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STUDY ON FACTORSAFFECTING BENDING STRESS

IN ASYMMETRIC GEARS

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Presented By:

Prabodh Sai Dutt R

1stSem M.Tech; CAMS

VVCE, Mysore

Under the guidance of:

Sri Thamme Gowda C.S.

Prof. Dept of Mechanical

VVCE, Mysore

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Gears are toothed members which transmit power / motion

between two shafts by meshing without any slip.

STUDY ON FACTORS AFFECTING BENDING STRESSES IN ASYMMETRIC GEARS

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Wooden Gears in olden wind

mills

Plastic gears

Compact Gears in modern wind mills

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Asymmetric Gears

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STUDY ON FACTORS AFFECTING BENDING STRESSES IN ASYMMETRIC GEARS

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Pressure Angle:

It is the angle at a pitch point between the line of pressure which

is normal to the tooth surface, and the plane tangent to the pitch

surface.

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STUDY ON FACTORS AFFECTING BENDING STRESSES IN ASYMMETRIC GEARS

Gear Tooth with different pressure

anglesPressure Angle and Profile Angle

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Peaking effect:

It is the phenomenon in which the top land of gear becomes

smaller with the increase in pressure angles and the tooth shape

becomes more and more pointed.

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Pointed gear tooth

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Table 1:Tip thickness for different pressure angles

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Comparison between symmetric and Asymmetric

Gears13-Dec-13

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STUDY ON FACTORS AFFECTING BENDING STRESSES IN ASYMMETRIC GEARS

Meshed gear tooth Stress distribution on gear tooth

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Gear model(drive/coast) von mises,N/mm2

Total

deformation,

mm20/20 47.06 0.003831225/20 44.21 0.003516030/20 41.03 0.003356535/20 37.98 0.0031818

Von Mises stress and distribution for symmetricand asymmetric gears

STUDY ON FACTORS AFFECTING BENDING STRESSES IN ASYMMETRIC GEARS

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Sl.

No. Description Value1 Number of teeth on

pinion 18 25 322 Module 2mm 4mm 6mm3 Pressure angle, Coast side 200 fixed4 Pressure angle, Drive side 200-350increment by 105 Back up ratio 1.2

Effect of module and number of teeth of a gear on the bending

stress

Gear tooth parameters with different module and

teeth

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STUDY ON FACTORS AFFECTING BENDING STRESSES IN ASYMMETRIC GEARS

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Tooth thickness at the critical section for different

modules.

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STUDY ON FACTORS AFFECTING BENDING STRESSES IN ASYMMETRIC GEARS

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Bending stress at the critical section for different number of

teeth.

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STUDY ON FACTORS AFFECTING BENDING STRESSES IN ASYMMETRIC GEARS

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Bending stress at the critical section for different modules

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STUDY ON FACTORS AFFECTING BENDING STRESSES IN ASYMMETRIC GEARS

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Displacement at the gear tooth root for different number of

teeth.

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STUDY ON FACTORS AFFECTING BENDING STRESSES IN ASYMMETRIC GEARS

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Potential Applications:

Automotive engineering

Aerospace engineering

Agriculture machines

Medical instruments

Toys

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Advantages of Asymmetric Gears:

Contact stress reduction on the drive flanks

Higher torque density (load capacity per gear size)

Reduced Weight & Size

Reduced Noise

Reduced Vibration

Disadvantage:

It can only be used for unidirectional power transmission

Higher cost of production

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CONCLUSION

Asymmetric gears have better performance in terms of load

bearing capacity compared to symmetric gears

Tooth peaking effect and safe contact ratio limits the degree of

asymmetry that can be achieved.

The bending stress in asymmetric gears decrease with the

increase in module

The bending stress decreases with the increase in number of teeth

of asymmetric gears

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References

1. Effect of Pressure Angle on Bending Stress and Deformation of Asymmetric

Spur Gear Using FEA- MR. K. D. DADHANIYA, PROF. K. P. HIRPAR, MR.

K. M. VYAS - IOSR Journal of Engineering Apr. 2012, Vol. 2(4) pp: 616-620

2. Improvement of Load Caring Capacity of Spur Gear by Asymmetric Teeth - D.

A. Patel, P. A. Vaghela, 5th International Conference on Advances in

Mechanical Engineering 2011

3. Parametric analysis of Asymmetric Spur Gear Tooth - G. Mallesh, Dr. V B

Math, Venkatesh, Shankarmurthy H J, Shiva Prasad P, Aravinda K

NaCoMM09, December 2009. Pg no 398-403

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Thank You

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