Thermo-Mechanical Test Procedures for X-38 Rudder

Kurzfassung

The challenging test procedures for a hot rudder model of the X-38 space plane are presented. These procedures comprised testing of mechanical and thermal behaviour as well as of kinematics under single and combined loading conditions. The objec-tives to be met were (1) verification of temperature distribution within the metallic rudder structure and the interface to the cold fin, (2) kinematical per-formance under thermal loading, (3) strength and stiffness under quasi-static mechanical and transient thermal load, and (4) functioning of sealing of clos-ing edge plates. The DLR THERMEX-A test facility was chosen for its adaptability to larger specimens and complex test procedures. Pure thermal and pure mechanical as well as combined thermo-mechanical tests may be carried out on larger components within a loading rack of 2 m x 4 m for modular assembly. In the first place, a basic set-up was designed par-ticularly for mechanical tests. A three-point sus-pension was selected (1) to introduce at nine discrete points me-chanical loads by a whiffletree, (2) to fix the hinge axis between rudder and fin dummy, and (3) to suspend the fin dummy. The thermal load was simulated by infrared lamps. To test kinematical behaviour of the rudder under thermo-mechanical load a sophisticated modifica-tion of the basic set-up was designed. The test set-up, the instrumentation with thermocouples, strain gauges and displacement transducers as well as the performed tests are presented.