Investigation of Effect of Different Shim Profiles on
Performance of Shim or Disc Coupling
Sachin R Patil & D. S. Chavan
Department of Mechanical Engineering, R.I.T, Sakharale, Sangli,Maharashtra, India
E-mail: sachinpatil09@gmail.com
Abstract – A coupling is a device used to connect two shafts
together at their ends for the purpose of transmitting
power. Couplings do not normally allow disconnection of
shafts during operation. Flexible disc coupling are being
used in various applications such as connecting turbine to
generator end, motor shaft to pump shaft etc. to
accommodate the radial and angular misalignments in the
coupled shafts and to avoid the undesired dynamic
characteristics of the rotating members. The SHIM/DISC
is the thin metal circular discs which can bend or twist in
order to take the angular and radial misalignment between
two connected shafts.
D. Deepak et al[2] investigated creep behavior of
rotating discs made of functionally graded materials
with linearly varying thickness. The discs under
investigation are made of composite containing silicon
carbide particles in a matrix of pure aluminum.
Paolo Pennacchi and Andrea Vania[3] has studied
severe misalignments can generate cracks in the stub
shafts, which can propagate in operating condition. Due
to the flexural flexibility of the load coupling, the shaft
vibrations may be not noticeably affected by some
typical symptoms that usually point out the presence of
a crack.
The main objective of the analysis of flexible coupling is
material saving. The work under this title is to investigate
the different shapes of the Disc and its effect on induced
stresses & strain in the disc. The disc profile is the factor
which affects the stiffness & thus stresses/strain induced in
the discs and thus effects indirectly to the maximum
allowable angular & radial misalignments. The analysis of
the Straight edge profile shim coupling is done by FEA. By
studying these results new shim or disc profile is designed
& analyzed. Finally from the comparing performance
parameters, optimum shim or disc profile is selected.
Jin-Yang Liu ·Hao Lu[4] studied not only coupling
between the large overall motion and the bending
deformation, but also coupling between the large overall
motion and the torsional deformation. Finite element
method is employed for discretization. Simulation of a
hub-beams system is used to show the coupling effect
between the large overall motion and the torsional
deformation as well as the longitudinal deformation.
The results got from FEA shows that the total deformation
and von-mises stresses are decreased for scalloped-3 shim
profile than straight edge shim profile for both radial and
angular misalignment load case. The overall material is
saved by 29% for scalloped-3 shim profile than straight
edge shim profile.
II. INTRODUCTION
A coupling is a device used to connect two shafts
together at their ends for the purpose of transmitting
power. Couplings do not normally allow disconnection
of shafts during operation. The primary purpose of
couplings is to join two pieces of rotating equipment
while permitting some degree of misalignment or end
movement or both.
Keywords— Disc Coupling, Finite Element Analysis, Shim,
Optimization
I.
LITERATURE REVIEW
Flexible couplings are used to transmit torque from
one shaft to another when the two shafts are slightly
misaligned. Flexible couplings can accommodate
varying degrees of misalignment up to 3° and some
parallel misalignment. In addition, they can also be used
for vibration damping or noise reduction[7]. Flexible
disc coupling are being used in various applications
K.M. Al-Hussain[1] has examined the effect of
misalignment on the stability of two rotors connected by
a flexible mechanical coupling subjected to angular
misalignment. The study performed is to understand the
effect of angular misalignment on the stability of
rotating machinery.
ISSN (Print): 2321-5747, Volume-1, Issue-2, 2013
54
International Journal on Mechanical Engineering and Robotics (IJMER)
such as connecting turbine to generator end, motor shaft
to pump shaft etc. to accommodate the radial and
angular misalignments in the coupled shafts and to
avoid the undesired dynamic characteristics of the
rotating members. The SHIM/DISC is the thin metal
circular discs which can bend or twist in order to take
the angular and radial misalignment between two
connected shafts[6].
III. FINITE ELEMENT ANALYSIS
The modeling of coupling was done in "Pro-E"
software. This model is imported in the workbench of
Ansys 13.0 software. The meshing was done with solid
186 element which is suitable for this model.
Fig.2 Total Deformation for Radial MisalignmentStraight Edge Shim Profile
Here, the area of interest is shim, so this model is
discretized with hex dominant. Various meshing
methods with mapped meshing & body sizing are
applied for each part of flexible coupling by keeping
same mesh sensitivity. The meshing controls like sweep
meshing method, mapped face meshing and body sizing
with solid element are applied for meshing of shim. The
loading and boundary condition of coupling is shown in
Fig.1.
Fig.3 Von-mises Stresses for Radial MisalignmentStraight Edge Shim profile
Fig.1 Loading and Boundary Condition
The finite element analysis of Straight edge disc
coupling was done. The maximum allowable axial
misalignment is 1.4 mm and angular misalignment is
0.5̊. The analysis was carried with two cases, first bolt
pretension, torque & radial misalignment and second
bolt pretension, torque & angular misalignment. Fig.2
& Fig.3 shows the ANSYS result of total deformation
and von-mises stresses for radial misalignment of the
straight edge disc respectively and Fig.4 & Fig.5 shows
the ANSYS result of total deformation and von-mises
stresses for angular misalignment of the straight edge
disc respectively.
Fig.4 Total Deformation for Angular MisalignmentStraight Edge Shim Profile
ISSN (Print): 2321-5747, Volume-1, Issue-2, 2013
55
International Journal on Mechanical Engineering and Robotics (IJMER)
Fig.7 Von-mises Stresses for Radial MisalignmentScalloped-1 Shim Profile
Fig.5 Von-mises Stresses for Angular MisalignmentStraight Edge Shim Profile
The results got from FEA analysis has shown that ,
the total deformation and von-mises stresses are
increased in angular misalignment load case than in
radial misalignment load case. The stresses at the bolt
periphery are neglected due to contact stress.
IV. DESIGN AND ANALYSIS OF NEW SHIM
PROFILES
The stresses generated in the middle span of bolts at
the edges of disc are lower. So by material can be
removed from the area in the middle of the span
between bolt holes without affecting the disc’s ability to
handle axial and angular misalignment, so that straightsided and scalloped discs perform equally. From this the
new shim profile called Scalloped-1 is designed. The
analysis of coupling with scalloped-1 shim profile by
keeping same loading and boundary is carried out. Fig.6
& Fig.7 shows total deformation and equivalent stresses
for radial misalignment of scalloped-1 shim profile
respectively. Fig.8 & Fig.9 shows total deformation and
equivalent stresses for angular misalignment of
scalloped-1 shim profile respectively.
Fig.8 Von-mises Stresses for Angular MisalignmentScalloped-1 Shim Profile
Fig.9 Von-mises Stresses for Angular MisalignmentScalloped-1 Shim Profile
Fig.6 Total Deformation for Radial MisalignmentScalloped-1 Shim Profile
ISSN (Print): 2321-5747, Volume-1, Issue-2, 2013
56
International Journal on Mechanical Engineering and Robotics (IJMER)
From above figures and results got from analysis,
For radial and angular misalignment load case total
deformation and von-mises stresses are decreased than
straight edge shim profile. For manufacturing simplicity
the corner edges at the periphery of the bolts are
removed and made it round with the bolt periphery and
analysis is carried out. The analysis is carried with this
newly design shim profile called scalloped-2 having
same loading and boundary condition. Total
deformation and equivalent stresses for radial
misalignment and angular misalignment of scalloped-2
shim profile is shown in Fig.10 & Fig.11.and Fig.12 &
Fig.13 respectively.
Fig.12 Total Deformation for Angular MisalignmentScalloped-2 Shim Profile
Fig.10 Total Deformation for Radial MisalignmentScalloped-2 Shim Profile
Fig.13 Von-mises Stresses for Angular MisalignmentScalloped-2 Shim Profile
The results shows that for radial misalignment load
case, total deformation and von-mises stresses are
increased than scalloped-1 shim profile. Though the
stresses are increased these are lower than yield strength
of material. For angular misalignment load case, total
deformation is decreased and von-mises stresses are
increased than scalloped-1 shim profile. Though the
stresses are increased these are lower than yield strength
of shim material.
V. RESULT AND DISCUSSION
The results got from analysis are tabulated in the
following Table I.
Fig.11 Von-mises Stresses for Radial MisalignmentScalloped-2 Shim Profile
ISSN (Print): 2321-5747, Volume-1, Issue-2, 2013
57
International Journal on Mechanical Engineering and Robotics (IJMER)
Table I. Results of Coupling Analysis
Profile
Name
Straight
Edge
Scalloped-1
Scalloped-2
Radial Misalignment
Total
VonDeformation
mises
(mm)
Stress
(MPa)
0.4390
880.90
Angular Misalignment
Total
VonDeformation
mises Stress
(mm)
(MPa)
0.7645
730.84
0.3540
587.44
0.7015
598.47
0.3825
592.78
0.6467
603.53
analysis for straight edge shim profile was done by FEA
and by using this results, new profile is designed. The
analysis for this profile is done for the same loading and
boundary condition.
From results got by FEA the following conclusions
are drawn:
1.
For flexible coupling having straight edge shim
profile has total deformation and von-mises
stresses are more than newly designed shim
profile called scalloped-2 for both radial and
angular misalignment cases.
2.
For flexible coupling with scalloped-2 shim
profile, the stresses are decreased by 32% for
radial misalignment and by 17% for angular
misalignment than straight edge shim profile.
3.
The overall material is saved by 22% for
scalloped-2 shim profile than straight edge
shim profile.
VII. REFERENCES
Fig.14 Graph of Total Deformation Vs Shim Profile
[1]
K.M. Al-Hussain, Dynamic stability of two rigid rotors
connected by a flexible coupling with angular
misalignment, Journal of Sound and Vibration 266
(2003) 217–234.D.
[2]
Deepak , V. K. Gupta and A. K. Dham, Creep
modeling in functionally graded rotating disc of
variable thickness, Journal of Mechanical Science and
Technology 24 (11) (2010) 2221~2232.
[3]
Paolo Pennacchi , Andrea Vania, Diagnostics of a
crack in a load coupling of a gas turbine using the
machine model and the analysis of the shaft vibrations,
Mechanical Systems and Signal Processing 22 (2008)
1157–1178.
[4]
Jin-Yang Liu, Hao Lu, Rigid-flexible coupling
dynamics of three-dimensional hub-beams system,
Multibody Syst Dyn (2007) 18: 487–510.
[5]
Fengyan Deng, Xingsuo He, Liang Li, Juan Zhang,
Dynamics modeling for a rigid-flexible coupling
system with nonlinear deformation field, Multibody
Syst Dyn (2007) 18: 559–578.
[6]
Jon Mancuso, Joe Corcoran, What are the differences
in high performance flexible coupling for
turbomachinary?
[7]
Joe Corcoran, Douglas Lyle, Patrick McCormack, Tim
Ortel, Advances in gas turbine couplings.
[8]
Jon R. Mancuso,“Coupling and Joints: Design,
selection, and application”, second edition, Marcel
Dekker,Inc,New York.
[9]
Shigley, “Mechanical Engineering Design”, Tata
McGraw Hill Company, New Delhi.
Fig.15 Graph of Von-mises stresses Vs Shim Profile
Fig.14 and Fig.15 Shows graph for total
deformation and von-mises stresses Vs shim profile
respectively. The results and graph shows that, for
scalloped-2 shim profile total deformation and vonmises stresses in radial misalignment case are decreased
than straight edge shim profile. In case of angular
misalignment, total deformation and von-mises stresses
are decreased for scalloped-2 shim profile than straight
edge shim profile. For scalloped shim profile the
stresses are decreased by 48% for radial misalignment
and by 21% for angular misalignment than straight edge
shim profile.
VI. CONCLUSION
The main objective of this analysis was material
saving of shim of flexible coupling by using FEA. This
paper presents the optimization of shim profile by using
finite element method for flexible coupling. First

ISSN (Print): 2321-5747, Volume-1, Issue-2, 2013
58