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3 Mechanical Design

3.2 Support structure

The design of the mechanical structure of the Aerogel threshold Counter has to take into account the resistance of materials due to the specific conditions during the launch of the Space Shuttle. The mechanical structure that supports the AMS Magnet and the other components of the AMS detector has been developed by Lockheed-Martin (Houston, TX) with whom we work closely in order to assure the reliability of the various components of the ATC being designed at ISN-Grenoble and INFN-Bologna.

The components of the mechanical structure have been designed after mechanical resistance calculations, using a finite element analysis method, using available software packages (SYSTUS and COSMOS). The calculation conditions imposed by NASA are given as a function of the loaded weight of each device. For this detector we have taken into account the acceptable mechanical constraints of acceleration of 17 g and a safety factor of two. The vibration modes have, also, been calculated in order to verify that their value is well above the values imposed by NASA (f>50 Hz). Results of this calculation are summarized in Appendix A.1.

The criteria for the design of the mechanical structure were:

  1. Minimization of the weight of every component in order to have a total weight close to 80 kg.

  2. Optimization of the mechanical rigidity in order to obtain eigenfrequencies of the order of hundreds of Hz.

  3. Modularity of the detector that will facilitate the assembly and the functional tests during its integration to the general AMS structure.

  4. Protection of the aerogel blocks from friction phenomena due to vibrations,

  5. Light tightness,

  6. Rapid depressurization.

Figure A-1 in Appendix A show details of the mechanical design of the honeycomb support structure, the assembly of modules and the assembly of PMT container boxes.

Issue: Draft - Revision: 04 - Last Modified: 20 April 1997