NVH Gear Whine Analysis...Gear Whine Analysis Select the “High Speed ruising” Load ase and go to the Editor tab This page provides the options for setting up the analysis You can

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NVH – Gear Whine Analysis

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What is Gear Whine?

➢ Gear Whine is a noise phenomenon in transmissions caused by the excitation of the system by Transmission Error at the gear meshes

Slide 2www.smartmt.com © 2018 SMART MANUFACTURING TECHNOLOGY LTD.

NVH Mode


Properties Grid

Load Cases Control

NVH Mode

Results Area

Status Area

Modal Analysis

➢ First we will run a modal analysis

➢ A modal analysis calculates natural frequencies and mode shapes

➢ These are dynamic characteristics of the system independent of a forcing function

➢ Select “Coupled Modal Analysis” in the drop down below the properties grid


Modal Analysis

➢ Select the “High Speed Cruising” Load Case and click the run button to run the analysis


Natural Frequencies


Mode Shapes


View the shafts as solid

Set to view the Linear Displacement as a contour

Select a mode shape to view

Scale the deflections in the view

Animate the mode shape

Mode Shape – Mode 11


Look at some modes which will be of interest when we run the gear whine analysis.

Mode 11 (1.7869 KHz) shows significant kinetic energy in the intermediate shaft and lots of motion at the gear meshes

Mode Shape – Mode 17


Mode 17 (2.6151 KHz) similarly shows significant kinetic energy in the intermediate shaft and lots of motion at the gear meshes

Gear Whine Analysis

➢ Next we will run a gear whine analysis

➢ A gear whine analysis calculates the forced dynamic response of the system model to excitation by Transmission Error at the gear meshes

➢ Select “Gear Whine/Harmonic Excitation Analysis” in the drop down above the Load Cases Control


Gear Whine Analysis

➢ Select the “High Speed Cruising” Load Case and go to the Editor tab

➢ This page provides the options for setting up the analysis

➢ You can leave them all as default but makesure the harmonic excitation type for eachgear set is “Basic LTCA”

➢ This performs a basic LTCA in Micro Geometrymode for each gear set and uses the TE calculated in there as an input into the gear whine analysis

➢ Click run in the load cases control


Gear Whine Analysis


➢ In a gear whine analysis usually the results of interest are on the housing on either▪ The housing surface – Leading to

airborne noise

▪ The housing mounts – Leading to structure borne noise

➢ We have no housing in this MASTA model

➢ We shall look at the response on the left bearing on the intermediate shaft.

Select this bearing

Gear Whine Analysis – Dynamic Response


➢ The Dynamic Response Tab shows the response at this bearing to the transmission error excitations

➢ Set all the chart settings as in the image



➢ We want to look at the linear magnitude of the acceleration at the inner of the bearing

➢ Set the options in the “Results Options” tab as in the image



➢ The Waterfall chart shows the dynamic response as the motor runs up in speed from 0 –11600 rpm

➢ The diagonal lines correspond to the frequency of the gear mesh tooth passing order and its harmonics as the motor speed varies

➢ Hovering the mouse over the diagonal lines tells you which harmonic they correspond toSecond harmonic of

the 2nd gear stageFirst harmonic of the 2nd gear stage



➢ Vertical lines show the natural frequencies

➢ Peaks in response occur at natural frequencies of the system, where excitations frequencies correspond with resonant frequencies

➢ Hovering the mouse over the vertical lines tells you which mode they correspond to

Mode 17 (2.6151 KHz) Mode 11 (1.7869 KHz)



As we saw when we looked at the mode shapes these modes have:• Significant movement at the gear meshes – So can be excited by TE• Significant strain energy in Intermediate Left Bearing where we are looking at the response

Mode 17 (2.6151 KHz)

Mode 11 (1.7869 KHz)

Next task…

➢ Please now work through the document:

9.Parametric Study

➢ The next slide in this document contains some additional tasks you might want to attempt after completing all the other tutorials


Some additional tasks

1. If you have done the Cylindrical Gear Micro Geometry section change the Micro Geometry Design being used and investigate the effect of transmission error on the Gear Whine Analysis results.

2. Investigate changing the bearings on the intermediate shaft and/or the shaft design and see how it affects the resulting response.


Documents

NVH Gear Whine Analysis...Gear Whine Analysis Select the “High Speed ruising” Load ase and go to the Editor tab This page provides the options for setting up the analysis You can