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#74135 - 11/12/19 04:08 AM Spring with friction modelling in caesar II
stress1698 Offline
Member

Registered: 11/22/08
Posts: 13
Loc: india
Dear experts,

I am working on reboiler-column stress analysis

during analysis, I found the requirement of spring support and modelled the same as per standard practice in caesar.

Nozzle loads on reboiler and column nozzles drop down drastically when modelling of spring.

here reboiler is supported from the column.

one question comes that what about the friction effect especially spring is design for huge vertical loads from reboiler

hence I decided to model spring support with friction.

can somebody guide me the procedure for modelling of spring support with friction when the connection to column(C-node is already been utilized for column connection)?

Thanks in advance for your help

note that spring is provided due to temperature difference between column and reboiler even though support is from column
_________________________
stressguy

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#74137 - 11/12/19 05:50 AM Re: Spring with friction modelling in caesar II [Re: stress1698]
Sigma Offline
Member

Registered: 10/22/06
Posts: 37
Loc:
Im referring the node numbers from the Model of Spring Can with Friction shown in CAESAR II Applications Guide, where friction is applied at node-20.
In your case, node 20 is supported from equipment clip, so IMHO modelling should be in similar way but with addition of Cnode

Node 20, Cnode 30, Restraint +Y, mu = 0.3
Node 20, Cnode 30, Restraint RX, RY, RZ

Node XX to node 30 could be clip from equipment OD.

What others have to say?

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#74196 - 11/20/19 07:34 AM Re: Spring with friction modelling in caesar II [Re: stress1698]
joeseagle Offline
Member

Registered: 05/19/10
Posts: 27
Loc: Louisville, KY
I'm curious why this feature can't be programmed into Caesar to automatically apply friction to spring cans?

The manual process seems quite tedious for something that would theoretically need to be applied to every single spring can application.

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#74197 - 11/20/19 09:42 AM Re: Spring with friction modelling in caesar II [Re: stress1698]
Michael_Fletcher Offline
Member

Registered: 01/29/10
Posts: 816
Loc: Louisiana, US
Every time I've done it, the friction force was so small that made the effort in the first place questionable.

Perhaps the small amount of accuracy increase keeps it down the priority list.

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#74198 - 11/20/19 10:02 AM Re: Spring with friction modelling in caesar II [Re: Michael_Fletcher]
joeseagle Offline
Member

Registered: 05/19/10
Posts: 27
Loc: Louisville, KY
Would the friction force not be directly related to the vertical load (which is subject to the spring's characteristics) and the coefficient of friction? In this case, it would in fact be worthwhile force. If you are using a large spring size then you would have a large vertical load. That translates to a large frictional force, no?

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