Dynamic Torsion Testing

For dynamic torsion testing, DyMaLab disposes of a Split Hopkinson Torsion Bar setup with a large deformation capacity. The setup is used to characterize the shear response of a wide range of materials at strain rates from 100 s-1 up to 10 000 s-1. For torsion tests, thin-walled tube samples are used sandwiched between two long bars: an input bar and an output bar. The sample is deformed at high speed by a torsional incident wave obtained by the sudden release of a pre-torqued part of the input bar. The torsional wave has a well-defined and controllable length and amplitude, which allows to adjust the strain rate and deformation imposed to the sample.

From strain gauge measurement on the Hopkinson bars, the total torque and rotation history of the specimen can be determined based on the principle of elastic wave propagation in slender bars. However, in order to obtain detailed information on the displacement and strain fields in the specimen, for most tests an additional full-field deformation measurement technique is used.

Technical Specifications

  • Total setup length = 9 meter, enabling loading times up to 1.5 ms
  • Strain gauge measurements on Hopkinson bars
  • Thin-walled tube samples with dimensions to achieve dynamic equilibrium during high strain rate deformation
  • Strain rates from 100 s-1 to 2 000 s-1 and strains exceeding 300% can be achieved
  • Dynamic torsional loading can be combined with static axial compression or tension load
  • Local strain measurements using high speed camera imaging and digital image correlation
  • Dynamic shear/torsion testing of advanced high strength steels, lightweight alloys, fibre reinforced composites, nanocomposites, …
  • Shear testing of glue connections, hybrid material connections, …
  • Characterization of high speed friction