Hi To all,

I want to change the expansion bellow convolution details. Because unfortunately i chose 4 convolutions. but i want to change 6 convolutions. here i am attaching the image for your reference.

Please try to solve my problem?

Hi anandh

Number of convolution is matter of concern of bellow designer not concern for piping stress engineer.
When number of convolution increase bellow stiffness property decrease as well as length of the bellow increase.

Piping stress engineer require only the bellow mention property to feed in caesar-------
Axial stiffness
Lateral stiffness
Tortional stiffness
Bending stiffness(optional for metallic bellow)
Effective Id of bellow
Overall length
Bellow weight.

Number of convolution not a require data for piping stress calculation with expansion bellow.


When you do not have any vendor data you ask caesar database to supply you approximation value it ask for number of convolution to decide what should be stiffness property , approximation length.
So number of convolution is a background calculation for bellow. All bellow data in caesar should be updated as per final vendor data.You need not to be worried about it.


Regards

Habib

Thanks For your reply SHR.

SHR .... beware of your statement "Bending stiffness(optional for metallic bellow)".

It's the most important spring rate in a hinge or gimble exj.

Hi MoverZ

Thanks for your comments.

"As per Caesar's user guide either transverse or bending stiffness must be omitted in case of non zero length metallic expansion bellow."

In my understanding caesar itself will calculate it based on length & transverse stiffness.
I really do not understand why caesar mention "must be omitted".

I know in case of rubber bellow all stiffness data should be filled.

Can you / Richard / Jouko please clarify the point.


Thanks & Regards

Habib

Zero-length XJs in CAESAR II require all stiffness terms. But finite length joints have a beam relationship between transverse and bending stiffness so both terms are not required in CAESAR II.
IMPORTANT: many XJ catalogs provide a bending "stiffness" based on a zero length model. That is NOT the right stiffness to enter on a CAESAR II, finite length XJ. This is why we suggest leaving that term blank. CAESAR II will calculate the proper bending term. BUT: you must provide the proper flexible length of the bellows - not the overall length - to do so.
This has been reviewed elsewhere on this Forum.

Thanks Dave
For your clarification.

if the finite length hinge or gimble exj , you input the manufactures catalogs bending stiffness,it should be multiplied by 4.0(Note that the case the transverse stiffness would be left blank)