Bolts and studs .

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

This thread follows on from discussion in the HT bolts thread .

 

Bolts and studs can almost never be designed on simple strength considerations and in most cases it is nescessary to analyse and understand what is happening in the entire system of joined components under load .

 

With two or more components held together by through bolts or studs and with or without gaskets at each interface the whole joint is effectively a system of springs and what happens to the load and stress in each part under initial tightening and subsequent fixed or variable load is complex and fascinating .

 

Apart from silly failures like overtightening when new most bolts or studs in highly loaded variable load joints like an engine cylinder head/block/crankcase assembly fail either by low cycle fatigue or in higher temperature situations by creep .

 

Bolts and studs are not quite interchangeable in the way they work . Generally bolts are used for thin joints and studs for thick joints but the choice of using one or other in a real job depends on many detail considerations .

 

Anyone interested in this subject might like to start off by considering one simple question :

 

In an engine assembly of crankcase/cylinder block/head held together by studs and which is initially all tightened up in the normal way and which is already at running temperature how does the load in the studs vary during each pressure/exhaust cycle ???

Edited By MICHAEL WILLIAMS on 06/02/2011 11:09:37

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

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