Applications in which materials in structures undergo large changes in temperatures, which results in larges forces between the components should be tested to determine high temperature low cycle fatigue characteristics. Historically load and strain controlled fatigue tests require servo hydraulic test machine technology. Recent test machine innovations make it possible to perform high force static tensile and compression tests and fatigue testing with all electric dynamic actuators. All electric machines are not only less expensive to purchase but also to operate in the long term. They are especially productive in applications that are 15 hz and lower and load more than 50 kN (11250 lb). Low cycle fatigue testing can be done with either strain control of load control. Both ASTM and ISO have standard test methods for strain and load control fatigue testing. For strain control, refer to ASTM E606 or ISO 12106. For load control refer to ASTM E466 or ISO 1099.
Fatigue testing is done using three different methods, all of which are covered by ASTM. First, ASTM E606 covers strain control axial fatigue. Third, ASTM E466 covers load controlled fatigue testing. 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 1099 Axial Force-Controlled Method of Fatigue Testing of Metallic Materials
- ISO 12106 Metallic Materials Axial-Strain-Control Fatigue Testing
- ASTM E606 Strain-Controlled High and Low Cycle Fatigue Testing
- ASTM E466 Load Controlled Constant Amplitude Fatigue Tests of Metals
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
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)
Rated from ambient temperatures to 1,200°C (2,200°F)
All standard units meet existing ASTM class B-1 and ISO 9513 class 0,5 requirements for accuracy
Allows for accurate, high temeperature strain measurement
Self-supporting on the test specimen
Maximum operating temperature options of 500°C or 1200°C (930°F or 2,200°F)
Minimum operating temperature of 300°C (570°F)
PID controlled temperature
Utilizes 120 V or 240 V power