1. Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 1 Design, Manufacture, Transport and Integration on-site in Chile of ALMA Antennas CFRP Status Dated 2006-09-13

2. Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 2 SUMMARY 4 different pre-preggers have been considered as alternatives to CYTEC: Preliminary tests performed on resin samples and on laminates have demonstrated that they all have characteristics equivalent to those of the CYCOM 737 used for the prototype and which meet the requirements. Oven-curing has been considered as an alternative to the autoclave curing process which has been used for the prototype antenna: Preliminary tests performed on laminate samples have demonstrated that oven curing and autoclave curing processes lead to characteristics similar enough to allow both processes to be used. On the basis of these results a resin different from the prototype has been selected and will be qualified.

3. Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 3 Change of the resin system (1/2) The resin system used for the prototype antenna (CYCOM 737) is compatible only with the autoclave curing process, with the following consequences: Reduction of the panel of subcontractors which can manufacture the big subsystems: these subcontractors need to possess autoclaves (and preferably big ones), Overall complexity of the resulting design: no autoclave being big enough to fit a complete BUS or Cabin, these subsystems need to be split into multiple sub- assemblies, Manufacturing difficulties due to the complexity of the design. Other resin systems have been selected, based on the following general requirements: They shall be compatible with both autoclave and oven curing processes, In both cases, the characteristics of the resulting laminates shall meet the technical requirements determined by EIE. Those resins are: « MTM 757 » from ACG (English pre-pregger), « FT1091 » from EPO (German pre-pregger), « M10 » from HEXCEL (French pre-pregger), « R 367-2 » from STRUCTIL (French pre-pregger).

4. Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 4 Change of the resin system (2/2) The main consequences of a change of the resin system could be: A change of inter-laminar properties, A change of the thermal and moisture related properties. Preliminary tests of Inter-Laminar Shear Strength have been performed on laminate samples which demonstrate that the different resins have similar properties. Preliminary tests have been performed on pure resin samples which led to the conclusion that all those resins have very similar thermal and moisture related properties. The results of these tests are supplied in the next page. CYTECACGEPOHEXCELSTRUCTIL ResinCYCOM 737MTM 57FT1091M10R367-2 ILSS (MPa)69,464,5-64,665,5

5. Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 5 Results of the tests on thermal and moisture related properties

6. Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 6 Change of the curing process (1/5) The main consequences of a change of the curing process can be: A change of the Fiber Volumic Ratio. A possible increase of the Void Ratio. A possible decrease of the mechanical properties of the resulting laminates. A variation of these properties over time (ageing). The mean Fibre Volumic Ratio and the maximum Void Ratio are parameters that are imposed to the manufacturers and checked during Process Qualification. Tests performed on laminates samples demonstrated that laminates cured in oven could have: A scattering of about +/- 3% of the FvR, which is similar to what is obtained for autoclave processes. A void ratio up to 2%. Data available from the pre-preggers show that the mechanical properties obtained after oven curing are very similar to those obtained on the prototype with CYCOM 737 cured in autoclave (see table next page).

7. Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 7 Change of the curing process (2/5)

8. Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 8 Change of the curing process (3/5) Ageing tests performed on laminates showed the same decrease of the mechanical properties (Compression Strength and ILSS) for samples cured in autoclave and in oven provided the resulting Void Ratio is inferior to 3% (source: Journal of Composite Materials, vol. 39, n°21, 2005).

9. Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 9 Change of the curing process (4/5)

10. Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 10 Change of the curing process (5/5)