2008 international ansys conference · 2016-12-13 · © 2008 ansys, inc. all rights reserved. 2...

© 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


FLAT BELTS

VEE BELTS

C S BLOAD AND

POWER

TRANSMISSION

Typical flexible machine components


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.


Present Work Process

Formulation

Verification / Validation

Applications


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


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


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)


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)


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


Application

1. Qualitative Design analysis of a simple pulley

2. Modeling self – locking wedges

TWO APPLICATIONS


Stresses in Pulleys : Belt–Pulley Interaction


Only Pulley – Centrifugal Load

Von MisesRadial

Tangential

(Hoop)

These Stresses are Steady


Analysis of Pulley with Belt

BELT TENSION

PLUS CENTRIFUGAL

TIGHT

SIDE

SLACK

SIDE


Directional Stress

RADIAL

STRESS

TANGENTIAL

STRESS

THESE

STRESSES ARE

UNSTEADY


Radial Stress in Four Arms

A1

A2A3

A4

B1B2

B3

B4


Tangential Stress in

Four Quadrants of Rim

C1

C2

C3

C4

D1

D2

D3D4


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


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


Self Locking Wedge – Assembly

Assembly

(Half)

Socket

Support


Wedge Belt - FillingBelt - Core

Free end

Load end

Wedge and Belt


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


Von-Mises Stress in the Socket


Deformation and Stress in the belt core


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


Slotted Side Plates

Pressure Plate

FE Model and a Typical Result


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.


Thank You

2008 international ansys conference · 2016-12-13 · © 2008 ansys, inc. all rights reserved. 2...

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