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Experimental Heat Transfer Study on the Shock Absorber Operation

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International Conference on Science &
Technology: Applications in Industry& Education (2008)
EXPERIMENTAL HEAT TRANSFER STUDY ON THE SHOCK
ABSORBER OPERATION
Mohd Shahrir Mohd. Sani, Erlifi Husin & Muhamad Mat Nor
Faculty of Mechanical Engineering Universiti Malaysia Pahang (UMP)
Tun Abdul Razak Highway 26300 Gambang Kuantan Pahang
e-mail: mshahrir@ump.edu.my, erlifi@ump.edu.my and Hmuhamad@ump.edu.my
phone: +609-5492209/+6013-3426076
0BAbstract. This paper focused on the experimental heat transfer study on the shock absorber operation. The
objective of this study is to analysis the heat transfer rate at surface absorber body. The shock absorber test rig
was developed to collect experimental data. This test rig also useful to test and indicates the condition of shock
absorber. A new and modify shock absorber twin tube type 1600cc will be used for this experiment. Ethanol and
water are using as alternative substance for damping fluid to improve the air gap between the internal and outside
body. Ten cycles of bounce and jounce shock absorber operation before heat transfer were measured. The
problem of overheating will be effect of damping fluid characteristics and decrease shock absorber performance.
However, using additive on damping fluid with water or ethanol will be good substance to improve heat transfer
inside the absorber. Ethanol as a substance can be increased heat transfer inside absorber up to 38%.
Furthermore, water has a higher thermal conductivity and increasing heat transfer rate better than ethanol; the
result shows that using the water can increased the rate of heat transfer up to 45%. Finally, additive with higher
thermal conductivity as the substance should give better heat transfer rate from inside absorber to surroundings.
Keywords: Heat Transfer, Shock Absorber, Damping Fluid, Water and Ethanol.
Introduction
An automotive suspension system is meant to provide safety and comfort for the occupants. Shock
absorber is an important part of automotive suspension system which has an effect on ride characteristics such as
ride comfort and driving safety. In every moving vehicle there must have a good suspension to absorb the shock of
the tires and wheels meeting bumps and holes in the road. The suspension system looks unnecessary to us but it
gives a great responsibility or doing an important job to give a safety ride. If there is no suspension install to the
vehicle, it will cause a great shock when the tire meets bad condition of the road and give some damage to the
component inside the vehicle. It also gives uncomfortable to the driver and passenger when the car is taking corner
or breaking.
One part of the suspension is the absorber. It is connected between the frame and suspension. Shock
absorbers may increase the ride-height which could affect the stability of the car and thus the safety. However, the
handling of some cars may even improve by using these shock absorbers. Thus the shock absorber can give results
in the best road holding, safety and comfort. Shock absorbers are also critical for tire to road contact which to
reduce the tendency of a tire to lift off the road [1]. This affects braking, steering, cornering and overall stability
[2]. The removal of the shock absorber from suspension can cause the vehicle bounce up and down. It is possible
for the vehicle to be driven, but if the suspension drops from the driving over a severe bump, the rear spring can
fall out [3].
The goal of the shock absorber is to dampen spring oscillation by converting the kinetic energy from
spring movement into heat energy [2]. In order to reduce spring oscillation, shock absorber absorbs energy. The
shock absorber absorbs different amounts of energy depending on how fast the suspension is moving. If high heat
inside the absorber occurs, it will heat the damping fluid. This will change the molecular structure and density of
fluid inside the absorber that cause it's damping capability to be decrease. In other words, shock absorber also
could be call as the energy converter.
Heat transfer occurs when there has a temperature different in a medium or between media. When a
temperature gradient exists in a stationary medium, which may be a solid or a fluid, the term conduction is use to
refer to the heat transfer that will occur across the medium [4]. Shock absorbers absorb shock on the road and
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International Conference on Science &
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change the kinetic energy into heat energy. The internal energy variation consists of one term of elastic energy
variation related to oil temperature [5]. Today’s shock absorber is either mono tube or double tube design. The
early style of shock absorber used friction to absorb the spring energy. Nowadays, modern shock absorber operate
hydraulically with one end is attached to the suspension and the other is attached to the frame. The hydraulically
shock absorber are basically oil pump that force the oil through the opening called orifice. This action generates
hydraulic friction, which convert kinetic energy to heat energy as it reduces unwanted motion [6]. The hydraulic
shock absorber can operate through many cycles without wearing because the internal friction is fluid friction. The
temperature of the working fluid in the liquid spring significantly alters the properties for working fluids, e.g. bulk
modulus and viscosity [7]. It is widely know that shock absorber characteristics vary with temperatures.[4]
Shock Absorber Test Rig
The design of shock absorber test rig has been developed for vibration measurement system. This
product actually developed to test and indicates the condition of shock absorber in automotive vehicle. As it
functioning, this product can be used as a tool to verify the capability of shock absorber. The Figure 1 shows the
complete of the design of shock absorber test rig.
This shock absorber test rig is a rigid structure with two main components connected vertical. The
upper vertical is the shock absorber while the lower connection to the base structure is the pneumatic cylinder. The
upper and lower component is divided by the middle plate. This middle plate is supported with two units of guide
shaft for smooth movement. The shaft holder is placed at each end of the guide shaft for protecting and secures the
guide shaft joints. The complete shock absorber test rig is system consist of a few important parts which are:
Shock absorber
Guide shaft
Linear guide bushes
Air cylinder
Air Regulator
Air pilot valve
Push Button
Accelerometer
Load Cell
Wire
Displacement
Sensor
Cylinder
Galvanized M16
Foot Mount Bottom
Plate
Regulator
Guide Shaft
Middle Plate
Linear Guide Bush
Shaft Holder Top Plate
Shock Absorber
Figure 1: The design of shock absorber test rig
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International Conference on Science &
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Result and Discussion
Result of Testing Aftermarket Shock Absorber (1st Design-Air Substance)
The testing of aftermarket shock absorber is started with getting the early absorber performance and
characteristic. Before the experiment is started, the room temperature and surface temperature of the absorber was
measured. The experiment is started to make 100 cycles of bounce and jounce for 10 times. Surface temperature
will be measure after the end of each experiment. The results are shown as follow:
Room temperature : 26.9 °C
Early temperature at the x (upper part) : 26.9 °C
Early temperature at the y (middle part) : 27.0 °C
Early temperature at the z (lower part) : 27.0 °C
Tab l e 1 : Arising temperature result for 1st design of absorber (air substance)
Exp. Cycle Temperature at x (C) Temperature at y (C) Temperature at z (C)
1 +100 26.9 27.0 27.0
2 +100 27.0 27.2 27.3
3 +100 27.1 27.3 27.5
4 +100 27.3 27.5 27.7
5 +100 27.6 27.8 28.0
6 +100 27.7 27.9 28.2
7 +100 27.8 28.3 28.6
8 +100 28.0 28.6 28.9
9 +100 28.4 28.9 29.2
10 +100 28.7 29.3 29.7
From the result above, the graph temperature against number of cycle can be plotted to show how the temperature
rising at the 3 part of the absorber.
(
g)
25.5
26
26.5
27
27.5
28
28.5
29
29.5
30
100 200 300 400 500 600 700 800 900 1000
Temperat ure a
t X
Temperat ure at Y
Temperat ure a
Number Of cycl
Temperat ure
°C
t Z
e
Figure 2: Graph temperature versus number of cycle for air substance
From the result and graph plotted above, it shows that the early temperature at the three places; upper,
middle and lower part is similar with the room temperature. The temperature for the three places on the surface
absorber is increases with number of cycle. This shows that the absorber is heated when it is operate. The lower
part at mark Z has a higher temperature rising between both the middle and upper part of the absorber that is 2.7 °C.
This is because the distance for the piston inside the absorber crossing at point Z is higher than at point X and Y.
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International Conference on Science &
Technology: Applications in Industry& Education (2008)
As the piston compress and expand to absorb the shock, it will give a force to the oil inside the absorber. The
friction force will occur at the piston surface and this friction force will transfer to heat energy around the surface
cylinder. The arising temperature at point X and Y is 1.8 °C and 2.3 °C for the total 1000 cycle of bounce and
jounce.
Calculation of Heat Flux :-
Heat Flux q x” = -K T/X …………………………………………………(1)
Where:
T = Temperature difference
X= Distance/ Thick of absorber body
K= Thermal Conductivity
At point X:
q x” = (-0.026 WM-1K-1) (-1.8K)/(0.02M) = U2.34 WM-2
At point Y:
q x” = (-0.026 WM-1K-1) (-2.3K)/(0.02M) = U2.99 WM-2
At point Z:
q x” = (-0.026 WM-1K-1) (-2.7K)/(0.02M) = U3.51 WM-2
Maximum heat flux for experiment using air substance is 3.51 WM-2
Result of 2nd Design of Shock Absorber: Using Ethanol As Substance
In order to modify and improve the heat transfer inside the absorber, an ethanol is use as a first
substance insert inside the absorber to fill the air gap between the internal cylinder (which contains piston and
damping fluid) and outside cylinder. The ethanol characteristic is shown as below:
Table 2: Properties of Ethanol
HMolecular formulaH C2H5OH
HMolar massH 46.06844(232) g/mol
Appearance Colorless clear liquid
HDensityH 0.789 g/cm³, liquid
Melting point 114.3 °C (158.8 K)
HBoiling pointH 78.4 °C (351.6 K)
HThermalH Conductivity 0.14 W/m K
Specific Heat Capacity 2.48 KJ/kgK
The room temperature and surface temperature of the absorber was measured in the beginning. The
experiment is started to make 100 cycles of bounce and jounce for 10 times. Surface temperature will be measure
after the end of each experiment. The results are shown as follow
Room temperature : 27.7 °C
Early temperature at the x (upper part) : 27.8 °C
Early temperature at the y (middle part) : 27.8 °C
Early temperature at the z (lower part) : 27.9 °C
Table 3: Arising temperature result for 2nd design of absorber (ethanol substance)
Exp. Cycle Temperature at x (C) Temperature at y (C) Temperature at z (C)
1 +100 28.0 28.0 28.3
2 +100 28.2 28.4 28.7
3 +100 28.5 28.7 29.0
4 +100 28.9 29.0 29.4
5 +100 29.3 29.5 29.8
6 +100 29.6 29.8 30.1
7 +100 29.9 30.2 30.5
8 +100 30.3 30.6 30.7
9 +100 30.5 30.8 31.0
10 +100 30.7 31.0 31.4
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International Conference on Science &
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(
g)
From the result above, the graph temperature against number of cycle can be plotted to show how the temperature
rising at the 3 part of the absorber.
26
27
28
29
30
31
32
100 200 300 400 500 600 700 800 900 1000
Temperature at X
Temperature at Y
Temperature at Z
Temperat ure
°C
Number Of cycle
Figure 3: Graph temperature versus number of cycle for ethanol substance
The temperature for the three places on the surface absorber is increases rapidly with number of cycle.
This shows that the heat inside the absorber is transfer out of the absorber very well. The lower part at mark Z has
a higher temperature rising between both the middle and upper part of the absorber that is 3.5 °C due to high
friction force occur at this area. The arising temperature at point X and Y is 2.9 °C and 3.2 °C for the total 1000
cycle of bounce and jounce. This shows that using ethanol as substance at the middle between internal and outside
cylinder has increase the rate of heat transfer from inside absorber through surrounding.
Calculation of Heat Flux:-
At point X: q x” = (-0.14 WM-1K-1) U(-2.9K)U (0.02M) = U20.3 WM-2
At point Y: q x” = (-0.14 WM-1K-1) U(-3.2K)U (0.02M) = U22.4 WM-2
At point Z:q x” = (-0.14 WM-1K-1) U(-3.5K)U (0.02M) = U24.5 WM-2
Maximum heat flux for experiment using ethanol is 24.5 WM-2
Result of 3rd Design of Shock Absorber: Using Water As Substance
After testing the absorber using ethanol, modification is continue by using water as substance. Water is
filling between the inside and outside cylinder. The characteristic of water is shown as below:
Table 4: Properties of Water
HMolecular formulaH H2O
HMolar massH 18.0153 g/mol
HDensityH and Phase 0.998g/cm³ (liquid at 20 °C) 0.92 g/cm³ (solid)
Melting point 0 HU°CUH (273.15 HUKUH) (32 HU°FUH)
HBoiling pointH 100 °C (373.15 K) (212 °F)
HThermalH Conductivity 0.67 W/m K
Specific Heat Capacity 4.184 KJ/kgK
The room temperature and surface temperature of the absorber was measured before starting 100 cycles
of bounce and jounce for 10 times. Surface temperature will be measure after the end of each experiment. The
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International Conference on Science &
Technology: Applications in Industry& Education (2008)
results are shown as follow:
Room temperature : 26.2 °C
Early temperature at the x (upper part) : 26.2 °C
Early temperature at the y (middle part) : 26.3 °C
Early temperature at the z (lower part) : 26.3 °C
Table 5: Arising temperature result for 3rd design of absorber (water substance)
Exp. Cycle Temperature at x (C) Temperature at y (C) Temperature at z (C)
1 +100 26.4 26.5 26.5
2 +100 26.8 26.9 27.0
3 +100 27.2 27.4 27.6
4 +100 27.6 28.0 28.2
5 +100 27.9 28.3 28.6
6 +100 28.3 28.5 28.9
7 +100 28.8 28.9 29.2
8 +100 29.0 29.3 29.4
9 +100 29.4 29.6 29.9
10 +100 29.5 29.8 30.4
g)
24
25
26
27
28
29
30
31
100 200 300 400 500 600 700 800 900 1000
Temperat ure at X
Temperat ure at Y
Temperat ure at Z
Temperat ure
°C
Number Of cycle
From the result above, the graph temperature against number of cycle can be plotted to show how the
temperature rising at the 3 part of the absorber.
Figure 4 : Graph temperature versus number of cycle for water substance
The temperature for the three places on the surface absorber is increases rapidly with number of cycle.
This shows that the heat inside the absorber is transfer out of the absorber very well similar with the result for air
and ethanol substance. The lower part at mark Z has a higher temperature rising between both the middle and
upper part of the absorber that is 4.1 °C due to high friction force occur at this area. The arising temperature at
point X and Y is 3.3 °C and 3.5 °C for the total 1000 cycle of bounce and jounce. This shows that using water give
a better result than using ethanol. From the graph, it is shows that the rate of heat transfer using water is higher
than ethanol and air substance.
Calculation of Heat Flux :-
At point X: q x” = (-0.67 WM-1K-1) U(-3.3K)U (0.02M) = U110.55 WM-2
At point Y: q x” = (-0.67 WM-1K-1) U(-3.5K)U (0.02M) = U117.25 WM-2
At point Z: q x” = (-0.67 WM-1K-1) U(-4.1K)U (0.02M) = U137.35 WM-2
Maximum heat flux for experiment using water is 137.35 WM-2
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International Conference on Science &
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765
From the analysis of shock absorber result for 1st, 2nd and 3rd design, the obvious difference of increasing
temperature at surface body of the absorber become a major parameter in this analysis. Based on the result that is
obtained from the experimental, the temperature rising for the modify design is better than the aftermarket design.
These values can be explained in percentage of difference. From the calculation based on the data that has been
gathered from the experimental, the percentages of difference between modify design using ethanol as the
substance and aftermarket design that contain the air gap inside the shock absorber 1600cc without spring in term
of arising temperature at point Z is 22.86%. Meanwhile, for the arising temperature at point Y, the percentage of
difference is 28.13%. For the arising temperature at point X, the percentage of difference is 37.93%. The
percentage of difference between the modify design using water as the substance and aftermarket design shock
absorber 1600cc without spring in term of arising temperature at point Z is 34.15%. Meanwhile, for the arising
temperature at point Y, the percentage of difference is 34.29%. For the arising temperature at point X, the
percentage of difference is 45.45%. From the experimental and analysis, it is obviously shows that the arising
temperature for modify design is much better than the aftermarket design. This is because the ethanol and water
has a high thermal conductivity than the air. The ethanol and water help transfer the heat inside the absorber
through the outside body proportionate with air. This experiment also proof that the higher value of thermal
conductivity can give a better heat transfer through the substance. The ethanol has a higher thermal conductivity
than the air but has a lower thermal conductivity comparing with water. Using water as the substance to fill the air
gap inside the absorber can give a more improvement to the absorber. The higher temperature rising at the surface
body of the absorber gives higher advantage to the absorber. This is because the temperature is transfer out of the
absorber and prevents the damping fluid inside the absorber from being heated. This can save the damping fluid
from changing its properties and the performance of the absorber can still maintain although being use for a long
time
Conclusion
The purpose of this project is to test and modify the absorber using the different working fluids. As the
absorber operates, it will become heated. If the heat cannot be transfer very well through the surrounding, it will
heated the damping fluid inside the absorber thus changes the damping fluid characteristic and decreasing the
absorber performance. In order to overcome this problem, a substance that has a high thermal conductivity must
be added inside the absorber. Many existence absorbers have an air gap between the internal cylinder and outside
body of the absorber. The air has a lower thermal conductivity which is a poor substance to transfer an amount of
heat. Using ethanol as a substance can improve the heat transfer inside the absorber up to 38%. However, using
water can give better result than the ethanol, increasing the rate of heat transfer up to 45%. This is because water
has a higher thermal conductivity than ethanol. This shows that water is a good substance to improve the heat
transfer inside the absorber and the absorber will have a long time usage.
Acknowledgement
The authors would like to express their thanks to the Universiti Malaysia Pahang for funding this project.
References
[1] Don Knowles. Today’s Technician: Automotive Suspension & Steering System, Shop manual, 3rd Edition. Cliftorn Park,
NY: Delmar Learning, 2003.
[2] Tim Gilles. Automotive Chassis: Brake, Steering & Suspension, 2005
[3] Thomas W. Birch. Automotive Suspension & Steering System, 3rd Edition, 1999.
[4] Incropera,Dewitt,Bergman and Lavine. Introduction to Heat Transfer, Wiley 5th Edition, 2007
[5] J.C.Ramos, A.Rivas, J. Biera, G. Sacramento and J.A.Sala. Development of a Thermal Model for Automotive Twin-Tube
Schock Absorbers. Journal Applied Thermal Engineering 25(2005) 1836-1853
[6] W. Schiehlen and B. Hu. Spectral Simulation and Shock Absorber Identification, International Journal of Non-Linear
Mechanics. Volume 38, Issue 2, March 2003, Pages 161-171
[7] A.K. Smantaray. Modeling and Analysis of Preloaded Liquid Spring/Damper Shock Absorbers
... The potential overheating of the composite needs to be taken into account in the application design. However, when designing shock and vibration dampeners the working temperature needs to be taken into account usually as well, since increased temperatures can effect even fluid based dampeners [26]. A reasonable working temperature range for the composite to achieve the highest vibration damping potential is from the glass transition temperature of 18.2 C to the A T temperature, which is the middle point for the austenite transformation, since the austenite transformation temperature is the highest temperature where the composites damping can be controlled with the magnetic field. ...
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Today's Technician: Automotive Suspension & Steering System
  • Don Knowles
Don Knowles. Today's Technician: Automotive Suspension & Steering System, Shop manual, 3 rd Edition. Cliftorn Park, NY: Delmar Learning, 2003.
Automotive Chassis: Brake, Steering & Suspension
  • Tim Gilles
Tim Gilles. Automotive Chassis: Brake, Steering & Suspension, 2005
Introduction to Heat Transfer
  • Dewitt Incropera
  • Lavine Bergman
Incropera,Dewitt,Bergman and Lavine. Introduction to Heat Transfer, Wiley 5 th Edition, 2007
Automotive Suspension & Steering System, 3 rd Edition
  • Thomas W Birch
Thomas W. Birch. Automotive Suspension & Steering System, 3 rd Edition, 1999.
Modeling and Analysis of Preloaded Liquid Spring/Damper Shock Absorbers
  • A K Smantaray
A.K. Smantaray. Modeling and Analysis of Preloaded Liquid Spring/Damper Shock Absorbers