Expansion joint modeling

hi
I have a question regarding the expansion joint modeling in CAESER,in reality we are introducing bellows and rigid element with degree of freedom restrains depending in expansion joint type so my question is how to obtain the parameters of the bellows (axial stifness,lateral stiffness,bending stiffness and the allowables axial,lateral and bendind displacements)these prameters are not available in suppliers catalogs we find only for example for gimbal joint the bending stiffness and the allowable angle rotation for the hole mechanism.
Should we calculate these parametrs by our self following for example the EJMA standard or there is another way.
thanks to clarify this point for me.

The expansion joint catalogs do usually contain all these values, but if not, contact the manufacturer.

Hi

In your question you refer to gimbal unit. Manufacturer doesn't need to give more than the maximum angular movement and the bending stiffness. Bellows element's axial and lateral stiffnesses are internal to the unit. Pipework outside the unit doesn't "see" any other value. Torsional stiffness is high. It is combination of the element and the gimbal ring/hinges and brackets. Axial and lateral stiffness cases are the same. For small bellows all 3 stiffness values values can be assumed high. With very large units you better talk to the supplier as movements can be several mm.

If you look on my site www.jat.co.za work samples you can find a compensator, which has 2 rods next to each other. Some stress engineer figured out that the elongation using only one per side was too much..... I have also seen about 1.2 m diameter tied unit where the deformation of rings holding the rods was causing larger movement for the bellows element than the lateral movement.

hi
thank you for your answer but when i use the CAESER epansion joint rating module i have to enter the values of the allowables displacements per convolution for the bellow.
If i have to check a lateral compensator with two bellows with this module i have to verify each bellow apart so i have to enter the allowables axial,lateral and bending displacements for a single bellow and these parametres are not given in catalogs.
i hope you undrestand my point.