|
 Select image to enlarge
A torsion test can be conducted on most materials to determine the
torsional properties of the material. These properties include but are not limited to:
While they are not the same, they are analogous to properties that can
be determined during a tensile test. In fact, the "torque versus angle"
diagram looks very similar to a "stress versus strain" curve that
might be generated by a tensile test.
Why Perform a Torsion Test?
Many products and components are subjected to torsional forces
during their operation. Products such as biomedical catheter tubing,
switches, fasteners, and automotive steering columns are just a few
devices subject to such torsional stresses. By testing these products
in torsion, manufacturers are able to simulate real life service conditions,
check product quality, verify designs, and ensure proper manufacturing techniques.
Types of Torsion Tests
Torsion tests can be performed by applying only a rotational motion
or by applying both axial (tension or compression) and torsional forces.
Types of torsion testing vary from product to product but can usually be
classified as failure, proof, or product operation testing.
- Torsion Only: Applying only torsional loads to the test specimen.
- Axial-Torsion: Applying both axial (tension or compression) and torsional
forces to the test specimen.
- Failure Testing: Twisting the product, component, or specimen until failure.
Failure can be classified as either a physical break or a kink/defect in the
specimen.
- Proof Testing: Applying a torsional load and holding this torque load
for a fixed amount of time.
- Operational Testing: Testing complete assemblies or products such as
bottle caps, switches, dial pens, or steering columns to verify that the
product performs as expected under torsion loads.
|