2008 international ansys conference · 2016-12-13 · © 2008 ansys, inc. all rights reserved. 2...
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© 2008 ANSYS, Inc. All rights reserved. 1 ANSYS, Inc. Proprietary
2008 International
ANSYS Conference
ANSYS Simulation of Flexible
Machine Elements and Practical
Applications
Dr. K. S. Raghavan
Structures Discipline Chief
Infotech Enterprises Limited, Hyderabad, INDIA
© 2008 ANSYS, Inc. All rights reserved. 2 ANSYS, Inc. Proprietary
FLAT BELTS
VEE BELTS
C S BLOAD AND
POWER
TRANSMISSION
Typical flexible machine components
© 2008 ANSYS, Inc. All rights reserved. 3 ANSYS, Inc. Proprietary
The Need
Structural Analysis of Complex Mechanical Assemblies that Include Flexible Components.
Appropriate Simulation of Load Path and Load Sharing Among Components and Sub-Assemblies.
© 2008 ANSYS, Inc. All rights reserved. 4 ANSYS, Inc. Proprietary
Present Work Process
Formulation
Verification / Validation
Applications
© 2008 ANSYS, Inc. All rights reserved. 5 ANSYS, Inc. Proprietary
Challenges
THE MAJOR CHALLENGE IS TO SIMULATE THE COMLEX NONLINEAR BEHAVIOR
• Effective only longitudinal tension.
• No resistance to longitudinal compression
• Resists thickness-wise compression
• Negligible flexural resistance
• Load transmission through contact only
• Friction plays a major role.
.. AND NO SINGLE CONVENTIONAL FINITE ELEMENT MEETS
THE ABOVE REQUIREMENTS
© 2008 ANSYS, Inc. All rights reserved. 6 ANSYS, Inc. Proprietary
SOLID ELEMENTS, VERY LOW MODULUS
TENSION - ONLY
MEMBRANE ELEMENTS
(FOR TENSILE STIFFNESS)
TWO INTERFACES:
1. BONDED CONTACT / MERGED D.O.F.
2. FRICTION WITH CONTACT
The “Belt” Element
© 2008 ANSYS, Inc. All rights reserved. 7 ANSYS, Inc. Proprietary
Applied Load (T1)
= 40000
Total Reaction (T2)
= 16149
T1 / T2 = 2.477
Theoretical value
(mu = 0.3, theta=180)
= 2.566
% Error < 3.5
Comparison with Euler’s Equation (T1 / T2)
© 2008 ANSYS, Inc. All rights reserved. 8 ANSYS, Inc. Proprietary
RATIO OF TENSIONS VS. COEFFICIENT OF FRICTION
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
0 0.1 0.2 0.3 0.4 0.5C. O. F.
T1
/ T
2
ANSYS-LMTHEORYANSYS-AL
Comparison with Euler’s Equation (T1 / T2)
© 2008 ANSYS, Inc. All rights reserved. 9 ANSYS, Inc. Proprietary
PERCENT ERROR VS. COEFFICIENT OF
FRICTION
-10.00
-9.00
-8.00
-7.00
-6.00
-5.00
-4.00
-3.00
-2.00
-1.00
0.00
0 0.1 0.2 0.3 0.4 0.5
C. O. F.
P.C
. E
RR
OR
P.C. ERROR, ANSYS LM
"P.C. ERROR, ANSyS AL"
Error Percentage
LAGRANGE MULTIPLIER
AUGMENTED LAGRANGIAN
© 2008 ANSYS, Inc. All rights reserved. 10 ANSYS, Inc. Proprietary
Application
1. Qualitative Design analysis of a simple pulley
2. Modeling self – locking wedges
TWO APPLICATIONS
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Stresses in Pulleys : Belt–Pulley Interaction
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Only Pulley – Centrifugal Load
Von MisesRadial
Tangential
(Hoop)
These Stresses are Steady
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Analysis of Pulley with Belt
BELT TENSION
PLUS CENTRIFUGAL
TIGHT
SIDE
SLACK
SIDE
© 2008 ANSYS, Inc. All rights reserved. 14 ANSYS, Inc. Proprietary
Directional Stress
RADIAL
STRESS
TANGENTIAL
STRESS
THESE
STRESSES ARE
UNSTEADY
© 2008 ANSYS, Inc. All rights reserved. 15 ANSYS, Inc. Proprietary
Radial Stress in Four Arms
A1
A2A3
A4
B1B2
B3
B4
© 2008 ANSYS, Inc. All rights reserved. 16 ANSYS, Inc. Proprietary
Tangential Stress in
Four Quadrants of Rim
C1
C2
C3
C4
D1
D2
D3D4
© 2008 ANSYS, Inc. All rights reserved. 17 ANSYS, Inc. Proprietary
Cyclic Variation of Radial and
Tangential Stress
-25
-20
-15
-10
-5
0
5
10
15
20
25
0 100 200 300
ST
RE
SS
ROTATIONAL ANGLE
RADIAL-A
RADIAL - B
-25
-20
-15
-10
-5
0
5
10
15
20
25
0 50 100 150 200 250 300 350
ROTATION ANGLE
ST
RE
SS
HOOP - C
HOOP - D
Stress due to Centrifugal
Force only
© 2008 ANSYS, Inc. All rights reserved. 18 ANSYS, Inc. Proprietary
The stress variation is caused by bending
and distortion of arms and rim.
This cannot be assessed without the use
of “BELT” element
Deformed Shape of Pulley
© 2008 ANSYS, Inc. All rights reserved. 19 ANSYS, Inc. Proprietary
Self Locking Wedge – Assembly
Assembly
(Half)
Socket
Support
© 2008 ANSYS, Inc. All rights reserved. 20 ANSYS, Inc. Proprietary
Wedge Belt - FillingBelt - Core
Free end
Load end
Wedge and Belt
© 2008 ANSYS, Inc. All rights reserved. 21 ANSYS, Inc. Proprietary
Contact / Target Surfaces
Five contact pairs
Three on wedge outer surface
Two on socket inner surfaces
Elements used
SOLID45
SOLID45 (Low Modulus)
SHELL181 (Membrane option)
CONTA174
TARGE170
© 2008 ANSYS, Inc. All rights reserved. 22 ANSYS, Inc. Proprietary
Von-Mises Stress in the Socket
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Deformation and Stress in the belt core
© 2008 ANSYS, Inc. All rights reserved. 24 ANSYS, Inc. Proprietary
Application for a Termination
Device Socket
Width
DD
DDD
DD
DDDDCDDD
DDDDDDD
DD
DDD
DD
DD
DDD
DDD
DDD
DD
D
DD
DDD
DD
DD
DDD
DD
DDDDCDDD
DDDDDDD
DD
DDD
DD
DD
DDD
DDD
DDD
DD
D
DD
DDD
DD
DD
DDD
DD
DDDDCDDD
DDDDDDD
DD
DDD
DD
DD
DDD
DDD
DDD
DD
D
DD
DDD
DD
DD
DDD
DD
DDDDCDDD
DDDDDDD
DD
DDD
DD
DD
DDD
DDD
DDD
DD
D
DD
DDD
DD
DD
DDD
DD
DDDDCDDD
DDDDDDD
DD
DDD
DD
DD
DDD
DDD
DDD
DD
D
DD
DDD
DD
DD
DDD
DD
DDDDCDDD
DDDDDDD
DD
DDD
DD
DD
DDD
DDD
DDD
DD
D
DD
DDD
DD Thickness
Socket
Wedge
Coated Steel
Belt
Loaded End
© 2008 ANSYS, Inc. All rights reserved. 25 ANSYS, Inc. Proprietary
Slotted Side Plates
Pressure Plate
FE Model and a Typical Result
© 2008 ANSYS, Inc. All rights reserved. 26 ANSYS, Inc. Proprietary
Contributions / Value Additions
1. An approach for modeling belt-like components has been developed and validated.
2. Through examples, it has been demonstrated that we need to have a more rigorous approach for the design of components that interact with flexible elements. Otherwise we may miss important “Design” information.
3. This work is an excellent example of using a FEA package beyond its boundaries. The usefulness of the package has been enhanced using innovative ideas.
© 2008 ANSYS, Inc. All rights reserved. 27 ANSYS, Inc. Proprietary
Thank You
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