Proposal Vibration Group 1F

8/18/2019 Proposal Vibration Group 1F

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1.0 PROBLEM STATEMENT

A vibrating plate at unknown frequencies is given in this laboratory and we need to propose a

vibration measurement to investigate the vibration. The measurement must provide the

following information :

a) Frequencies of the first five dominant modes

b) Changes on vibration magnitude if the plate is vibrated the lowest frequency mode

2.0 HYPOTHESIS

The frequency and the amplitude depends on the vibrating plate. The higher the frequency the

higher the amplitude.

3.0 PROPOSED SOLUTION AND REASON

The solution is to use the modal analysis using shaker testing.

!odal analysis is a process whereby we describe a structure in terms of its natural

characteristics which are the frequency damping and mode shapes which are its dynamic

properties. "n modal testing F#F measurements are usually made under

controlled conditions where the test structure is artificially e$cited by using either an impact

hammer or one or more shakers driven by broadband signals. A multi%channel FFT analy&er

is then used to make F#F measurements between input and output '(F pairs on the test

structure.

*AT "+ F#F !,A+-#,!,T+/


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The Frequency #esponse Function 0F#F) is a fundamental measurement that isolates the

inherent dynamic properties of a mechanical structure. ,$perimental modal parameters

0frequency damping and mode shape) are also obtained from a set of F#F measurements.

The F#F describes the input%output relationship between two points on a structure as a

function of frequency. ince both force and motion are vector quantities they have directions

associated with them. Therefore a F#F is actually defined between a single input '(F 0point

1 direction) and a single output '(F.

+*A2,# T,+T"3

hen the input is fi$ed and F#Fs are measured for multiple outputs this corresponds to

measuring elements from a single column of the F#F matri$. This is typical of a shaker test.

+ingle #eference 0or +"!() Testing is the most common type of modal testing is done with

either a single fi$ed input or a single fi$ed output. hen a single fi$ed input 0a shaker) is

used this is called +"!( 0+ingle "nput !ultiple (utput) testing. "n this case the single fi$ed

input is called the reference. ot all structures can be impact tested however. For instance

structure with delicate surfaces cannot be impact tested. 4ecause hitting the surface with

hammer will surely ruin the surface. (ther than that because of its limited frequency range or

low energy density over a wide spectrum the impacting force is not be sufficient to

adequately e$cite the modes of interest. +haker test usually is continuous and it is easy for the

sensor to take readings compare to impact test which is not so consistent. A shaker is usually

attached to the structure using a stinger 0long slender rod) so that the shaker will only impart

force to the structure along the a$is of the stinger the a$is of force measurement. A load cell

is then attached between the structure and the stinger to measure the e$citation force. At least

a 5%channel FFT analy&er and a single a$is accelerometer are required to make F#F

measurements using a shaker.

4.0 DESIGN OF EXPERIMENT


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Figure 1 ,$perimental setup

Pr!"e#ure

1. Make sure the accelerometer is frmly attached, or the accelerometer to

detect true vibration behaviour.2. Install The plate on the table at the horizontal position.3. un the !ab"I#$ sot%are in the computer.

&. 'onnect the (unction )enerator, si)nal conditioner, *I data lo))er,accelerometer and 'omputer %ith each other to sho% the output result or

the re+uency.. -ttach a sensor that can detect vibration behaviour and convert it into

si)nal.. ecord the values o The re+uency o the vibration on plate rom the

!ab"I#$./. epeat the 0rocedure by usin) 2 z at unction )enerator.

$.0 FLO%&HART

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'.0 SIGNAL ANALYSIS

The investigation of vibration analysis is used to measure the vibration of flat plate based on

given parameter:

6. (btain the frequencies of first five dominant modes.

5. !easure and compare the measured and actual value when the signal is obtained

7. The differences on vibration magnitude if the plate is vibrated the lowest frequency

mode.

(.0 MEASURED PARAMETERS

The investigation of vibration analysis is used to measure the vibration of flat plate based on

given parameter:

6 (btain the frequencies of first five dominant modes.

5 The differences on vibration magnitude if the plate is vibrated the lowest frequency

mode

T80


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).0 SENSOR AND INSTRUMENTS

*i+r,-i! /,er

%'evice in vibration to e$cite the structure either for endurance testing

I&P Sig, &!#i-i!er

%!easure dynamic pressure force or strain which convert mechanical strain into electrical

signal or waveform)

S-r,i G,uge

%!easure strain on ob8ect

D,i" S-r,i Me-er

%!easuring the dynamic strain caused by vibration the dynamic behavior of a structure can

be numeri&ed and graphed in wave form. The analog signal is amplified output and recorded

to an e$ternal recorder

A""eer!e-er

%!easuring the acceleration of a moving or vibration body

O/"i!/"!5e

%'isplays and analyse the waveform of electronic signal and draws a graph of instantaneous

signal voltage as a function of time


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NI USB D,-, L!gger

%!easurements at set intervals over a period of time

L,+*IE% Sig, Pr!"e//ig

%Create simulation

6.0 &ON&LUSION

As a conclusion students was e$posed to more understanding about vibration analysis on

plate. "n the e$periment we have studied the frequencies of first five dominant nodes and

changes of vibration magnitude if the frequency vibration is lower. From our observation we

can conclude the different of the e$perimental frequency compare than actual frequency is

due to errors that disturb with the vibration of the plate. *ence that we was understand about

vibration analysis on plate and the ob8ectives of this e$periment is achieved.

10.0 REFEREN&ES

'ibble #obert . 9!, 6;A < ,$perimentation and !easurement= -niversity of California

at 4erkeley.

#einkensmeyer 'avid >. 9!A, 6? !echanical +ystems @aboratory= -niversity of

California at "rvine.

2iritsis . *uang . 1 Ayrapetyan '. 057). A multi%purpose vibration e$periment using

@abview. American +ociety for ,ngineering retrieved from

http:BBwww.my.ni.comBpdfBacademicBusB8ournalsBamultipurposevib.pdf

http:BBwww.reliabilityweb.comBinde$.phpBarticlesBhowisvibrationmeasuredB

Proposal Vibration Group 1F

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