Fatigue Testing of Finger Implants
Orthopaedic fixation devices are used during reconstructive surgery to treat fractures of bones and soft tissue injuries normally caused by trauma. Devices, such as bone plates, compression screws and femoral nails, are used to provide stability and maintain the alignment of bone fragments during the healing process. Quantification of important characteristics, such as bending strength or stiffness, can provide surgeons with insight into implant performance, while allowing researchers to compare device materials and designs. The fatigue life of the implant over a specific time period or range of maximum loading must also be determined.
Typically following ASTM guidelines, fixtures are often unique to the objective and application of the tests and results. Features of both the ElectroPuls™ test instruments and 8870 servohydraulic testing systems, such as integral t-slot base, ability to mount the Dynacell® load cell to the moving actuator, and saline chamber accessories for in vivo simulation, allow laboratories to investigate a comprehensive range of device characteristics and performance.
For this test a small implant, commonly used to treat fracture of the phalangeal, metacarpal or carpal bones, was subject to dynamic loading to verify the fatigue life. The fixation plate was set up on both the ElectroPuls E3000 and E1000 machines. After a simple stiffness tune, a compression bending test was run at 20 Hz between 0.3 and 3 N. The test was successfully run by utilizing a lower force Dynacell load cell, a small compression platen and a clamp to fix the implant, and mounting block in position on the lower t-slot table.
The ElectroPulsTM E1000 is a state-of-the-art, all-electric test instrument designed for dynamic and static testing on a wide range of materials and components. It includes Instron® advanced digital control electronics, DynacellTM load cell, Console software, and the very latest in testing technology – hassle-free tuning based on specimen stiffness, electrically operated crosshead lifts, a T-slot table for flexible test set ups, and a host of other user-orientated features. Powered from a single-phase supply it requires no additional utilities for basic machine operation (for example, pneumatic air, hydraulics, or water).
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ElectroPuls instruments are state-of-the-art electrodynamic test systems for dynamic and static tests on materials & components. Powered entirely from a single-phase mains supply, they feature the latest in testing technology and a host of other user-oriented features.
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