and relates to a control system of experimental equipment for testing dynamic mechanical properties of materials, in particular to a control system of experimental equipment based on a double-axis separated multi-pulse width Hopkinson pull-and-compression bar. Background technique [0002] In engineering applications, the strain rate of material deformation varies greatly due to the complexity of the material's service environment, and the mechanical behavior of materials in different strain rate ranges is often different, which requires research on the mechanical behavior of materials in different strain rate ranges. At present, the split Hopkinson pressure bar technique (SHPB) has been widely used in the testing of mechanical properties of materials under high strain rates. However, in the SHPB technology, the air cannon is widely used to shock the short rod to ma...

AI Technical Summary

Problems solved by technology

However, in the SHPB technology, the air cannon is widely used to shock the short rod to make it shoot out at high speed to generate the incident wave. The disadvantage of this method is that the air is compressible, and the relationship between the shooting speed of the short rod and the air pressure cannot be accurately determined, which leads to the failure of the sample. The strain rate cannot be precisely controlled; under the same setting conditions, the amplitude of the incident wave obtained will not be completely consistent, and the repeatability of the experiment is poor; there is a lower limit for the firing speed of the impact rod, and the low strain rate environment in many engineering practices cannot pass the traditional Hopkinson Obtained from the compression rod experiment; in a high strain rate environment, the size of the impact rod is required to be large and the firing speed is high, so the same Hopkinson compression rod experimental device cannot simultaneously satisfy the experiment with a large strain rate span

Although the device realizes the control of the Hopkinson pressure bar, it cannot solve the problems of triggering capacitor charging, triggering capacitor discharge, triggering capacitor leakage, and triggering capacitor selection when dual axes are loaded at the same time.

At the same time, the device also has charging voltage accuracy is not high, the pulse width adjustment is too complicated, not easy to operate

In addition, the discharge switch in this invention needs to withstand a huge current, which makes it difficult to select the switch. The reverse current generated by the discharge circuit will elongate the pulse width, which will affect the experimental results. The delay time of dual-axis simultaneous loading and discharge cannot be accurately guaranteed

Images