Boosted Modal Survey Test on the European Robotic Arm

Abstract

The European Robotic Arm (ERA) is a part of the European contribution to the International Space Station (ISS) and has been developed under ESA contract with Fokker Space as the prime contractor. The integration of the Flight Model has been completed. In the framework of its structural qualification a modal survey test and a boosted modal survey test were performed on the SETEC acoustic facility using the DLR mobile vibration test facility. The purpose of the modal survey test was to determine the modal parameters of ERA and its launch configuration mounted on the actual fixation mechanism. These modal parameters are used to validate the system level FE model, which is based upon the sub-system FE models supplied by the respective sub-contractors. The main goal of the boosted modal survey test is to qualify the strength of the interface between ERA and launcher. The idea of how to achieve the qualification loads is to use inertia forces stemming from excited eigenmodes using suitable excitation points. Small-banded swept-sine excitation in the neighbourhood of appropriate eigenmodes is used to reduce the number of cycles with high load levels to their minimum.