# Corrugated tube (bellow) - problem with analytical verification

**URL:** <https://calculix.discourse.group/t/corrugated-tube-bellow-problem-with-analytical-verification/3774>\
**Category:** Analysis issues\
**Created:** [February 9, 2026, 3:33pm UTC](https://calculix.discourse.group/t/corrugated-tube-bellow-problem-with-analytical-verification/3774 "2026-02-09T15:33:01Z")\
**Posts on this page:** 1\
**Showing post:** 6

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**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\
**Post date:** [February 10, 2026, 3:07pm UTC](https://calculix.discourse.group/t/corrugated-tube-bellow-problem-with-analytical-verification/3774/6 "2026-02-10T15:07:30Z")

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Thanks for the comments. I’ve tried interpreting BCs from the paper:

 ![bellow paper](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/c/c27f879d6a85b060e231020f4fba0ea521a09833.png)

And this is my updated setup:

 ![image](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/7/784fdd577402bded1f212dea35dae6ae9b3b355b.png)

The result I get is:

 ![image](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/f/f1bcc1fe9731439df28dc2065fa348a24f6bdc45.png)

I don’t think I can give it more flexibility. The straight ends are removed to make it easier to constrain and closer to the paper.

[PrePoMax file for this configuration](https://www.dropbox.com/scl/fi/3qvdxspfsmjm7t2bsbrlq/Bellow-axi-symm.pmx?rlkey=k4inyp134tfdqfqne8l8z7lm4&st=8lekmdp6&dl=0)

[Input file for the same configuration](https://www.dropbox.com/scl/fi/5b8rc6t7l1ll02jrh1ew7/Bellow-axi-symm.inp?rlkey=48g0umaj1ug7vtmfp349ld1kn&st=guh83s0z&dl=0)

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