For a detailed description of fracture and deformation behavior of fiber-reinforced thermoplastics it is crucial to conduct material tests under multiaxial loading conditions.
A suitable approach is testing tube specimens under combined axial and torsional loading. Therefore, IVW acquired a tension-/compression-torsions testing machine manufactured by ZwickRoell in 2020.
With this testing machine, it is possible to apply axial loading (tension/compression up to ±250 kN) and/or torsional loading (up to 4000 Nm). Both axes can be controlled simultaneously to generate defined biaxial load condition. By utilizing only one axis, uniaxial tests are performable, too.
Using hoop wound tube specimens, material properties and nonlinear stress strain curves can be determined with different in-plane shear and transversal tension/compression ratios. This makes analyzing the interactions between the stress components in the in-plane stress space possible.
For the fixture of the specimens a quick-clamping system was designed, that grips the inner surface and allows for a precise alignment. Backlash-free cardan joints where developed as load transmission. These joints ensure that no bending stresses are superimposed. Furthermore, the fixture can be used in combination with a temperature chamber, which allows tests within a temperature range of -40 °C to +250 °C.
With this procedure, material response and material properties can be studied under uniaxial and multiaxial loading (plane stress state) which provides data for comprehensive fracture and yield criteria (e.g. Puck or Cuntze fracture criterion).
Additional test capabilities:
- Tensile tests with flat specimens using hydraulic grips
- Compression tests with flat specimens using hydraulic composites compression fixture (HCCF)
- Component tests: individual designed test setups for component and special-purpose tests
Technical data: Tension-/Compression-Torsion Testing Machine
Max. Axial force
± 250 kN
Max. torsional moment
Axial testing speed
0,00005 – 600 mm/min
Rotational testing speed
0,0002 – 5 U/min
Temperature chamber temperature range
-40 °C – +250 °C
M.Sc. Andreas Kenf
Mechanical Characterization & Modeling
Leibniz-Institut für Verbundwerkstoffe GmbH
Telephone: +49 631 2017-327