EUROPEAN DRAWER RACK (EDR) STATIC TEST

摘要

The European Drawer Rack has been obtained byAlenia modifying internally a standard Japanese Rack,provided by the Japanese Company IHI throughoutESA, to allow a new layout for lockers accomodationand internal equipments.Through its internal subsystems, the EDR is able togenerate additional services and make them availableto the experiments contained in the standardized lockersin order to increase the resource utilization flexibility.Due to these changes, a static test campaign has beenperformed to qualify the Internal SecondaryStructure(SSI) including frames, panels and posts whichsupport internal equipments and lockers.The Static Test Model (STM) was representative of theFlight Unit (FU) with regard to the SSI to be qualified,all the internal payloads having been removed.External constraints of the rack to the test fixture, werethe same of the flight conditions.The basic choice was to perform the test by avoiding,were possible, the use of dummy masses simulating thereal drawer or equipments; this allowed to directlyapply and monitor the forces on missing unit attachment points.However in the rack lower side, to solve accessibilityproblems and to simplify the loading whiffle-tree, atotal of 4 pyramidal dummies has been used.The mechanical whiffle-tree device transferred theloads from seven hydraulic jacks to 28 attachmentpoints, in X,Y,Z direction simultaneously.Two whiffle-tree set ups were designed to apply the twotest cases, sufficient enough to cover the most criticalFU design load conditions.More than 200 strain gauges have been used for theinstrumentation of the internal posts, some bi-axialgauges for panels and about 20 channels fordisplacements transducers.During the test , the major difficulty encountered hasbeen the realization of an ' hard mounted' restraintcondition.For this reason, additional transducers have beenforeseen to measure the displacements in the 'fixationpoints' of the STM. Experimental measures are discussed in the paper andthe comparison with analysis predictions is provided.Test results and test data evaluation demonstrate that:? The SSI is capable of withstanding theultimate load without failure? The mathematical model used for thepredictions can be considered test verifiedThe following reccomandations for the future:? The stiffness of the text fixture should becarefully accounted in test predictions andcorrelation? Dummies require additional design to properrepresent the stiffness of the missingequipment, but could be the most efficientsolution for simplicity and cost? A mixed approach of dummies and directloading method (able to monitor the mostimportant interface forces) could represent agood compromise in a static test.