Modified model for CPU speed-up

A solution to speeding up the solving time consists in setting a better damper rating in the spring and in the gap model. Remember that they were previously deliberately set to zero. A value of 50 N/(m/s) in the spring and damper and in the gap will give a 3.2 % damping ratio for the highest frequency. Results with this setting are shown below.

Figure 19: Performance Analyzer Run statistics after damping modification

The CPU time is 2.53 seconds against 3.14 seconds previously. We can see that the minimum integration step does not step down anymore and the number of discontinuities has been greatly reduced.

Figure 20: Performance Analyzer Frequencies after damping modification

Here we see that the 1233 Hz mode is now lightly damped and colored with a green tag. The consequences are visible in the time plots of displacement, velocity and acceleration of the masses shown below.

Figure 21: Displacements velocities and accelerations after modification

Top: left-hand mass Bottom: right-hand mass

Even though this model was made to amplify the issue, this type of under-damped natural mode is fairly common in models and should be looked for using the general methodology described so far.

Note

Always check following items:

• number of discontinuities,

• undamped oscillatory modes with a high frequency, look for orange and red eigenvalues in the frequencies list,

• change of CPU time slope,

• sudden decrease of minimum integration step.

In the next part of this manual you will learn more about all the information given by the Performance Analyzer.