It is common for parts to be held together only by contact. In such cases it is hard to solve a nonlinear problem accurately due to theoretical limitations of the singular stiffness matrix when rigid body modes are not constrained. Many options are available to solve this class of problems. Each method has it’s own advantages and disadvantages.
Comparing the computational effort and accuracy of the different stabilization methods used for this particular coil spring example, the following hints and recommendations may be considered:
The quasi-static simulation (TINTP,QUAS) works well with minimal user intervention.
In a pure static solve, both contact damping and global nonlinear stabilization can help achieve correct results. However, both require you to specify the amount of damping. Program defaults work for most cases, but if they do not work you must adjust the damping to make the solution converge.
When weak springs are used in a static analysis, the analysis requires significantly more iterations than other methods.
Always check the ratio of kinetic, artificial/stabilization energy with the total strain energy of the model to verify the quality of the results.
For parts held together only by contact, Ansys, Inc. recommends you model the surfaces as frictional wherever possible. Frictional stress helps prevent rigid body motion in the contact tangential directions, making the problem more stable.
In general, there is no way to predict which stabilization method will work the best when solving a model held together only by contact. Ansys, Inc. recommends you attempt a quasi-static simulation first. If dynamics are of concern or the quasi-static simulation fails, then try using global nonlinear stabilization or contact stabilization damping.