# Stress/displacements according to cylindrical coordinates system **URL:** \ **Category:** Tips & Tricks\ **Created:** [June 20, 2025, 7:53am UTC](https://prepomax.discourse.group/t/stress-displacements-according-to-cylindrical-coordinates-system/2786 "2025-06-20T07:53:15Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![Paul18fr](https://avatars.discourse-cdn.com/v4/letter/p/35a633/32.png) [@Paul18fr](https://prepomax.discourse.group/u/Paul18fr)\ **Post date:** [June 20, 2025, 7:53am UTC](https://prepomax.discourse.group/t/stress-displacements-according-to-cylindrical-coordinates-system/2786/1 "2025-06-20T07:53:15Z")
Hi Once again i’ve tested how PrePomax is “user friendly”; even if i’ve no doubt about the accuracy of the interface, i wanted to test a well known test case: **a thick cylinder under pressure**. Equations for the radial/tangential stress are: ![Equation](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/2/2666871cffbda265cf4436af3eb74a56cf6840d9.png) Hand calculation using Excel: ![image_2025-06-20_093540928](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/e/e4bfaf2388824988e74f4e7421e36ee5ad78388b.png) 2 test cases have been modelled under PrePomax: 1. the cylinder axis coincides with the Z axis 2. the cylinder is rotated and its axis is different from Z accordingly For the 2nd test case, i noticed how **it’s very easy to create the local (cylindrical) coordinates** system using 3 nodes 😄 Obviously the results are identical in the 2 test cases and they follow the theory … once again it highlights how PrePomax is easy to use: congratulation for the Team 👍 Screenshots: Test 1: sigma\_rr ![test1_sigma_rr](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/d/da413278d18c50dd36344ea2d2281e2e37847fc6.png) test 1: sigma\_tt ![test1_sigma_tt](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/9/9e89242c46d9c35a98ee78fc9c13733fe61f00b5.png) test2: sigma\_rr ![test2_sigma_rr](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/3/36c3f1489666b458bf18bffc60b7e0eeef3dac04.png) test2: sigma\_tt ![test2_sigma_tt](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/e/e85032bf247f95c8dfdca6f82d157dfa6be80a87.png) Input files: [TubeQuarter.pmx](https://prepomax.discourse.group/uploads/short-url/twsPM7VYqnzHfKr3PAwva0xK9TP.pmx) (4.1 MB) [TubeQuarter2.pmx](https://prepomax.discourse.group/uploads/short-url/3hKRqAn9m15g7wisHlUcndeuFIe.pmx) (8.3 MB) ---
**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\ **Post date:** [June 20, 2025, 8:40am UTC](https://prepomax.discourse.group/t/stress-displacements-according-to-cylindrical-coordinates-system/2786/2 "2025-06-20T08:40:59Z")
I also verified it here: [![](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/4/465a81beed49613f454105d17565662aa9038e4f.jpeg "PrePoMax (CalculiX FEA) - Tutorial 47 - Thick pipe segment - local coordinate systems") ](https://www.youtube.com/watch?v=F9j0iEf3_4o)