Vibration Analysis of Composite Leaf Spring for a Light ...
Transcript of Vibration Analysis of Composite Leaf Spring for a Light ...
International Journal of Scientific Engineering and Technology (ISSN : 2277-1581)
Volume No.3 Issue No.7, pp : 871-875 1 July 2014
IJSET@2014 Page 871
Vibration Analysis of Composite Leaf Spring for a Light Commercial Vehicle
(TATA ACE)
Manjunath H.N1, Manjunath.K
2, T.Rangaswamy
3
1M.Tech Student, Dept. of Mechanical Engineering, Govt. Engineering College, Hassan 2
Asst.Professor, Dept. of Mechanical Engineering, Govt. Engineering College, Hassan 3Professor and Head, Dept. of Mechanical Engineering, Govt. Engineering College, Hassan
Abstract— Vibration analysis plays a very important role in
the design of composite leaf spring, since the failure due to
vibration is more prominent rather than material failure. In
this research work an attempt has been made to predict the
vibration behavior of leaf spring under dynamic forces and to
check the suitability of composite materials like E-
Glass/Epoxy, Graphite/Epoxy, Boron/Aluminum,
Carbon/Epoxy and Kevlar/Epoxy for light commercial vehicle
leaf spring. First the modal analysis is performed to determine
the eigen values (natural frequencies) and mode shapes (eigen
vectors), Harmonic analysis is carried out to determine the
amplitude of response and random vibration analysis is
carried out for smooth and rough road excitations using FE
solver ANSYS V10. Obtained results show that
Boron/Aluminum is best suitable composite material for leaf
spring from vibration point of view.
Keywords—leaf spring, composite, Conventional steel leaf
spring
I. Introduction
Composite materials consist of two or more physically
dissimilar and instinctively separable components called
reinforcement and matrix. These two components can be mixed
in a restricted way to achieve optimum properties, which are
superior to the properties of each individual component.
Composite materials have been widely used in automobile
industry because of its high strength and modulus to weight
ratio, low cost and flexibility in material and structure design.
The suspension leaf spring is one of the potential items for
weight reduction in automobile as it accounts for ten to twenty
percent of the unsprung weight. This helps in achieving the
vehicle with improved riding qualities. Since the strain energy
in the spring is inversely proportional to density and young’s
modulus of the material, it is always suggested that the material
for leaf spring must have low density and modulus of elasticity.
Many research have been carried out in the direction to replace
conventional steel leaf spring by composites. Ramamurti et al.
[13], (1990), have studied bus body vibration and also compared
theoretical and experimental response acceleration and stress
using random vibration concepts. Karuppaiah et al. [12] (2002),
have conducted vibration analysis of a light passenger vehicle
using a half car rigid body model and a finite element model.
The power spectral densities of acceleration of road sections
measured were fed as input load and the dynamic response of
the vehicle was computed in frequency domain using finite
element models and random vibration concept. Manjunath [14]
(2002) has carried out random vibration analysis of a bus body
structure using FEM. Rangaswamy et al. [15] (2005), have
proposed a design methodology for drive shaft of passenger
vehicles by considering torsional transmission capability,
bending natural frequency and buckling torque as design
constraints and number of plys, stacking sequence and thickness
of the play as design variables. Shiva Shankar and Vijayarangan
[5] (2006) have designed, fabricated (hand- lay up technique)
and tested of a single leaf with variable thickness and width for
constant cross sectional area of unidirectional glass fiber
reinforced plastic (GFRP). Senthil Kumar and Vijayarangan [6]
(2007) have carried out design and experimental fatigue
analysis of composite multi leaf spring using data analysis.
Patunkar and Dolas [8] (2011) have carried out modeling and
analysis of composite mono GFRP leaf spring. Shishay [1]
(2012) has designed and simulated a single E-glass/Epoxy leaf
spring for light weight three wheeler vehicles. Ranjeet et al. [2]
(2012) have carried out stress analysis of mono composite leaf
spring under the dynamic load conditions. Anuraag and
VenkataSivaram [7] (2012) have modeled and analyzed two &
five layered composite leaf spring to predict the behavior under
static, dynamic & shock loads. Vijaya Lakshmi and
Satyanarayana [10] (2012) have compared the steel and
composite leaf spring for load carrying capacity, stiffness and
weight savings point of view. Sailaja et al. [3] (2013) have
modeled and analyzed a master leaf spring made up of carbon
fibre, boron fibre and conventional steel with respect to weight
and strength. Digambar et al. [4] (2013) have analyzed steel leaf
springs made of SUP 10 & EN 45. Ghodake and Patil [9] (2013)
have presented the design and analyzed the composite leaf
spring made of glass fibre reinforced polymer. From the
literature survey it is observed that the vibration analysis of
mono composite leaf spring and the performance characteristics
with respect to random vibration has not been done to check the
suitability of leaf spring for automotive suspension application.
II. Leaf Spring Specifications of TATA ACE
In this research work TATA ACE mono composite leaf
spring with constant width and constant thickness with uniform
cross section is considered and is as shown in Figure1. The
design parameters such as spring length, spring thickness,
spring width and camber are kept to be the same in both steel
and composite leaf springs. The specifications of leaf spring are
shown in table 1. The material properties of 55Si2Mn90 steel
are shown in table 2.
International Journal of Scientific Engineering and Technology (ISSN : 2277-1581)
Volume No.3 Issue No.7, pp : 871-875 1 July 2014
IJSET@2014 Page 872
Figure 1 2D drawing of TATA ACE Master Leaf Spring
Table 1 Leaf Spring Specifications of TATA ACE Total Length (L) 930 mm
Length of leaf spring from Eye to Eye 754 mm
Thickness (t) 8 mm
Width (b) 60 mm
Load (W) given on leaf spring 1000 N
Table 2 Material Properties of 55Si2Mn90 Steel [5] 1 Ultimate tensile strength Su (Mpa) 1962
2 Yield tensile strength Su (Mpa) 1470
3 Modulus of elasticity E (Gpa) 210
4 Poisson ratio 0.3
III. Design Requirements of Composite Leaf
Spring
The objective for the optimum design of the composite leaf
spring is the minimization of weight, this objective function is
constrained by the functional requirements of the leaf spring,
which is,
Fundamental natural frequency in bending : maxcrt NN Thus
together with constraints from the functional requirements, the
objective function is optimized by varying the design variables
so that functionally sound, minimum weight leaf spring is
realized. Material
properties of different composites are listed in the table 3.
Table 3 Material Properties of different Composite Materials
[11]
Material
Properties
E-Glass/
Epoxy
Graphite/
Epoxy
Boron/
Aluminum
Carbon
/ Epoxy
Kevlar/
Epoxy
E11 (MPa) 34000 142600 215000 142000 80000
E22 (MPa) 6530 9600 14410 9810 5500
G12 (MPa) 2433 600 5720 657 220
G22 (MPa) 1698 310 4590 377 180
V12 0.217 0.25 0.19 0.3 0.34
V23 0.366 0.35 0.29 0.34 0.65
IV. Finite Element Analysis of Steel and
Composite Leaf Spring
A. Modal Analysis
Modal analysis is a technique used to obtain Eigen
value and Eigen vectors under forced free vibration. The first two
bending frequency modes of Steel, E-Glass/Epoxy,
Graphite/Epoxy, Boron/Aluminum, Carbon/Epoxy and
Kevlar/Epoxy leaf springs are as shown in Figures 2 to 7
respectively.
Figure 2 First and Second Bending Frequency modes of Steel
Leaf Spring
Figure 3 First and Second Bending Frequency modes of E-
Glass/Epoxy Leaf Spring
Figure 4 First and Second Bending Frequency modes of
Graphite/Epoxy Leaf Spring
Figure 5 First and Second Bending Frequency modes of
Boron/Aluminum Leaf Spring
Figure 6 First and Second Bending Frequency modes of
Carbon/Epoxy Leaf Spring
International Journal of Scientific Engineering and Technology (ISSN : 2277-1581)
Volume No.3 Issue No.7, pp : 871-875 1 July 2014
IJSET@2014 Page 873
Figure 7 First and Second Bending Frequency modes of
Kevlar/Epoxy Leaf Spring
B. Harmonic Analysis Harmonic response analysis is a technique used to
determine the steady-state response of a linear structure to
loads that vary harmonically with time. The harmonic
response of Steel, E-Glass/Epoxy, Graphite/Epoxy,
Boron/Aluminum, Carbon/Epoxy and Kevlar/Epoxy leaf
springs are as shown in Figures 8to 10 respectively.
Figure 8 Harmonic responses of Steel and E-Glass/Epoxy Leaf
Springs
Figure 9 Harmonic responses of Graphite/Epoxy and
Boron/Aluminum Leaf Springs
Figure 10 Harmonic responses of Carbon/Epoxy and
Kevlar/Epoxy Leaf Springs
C. Random Vibration Analysis An automobile moving on smooth or rough road is
subjected to random base excitation. The road profiles
measured for some portions of smooth and rough road for
vehicle moving with speed of 30 km/hr is given in Figure
11[12]. Initially the road profiles are measured in time
domain and converted in to frequency domain (power spectral
density) using fast Fourier transformer as shown in Figure
12[12].
Figure 11 Smooth and Rough Road Profiles [12]
Figure 12 Smooth and Rough Road Profiles Acceleration
PSD[12]
The displacement and von mises stress distributions of Steel, E-
Glass/Epoxy, Graphite/Epoxy, Boron/Aluminum,
Carbon/Epoxy and Kevlar/Epoxy leaf springs for both smooth
and rough excitations are as shown in Figures 13 to 24
respectively.
Figure 13 Displacement contour and Von Mises Stress
Distribution of Steel Leaf Spring for Smooth Excitation
Figure 14 Displacement contour and Von Mises Stress
Distribution of E-Glass/Epoxy Leaf Spring for Smooth
Excitation
Figure 15 Displacement contour and Von Mises Stress
Distribution of Graphite/Epoxy Leaf Spring for Smooth
Excitation
International Journal of Scientific Engineering and Technology (ISSN : 2277-1581)
Volume No.3 Issue No.7, pp : 871-875 1 July 2014
IJSET@2014 Page 874
Figure 16 Displacement contour and Von Mises Stress
Distribution of Boron/Aluminum Leaf Spring for Smooth
Excitation
Figure 17 Displacement contour and Von Mises Stress
Distribution of Carbon/Epoxy Leaf Spring for Smooth
Excitation
Figure 18 Displacement contour and Von Mises Stress
Distribution of Kevlar/Epoxy Leaf Spring for Smooth
Excitation
Figure 19 Displacement contour and Von Mises Stress
Distribution of Steel Leaf Spring for Rough Excitation
Figure 20 Displacement contour and Von Mises Stress
Distribution of E-Glass/Epoxy Leaf Spring for Rough
Excitation
Figure 21 Displacement contour and Von Mises Stress
Distribution of Graphite/Epoxy Leaf Spring for Rough
Excitation
Figure 22 Displacement contour and Von Mises Stress
Distribution of Boron/Aluminum Leaf Spring for Rough
Excitation
Figure 23 Displacement contour and Von Mises Stress
Distribution of Carbon/Epoxy Leaf Spring for Rough Excitation
Figure 24 Displacement contour and Von Mises Stress
Distribution of Kevlar/Epoxy Leaf Spring for Rough Excitation
VI. Result and Discussion
A. Modal Analysis of Steel and Composite Leaf
Springs The results obtained from analysis for steel and various
composite leaf springs are tabulated in table 4 respectively.
From table 4, it is observed that Boron/Aluminum posses high
natural frequency compared to other materials.
Table 4 Natural Frequencies of various Leaf Springs
Material
Natural Frequencies in Hz
Mode 1 Mode 2
Steel 22.912 100.81
E-Glass/Epoxy 14.694 59.612
Graphite/Epoxy 21.067 67.085
Boron/Aluminum 39.836 147.17
Carbon/Epoxy 21.610 69.158
Kevlar/Epoxy 9.4525 29.520
B. Harmonic Analysis of Steel and Composite
Leaf Springs
The response for steel and composite leaf springs at
their corresponding resonance frequencies are tabulated in
table 5. It is observed that E-glass/Epoxy and Kevlar/Epoxy
are having more amplitude of response when compared to all
other materials. The Steel and Boron/Aluminum are having
less amplitude of response compared to other materials.
International Journal of Scientific Engineering and Technology (ISSN : 2277-1581)
Volume No.3 Issue No.7, pp : 871-875 1 July 2014
IJSET@2014 Page 875
Table 5 Harmonic Analysis Results for various Leaf Springs
Material Frequency (Hz) Amplitude
(mm)
Steel 23.509 0.88
E-Glass/Epoxy 15.061 6.2
Graphite/Epoxy 21.528 5
Boron/Aluminum 40.766 1.1875
Carbon/Epoxy 22.085 4.75
Kevlar/Epoxy 9.6575 9.99
C. Random Vibration Analysis of Steel and
Composite Leaf Springs
The results obtained for steel and composite leaf
springs for both smooth and rough road excitations are
tabulated in the tables 6 and 7 respectively. FEA solver results
shows that the deflection and von mises stress for
Boron/Aluminum leaf spring is comparatively less than other
leaf springs, hence vibration capacity is more in composite
leaf spring than conventional steel leaf spring.
Table 6 Random Vibration Analysis results of various Leaf
Springs for Smooth Road Excitation
Material Maximum
Deflection
(mm)
Maximum
Von Mises
Stress (MPa)
Steel 2.035 21.891
E-Glass/Epoxy 4.562 6.84
Graphite/Epoxy 2.226 4.508
Boron/Aluminum 0.611019 4.571
Carbon/Epoxy 2.214 4.54
Kevlar/Epoxy 7 6.131
Table 7 Random Vibration Analysis results of various Leaf
Springs for Rough Road Excitation
Material Maximum
Deflection
(mm)
Maximum
Von Mises
Stress (MPa)
Steel 2.843 31.356
E-Glass/Epoxy 8.625 13.257
Graphite/Epoxy 3.047 6.367
Boron/Aluminum 0.815865 6.252
Carbon/Epoxy 2.876 6.338
Kevlar/Epoxy 8.714 7.914
VII. Conclusion
In this research work, eigen value, harmonic and
random vibration analysis for steel and various composite leaf
springs is carried out using ANSYS 10. From the obtained
results it can be concluded that,
1. Boron/Aluminum high natural frequency compared to
other materials.
2. E-Glass/Epoxy and Kevlar/Epoxy are having high
amplitude of response than other materials. And also
3. Steel and Boron/Aluminum have minimum amplitude
of response.
4. Boron/Aluminum has minimum deflection and von
mises stress compared to other materials
Boron/Aluminum possesses more vibration capacity than
conventional steel leaf spring. And also it has good performance
characteristics as compared with other materials with similar
design specifications.
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