From the latest M1SS design one engineering model (EM) and six qualification models (QMs) have been manufactured recently, which have tested intensively to verify their performance. This work will present the test procedure employed to validate the dynamic behavior, describe these dynamic tests and present their results in detail. During these tests a QM, including a dummy segment, has been placed on a heavy rigid structure and three accelerometers have been mounted across the assembly. The structure has then been excited on several strategic locations using a roving hammer technique,3 resulting in a large collection of frequency responses. From these, the eigenfrequencies and accompanying mode shapes have been estimated, resulting in accurate determination of the clocking, lateral, piston and tip/tilt modes of the structure. This allows for correct assessment of the dynamic performance and comparison to the design objectives and finite element model (FEM) predictions.
This procedure has been applied to two different QMs, but since each M1SS consists of a fixed frame (FF) and a removable segment assembly (SA), four different configurations have been tested. The results demonstrate compliance with the challenging design objectives for all QMs, and they show only small variations among the configurations, demonstrating that the dynamic performance of the M1SS design is very reproducible.