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Problem with production of carbon Bent shaft with Bladder Inflation Molding method

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Buryk

Mechanical
Nov 13, 2013
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Hello Guys
i used got useful info here.
I produce paddle for my friends with carbon bent shaft. For bent shaft I have 2 parts composites mould and I use wet hand lay up lamination and straight silicone tube which I buy from Essentrea components.
My process is - 1. carbon 200 plain to each half of mould. 2. UD 300 carbon 3. silicon tube with carbon kevlar braid sleeve. Clouse the mould with silicone tube with carbon kevlar sleeve than I clamb one end and another end I have valve to put air inside with 2 bar presure.I think is enought.
I have problem that when the shaft is cured and ready to open the mould. I can see in curve (the place where the shaft is bent) kvelar carbon braid close on. It dosn't look profesional and I have problem with water leaking inside the shaft. I don't know If should used custom silicone tube which is already shaped - bent, because the straight silicone tube with air inside tend to go straigt in mould and press the kevlar carbon sleeve in curve of mould. What do think ? What I am doing wrong ?? [URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1430980696/tips/Bent_shaft_h7dymz.bmp[/url]
 
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First, it is silicone rubber, not silicon, which is a metal. Composite resins "cure", they do not "dry".

You have to remember that you are working with high strength fibers that do not stretch or compress during molding. Making a curved tube is easy if use a braid to start with, but a braid will not give the mechanical properties (bending stiffness) you need. To make UD material fit this part you will need to lay it in carefully in narrow strips, or else it will wrinkle very badly.
 
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