Computer Applications in Full-Scale Aircraft Fatigue Tests

The development of computerized load processing techniques for application to a full-scale fatigue test of the aft fuselage and empennage of a Canadian Forces CT-114 (Tutor) aircraft is described. The procedures used to select significant end points from the flight loads and to eliminate nondamaging maneuvers are presented together with the development of the test actuator loads required to simulate the flight cases. The optimization procedure used to minimize the error in the applied load distribution, based on the sensitivity of stresses at critical locations to errors in the test loads, is also given. The integration of the load control and multichannel data acquisition systems is described. By taking and automatically checking data on specific load cycles on a continuous basis throughout the test, it was possible to get immediate notification of any structural changes that occurred and check the functioning of the test system. Two examples are given that demonstrate the use of this integration.