Cylinder Head Cover Natural Frequency Analysis

International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),
ISSN 0976 – 6359(Online), Volume 5, Issue 5, May (2014), pp. 170-179 © IAEME
170
NORMAL MODE ANALYSIS OF CYLINDER HEAD COVER
Shahim Haider Abidi1
, Deo Raj Tiwari2
1
Dept. of Mechanical Engg. ZHCET, Aligarh Muslim University, India
2
Dept. of Mechanical and Automobile Engg., Sharda University, Greater Noida, India
ABSTRACT
Vibration in IC engines is a significant factor to be considered while designing IC engine as it
can have a negative impact on various engine components. This happens when the natural frequency
of component coincides with the forced frequency produce by the engine leading to the phenomenon
of resonance.
One of the part which can be effected is the cylinder head cover, if due consideration is not
taken in the designing of the CHC, it might lead to the failure of component. If the CHC fails their
might be leakage of engine oil due to which there is possibility of catastrophic accident hence it
becomes important to design the CHC properly and this paper is based on evaluating the natural
frequency of an Aluminum CHC through the FEM analysis. This paper is based on the work that
CHC model is imported to HYPER-WORKS 9.0 to generate a high quality of mesh. Finally the mesh
model is ready for analysis using Optistrut.
The result obtained are analyzed and further modifications are recommended for optimization
of model. Finite Element analysis results for safe Cylinder Head Cover model which is prone to
failure due to resonance condition.
Keyword: Cylinder Head Cover, FEM Analysis, Hyper-Works 9.0, Optistrut, Natural Frequency.
I. INTRODUCTION
The use of FEM has also been substantial in development of many theories and and analysis
of various models in automobile sector. Initially Prashant D Parikh [1] in 1977 did work on “Finite
element analysis of the static and dynamic behavior of automobile tyre”, He used a mathematical
model to represent a radial ply passenger car tire for axisymmetric and asymmetric static and
dynamic eigenvalue analysis by the use of a direct stiffness finite element method. . The finite
element chosen had a shape of a conical frustum with five degrees of freedom at each node in the
INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING
AND TECHNOLOGY (IJMET)
ISSN 0976 – 6340 (Print)
ISSN 0976 – 6359 (Online)
Volume 5, Issue 5, May (2014), pp. 170-179
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171
local coordinate system of the element. The tire properties were derived by assuming the tire to be
composed of thin layers of composite materials, linearly orthotropic in nature. Hamilton's principle
has been applied to derive the equation of motion of the element. In 1992 work on “A consistent
Vlasov Model for analysis of plates on elastic foundations using Finite Element Method” was
completed successfully by Wai Hung ho[2]. A one dimensional periodic Vlasov-Poisson equation
with various approximations was considered. This included the particle-in-cell method, the
upstream-downstream method (a finite element method) and the Lax-Wendroff method (a finite-
difference method).ThyssenKrupp Tallent[3], a chassis structural and suspension products developer
for the automotive industry, has gone through the HyperWorks CAE platform from Altair
Engineering as an enterprise simulation system for design, optimization and virtual manufacturing of
its automotive chassis components. The result of this co-operation is ThyssenKrupp's system, which,
when combined with HyperWorks, has allowed ThyssenKrupp Tallent to increase productivity and
deliver lighter products to their clients in shorter timescales. ABstructures[4] has been using the
HyperWorks suite since its foundation in 2008. The company initially employed OptiStruct, from the
HyperWorks suite for topology optimization, along with HyperMesh, the HyperWorks meshing tool.
In December 2010, the company extended its use of HyperWorks to RADIOSS, the product suite's
solver, to its development process for the analysis of the behavior of composite materials. To design
and optimize the carbon structures of the yachts, ABstructures is using HyperWorks together with
other computer-aided engineering (CAE) tools to simulate composites and fluid-structure
interactions. ABstructures has achieved fundamental structural improvements of all the yachts it has
designed, compared to older-generation yachts. Arif Senol Sener[5], in his work studied the
construction and standardization of a track for performing fatigue and reliability test of light
commercial vehicles is described. For the design and process verification of the company’s vehicles
one test track is defined. A questionnaire was used to determine the average usage of light
commercial vehicles in Turkey. Fatigue characteristics of Turkish roads were determined by
analyzing fifty different roads and this article focuses on defining the load spectrum and equivalent
fatigue damage of the leaf spring resulting from the accelerated test route. Fatigue analysis and
estimated lifespan of the part were calculated using Finite Element Analyses and verified by the
Palmgren-Miner rule. When the customer profile is taken into consideration; Turkish customer
automotive usage profile, the aim of usage of this kind of vehicle (LCV), fatigue characteristics of
Turkish roads for this vehicle were determined and around Bursa one accelerated test tracks were
formed for the reliability and fatigue test for the related company, linear analysis executed on the
FEA of the spring was more convenient were obtained.
II. VIBRATION AND NATURAL FREQUENCY
Most of the IC engines developed earlier were less fuel efficient, more polluting and noisy,
but recently there has been a growing concern in society toward environment and aesthetic
awareness. This had let to the development of advanced engines using state of art technology.
Vibration in IC engine has emerged as a significant factor to be considered in designing IC engine as
it can have a negative impact in various engine components. This happens when the natural
frequency of the component coincides with the forced frequency produce by the engine. One of the
parts which can be affected by this phenomenon is the cylinder head cover. If due care is not taken in
the designing of the CHC, it might lead failure of component. If the CHC fails their might be leakage
of engine oil due to which there is possibility of catastrophic accident hence it becomes important to
design the CHC properly. This work is based on evaluating the natural frequency through the FEM
analysis.

172
III. REASON OF USING FEM FOR THE WORK
In the present scenario the Cylinder Head Cover is being analyzed, and due to the advantage
of nondestructive testing associated with FEM, it is possible to analyze a large number of
modifications of the component without being actually manufacturing it. Also as observed from
previous studies the results of FEM analysis have shown considerable accuracy with the actual
results.
IV. FEM ANALYSIS
The finite element method (FEM) also known as finite element analysis (FEA), with help of
this numerical technique we can find approximate solutions of partial differential equations (PDE)
as well as of integral equations. This approach for the solution of steady state problems is based
either on eliminating the differential equation completely, or rendering the PDE into an
approximating system of ordinary differential equations, which are further numerically integrated
using standard techniques such as Euler's method, Runge Kutta, etc. The primary challenge in
solving partial differential equations, is to create an equation that approximates the equation to be
studied, but is numerically stable, meaning that errors in the input and intermediate calculations do
not accumulate and cause the resulting output to be meaningless. There are many ways of doing this,
all with advantages and disadvantages. The Finite Element Method is a good choice for solving
partial differential equations over complicated domains (like cars and oil pipelines), when the
domain changes (as during a solid state reaction with a moving boundary), when the desired
precision varies over the entire domain, or when the solution lacks smoothness. For instance, in a
frontal crash simulation it is possible to increase prediction accuracy in "important" areas like the
front of the car and reduce it in its rear (thus reducing cost of the simulation); another example would
be the simulation of the weather pattern on Earth, where it is more important to have accurate
predictions over land than over the wide-open sea [1]. A variety of specializations under the umbrella
of the mechanical engineering discipline (such as aeronautical, biomechanical, and automotive
industries) commonly use integrated FEM in design and development of their products. Several
modern FEM packages include specific components such as thermal, electromagnetic, fluid, and
structural working environments. In a structural simulation, FEM helps tremendously in producing
stiffness and strength visualizations and also in minimizing weight, materials, and costs. This
powerful design tool has significantly improved both the standard of engineering designs and the
methodology of the design process in many industrial applications.[7] The introduction of FEM has
substantially decreased the time to take products from concept to the production line. It is primarily
through improved initial prototype designs using FEM that testing and development have been
accelerated. In summary, benefits of FEM include increased accuracy, enhanced design and better
insight into critical design parameters, virtual prototyping, fewer hardware prototypes, a faster and
less expensive design cycle, increased productivity, and increased revenue.
V. ANALYSIS
Meshing
This exercise involves changing the shape of a part in order to simplify the geometry. Certain
details of the shape, such as small holes or blends, may simply not be necessary for the analysis
being performed. When these details are removed, the analysis can run more efficiently.
Additionally, mesh quality is often improved as well. Changing the geometry to match the desired
shape can also allow a mesh to be created more quickly.

173
Meshing includes -:
• Mesh the clip, review the mesh quality, and determine the features to be simplified
• Remove surface fillets
• Remove edge fillets
The model file has geometry that has been midsurfaced. (Surfaces have been created on the
mid-plane of the part.
Fig 1: Meshing of an small element is shown below.this mesh is generated by using command
“auto mesh”
Fig 2: The element selected for the meshing is “quads” and the element size is 10.0.
Fig 3: The above fig explains how the whole as geometry is meshed. In some places it is required to
generate the mesh type of “mixed”
Analysis setup in Optistruct
This section will contain analysis part of meshed mid plane. The solver used is Optistruct.
a) Control cards will be allotted
b) Different material to the geometry will be assigned.
c) Property card will be assigned.
d) Creation of load collectors.
e) constrained will be applied

174
Fig 4: Component Table
Fig 5: Material Table
Constrained Will Be Applied
• The process of debarring of the motion is performed by applying constraints on the system
during simulation on OPTISTRUCT.
• These applied constraint acts as boundary conditions while solving the equations generated by
the solver OPTISTRUCT to derive a conclusion.

175
Fig 6: Node to be Constraint Fig 7: Node selection for Constraint
Fig 8: Bolt Constraint Fig 9: Constraint along bolt and seal
The purpose for using a finite element (FE) pre-processor is to create a model, which can be
run by a solver. A finite element solver can solve for responses of parts to loading conditions on
them. The loads can be in the form of boundary constraints, forces, pressures, temperatures, etc. In
this the solver input files are created using different templates. More specifically, loading conditions
on a model specify solver specific controls are defined and input file to a solver from Hyper Mesh
will be submitted.
Fig 10: The constraints are applied on the place where gasket is to be attached throughout the edges
of CHC. The white pattern in above pic shows that constrained has been applied throughout the
nodes at the edges (nodes) represented by the color purple

International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976
ISSN 0976 – 6359(Online), Volume 5, Issue 5, May (2014), pp.
For Aluminum material
The further analysis results in next mode natural frequency as follows
Fig 11: For the mode 1, the graphical
representation for displacement. The red color
shows the max displacement and then in
decreasing order till the blue color
Fig 13: White point denotes the location
of node formaximum displacement.
NODE ID 303314(DOF)
International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976
6359(Online), Volume 5, Issue 5, May (2014), pp. 170-179 © IAEME
176
The further analysis results in next mode natural frequency as follows -:
, the graphical
representation for displacement. The red color
shows the max displacement and then in
decreasing order till the blue color
Fig 12: For the mode 1, the graphical
representation or stress is shown. The red color
shows the maxstress and then in decreasing order
till the blue color
White point denotes the location
of node formaximum displacement.
NODE ID 303314(DOF)
Fig 14: White point denotes the location of
node for maximum stress.
NODE ID 325832(DOF)
, the graphical
representation or stress is shown. The red color
shows the maxstress and then in decreasing order
till the blue color
White point denotes the location of
node for maximum stress.
NODE ID 325832(DOF)

177
For Aluminum material and thickness is reduced
When the thickness of CHC is reduced to half, it will influence the structure. As natural
frequency is a geometric property hence get changed. The observed natural frequency at mode1 is
693 Hz.
The further analysis results in next mode natural frequency as follows -:
VI. RESULTS AND DISCUSSION
Natural frequency is a function that depends on the geometry, material properties and
structure. Generally for a four stroke vehicle with the engine of 1100cc has the vibrating frequency
of 300-400 Hz at full speed. Therefore our first aim is to produce a design which has natural
frequency well above the 1000 Hz, so that at any conditions the structure must not fail due to
resonance.
Fig 15: For the mode 1, the
graphical representation for
displacement is shown below. The
red color shows the max.
Displacement and then in decreasing
order till the blue color.
Fig 16: For the mode 1, the
graphical representation for stress is
shown. The red color shows the max.
Stress and then in decreasing order
till the blue color

178
Comparison of natural frequency in different
cases. For the given geometry, material properties and structure of the CHC, the analysis comes to
the output natural frequency for different cases as below-:
Column1 Aluminum Aluminum with halved thickness
mode1 1195 Hz 693 Hz
mode2 1346 Hz 843 Hz
mode3 1542 Hz 1045 Hz
mode4 1785 Hz 1241 Hz
mode5 2051 Hz 1256 Hz
mode6 2288 Hz 1323 Hz
This table shows that the min natural frequency so obtained at 1st
mode is for the aluminum
CHC which is 1195 Hz, but still, it can be concluded aluminum system is well safe for the expected
conditions of the vehicle. But to improve the performance and reduction in weight, it requires slight
variation. The variation is generated by reducing the thickness of aluminum CHC to half. By
reducing the thickness to half, the weight of the aluminum CHC is reduced to half but the strength of
the system also decreases mentionable. But as far as natural frequency is concerned, it decreases
dramatically to 693 Hz for 1st
mode. This means now this CHC is able to avoid resonance condition
to a much greater extend and hence, may be used for bigger vehicles. The parameter for the Eigen
mode is displacement in our case the Eigen mode gives i.e. displacement for a given mode at every
node. To find the required from the multi degree of freedom system it is needed to be solved by the
matrix method. In this the parameter to be finding is represented by the Eigen values of the matrix
system. Each node has its own boundary condition and its own Eigen value for matrix system.
Therefore by solving the matrix system under a given set of boundary conditions i.e. constraint it can
be solved for the Eigen value at every node. Hence different parameter such as displacement stress
can be finding at each node by appointing them as Eigen value for the each node in the system.
Comparison of Eigen modes in different cases
In the analysis of CHC to avoid the condition of resonance, it is required to find the natural
frequency of the system. When a given system is being vibrated under the set of constraint the each
element at molecular level displaces from its position. The molecular level in this case of analysis is
defined by the nodes and the rectangular elements. When displacement is defined as the parameter
and appointed as Eigen mode then the solver will solve the system equation for the displacement at
each node. This whole process of solving the different equation and matrixes is carried out in
Optistruct and result so obtain of Eigen values is shown in hyper view. On defining the displacement
as Eigen mode the result concluded are as follows for different cases.

179
For Mode 1
Natural
frequency
Maximum
displacement Minimum displacement
Aluminum 1195 Hz 45.83 mm 5.79 mm
Aluminum with
halved thickness 693 Hz 67.42 mm 7.49 mm
The above displacement-comparison table shows that when “aluminum” is used as material
the natural frequency, at first node was 1195 Hz. And the maximum displacement is of 45.83mm
mainly at top center part nodes. Also the minimum displacement for the same condition is 5.79mm is
observed at edges and nearby regions.
Conclusion and future work
In our normal mode analysis of cylinder head cover for aluminum material, it is found that
natural frequency for mode 1 is natural frequency 1195 Hz. For saving the cost of aluminum material
r the thickness of cylinder head cover can be reduced by the factor of 0.5 times. For this thickness we
had obtained the natural frequency 693 Hz.
After finding the natural frequency of aluminum cylinder head cover. Now we can convert
this aluminum CHC into plastic material and can found natural frequency of plastic component, the
advantage of conversion may be reduced the cost and weight of the component.
REFERENCES
1) Prashant D. parikh, “A finite element analysis of the static and dynamic behavior of
automobile tire, 1977.
2) Wai Hung ho, B.S, “A comparison of simulation methods with finite- difference and finite
element method for solving Vlasov-Poisson system” August, 1986.
3) www.tallent.thyssenkrupp.com
4) www.abstructures.com
5) Arif Senol SENER Head of Automotive Technology Division, Vocational High Schools,
Istanbul Aydin University.
6) Brian D. Camp, “A class of immersed finite element spaces and their Application to Forward
and inverse interface problems” November 19, 2003.
7) Syed Faheem Haider Abidi, “Determination of mechanical properties of EN24 alloys using miniature
specimen test technique and FEM, may 2008.
8) Rao V. Garimella, “Anisotropic Tetrahedron Mesh Generation” May 1999”
9) Mustafa Elsheikh, “A Generative Approach to Meshing Geometry” September 2010.
10) Rahul Davis, “A Parameteric Design Study of Surface Roughness in Dry Turning Operation
of EN24 Steel”, International Journal of Mechanical Engineering & Technology (IJMET),
Volume 3, Issue 2, 2012, pp. 410 - 415, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359.
11) Madhura.S, Pradeep B Jyoti and Dr.T.V.Govindaraju, “FEM Based Modelling of Amb
Control System”, International Journal of Mechanical Engineering & Technology (IJMET),
Volume 4, Issue 3, 2013, pp. 191 - 202, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359.

Cylinder Head Cover Natural Frequency Analysis

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