Whatever the mission, be it manned or unmanned, for scientific research, applications or space transportation, a spacecraft must withstand the extreme stresses which occur during the launch phase, and once in orbit, the rigours of the space environment. There is one way of making sure of this: to test the spacecraft on Earth under conditions simulating, as closely as possible, those it will meet during the launch and its orbital life. This can be done with with tests which demonstrate by application of static or quasi-static loads that the spacecraft design can withstand the static and dynamic accelerations produced by the launcher, apogee motor, and spin-up without suffering permanent deformation or failure. Of the three existing methods used to impose quasi-static loads on a test object - whiffle tree, centrifuge, and acceleration tests - the centrifugation offers distinct advantages for qualification of a spacecraft structure and this will be considered in detail.. Static tests are needed to establish the integrity of a spacecraft structure when subjected to loads which resemble in-flight conditions. Deformations and strains are measured during static tests to confirm the adequacy of the structure, and may identify the need for design changes. Static tests are usually performed on the structural model of a spacecraft during qualification testing. In all three test methods mentioned above, the test object is supported by an adaptor whose characteristics represent those of the flight attachment interface. A whiffle tree tests applies point loads to the test item through a system of jacks, with the test adaptor bolted to the floor. This test is normally used for items too large and heavy for testing by acceleration or centrifuge methods. Test loads are applied in steps: first the predicted flight load, followed by increases of 10% and 25%, the qualification limit. Source : http://esapub.esrin.esa.it/pff/pffv6n4/vigv6n4.htm
The structural tests are usually...
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