CW1: Individual Assignment – Noise Vibration & Harshness

© 2019 Faculty of Engineering & Informatics
Automotive Tribology and Noise, Vibration & Harshness -B)

CW1: Individual Assignment – Noise Vibration & Harshness
1 Introduction
Noise, vibration and harshness (NVH) causes many refinement issues for the automotive industry,
therefore the ability to measure, model and analyse NVH problems is a desirable skill for automotive
engineers.
In this individual assignment you will demonstrate the use of both CAE and analysis techniques in
the analysis of noise, vibration & harshness (NVH), together with the experimental techniques that
have been demonstrated in the lecture sessions.
This report will contribute towards 50% of your coursework mark (i.e. 25% of the module).
2 Learning outcomes
Successful completion of this assignment enables you to demonstrate the following learning
outcomes of the module:
1. Critically evaluate vehicle component behaviour and the influence of tribology and NVH on
such systems.
2. Use CAE tools competently to design, simulate and critically analyse component behaviour.
3. Apply experimental techniques to analyse vibrating systems.
4. Present and interpret experimental and CAE results
5. Communicate effectively and manage your own learning.
3 Tasks
Automotive brake systems are susceptible to frictionally induced dynamic instabilities which can
result in brake squeal. Dynamic instability can be related to the coefficient of friction between the
brake pad and brake disc, with higher friction coefficients generally generating more instability. This
can be demonstrated theoretically whereby two mode pairs will combine at a bifurcation point and
will generate instability (Figure 1). You are to investigate mode-coupling phenomenon as a potential
mechanism for brake noise.
Figure 1: Graph showing the coupling of two unstable modes at various coefficients of friction

© 2019 Faculty of Engineering & Informatics
Automotive Tribology and Noise, Vibration & Harshness -B)

3.1 Identification of system parameters
You will be provided with a CAE model of the brake disc. Predict the free-free natural frequencies
using Finite Element analysis (FEA) and compare to the measured values that have been provided to
you. Investigate and explain any differences in the correlation between the predicted and measured
values. Using the experimentally measured modal analysis data, identify values for modal damping
and stiffness for the frequency peaks that are closest to your provided data.
To identify stiffness, you should assume that the entire component mass (m) vibrates at each natural
frequency
(

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