In this work, an attempt has been made to establish the time-temperature-stress characteristics and capabilities for several classes of high-temperature composite materials to determine their suitability for supersonic cruise aircraft applications. Five advanced composite materials are being evaluated: Rigidite 5505 boron epoxy, B/P105AC boron polyimide, Type A-S/3501 graphite epoxy, Type HT-S/710 graphite polyimide, and diffusion-bonded boron aluminum. The flight test simulator is capable of long-time automatic testing using random loading and realistic flight temperature profiles. Both load level and maximum temperature were adjusted to suit the particular capabilities of each composite system.

The design, construction, and checkout of the flight simulator is discussed. The test fixture consists of 10 load frames, 10 whiffletree assemblies, attachment hardware for 100 specimens, 100 removable specimen stiffener assemblies, 20 lamp rack assemblies, and lateral support hardware. A digital load programmer (MTS) and 10 Servac load magnitude controllers program and control the fatigue loading spectrum and synchronize the heating and cooling cycles. The load and temperature programming systems have a number of self-checking safety features which will automatically stop all test operations when preset levels are exceeded. The hydraulic pumping system, the heating and cooling systems, control console, and data recording system also are discussed.

Short-term tests were done at constant temperatures and accelerated load rates to establish the load ranges that are being used for the 50 000-h simulated flight testing. Typical results for the accelerated load-rate tests (short-term tests) are presented using a random load spectrum and wearout model. The long-term tests are underway, and 2500 h of simulated flight testing have been completed.