Metal matrix composites are high strength materials used in a wide range of applications including automotive and military vehicles. Metal matrix componstes can be designed to have specific stiffness, controlled thermal expansion cofienents, and specific thermal conductivity. Fatigue testing metal matrix composites is an essential part of reasch and development, design, and quality adduence. Fatige testing MMC's can be done a number of different ways; strain controled fatigue, load controlled fatigue, and thermomechanical fatigue are the most common. Currently, there is not an ASTM or ISO test method for determining the fatigue charicteristics of metal matrix composites. However, TestResources suggests the use of metal fatigue test standards. High 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.
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 E466 Load Controlled Constant Amplitude Fatigue Tests of Metals
- 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
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