# SAE Update - February 2021 - 6

SAE NEWS

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Transient Heat Transfer Simulation and Buckling Analysis of Disc Brake in In-wheel
Motor Driven Vehicle
Kingsford Koranteng, Joseph-shaahu Shaahu, Yun-Bo Yi
Department of Mechanical and Materials Engineering, University of Denver, Denver 80208, Colorado, USA

Methodology (Cont'd)

Introduction

ANALYTICAL MODELING
There are increasing demands and research on in-wheel motor- ❑ The eigenvalue is used to estimate the critical thermal
The heat flux on one side of a single rotor for a single front wheel can
driven vehicles for both hybrid and fully electric vehicles due to
buckling temperatures during braking. A linear
2
be computed as: q(r, t) = Qሶ in = γ. ff . v(t) = (0.59) 1 (0.5)γ( MR αt r(ωo + αt t)) [1]
several advantages provided by this technology [1]. The
perturbation procedure was used in this analysis.
40re Ap
4
innovation makes it easier to develop simple intelligent brakes ❑ A coupled temperature-displacement analysis using
The equilibrium equation for the heat generated was expressed as:
with an appropriate control strategy for the anti-lock brake system
ABAQUS dynamic temp-disp explicit scheme was used to
dT
= Qሶ in − Qሶ out
[2]
Cp . md .
and it has the potential to create an all-wheel-drive [2]. In this
dt
determine the influence of the pad contact geometry on the
work, a 10x10 in-wheel motor-driven vehicle with its brake system
The
expression
to
compute
the change in temperature was
disc brake by maintaining the same friction work.
mounted within the wheels is considered. Due to the enclosed
given as:
dT
K A T
hA T
=− d d s− s s+
Cp md
Cp md
dt
nature of the brake system, there is an issue with temperature
[3]
1
MR2 α
(0.59)4(0.5)γ(40r Apr(ωo +αt t))+Kd Ad Ta +hAs Ta
distributions in the disc brake, which have several negative effects
e
Cp md
Fig. 3 3-D mesh of the brake disc and pads
on braking performance. A high rise in temperature may lead to
thermal buckling and hot spots which may onset thermoelastic
Results
instability. Numerical analysis is conducted to investigate the
variation of temperature field in such a disc by considering
S8
S9
different contact geometry of the brake pads on the disc during
S1
P1
P7
P8
braking while maintaining the same moment of friction, by using a
transient modeling approach. The effect of the resulting Fig. 4 Variation of temperature field on the disc for pads cover angles of 20ºC, 30ºC, 90ºC
Fig. 8 Variation of temperature field on disc for pad position P1, P7 and P8
temperature distribution on thermal buckling of the disc is
and 100ºC
investigated.

Objective

❑Investigate the effect of different pad cover angles on
temperature field distribution in the disc brake given the same
friction work.
❑Investigate the influence of pad positions on temperature field
distribution in the brake disc given the same friction work.
❑Examine the effect of the resulting temperature field distribution
on thermal buckling of the brake disc.

Fig. 5 Distribution of temperature along the

Fig. 6 Temperature distribution through
the disc rotor at 30°C pad cover angle

Fig. 9 Variation of maximum temperature with
time at different cover angles of the pads

BUCKLING ANALYSIS

Fig. 10 Distribution of temperature along the
radial of the disc for different cover angles of

Methodology

❑ The discs were labelled S1 to S9 with corresponding pad cover
angles (
https://www.sae.org/attend/brake/ https://www.sae.org/attend/brake/

# SAE Update - February 2021

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