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About this modelAbout this model
• This model employs 3 inverted ‘bipods’ for baffle. Bipods in quotes because legs are not pinned at ends, but are fixed-fixed.
• No skins are included in the FEA, but are certainly necessary for contamination and light control...skins would carry loads in FEA, and I want to show the structure is adequate w/o them.
• In FEA, instrument deck/lower closeout is modeled as aluminum/honeycomb sandwich with 1mm skins and 25mm core, not populated with instrument electronics in FEA.
— Not sure how exactly this would integrate with the 12-sided angle aluminum structure that forms the interface between baffle and s/c.
— Boxes carried on deck should be pushed as far toward perimeter as possible.
• A similar model with 5 inverted ‘bipods’ was analyzed.— Different material thicknesses from this model.— Basically copy the struts from this model, clocked 60 degrees, omit a pair by
instrument.— 5 bipod model is 16kg lighter than 3 bipod model.
• 5 bipod natural frequencies: 18.4, 21.0 Hz.• 3 bipod natural frequencies: 18.7, 19.2 Hz.• At Delta IV launch accelerations, mat’l safety factors are 10 in aluminum and 5
in Ti thermal standoffs.
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Model specifics (see slide 7)Model specifics (see slide 7)
• Inst deck/baffle bottom closeout: 1mm Al skins on 25mm thick Al honeycomb core.
• S/C adapter/handling ring: Aluminum angle, 150mm x 75mm, longer leg of angle is 3mm thick, shorter leg is 5mm thick.
• Thermal standoffs, 50mm dia, 1.5mm thick Ti tubes.
• Baffle support legs: closed rectangular sections, ~110mm x ~50mm, 3mm thick walls.
• Stiffening gussets in angle near thml standoffs: 5mm thick Aluminum.
• Flange at base of upper baffle: 5mm thick.
• Bottom 200mm of upper baffle tube: 3mm thick.
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Observatory, dummy OTAObservatory, dummy OTA
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Lower baffle area, no skins in modelLower baffle area, no skins in model
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Array turned offArray turned off
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inst deck/bottom closeout
1.5mm thick Ti thermal break3mm thick, 150mm tall part of angle
5mm thick, 75mm wide part of angle
5mm thick gusset 110mm x 50mm x 3mm legs
5mm thick upper baffle flange
3mm thick bottom 200mm of upper baffle
1mm thick nominal
upper baffle
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Inst. deck/lower closeout turned offInst. deck/lower closeout turned off
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OTA turned offOTA turned off
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Angle web turned offAngle web turned off
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Just baffle support legsJust baffle support legs
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‘‘detail’ viewdetail’ view
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inst deck turned offinst deck turned off
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