Original Date: 10/14/1988
Revision Date: 01/18/2007
Information : Adaptive Fatigue Testing
Fatigue testing of primary flight structures at Bell Helicopter Textron, Inc. (BHTI) is performed using the internally developed Automatic Fatigue Test Control System (AFTCS). The system acts as a controller, monitor, and data acquisition system.
Ideal displacement levels are established for various locations on the test article. Strain gauges are placed at these locations in order to provide feedback to the load controller. The test is initiated by placing a load of 10% on the specimen. If the displacement data returned by the feedback system agrees with predetermined results the cyclic loads are gradually increased to 100%.
As the test progresses, the system compensates for changes in the stiffness of the test article or for wear in the test fixture. The controller has a critical limit which if exceeded will stop the test. Exceeding the critical limits is the result of large strains or redistribution of loads which are indicative of crack initiation.
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