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The main sections of the museum are listed below;

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Polymers
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Tools of the trade, some ways to investigate problems;
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Polymer failures

Stress corrosion cracking of nylon 6,6 - Page 2

However advice from mechanics suggested that the break was on a part of the pipe almost impossible to access in the confines of the engine bay (image above), and the break occurred in a moulded junction in the fuel return pipe, which is more difficult to cut than the softer pipe.

Closer inspection of the moulded part using optical microscopy, revealed a brittle fracture which showed several growth phases, the first being initiated by stress corrosion cracking of the nylon connector in the pipe. The junction was immediately below the battery and it is likely that a drop of acid spilled onto it, starting the crack. It then grew at each successive engine start-up until final breakage.

Detailed examination >

 

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ed: PRL 21/6/02

 
 
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