1. Operational Deflection Shape
(ODS) Analysis
Taqi-Ud-Din Haider
Vibration Analyst Level – III

2. What is Operational Deflection Shape (ODS) Analysis
• ODS models is a technique for observing the real behavior of
system vibration against any forcing function.
• ODS is the actual machine response, and contains the overall
vibration of components of any system, of both the forced
and resonant (natural frequency) vibration.

3. • Model of the system is created, and then its motion is driven by
sensor measurements (phase and amplitude) called as relative
motion/vibration.
• The relative vibration is measured at various points across the system,
that vibration/motion is known as degrees of freedom (DOF).
What is Operational Deflection Shape (ODS) Analysis

4. Difference between ODS and Modal Analysis
• ODS is performed when machine is in running mode and Modal
Analysis is performed when machine is in stop condition.
• An operating deflection shape shows the deformation of a structure
at a specific frequency or during a time waveform playback.
• The method of modal analysis is similar to ODS, in that, system is
excited by external known force (With Modal Hammer) and response
is measured at various locations of system.
• The primarily concern of modal analysis is to deal with resonance
frequencies (natural frequencies) of a structure, to visualize the
deformation in shape when excited by force.

5. Why ODS Analysis?
• When failed to analyze the problem in routine vibration analysis .
• To locate the origin of forcing function in the system.
• When resonance is suspected and source to identify .
• When the vibration transmission path to identify.
• To study the mode shapes of system.
• To identify non linearity in the system.

6. Resource for ODS Analysis
• Tools
• 2-Channel vibration analyzer with cross channel measurement option.
OR
• Single channel analyzer with tech option for peak and phase measurement.
• Software
• ODS analysis software.
• Skills
• Knowledge of phases analysis.
• Knowledge of coherence analysis.
• Knowledge of mode shapes and resonance
• 3D object modeling skill (CAD) for ODS software

7. Testing Resonance
Cascade Plot Bump Test

8. Measuring Phase Analysis
• Phase is the time difference between two measurements points
of a same cycle of frequency, from a fixed reference point
(Presented in Angle)
10 Time in Sec
``
Heavy
Spot

9. ODS Data Collection Procedure
• Make a sketch of machine with dimension in MM or Inch.
• Marks the points on machine according to sketch.
• Mark No. of point on sketch and machine, points depends upon the
machine size. (don’t mark too close or too far).
• Consider concrete base, foundation, sole/base plate, motor/pump foot,
and associated piping (suction and discharge line) a part of the machine.

10. ODS Data Collection Procedure Cont…
• Identify the nods and antinode points of machine.
• Measure the vibration at different location to point the reference sensor.
• Vibration at reference point should be strong and comparable with other
points for good data and stable phase reading.
• Collect the data from all points if possible e.g. Point 1XYZ, Point 2XYZ …..

11. Example of Machine Sketch
1
8
23
9
4567
1011121314
15
16
17
18192021

12. Example of Marking on Machine
27
6
10
11
14
15
16
17
18
19
20
21
22
23
24
25 26
28

13. ODS Data Collection Procedure Cont…
• Make a worksheet to note down the vibration amplitude and phase.
• In the case of opposite direction of sensor mark (-) negative in sheet.
• Phase reading should be stable.
• Coherence should be stable and > .8,
• In the case of low coherence following point should be consider.
• Sensor location and mounting.
• Change in reference or operating frequency.
• Problem with cable/sensor.
• Non linearity in structure (e.g. loose bolt, and welding cracks, etc.)

14. Datasheet
Point Axis
Sen.
Dir.
Amp. Ph. Coh.
1
X + 5.3 0 .99
Y + 5.2 90 .99
Z + 1.7 235 .99
2
X + 4.3 10 .81
Y + 3.9 110 .70
Z + 5.7 190 .82
3
X - 8.2 180 .92
Y - 6.5 270 .99
Z + 1.6 75 .75
Point Axis
Sen.
Dir.
Amp. Ph. Coh.
4
X - 5.3 100 .81
Y + 5.2 190 .70
Z + 1.7 35 .82
5
X - 4.3 170 .92
Y + 3.9 130 .99
Z + 5.7 160 .99
6
X + 8.2 80 .79
Y + 6.5 27 .78
Z + 1.6 17 .71
Machine ID: RAW Water Pump No. 1. Running RPM: 2450 Frequency: 42 Hz

15. Assigning the Data (Vibration And Phase) to Node Points
• Draw machine model with
same dimension.
• Data to be assign to the
nodes, marked on machine
and raw sketch.
• Good model help to analyze
the problem.
• More data to model,
animation/Mode Shape will
more clear.

16. ODS Animation

17. ODS Frame Sequence

18. Thank You
For any query please contact
Taqi Ud Din Haider
Email: taqi.haider@live.com