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Overview of Prototyping Techniques for Barrel and Forward Tubes in PST Fabrication

This overview discusses the prototyping techniques for Barrel and Forward Tubes utilized in PST (Pixel Support Tube) fabrication. Key highlights include the construction of 6-Ply QI Laminate Barrel Tubes and 8-Ply Hybrid Laminate Forward Tubes, emphasizing heater bonding methods and material properties. The document also addresses common issues like wrinkling and provides insights into the latest fabrication methods that enhance precision and reduce costs. Part size prediction and the apparent significance of material properties are discussed, aiming to ensure efficient and accurate tube development.

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Overview of Prototyping Techniques for Barrel and Forward Tubes in PST Fabrication

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  1. PST PrototypingSeptember 2002

  2. Pixel Support Tube (PST) Overview • Prototypes • Barrel Tubes • Forward Tubes • Heater Bonding • Fabrication • Wrinkling- our nemisis • Flat Plate Compaction • 1D and 2D Wrapping • Part Size Prediction • Discussion and results

  3. Introduction to the Barrel and Forward Tube Prototypes

  4. Barrel Tubes • 6 Ply QI Laminate • Possible 2 Hoop plies for stiffness • Insulating Glass Mat inner layer • Heater co - bonded to outer layer • YSH-80 Carbon Fiber • Made using a steel mandrel

  5. Forward Tubes • 8 Ply Hybrid Laminate • 2 extra Hoop plies are YSH-80 for stiffness • Insulating Glass Mat inner layer • Heater Co-bonded to outer layer • YSH-80 Carbon Fiber / AQII Quartz • Made using steel mandrel • Can be ‘push’ released from mandrel

  6. Heater Bonding • Heaters can be Co-bonded directly to PST during cure • The heaters can be applied individually or as a single hoop layer • Heaters are shingled to provide a continuous aluminum EMI shield for the barrel

  7. Prototype Fabrication Methods Current and Future methods

  8. fabrication • Barrel and Forward PSTs can both be made the same steel Mandrel • Greatly reduces cost of tooling • increases relative accuracy between PST sections • Layers are compacted into sheets and then rolled by hand onto the mandrel • Minimizes hand error during layup of individual ply sections • Reduces chance of wrinkling due to uneven hand compaction using only a roller or other tool • A special jig may be used to facilitate alignment • Reduces the angle error during layup onto the mandrel • Increases reproducibility of a layup

  9. The low CTE of the Forward Hybrid Layup makes it possible to use the same steel mandrel for Both the Barrel and Forward PSTs. Common Mandrel

  10. Jigs • A swiveling arm can serve to align the compacted ply stack onto the mandrel.

  11. Layer 3 1/32” compaction gaps Layer 2 Layer 1 Mandrel 1D Ply Stacks – today’s method • Multiple layers of Laminate are compacted onto a single stack using vacuum pressure. • Removes trapped air • Joins layers into easy to handle stacks • Reduces layup time • Facilitates alignment • Appropriate for 18” or smaller PST

  12. 0 degree 60 degree -60 degree -60 degree (2nd layer 2D Ply Stacks – tomorrow’s method • This Stacking method provides the most continuous fiber for a larger mandrel. • Precision built into the stack during formation • Simple wrapping method reduces errors • Can be used for any length PST

  13. Wrinkling • Wrinkling will only occur in certain conditions, and can be avoided by using certain fabrication methods • Compacting each stack of plies flat, and then on the mandrel • Rolling the ply stacks onto the mandrel under tension • Using the common procedure of waiting until the laminate has reached flow temperature to pressurize the autoclave BAD

  14. PST Diameters Prediction and errors

  15. Prediction of PST Diameters • TO predict PST Diameters one must know: • CTEs of all involved materials • All known, measured, calculated, or estimated • Mandrel Diameters at room temperature • Measured • Laminate properties and thicknesses • Calculated and Measured • Gel temperature of Laminate • Known range

  16. Calculated or Known CTEs for various Laminates and Materials used in Size Predictions

  17. Prediction of DiameterSimplified Example • Prediction • Mandrel Diameter, CTEs, and Gel temp are assumed Known. • Gel temp range is known so calculation in performed for a variety of actual gel temperatures • Mandrel O.D. at temperature is predicted • Thickness of release layer is added • PST I.D. at temperature is inferred to be the same • PST I.D. at room temperature is predicted • Measurement • PST O.D. and thickness are measured • Error Measurement • Error is calculated as the difference in predicted and measured I.D.

  18. PST Diameter Precision • 13 Measurements were taken using this method • The results were tabulated assuming 100, 110, or 121 degree gel temperature. • Max average error: +/- 0.004 in (100 microns) All Error Data:

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