LIGO Document T2000002-v2

A+ Filter Cavity Tube, Expansion Joints and Tube Supports: Conceptual Design and Requirements

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Document type:
T - Technical notes
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This document provides the layout and conceptual design of the expansion joints (bellows) and tube supports for the A+ Filter Cavity Tube.
Notes and Changes:
Changes from -v1 to -v2 based on the CDR review:
1) updated references from D1900485-v1 to -v3
2) updated references from D1900443-v5 to -v7
3) Changed FCT wall thickness from 0.25" to 0.125" in accordance with D1900443-v7
4) Recalculated FCT bending (section 5.1.3) based on the change to a thinner wall tube. No issues or impact.
5) Added bellows at BSC3 door end (between BSC3 and HAM7). Reflected in D1900456.
6) The plan is now to stretch many of the bellows up to 0.4" during assembly per D1900456-v6. This pre-stretch of 0.4" has now been included in section and included in the combined effective rated movement of the bellows (section 4.1.5 and the associated spreadsheet).
7) Added a requirement to include covers on the bellows to protect them from accidental impact damage.
8) Defined the following action items within the CDR document as action items to resolve for the PDR/FDR:
a) section 3, straightness of the FCT central axis.
b) Determination of whether stick-slip at the FCT support interface is a problem to be prevented or not.
c) The bellows final length confirmation (from the manufacturer).
d) What are the permitted vacuum states (which gated sections can be at vacuum or at atmospheric pressure) at any given time.
e) Complete the Ansys FCT FEA for use in dead-weight and seismic loading calculations.
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