Brake Noise Simulation using Multibody Simulation Analysis

2014 European Altair Technology Conference

June 24-26, 2014 | Munich, Germany

Join, Contribute, Exchange Brake Noise Simulation

using Multi-Body Simulation Analysis

Dr. Armin Veitl

Benjamin Leblanc

See full agenda: www.altairhtc.com/europe

Copyright © 2012 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved. Copyright © 2012 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.

Agenda

• Motivation

• Self excited system

• Tribology effects

• Contact modeling

• Model build-up

• Simulation setting with a driving rotation

• Results & discussion

• Planed enhancements


Motivation

• The level of noise heard within a vehicle’s interior can drastically impact

a passenger’s comfort. Brake noises can give the customer a poor

impression of product quality. Within the C.A.E. industry, the study of

mode coupling instability by the use of F.E.M. and modal complex

analysis, is widespread to reduce those phenomenon.

• An complementary method is presented in this paper where brake noise

issues are predicted by the use of a time transient integration using

multi-body system analysis


Brake - Vibration and Noise

Judder

Moan

Groan

Low Frequency

Squealing

High Frequency

Squealing

10 100 500 1k 3-4k 10k

Type o

f oscill

ation

forc

ed

s

elf-e

xcited

Frequency [Hz]

Low frequency Effects

High frequency

Effects

Usual application

field for MBD

Domain that we

intend to cover


Brake - Vibration and Noise

Brake Squeal Issue

CAE model – CAE Labor

Differential Equation of motion

Linearization and Instability

Analysis

Frequency Domain

Results:

Frequency of instability

complex mode shape

Integration of the differential

equation system

Time Domain

Results:

Analyze by Fourier in frequency

domain

time shape animation

Problem Identification /

Engineering a solution


Self excited system

• Phenomena that leads from

a steady state to an

oscillatory state without

external oscillatory excitation

• Comparison to aero-elasticity

“Limit Cycle Oscillations (LCO)” Excitation system pad ↔ disc (stick-slip effect)

Resonant system suspension

Input: - vehicle speed - brake pressure - friction law

Output: - resonance phenomena - brake noise

Feedback loop: - suspension vibration

self-excited system

LCO pictures source: Wind tunnel analysis of separated aerodynamcis leading to different types of torsional flutter in bluff-bodies,

T. Andrianne – Université of Liège

Animation Gif source: AcuSolve Example – Altair Engineering

constant flow

section from a beam


Tribology effects

• Tribology is the science of interacting surfaces in relative motion

pictures source: Thèse: Apport des analyses numériques temporelle et fréquentuelle dans l´étude des instabilités de contact, A.Meziane

Animation Gif source: Arnol'd tongues arising from a grazing-sliding bifurcation of a piecewise-smooth system, Szalai, R; Osinga, HM, University of Bristol

self-oscillations that appears due to contact can be

classified in 2 categories:

• stick-slip vibration

• quasi-harmonic vibration

stick-slip vibration

quasi-harmonic vibration

Normal force on pad

Friction force on pad

friction law example

Ft = µ(v).Fn


Contact modeling

• Friction Law

• Flexibility of the disk

• Flexible surface:

• a marker can slide along the whole

surface

• surface deformation is interpolated

between reference points

• A modal basis provides the stiffness of

the surface. Static correction modes

are not required for the surface

• Static correction modes only used for

the connection to the strut

…

mode 7

mode 8

mode 9

mode 10

mode 11

mode 12


Contact modeling

• Friction Law

• Flexibility of the disk

• User-Subroutine

• Compute normal force at contact point

• Compute friction force at this point

Python Script: no compilation required

Call of the User-Subroutine in MotionSolve


Model build-up

Mac-pherson axle system

Strut idealized as one flexible body

control arm

as one flexible body

…

… toe link modeled with a poly-beam

connected with a ball and a constant

velocity joints

All bushings parameterized with

a dataset


Model build-up

floating brake caliper system

Brake caliper as flexible body

Brake bracket as flexible body

…

…

Brake piston as a rigid body

Brake pads as flexible too

Disk and hub as one flexible body

and

modeled with deformable surface

as shown on a previous slide


Simulation setting with a driving rotation

• Virtual actuator

• 2 degree of freedom

• Impose rotation

• Constant velocity

• 2 [km/h]

• brake disk free to move

in other directions

• Brake pressure

• Constant 20 [bar]

• Simulation settings

• Transient : 2 [sec]

• Integrator : DSTIFF

constant velocity joint

constant velocity joint

revolute joint attached to GROUND

motion boundary condition

translational joint attached to DISK

Body 1

Body 2

Body 3


The model in HyperWorks

model database structured with a browser

All contact instance included in is own system

Dataset to manage input parameter

Axle and Brake separated into 2 systems to enable easy model update

Virtual system to rotate wheel

GUI entry to manage simulation variants


Results & discussion

• Relative speed at contact

point between pad and

disk surface

• Stick-slip characteristic

• increasing area until

constant amplitude

• Stick area

• Slip area

• “quasi-harmonique”

ST

ICK

ST

ICK

ST

ICK

SL

IP

SL

IP

SL

IP

SL

IP

transition



Results animation : friction directions are changing when system start vibrating

the displayed forces are applied on pad



Results animation : friction directions are changing over time, but system behaves quasi-harmonic

the displayed forces are applied on pad



• Acceleration time history can be filtered by Fourier and displayed in water fall

diagram in a frequency range from [0 – 4000 Hz]

• Critical frequencies appear in the diagram and can be compared to component

normal frequency or complex modes 1 3 2



Results animation : scale 500 in deformation, deformation shapes can be compared to normal modes

or to complex modes analysis



• Brake Noise Simulation: Resume of the CAE-Knowledge

• Finite element modal complex

• Multi-body

FFT‘s

1



• Brake Noise Simulation: Resume of the CAE-Knowledge

• Finite element modal complex

• Multi-body

Instable mode animation with FE modal

complex (Frequency domain)

Time animation with Multi-body Simulation

1


Process Implementation

pictures source: http://www.ganttproject.biz

GanttProject is a cross-platform desktop tool for project scheduling and management.

• Implementation in vehicle development

• build on existing CAE information: no double effort to invest

• win twice more information on the same project

• CAE tasks can be performed in parallel and validate each other

• increase CAE predictivity / reporting value from CAE Labor

http://www.ganttproject.biz/

http://www.ganttproject.biz/



• Summary

• multi-body simulation method enable self excited system simulation

• “Stick-Slip” characteristics clearly shown

• frequency responses appear in the expected range [0Hz – 4000 Hz]

• the method matured for vehicle development

• enable comparison with modal complex analyze / reciprocal validation of CAE

• Planed enhancements

• Post-processing tools to more easily identify the critical peak

• Automation to enable better model build-up