ASTM and ISO have standard test methods for strain controlled fatigue. Following a standardized test procedure helps with quality control and provides data that can be compared to data of different tests that followed the same test procedure. Applications that deform in predicable strain amounts should be tested with a strain control system. Also, strain control fatigue testing is necessary in applications which the mechanical properties of the material in question are strain rate sensitive. Strain control fatigue testing is often done to simulate the expansion and contraction of a material as temperatures vary. As a component is exposed to different temperatures is expands or contracts.
When confined, components can be put under large stresses that eventually lead to fatigue failure. For ASTM standardized strain controlled fatigue testing we suggest ASTM E606, and for testing at elevated temperatures we suggest testing with ASTM E2368. ASTM E606 is a standard practice for strain controlled fatigue testing. ASTM 2368 is a standard practice for strain controlled thermomechanical fatigue testing. For ISO standardized strain controlled fatigue testing we suggest ISO 12106 for general strain controlled fatigue testing, and ISO 12111 temperature dependent strain control testing. ISO 12106 is an axial strain controlled test method. ISO 12111 is a standard practice for strain controlled theromechanical fatigue testing of metals. TestResources suggests either a servo hydraulic or servo electric t dynamic testing machines for fatigue testing materials. Servo hydraulic test machines, such as the 902 series has high load capabilities up to 22 kip and high cyclic frequency capacity up to 100 Hz.
Servo electric test machines, such as the 830 and 810 series, have lower load capacity and lower speed capacity then the servo hydraulic models. However, this makes them much less expensive then the servo hydraulic test machines and just as capable in terms of meeting the requirements of ASTM and ISO strain controlled fatigue testing standards. There are a wide variety of controllers that can be used with the dynamic test machines. TestResources application engineering team will fit the controller with the desired testing application to minimize cost and meet the desired performance.
Applicable Testing Standards
- ISO 12111 Strain-controlled thermomechanical fatigue test of metals
- ISO 12106 Metallic Materials Axial-Strain-Control Fatigue Testing
- ASTM E606 Strain-Controlled High and Low Cycle Fatigue Testing
- ASTM E2368 Thermomechanical Fatigue Test Equipment
Recommended Test Machine
Static and fatigue forces up to 50 kN (11,250 lbf)
Frequency ratings up to 75 Hz
Oil-free, all electric actuator for clean test conditions
Lower purchase, operating, and maintenance costs than hydraulic equivalents
Force ratings up to 50 kN (11,250 lbf) and torque ratings up to 180 Nm (1,600 lbf∙in) Can apply axial and torsional loads simultaneously Performs both static and dynamic tests All electric and oil-free operation
>Load ratings from 100 kN to 5 MN (22,500 lbf to 1,125,000 lbf)
Servohydraulic
Can perform both static and dynamic tests
Static and fatigue forces up to 25 kN (5,500 lbf)
Frequency ratings up to 100 Hz
Servohydraulic
Small, portable footprint
Recommended Testing Accessories
Load ratings from 50 kN to 300 kN (11,250 lbf to 67,500 lbf)
Hydraulic actuation
Designed to cycle dynamically through zero-load
Temperature ratings up to 1,000°C (1,800°F)
Measures displacement for axial tensile, compression, and cyclic testing
Gage lengths from 10 mm to 50 mm (0.5 in to 2.0 in)
Measuring ranges from 5% to 100% strain
Lightweight and self-supporting