Plastic materials pervade our entire lives, used in products from computers and cell phones to bullet proof personal and vehicle armor. We don't often consider plastics as structural materials, however we use plastic chairs and tables, ride in cars whose interiors are mostly constructed of plastic, and wear bicycle helmets with protective plastic shells. Many of the products that use plastics undergo torsion loading; therefore the mechanical properties of plastic materials in torsion must be tested and characterized. The stiffness measured in plastic torsion tests is an apparent shear modulus, G, and describes the materials resistance to shear deformations through either tensile, compression, or torsional loads. Torsion tests can be conducted with monotonic loading or dynamic loading, capturing the viscoelastic load response properties of the plastic. Plastic torsion tests are typically carried out at a range of temperatures, to fully characterize the temperature dependent nature of plastics. This is especially important for thermoplastics, whose properties are highly temperature dependent, having brittle characteristics at low temperatures, and losing all structural integrity at temperatures near their melting point.
Most test methods use rectangular shaped plastic test specimens, whose dimensions may be varied depending on the plastic stiffness. ASTM and ISO have developed standard test methods for determining the torsional properties of plastic materials. These test methods encourage consistent test practices that can be replicated between laboratories and manufacturers for data verification. Popular test methods for torsional properties of plastics are ASTM D1043 for temperature dependent stiffness properties of plastics, ASTM D5279 for dynamic properties of plastics in torsion, and ISO 6721-2 for dynamic mechanical properties of plastics in torsion. ASTM and ISO have developed standard test methods for determining the torsional properties of plastic materials. These test methods encourage consistent test practices that can be replicated between laboratories and manufacturers for data verification. Popular test methods for torsional properties of plastics are ASTM D1043 for temperature dependent stiffness properties of plastics, ASTM D5279 for dynamic properties of plastics in torsion, and ISO 6721-2 for dynamic mechanical properties of plastics in torsion.
Applicable Testing Standards
- ASTM D1043 Torsion Plastics Test Equipment
- ASTM D5279 Thermoset & Thermoplastic Dynamic Torsion Testing Machine
Recommended Test Machines
Axial Load Capacity: 0.8 to 300 kN (180 to 67000 lbf)
Torsion Capacity: 1 to 300 Nm (9 to 2655 in-lb)
Static and dynamic options available
Torsion Capacity: 1 Nm to 5650 Nm (9 to 50,000 in-lb)
Type: Electromechanical Gear or Electrodynamic Direct Drive
Available in both horizontal and vertical orientations
Recommended Testing Accessories
Inexpensive conversion from an axial test machine to a torsional test machine
Torque ratings of 20 Nm and 300 Nm (180 lbf∙in and 2650 lbf∙in)
Adjustable mounting head allows for various specimen sizes
Rotates a full 360°
Standard temperature range of -155°C to 620°C (-247°F to 1150°F)
Accompanied by a broad set of accessories that are capable of withstanding the heat or cold
PID controlled internal temperature
Mounts directly to the test frame
Allows for testing in temperature-controlled water or saline solution
PID controlled temperature up to 45°C (113°F)
Size is optimized per application
Accompanied by a broad set of accessories that are designed for biomedical baths
