# Simcenter 3D Solutions Motion transmission frequency analysis with discrete and continuous speed sweep driver

2022-03-17T16:23:19.000-0400
Simcenter 3D

## Summary

Simcenter 3D Motion Best Practice and How to for frequency analysis of transmission. The scope is for identifying critical shaft speeds with according vibration levels. Learn how to apply discrete and continuous sweep driver in time domain for obtaining accurate FFT results along waterfall of time plots (also called Campbell diagram). Application on a practical model example with Gear and Bearing in a casing Flexible Body. Simcenter 3D version 2021.1 and up.

## Details

 Attachments:
A full detailed document is attached with this article along a demonstration model in version 2021.1

Summary and Conclusion

This document is addressed to Simcenter 3D Motion users working on system including gears transmission for vibration analysis before eventual acoustic simulation for noise and signature. It includes FFT theory reminders and a practical example workflow comparing waterfall (Campbell) plot results on a demonstration model. The end scope if for identifying critical shaft rotation speeds and the according vibration levels.
This model is a simple transmission with 2 gears on 2 shafts connected via bearings to a housing made flexible. This model is available for download.

Table of content of the PDF document (extract)
1.      Scope
2.      Summary and Conclusion
3.      Theory FFT (Reminder)
4.      Simcenter 3D Documentation
5.      Example Hands-on
5.1 Discrete Sweep 1000-5000 RPM, increment 1000 RPM; Motion solver CPU 1415 sec
Model and Load Pre-processing (FFT) of the Discrete sweep results – CPU 11 sec
5.2 Continuous Sweep 1000-5000 RPM (10,100) Print 0.1 ms; Motion Solver CPU 1484 sec
Model and Load Pre-processing for this 1st continuous sweep results - CPU 5 sec
We need to increase the sampling rate. A better solution should use a print of 0.02 ms (or less) instead of 0.1 ms.
5.3 Continuous sweep 1000-5000 RPM (20,200) Print 0.02 ms; Motion Solver CPU 3128 sec
Model and Load Pre-processing for this 2nd continuous sweep results (FFT) - CPU= 450 sec
6.     Conclusion when comparing Discrete sweep with Continuous sweep driver solutions

Demonstration model and results (extract)

Picture of the demonstration model provided

Waterfall color map results for a radial force reaction at a shaft bearing

Waterfall plot of a shaft radial acceleration

Data files
Simcenter3DMotion_Waterfall_Best_Practice_Sine_Sweep_v3.pdf
Simcenter3DMotion_Waterfall_Best_Practice_Sine_Sweep_v3.7z

SummaryDetails

### Associated Components

Acoustics Additive Manufacturing Assembly FEM Correlation and Updating Durability Electromagnetics (High Frequency) Electromagnetics (Low Frequency) Flexible Pipe Laminate Composites Margin of Safety Motion Multiphysics NX Open Nonlinear Optimization Pre/Post Response Dynamics Rotor Dynamics Samcef Environment Simulation Process Management Thermal / Flow