Test Basics

Typical Configuration

An electromechanical or hydraulically-powered testing machine can be used for torsion testing. An electromechanical drive system transfers the rotational motion of a motor to the specimen while a hydraulic system employs closed loop servo control together with a hydraulic power supply to apply torsion loads.

Both electromechanical and hydraulic systems should be fitted with a control system that is capable of controlling the test and collecting data at high frequencies.

Either style of testing machine may have a horizontal or vertical test space and can be fitted with a variety of grips to hold the specimen during a test. Standard torsion grips include drill-type chucks, collets, and sockets.

Materials

Specimens suitable for torsion testing can take many forms. Torsion properties can be determined from a machined metal sample, wire/bar/cable, or from complete products and components.

  • Small Diameter Specimens: Wire and Machined Samples
    Small diameter specimens such as wire, bar, or machined samples can be twisted to determine the shear modulus, peak torque, and breaking strength.

torsional tests on wire

  • Fasteners
    Many companies currently perform proof and axial tensile tests on fasteners. However, during installation of the fastener and service life conditions, the fastener also experiences torsional forces. A torsion test reveals the fasteners behavior under service load torques and can be used to determine the torsional breaking strength.

torsional tests on fasteners

  • Automotive Component Testing
    Many product components such as steering columns are subjected to torsional forces under service life conditions. Torsion testing can be used to investigate the product quality of such devices revealing information about the design, weld seams, and ultimate strength of these products.

torsional tests on components

  • Biomedical Testing
    Biomedical products such as catheter tubing, prosthetics, containers/dispensers, and surgical devices experience torsional forces during use. Testing these products is vital to ensure quality, safety, and reliability.

biomedical or medical device tests involving torsion

Standards

  • ASTM A938-97 - Torsion Testing of Wire
  • ASTM E143-01 - Standard Test Method for Shear Modulus at Room Temperature
  • ASTM F543-02/ISO 6475 - Standard Specification and Test Methods for Metallic Medical Bone Screws
  • ASTM D3198-97 - Standard Test Method for Application and Removal Torque of Threaded or Lug-Style Closures