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#39613 - 12/17/10 12:57 AM Use of offset method for horizontal trunnions
pcrowther Offline
Member

Registered: 05/26/10
Posts: 2
Loc: UK
Hello,

What are the opionions for the use of the offset method for horizontal trunnions? In the Caesar help, it only seems to describe what looks like the near-far point method with horizontal dummy legs, but describes all three for vertical legs.

Does anyone know of a reason for this?

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#39625 - 12/17/10 06:30 AM Re: Use of offset method for horizontal trunnions [Re: pcrowther]
danb Offline
Member

Registered: 04/22/05
Posts: 1320
Loc: ...
I think that the reason is that normally for a horizontal trunnion it is not so critical the real location of the connection point.

I personally use another method for vertical trunnion, the one with one rigid (bend radius length) that double the bend plus the trunnion.

Offset method have advantages and disadvantages. It will consider the real length but will ignore the displacements. So it is up to you how detailed you want (or need) to model the trunnion.

Best regards,
_________________________
Dan

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#39718 - 12/23/10 05:54 AM Re: Use of offset method for horizontal trunnions [Re: danb]
Rajinder Singh Offline
Member

Registered: 07/25/06
Posts: 55
Loc: New Delhi
In beam based FEA programme, creating proper elements (node points) is essential.
For vertical trunion, line of action of force is critical. Hence the connection (node) point. As Dan cited, it also depends upon the critically of the system.
I would rather prefer to model trunion with near/far point method on low temperature/pressure water line and use offset element model for critical line such as lines connected to turbine.
In horizontal trunion, moments are rather important (distance from elbow to point of support). You can use offset element method for horizontal trunion also (I haven't used it) but it need validation from experts.
_________________________
Rajinder

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