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Trident separator window investigation. Matthew Brock (Oxford ) 16 th October 2012. Context. The picture to the right from Roger Forty’s presentation at Davos on the 3 rd September shows a concept for Trident requiring a window separating the gases.
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Trident separator window investigation Matthew Brock (Oxford) 16th October 2012
Context The picture to the right from Roger Forty’s presentation at Davos on the 3rd September shows a concept for Trident requiring a window separating the gases. Two window concepts were proposed for investigation by finite element analysis • Glass of varying thickness • Polymer, possibly Mylar (polyester), possibly a film xd x0
Loading • Sheet is split into 20 horizontal strips 250mm high • Differential pressure applied from 1.74 mbar at the top to -1.74 mbar at the bottom calculated assuming a density of 11.21 for C4F10 and 3.72 for CF4 • Fixed constraint around the external edges and at the beam pipe • Gravity also applied
6 mm thick glass stress Glass failure stress of 30-90 MPa depending on grade so 6mm gives a reasonable margin.
Variation with glass thickness The model becomes less accurate with reduced thickness. Some random errors occur due to modelling problems. A single node error for 5mm and 8mm thickness means the peak stress is estimated.
Comparison of glass with polymers • Displacement is much larger for polymers due to the lower Youngs modulus • FE model becomes unstable at thicknesses lower than 4mm but displacements would be very large at this point. • Mylar film is available in 12-300 micron thicknesses but defection would be beyond the linear range. • The materials chosen were those in the standard materials database. Polyester is not in the database however the other polymers give an indication of the displacement.
Discussion points • The modelling shows some quite high displacements and it may be worth making some physical models to verify this. • What deflection of the window would be acceptable? • Should we be carrying out some optical modelling? • If we are going to consider a polymer which transparent material would best survive the environment?