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 FE Modelling Activities PM# September 2006

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 2 STATUS OF THE FEA MODEL AND ACTIVITIES DONE UP-TO-NOW FEA MODEL - THE FEA MODEL HAS BEEN UPDATED MAIN CHANGES INTRODUCED: - NEW SHAPE OF THE BASE STRUCTURE - NEW LAYOUT OF THE PLATFORMS - CONTACT ELEMENTS TO CONNECT SHELL ELEMENTS TO SOLID ELEMENTS - SOME CHANGES IN THE MESH NEAR THE AZIMUTH BEARING FEM ANALYSES DONE - ALL ANALYSES ON THE GLOBAL MODEL - CHECK OF THE STRESSES IN STEEL SHEETS AND IN THE CFRP - LOADS ON THE MECHANICAL INTERFACES FEM model for a detailed stiffness verification of the azimuth bearing - DONE

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 3 FEA MODEL NEW MODEL OF BASE STRUCTURE OLD MODEL CONICAL SHAPE 60 INTERFACE NODES WITH THE AZIMUTH BEARING NEW MODEL PRISMATIC SHAPE 96 INTERFACE NODES WITH THE AZIMUTH BEARING (LIKE THE BOLTS NUMBER) MORE RIBS UNDER THE BEARING FLANGE

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 4 FEA MODEL NEW MODEL OF PLATFORMS OLD MODEL NEW MODEL NEW DESIGN OF UPPER AND LOWER LEVELS MODIFIED POSITION OF HVAC, CRYOGENIC COMPRESSOR AND UPS BATTERIES

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 5 FEA MODEL NEW MODEL OF PLATFORMS NEW MODEL FIRST EIGENFREQUENCY = 11.60Hz OLD MODEL FIRST EIGENFREQUENCY = 10.12Hz

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 6 FEA MODEL NEW MODEL OF SUBREFLECTOR NEW MODEL 9 RIBS / NO CENTRAL HOLE / 3 FIXING POINTS MASS = 22.9 kg OLD MODEL 8 RIBS / CENTRAL HOLE / 8 FIXING POINTS MASS = 22.1 kg

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 7 FEA MODEL NEW MODEL OF SUBREFLECTOR GRAVITY IN Z DIRECTION (ANTENNA POINTING ZENITH) DISPLACEMENT IN Z DIRECTION (MAX = 2.5 microns) WITH ALSO THE CONTRIBUTION OF THE INTERFACE CYLINDER

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 8 FEA MODEL NEW MODEL OF SUBREFLECTOR DISPLACEMENT IN X DIRECTION (MAX = 4.6 microns) DISPLACEMENT IN Z DIRECTION (MAX = 4.8 microns) GRAVITY IN X DIRECTION (ANTENNA POINTING HORIZON) WITH ALSO THE CONTRIBUTION OF THE INTERFACE CYLINDER

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 9 FEA MODEL NEW MODEL OF SUBREFLECTOR THERMAL GRADIENT IN X DIRECTION  T = 10 °C DISPLACEMENT IN Z DIRECTION MAX = 30 microns DUE TO THE DEFORMATION OF THE INTERFACE CYLINDER DISPLACEMENT IN Z DIRECTION MAX = 6.4 microns WITHOUT THE CONTRIBUTION OF THE INTERFACE CYLINDER

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 10 Modelling activities ► Exigence: Implementation of a ligther global model of the antenna to perform: ► Reduced modal analysis for Servo and other Dynamic Analysis ► Super-elements generation for detailed analysis of Az Bearing ► Activity: Remodelling of most composite parts (Cabin and BUS) with equivalent isotropic elements 8-nodes SHELL99 elements replaced by 4-node SHELL63 elements Nodes # from to Nodes # reduction: -50%

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 11 Super-elements for detailed analysis of Az Bearing ► Super-elements have been generated for both the lower and the upper supporting structures of the Az Bearing ► Each superelement: ► is representative of the corresponding structure stiffness and mass ► is provided with 96 interface nodes to be connected with the bearing model and with an additional reference node ► Superelements will allow Rothe Erde to effectively include full influence of the supporting structures in performing detailed analysis of Az Bearing

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page interface nodes on flange midplane Azimuth structure super-element Base structure super-element Super-elements for detailed analysis of Az Bearing Equivalent inertia for BUS, legs and apex interface nodes on flange midplane

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 13 ACTIVITYSTATUS Implementation of a ligther global model of the antenna Completed Super-elements generation for Az bearing detailed analysis Completed Reduced modal AnalysisIn progress