AJSR_46_08.pdf
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Transcript of AJSR_46_08.pdf
American Journal of Scientific Research
ISSN 1450-223X Issue 46 (2012), pp. 67-78
© EuroJournals Publishing, Inc. 2012
http://www.eurojournals.com/ajsr.htm
Bending and Deflection Analysis of Thin FGM Skew
Plates using Extended Kantorovich Method
Amin Joodaky
Corresponding Author, Graduate Student.Young Researchers Club
Arak Branch, Islamic Azad University, Arak P. O. Box: 38135, I.R. Iran
E-mail: [email protected]
Mohammad Hossein Kargarnovin
Department of Mechanical Engineering Sharif University of Technology
Tehran P. O. Box: 14588-89694, I.R. Iran
E-mail: [email protected]
Fax: +9821-6600-0021
Saeid Jafari Mehrabadi
Department of Mechanical Engineering, Islamic Azad University
Arak Branch, Arak P. O. Box: 38135, I.R. Iran
E-mail: [email protected]
Amir Hossein Nasrollah Barati
Young Researchers Club, Aligudarz Branch, Islamic Azad University
Aligudarz, I.R. Iran
E-mail: [email protected]
Abstract
An accurate approximate closed-form solution is presented for bending of a FGM
skew plate with clamped edges, loaded uniformly by using the extended Kantorovich
method. Successive application of EKM together with the idea of weighted residual
technique converts the governing partial differential equation into two ordinary differential
equations. The obtained ODE’s are solved iteratively and the results are compared with
other existing results. It is shown that some factors such as angle of skew plate and power
law index of FGM have important effects on the obtained results.
Keywords: Extended Kantorovich Method; Bending analysis; Von Karman plate theory;
Skew plate; Uniform loading; Galerkin method
1. Introduction Extended Kantorovich Method (EKM) introduced by Kerr [1] using the idea of the well-known
Kantorovich method [2] to obtain highly accurate approximate closed-form solution for torsion of
prismatic bars with rectangular cross-section. The method employs the novel idea of Kantorovich to
reduce the governing partial differential equation of a two-dimensional (2D) elasticity problem to a
double set of ordinary differential equations. Since then, EKM has been extensively used for various
Bending and Deflection Analysis of Thin FGM Skew
Plates using Extended Kantorovich Method 68
2D elasticity problems in Cartesian coordinates system. Among these applications, one can refer to
eigenvalue problems [3], buckling [4] and free vibrations [5] of thin rectangular plates, bending of
thick rectangular isotropic [6,7] and orthotropic [8] plates and free-edge strength analysis [9]. Most
recent EKM articles include vibration of variable thickness [10] and buckling of symmetrically
laminated [11] rectangular plates. Accuracy of the results and rapid convergence of the method
together with possibility of obtaining closed-form solutions for ODE systems have been discussed in
these articles and others [12]. Finally, a few articles consider polar coordinates and such as using the
EKM for sector plates [13]. All these applications of the EKM, are devoted and restricted to the
problems in the Cartesian and Polar coordinate systems. Among the open literatures, except previous
studies of the authors of the present article [14], no researcher has employed EKM in terms of Oblique
coordinates system. Based on other solution methods, several articles have studied bending, buckling,
vibration, stress and other analysis for skew plates in term of oblique coordinate system [15-20].
Functionally graded materials (FGMs) are composite materials, which are microscopically
inhomogeneous and their mechanical properties vary continuously in one (or more) direction(s). This is
achieved by gradually changing the composition of the constituent materials along one direction,
usually in the thickness direction only, to obtain smooth variation of material properties and optimum
response to externally applied loading. The concept of FGMs, was first introduced in Japan in 1984.
Since then it has gained considerable attentions [21, 22]. Many different applications of FGMs, could
be found in references [23].
This study aims to examine the applicability of the EKM to obtain highly accurate approximate
closed-form solutions for 2D elasticity problems in oblique coordinate system. Bending and
consequently, deflection of thin FGM skew plates with clamped edges subjected to uniform loading
conditions, is considered. Application of the EKM together with the idea of weighted residual
technique converts the forth-order governing equation into two ODEs in terms of X and Y in oblique
coordinates. Both resulted ODEs, are then solved iteratively in a closed-form manner and a very fast
convergence is achieved. A close study on the obtained results revealed that the method provides
sufficiently accurate answers for FGM skew plates. Comparison of the results of various points of the
FGM skew plate show very good agreement with results out of FEM software and other valid
literatures.
2. Analysis and Solution Method 2.1. FGM Plate
Figure 1: Rectangular FGM plate in Cartesian system of coordinates.
In a FGM plate either of material properties namely P is primarily a function of volume
fractions, V, of all comprising materials which can be expressed for two different constituents as [25],
1 1 2 2P PV PV= + (1)
69 Amin Joodaky, Mohammad Hossein Kargarnovin
Saeid Jafari Mehrabadi and Amir Hossein Nasrollah Barati
where indices 1 and 2 address the constituting materials one and two respectively. Moreover, referred
to Figure (1), for example Vi the volume fraction of the constituting materials, can be expressed
according to the power law distribution as [25];
1
12
2( )
2
( ) 1 ( )
,n
h zV z
h
V z V z
−=
= −
(2)
where n denotes the power law index which takes values greater or equal than zero and h is the plate
thickness. Using Eqs. (1) and (2), the material properties P such as Young’s modulus E for a FGM
plate made of metal at the top surface and ceramic at the lower surface can be written as follow:
1( )
2m cm
cm c m
nz
E z E Eh
E E E
= + ⋅ −
= −
(3)
That cE and mE
are Young’s modulus of elasticity coefficient for Ceramic and Metal
respectively. n is the non-negative exponent of power, h is the plate thickness and z is the coordinate in
the thickness direction. Generally, the value of Poisson’s ratio varies in a small range, for simplicity, it
is assumed a constant. In this study we consider a FGM plate in which the upper surface of plate (z =
h/2) is purely metallic and the lower surface (z = -h/2) is purely ceramic.
Classical nonlinear laminated plate theory and the concept of physical neutral surface are
employed to formulate the basic equations of the FGM thin plate [25]. According to the classical
theory of elasticity, in a pure bending of a FGM plate a surface can be found (neutral plane) whose
strains and stresses are zero. The distance of this plane to the mid-surface plane (z = 0z) is defined as
Figure (1) and [25];
2
2
2
2
0
( )
( )
h
h
h
h
zE z dz
E z dz
z−
−
=
∫
∫ (4)
Using the physical neutral surface concept and classical nonlinear Von Karman plate theory
[25], the displacements take the following forms:
( )0 0
wu u z z
x
∂= − −
∂
( )0 0
wv v z z
y
∂= − −
∂
( ),w w x y= (5)
where u and v stand for the in plane displacement and w for the z direction deflection of an arbitrary
point in the plate. Moreover, u0 and v0 represent the in plane displacement of any point on the neutral
surface. If small displacement theory is considered then, 0u and 0v
are very small compared to other
terms therefore they can be neglected. Therefore, displacements field take the following form:
( )0
wu z z
x
∂= − −
∂
( )0
wv z z
y
∂= − −
∂
( ),w w x y= (6)
Bending and Deflection Analysis of Thin FGM Skew
Plates using Extended Kantorovich Method 70
The strain field (kinematic relation) is [25],
{ } ( ){ }(1)
0z zε ε= −
where
{ } { }
{ }(1)
2 2 2
2 2 2 2
, ,
2,,
x y xy
T
Tw w w
x y x y
ε ε ε ε
ε
=
∂ ∂ ∂= − − −
∂ ∂ ∂ ∂
(7)
and stress field become [25],
{ } [ ]{ }Qσ ε= (8)
where
[ ]2
2
1
2
1 0( )
1 01
0 0
E zQ
υ
υ
υυ
−
=−
(9)
In a plate-bending problem, moments are defined as [25],
{ } [ ]{ }(1)M D ε= (10)
where
[ ]2
1
2
1 0
1 0
0 0
D D
υ
υ
υ
−
=
(11)
and
( ) ( )02
2
2
21
h
h
z z E zD
υ−
−
−= ∫ (12)
If no axial force existences differential equation of motion based on the physical neutral
surface, can be expressed as [25] 2 22
2 22 0
xy yxM MM
qx x y y
∂ ∂∂+ + + =
∂ ∂ ∂ ∂ (13)
Or in terms of w [26-29],
4 ( , ) /w x y q D∇ = (14)
The last equation is the well-known governing equation for a thin isotropic plate, in which w(x,
y) is the deflection, q is the applied distributed load, and D (flexural rigidity) for a FGM plate. Now,
consider a thin skew FGM plate with dimensions of 2a×2b and tilting angle of ϕ along with reference
rectangular (x, y) and local oblique (X, Y) system of coordinates as depicted in Figure (2).
If all edges are clamp, then the deflection and its first derivative with respect to the normal
direction to the boundary should vanish at such boundaries, i.e.:
0, / 0Xw dw d= = for X a= ± where b Y b− ≤ ≤
0, / 0Yw dw d= = for Y b= ± where a X a− ≤ ≤
71 Amin Joodaky, Mohammad Hossein Kargarnovin
Saeid Jafari Mehrabadi and Amir Hossein Nasrollah Barati
2.2. Iterative Solution by EKM
Figure 2: Skew plate in oblique coordinate (X,Y).
According to the Extended Kantorovich Method (EKM)[1], the function for the deflection of
the plate is assumed as multiplication of different single variable functions as:
( , ) ( ) ( )X Y f X g Yij i jw ≅ ⋅ (15)
where ( )Xfi and ( )j
Yg are unknown functions to be determined and subscripts i and j denote number
of iterations. For the plate deflection function of w(x, y), according to the Galerkin weighted residual
method, we have [13]:
4 0( )a b
a bD X Yw q wd dδ
− −∇ =−∫ ∫ (16)
Now, for a prescribed function of ( )j
Yg , j=0 and referred to the Eq. (15), wδ becomes:
( )j
Yi
g fwδ δ= ⋅ (17)
Substitution of Eq. (15) into Eq. (16) in conjunction with Eq. (17) leads to,
( )40( )i j j
a b
a b if dXD f g q g dY δ
− −= ∇ ⋅ − ∫ ∫ (18)
Based on the existing rules in the variational principle, Eq. (18) is satisfied if the expression in
the bracket is vanished, hence,
( )4 ( ) 0i j j
b
bD f g q g dY
−∇ ⋅ − =∫ (19)
in which operator ∇ is in the Cartesian coordinate, (x, y), and has to be converted to the oblique
coordinate (X, Y), i.e.:
tanX x y ϕ= − and / cosY y ϕ= (20)
Hence, by doing some mathematical manipulations one would get:
2 2 22
2 2
1( 2 sin )
cos X YX Y
ϕϕ
∂ ∂ ∂∇ = − +
∂ ∂∂ ∂
And consequently, 4∇ becomes,
( )44 4 4 4 4
1 22 1 2 sin 4 sin
4 4 2 2 3 3 4cos X X Y X Y X Y Y
ϕ ϕ
ϕ
∂ ∂ ∂ ∂ ∂∇ + + − + +
∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂
=
(21)
Having on hand 4∇ operator in conjunction with Eq.(14), governing equation becomes:
Bending and Deflection Analysis of Thin FGM Skew
Plates using Extended Kantorovich Method 72
( )4 4 4 4
2
4 2 2 3 3
4
4
4
4cos
( , )
2 1 2sin 4sinD
D
X Y
w w w w
X X Y X Y X Y
wq
Y
wϕ
ϕ ϕ∇∂ ∂ ∂ ∂
+ + − +∂ ∂ ∂ ∂ ∂ ∂ ∂
∂
∂
= +
=
(22)
Eq.(22) along with Eq.(15), and with an initial arbitrary guess of ( )j
Yg , j=0 turns the result
into a forth order ODE as:
( )2 2
42 2
3 3 4
3 3 4
4 ( ) ( )( ) 2( , ) ( )
4 4cos
( ) ( ) ( ) ( ) ( )4 sin ( ) ( , ) 0
( . ) 2 1 2sinY XD f X
D X Y g YX
g Y f X g Y f X g Yf X q X Y
Y XX Y Y
g ff g q
Y Xϕ
ϕ
ϕ
∂∇ +
∂
∂ ∂ ∂ ∂ ∂+ + − =
∂ ∂∂ ∂ ∂
∂ ∂− = + −
∂ ∂
(23)
The integrating with respect to Y of Eq. (19) as,
( ) ( )4
42
4
( )4( )( )
b b
i j j bb
A
d f XdY g Y dY
dXD f g q g
−−+∇ ⋅ − = ∫∫
�������
( ) ( )
32
2 2 32
2 2 3
( ) ( ) ( ) ( )2 1 2sin ( ) 4sin ( )
b b
b b
AA
d g Y d f X dg Y d f Xg Y dY g Y dY
dYdY dX dXϕ ϕ
− −+ + − +
∫ ∫
����������������������������
( ) ( )1 0
3
3
5
4 4
4
( ) ( ) ( ) cos4sin ( ) ( ) ( ) ( ) 0
bb b
b b b
AA A
dg Y df X d g Y qg Y dY g Y dY f X
dX DdY dYg Y dY
ϕϕ
− − −− +
− =∫ ∫ ∫���������
������������� ���������
(24)
and in concise form,
54 3 2 1 0
4 3 2( ) ( ) ( ) ( )( )
4 3 2
d f X d f X d f X df XA A A A A f X A
dXdX dX dX+ + + + = (25)
Dividing both sides by A4 , yields: 4 3 2
3 0 52 14 3 2
4 4 4 4 4
( ) ( ) ( ) ( )( )
X X X XX
XX X X
A AA A Ad f d f d f dff
A A A d A Ad d d+ + + + = (26)
In order to obtain the homogeneous solution for the above forth order ODE we assume
f(X)=CemX
then, the corresponding characteristic equation will be:
4 3 23 02 1
4 4 4 4
0A AA A
m m m mA A A A
+ + + + = (27)
Eq. (27) has four roots: 1 1im a i b= ± ± . Therefore, the final answer for the homogeneous and
particular solutions for f(X) becomes as:
1 1 1151 1 2 1 3 1 14
( ) cos( ) sin( ) cos( ) sin( )XX X Xaa a a
X C b X C b X C b X C b X Ce e e ef = + + + + (28)
where 055 /C A A= . The updated forms of boundary conditions for clamped plates in terms of f(X) and
g(Y) would be as:
0, / 0i i
f df dX= = for X a= ±
0, / 0j j
g dg dY= = for Y b= ±
Solving Eq. (25) in conjunction with the first series of new boundary data leads to the first
estimate of the function ( ) 1,i X if = , which we call it ( )f X . Now, having on hand the primary answer
73 Amin Joodaky, Mohammad Hossein Kargarnovin
Saeid Jafari Mehrabadi and Amir Hossein Nasrollah Barati
for ( )if X , it is possible to continue the procedure by introducing the obtained function ( )f X to the
Eq.(26). This yields to a new form of wδ and the Galerkin equation as,
( ) jf X giw δδ = ⋅ (29)
and,
( )4( ) 0i j
b a
jb a iD f g q dX dYf gδ− −
∇ ⋅ − =∫ ∫ (30)
Again, in order to satisfy Eq.(30), the bracket should be vanished. The integration with respect
to X of the expression in the bracket leads to the second forth-order ODE in terms of ( )jg Y as,
54 3 2 1 0
4 3 2( ) ( ) ( ) ( )
( )4 3 2
Y Y Y YY
d g d g d g dgB B B B B g B
dYdY dY dY+ + + + = (31)
The corresponding characteristic equation related to Eq.(31) turns to:
03 2 1
4 4 4 4
4 3 2 0B B B B
n n n nB B B B
+ + + + = (32)
Again Eq.(32) has four roots as: 2 2in a b i= ± ± . So g(Y) could be shown as,
2 2 2 22 2 22 51 2 3 4
( ) cos( ) sin( ) cos( ) sin( )Y Y Y Ya a a a
Y D b Y D b Y D b Y D b Y De e e eg = + + + + (33)
where 05 5 /D B B= .
The procedure is continues by solving ODE (31) together with the second series of new
boundary data and obtaining the new prediction for ( ), 1j
Y jg = which we call it ( )Yg . This will finish
the first cycle of our iteration for determination of deflection equation, i.e. 11
( , ) ( ) ( )X Y f X g Yw ≅ ⋅ . Eqs.
(25) and (31) should then be solved iteratively and new updated estimates for functions ( )Xfi and
( )j
Yg are determined. Iterations continue in the same way until a prescribed level of convergence is
achieved. The initial guess for the function of ( )Yg does not need necessarily to satisfy all of the
boundary conditions. Moreover, if we wanted to consider f(X) as an initial guess it would be,
0
2 2 2( ) ( )XX af = − .
It is worth of mentioning that after calculation of deflection, one can determine all other
mechanical parameters, i.e. rotations, forces and moments using well-known expressions presented
elsewhere, see for instance, [26-29].
3. Results and Discussion Consider a FGM skew plate made of Alumina- Aluminum with all sides clamped and subjected to a
uniform loading. The following plate properties and initial guess for0
( )Yg , are considered in the most
cases although some parameters may have other values for examining their effect on the results:
1,0.3 ,15 /12, 2 0.6 , 2 0.8 , 0.008 , 1000 Paa m b m h m qυϕ π == = = = = =�
0 ,
2
2
2min , ( )70 380 , 0.25 ( )Al Alu a
YYE GPa aE Gpa n g == −= = (34)
The convergence of all parameters used in Eqs. (28) to (33) are, tabulated in the Table 1. The
listed values in this table demonstrate that the convergence rate of the method is very high as there are
no major changes after the second iteration.
Bending and Deflection Analysis of Thin FGM Skew
Plates using Extended Kantorovich Method 74
Table 1: Convergence of parameters in closed-form solutions of a FGM skew plate listed in Eqs. (28), (33).
Parameters Iterations, i, j
Parameters Iterations, i, j
1 2 3 1 2 3
1ia
5.3075 -5.3837 -5.3837 2ia
-7.0697 -7.0697 -7.0697
1ib
2.6283 3.0633 3.0633 2ib
3.6269 3.6260 3.6258
1iC
0.981e-3 0.790e-3 0.790e-3 1iD
-0.391e-2 -0.392e-2 -0.392e-2
2iC
0.283e-3 -0.767e-4 -0.767e-4 2iD
-0.15e-2 -0.145e-2 -0.145e-2
3iC
0.981e-3 0.790e-3 0.790e-3 3iD
-0.391e-2 -0.392e-2 -0.392e-2
4iC
-0.28e-3 0.767e-4 0.767e-4 4iD
0.1453e-2 0.1454e-2 0.1454e-2
5iC
-0.26e-2 -0.221e-2 -0.221e-2 5iD
0.322e-1 0.322e-1 0.322e-1
The FGM skew plate, is modeled in commercial version of ANSYS software using Solid45
element, similar geometrical and material properties listed in (34) and with all four sides clamped. For
considering FGM properties, twenty layers that elasticity modulus of each is obtained from FGM
function of (3) are considered in z direction and then they are glued. Then a normal uniformly
distributed load clamp condition for supports are applied. Finally, a regular meshing by dividing each
side by fifty parts is considered and then the model was analyzed. Tables 2 shows the maximum
deflection (w) which occurs in the center of the skew plate with corresponding values obtained out of
ANSYS, FEM package.
Table 2: Maximum deflection (w), in center of skew FGM plate with angle of 15�, compared to ANSYS
results.
Deflection Iterations, i, j
FEM 1 2 3 4
w (meter) -0.1616e-4 -0.1526e-4 -0.15428e-4 -0.15428e-4 -0.1535e-4
The stresses and moments functions are defined in terms of lateral deflection of w [26-29].
Therefore, after obtaining these functions in Oblique coordinates system, one can let in them,
deflection amounts of every point of the FGM skew plate and achieve stress components for those
points. Figure 3 shows amounts of the stress components of , ,X Y XYσ σ σ as Sx, Sy and Sxy
respectively, for the clamp FGM skew plate.
Figure 3: Stress components diagrams of clamp FGM skew plate for various points of X-axis along Y=0 axis.
75 Amin Joodaky, Mohammad Hossein Kargarnovin
Saeid Jafari Mehrabadi and Amir Hossein Nasrollah Barati
Angle of phi (ω) which is shown in Figure 2, is the factor that changes deflection function of
the skew plate conspicuously. Figure 4 shows the effect of phi (ω) in term of degree, on deflection
function. When phi (ω) is increasing, the non-opposite edges of the skew plate are closer to each other,
so deflection amounts decrease.
Figure 4: Comparison of deflection diagrams of the clamp FGM skew plate vs. X and Y axes in Oblique
coordinates system for different angle of phi (ω) of the skew plate in term of degree.
Figure 5: Comparison of deflection diagrams of the clamp FGM skew plate vs. X and Y axes in Oblique
coordinates system for different amounts of n in FGM function of (3).
Power index of n in FGM function (3), has its effect on deflection diagrams because it changes
elasticity modulus. Figure 5 compares various diagrams for different amounts of n. When n increases,
elasticity decreases, so deflections increase too.
Table 3: Deflection in the center of the FGM skew plate for various n, ϕ and plate dimensions.
Various n and
ϕ Deflection in the center of the FGM skew plate (a, b)
2a=0.5, 2b=1 2a=1, 2b=1 2a=1, 2b=1.5 2a=1, 2b=2 2a=1, 2b=3
n=0
0
15
30
45
60
ϕ
ϕ
ϕ
ϕ
ϕ
=
=
=
=
=
�
�
�
�
�
-0.8859e-5 -0.7093e-4 -0.1228e-3 -0.1417e-3 -0.1464e-3
-0.7600e-5 -0.5985e-4 -0.1047e-3 -0.1216e-3 -0.1271e-3
-0.4740e-5 -0.3578e-4 -0.6361e-4 -0.7585e-4 -0.8162e-4
-0.2007e-5 -0.1441e-4 -0.2618e-4 -0.3211e-4 -0.3540e-4
-0.4788e-6 -0.3296e-5 -0.6094e-5 -0.7664e-5 -0.8744e-5
Bending and Deflection Analysis of Thin FGM Skew
Plates using Extended Kantorovich Method 76
Table 3: Deflection in the center of the FGM skew plate for various n, ϕ and plate dimensions. - continued
n=1
0
15
30
45
60
ϕ
ϕ
ϕ
ϕ
ϕ
=
=
=
=
=
�
�
�
�
�
-0.1783e-4 -0.1424e-3 -0.2467e-3 -0.2852e-3 -0.2937e-3
-0.1523e-4 -0.1201e-3 -0.2102e-3 -0.2437e-3 -0.2550e-3
-0.9504e-5 -0.7172e-4 -0.1275e-3 -0.1521e-3 -0.1637e-3
-0.4031e-5 -0.2892e-4 -0.5246e-4 -0.6449e-4 -0.7168e-4
-0.9587e-6 -0.6628e-5 -0.1224e-4 -0.1535e-4 -0.1762e-4
n=5
0
15
30
45
60
ϕ
ϕ
ϕ
ϕ
ϕ
=
=
=
=
=
�
�
�
�
�
-0.2691e-4 -0.2156e-3 -0.3740e-3 -0.4306e-3 -0.4464e-3
-0.2315e-4 -0.1818e-3 -0.3179e-3 -0.3705e-3 -0.3859e-3
-0.1442e-4 -0.1087e-3 -0.1934e-3 -0.2308e-3 -0.2479e-3
-0.6106e-5 -0.4379e-4 -0.7956e-4 -0.9770e-4 -0.1079e-3
-0.1458e-5 -0.1002e-4 -0.1853e-4 -0.2334e-4 -0.2672e-4
Considering properties of (34), for various n, ϕ and plate dimensions, Table 3 gives center
deflections of the FGM skew plates. Increasing inclination angle of ϕ causes non-opposite edges of
the plate come closer, so deflections decrease. When power index of n in FGM function in (3)
increases, elasticity module decreases, and consequently, deflections increase. It is conspicuous that
enlarging plate dimensions certainly causes larger deflections.
A skew plate, could be compared to, a Rectangular plate when inclination angle equls zero. In
the Table 3, those results for 0ϕ = , could be compared to similar FGM rectangular plate in other
literatures. Table 4 compares the maximum deflection results for a clamped isotropic rectangular plate,
which is obtained, from a skew plate by considering 0ϕ = to a similar rectangular plate in [24] for
different dimensions of the plate.
Table 4: Comparison of maximum deflection (w), in the center of isotropic rectangular plate, which is
obtained from a skew plate by considering, 0ϕ =
with similar results from [24] for different plate
dimension.
Deflection in (a, b) 2a=1 , 2b=1 2a=1 , 2b=1.5 2a=1 , 2b=2
Present [24] Present [24] Present [24] 3
10w−× -0.3905 -0.3894 -0.6775 -0.6800 -0.7806 -0.7851
4. Concluding Remarks Application of EKM based on Galerkin method could successfully obtain a highly accurate
approximate closed-form solution for deflection analysis of FGM skew plates subjected to uniform
loading for clamp boundary conditions. EKM iterative procedure extracts two sets of decoupled
ordinary differential equations in terms of X and Y in Oblique coordinates system from the coupled
forth-order partial differential governing equation of the main problem. The solution procedure then
completes by presenting an exact approximate closed-form solution for two sets of ODE systems in an
iterative scheme. Present study shows that the method provides very fast convergence and highly
accurate predictions. Angle of skew plates has an important role in deflection function. Power index in
FGM function could changes deflection diagram obviously for different presented dimensions of the
skew plate. Comparing to results of other valid literatures and FEM software of ANSYS, there are very
77 Amin Joodaky, Mohammad Hossein Kargarnovin
Saeid Jafari Mehrabadi and Amir Hossein Nasrollah Barati
good agreements with the results of the present studies in every case. Finally, by considering
inclination angle of skew plate equals zero, the present studies could be developed and compared to
rectangular plates.
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