# ODS (Operational Deflection Shape) Analysis, When and Why?

Vibration Analyst Cat - III, Mobius Institute Approved Instructor em SUMICO Technologies Pvt Limited
12 de Dec de 2018
1 de 18

### ODS (Operational Deflection Shape) Analysis, When and Why?

• 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