# Convergence of crown gear pair contact

**URL:** <https://prepomax.discourse.group/t/convergence-of-crown-gear-pair-contact/1588>\
**Category:** General Questions\
**Created:** [March 8, 2024, 1:36pm UTC](https://prepomax.discourse.group/t/convergence-of-crown-gear-pair-contact/1588 "2024-03-08T13:36:44Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Sandor\_28](https://avatars.discourse-cdn.com/v4/letter/s/7bcc69/32.png) [@Sandor\_28](https://prepomax.discourse.group/u/Sandor_28)\
**Post date:** [March 8, 2024, 1:36pm UTC](https://prepomax.discourse.group/t/convergence-of-crown-gear-pair-contact/1588/1 "2024-03-08T13:36:44Z")

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Esteemed Users,  
I run a tooth root stress analysis of a crown gear pair. Driver is the steel pinion, driven is the POM gear.

 ![Crown_Gear_FE_Model_1](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/0/039fe3023e7dac3b2ec7aa8cb85a9fe08b85515c.jpeg)  
The contact does not converge unless I added a small spring to the pinion to generate a counter torque to the load torque. The influence of the spring is neglectable, since the displacement is very small. The result is creditable.  
 ![Crown_Gear_Prin_Max_1](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/4/4802bf7ecfb3b6cefdce6919da8583ac1159fa80.jpeg)  
The default amplitude was used.

Sandor

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**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:** [March 8, 2024, 1:42pm UTC](https://prepomax.discourse.group/t/convergence-of-crown-gear-pair-contact/1588/2 "2024-03-08T13:42:51Z")

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Check this thread: [Zero reaction moment when reading from ROT NODE in 2D - CalculiX (official versions are on www.calculix.de, the official GitHub repository is at https://github.com/Dhondtguido/CalculiX).](https://calculix.discourse.group/t/zero-reaction-moment-when-reading-from-rot-node-in-2d/1312)

Such an approach with soft springs or dashpots isn’t uncommon and may often be utilized in analyses of mechanisms. You could also try running a dynamic analysis: [Bevel gear dynamic simulation](https://prepomax.discourse.group/t/bevel-gear-dynamic-simulation/1433)

Or use prescribed rotation BC instead of torque. Or use an additional step with such a BC to establish contact and then follow it with a step applying the actual loading. There are several approaches here.