Design Of Tuned Mass Design Of Tuned Mass Vibration Absorber To Vibration Absorber To Reduce Vibrations In Reduce Vibrations In Primary System.Primary System.Plz Subscribe for morePlz Subscribe for more www.fastrackengine.com

Overview Of Vibration-Vibration is the study of the repetitive motion

of objects. Vibration is caused by anything that oscillates and it is transmitted through continuous media.

When elastic bodies such as a spring, a beam or a shaft are displaced from the equilibrium position by the application of external forces, and then released, they execute vibratory motion.

Vibrations caused by a system effect other systems, unless the systems are separated.

Causes of vibration-Unbalanced forces in system.Elastic nature of the system.External excitations applied on the system. Dry friction between two mating surfaces causes vibration. Vibration created by strong winds.Earthquake or seismic activity.Defects in assembly of machines such as broken welds, loosely fitted bolts.

Effects Of Vibration-

(A) Desired Effects of vibrations:Musical InstrumentsCompactersVibratory Conveyers ShakersStress RelievingHoppersSieves

(B) Undesirable Effects of vibrations:Unwanted noise. Loosening of the machines parts.Excessive stresses induced in the system. Vibration creates rapid wear of machine parts.Due to heavy vibrations it is difficult to get exact & Correct readings from the instruments.Structural vibrations may collapse the structures such as buildings, bridges etc.Excessive vibration is harmful for humans (kinetosis).‘Resonance’-which may lead to failure of component.

Methods of reducing vibrations-(A) Removing external excitation if possible.(B) There are certain advanced methods available to reduce the vibrations to required level. & These are,

1. Vibration Isolators2. Vibration Dampers3. Vibration Absorbers

Why we select Vibration Absorber-

Ease Of DesignAvoids ResonanceEase Of ModificationNo Effect Of Temperature On WorkingLess Initial CostLess Modification Cost In ComparisonCompact In Nature

Objective- To reduce the vibrations in a primary system

by adding an tuned mass vibration absorber to the system so as to avoid resonance & to achieve optimized performance of machine or equipment.

How It Works?

The principle is that, if a system (Primary system) has undesirable vibrations at an operating frequency which approaches its natural frequency, then to avoid vibrations a secondary system (Absorber System) having its natural frequency equal to the operating frequency, is coupled to the Primary System to reduce its amplitude to zero.

Design Procedure-

Fn1 = (1/2П ) (3E1 I1 /m1 l1³)1/2

Where:Fn1 = Natural frequency of primary system(Hz)m1 = End Mass of primary system(Kg).E1=Modulus of Elasticity of primary system(N/m2).I1= Moment of inertia of primary system(m4).l1= Length of primary system (m)

Fn2 = (1/2П ) (3E2 I2 /m2l2³)1/2

Where:Fn2 = Natural frequency of absorber system(Hz) m2 = End Mass of absorber system(Kg).E2=Modulus of Elasticity of absorber system(N/m2).I2= Moment of inertia of absorber system(m4).l2= Length of absorber system(m).

TO AVOIDE RESONANCE,

Fn1=Fn2= Fn(excitation)

Procedure of calculation of natural Procedure of calculation of natural frequency of frequency of primary system:primary system:

l1 , b1 , t1

I1 = ( b1 * t13) /12

Where, I1 = Moment of inertia of cantilever beam(primary system) b1= Width of cantilever beam (primary system) t1 = Thickness cantilever beam (primary system)

(E1) From Design data book

Procedure of calculation of natural Procedure of calculation of natural frequency of frequency of secondary system:secondary system:

VALIDATION

EXPERIMENTAL SET UP:

EXPERIMENTAL STEPS

GRAPH REPRESENTING EFFECT OF TUNED MASS VIBRATION ABSORBER

ON AMPLITUDE OF VIBRATION

Equipments Used-Equipments Used-

FFT AnalyzerExciterOscillatorAccelerometerNVGATE SoftwareWeighing MachineSpring with end mass

Oscillator NVGATE Software

Weighing Machine

Spring with end mass

Primary system

Accelerometer

Exciter

Applications:•Reciprocating machines.

•Vibration absorber in the transmission lines.

Analysis by comparing Analysis by comparing Unbalanced & balanced mass Unbalanced & balanced mass by ANSYSby ANSYS

Conclusion-

The use of tuned mass vibration absorber easily &

effectively enables us to protect primary system from

undesired self generated or external vibrations by

avoiding resonance & thereby leads to optimized the

performance of primary system.

REFERANCES-REFERANCES- “Mechanical Vibrations”, by G.K.Grover, Nem Chand & Bros, Roorkee, U.K., India, 8th Edition, 2009. “Mechanical Vibrations”, by V.P.Singh,DhanpatRai&Com.Pvt.Ltd, Revised Edition 2009. “Theory of Machines” by R.S.Khurmi, S.Chand Publications Co Ltd India; 15th Revised Edition,2006.“Basic Vibration Theory”, Ralph E. Blake (e-book).www.csaengineering.com

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