I have a research article that describes the simulation of a spring. I believe I am reproducing their model and study correctly but please have a look (paper attcahed). A negative Jacobian keeps occurring:

**Numerical difficulties. (Solver failed because of negative Jacobian). Please investigate the mesh.**

Attached is my latest attempt. Note that the paper is successful at simulations with larger rotational displacements like 0.05 and 0.1 radians than the one I attached with 0.025 radians. What did i not understand about this paper or how to set up the model or simulation?. BTW, it's my first time running a simulation, please give a detailed enough response. Thank you.

Hi Mark,

The study you have appears to be unstable due to a small cylindrical body at the center of the spring. I didn't see it attached to the other body in any way so I excluded it from the analysis, redefined the On Cylindrical Face fixture (it was broken when the small cylinder was excluded), then ran the analysis. It seemed to then solve to completion: