Advanced polymer matrix composites have increased in popularity of the past decade because they provide high strength and stiffness properties at a fraction the weight of steel. Specifically, polymer matrix composites (PMC's) such as fiber glass, and carbon fiber. These advantages of composites come at a price; they are difficult to machine, expensive, and are susceptible to fatigue failure. Fatigue crack growth is a major concern in the aerospace industry where fatigue crack growth in composites can quickly lead to failure, and composite crack repair is still being investigated.
It is critical to applications that use composites to perform materials testing in order to determine the fatigue properties and crack growth characteristics. TestResources has a number of referred composite fatigue testing standards to help with your testing application. 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
- ASTM D3479 Tension-Tension Fatigue of Polymer Matrix Composite Materials
- ASTM D6873 Fatigue Equipment for Bearing Fatigue Response of Composites
- ASTM D7615 Open Hole Fatigue Equipment for Polymer Matrix Composites
- ASTM E1922 Fracture Toughness Polymer Matrix Composites Notched 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