Achieving Combined Tension-Torsion Split Hopkinson Bar test based on electromagnetic loading

This paper presents a Combined Tension-Torsion (or Compression-Torsion) Split Hopkinson Bar (T-TorSHB or C-TorSHB) system which is able to load a specimen by and torsion stress pulse synchronously under high strain rates. To achieve the precision control of synchronous loading, electromagnetic energy conversion technique is adopted. A new Electromagnetic-release Split Hopkinson Torsion Bar system (E-SHTorB) is proposed to generate the torsion stress pulse, while the tension stress pulse is generated by the technique we previously proposed. A trapezoidal torsion stress pulse with rising time of 200μs is acquired and repeated tests show very good consistency in generating time and pulse shape. A synchronous system is designed to control the trigger time of the tension and torsion stress pulse generator. Repetitive experiments are performed and the results prove that the time difference of stress pulses arriving at the specimen between tension and torsion pulses is less than 5μs. The proposed T-TorSHB system is verified by tests on specimens made by T2 copper.