ODS modeling visualizes how a machine or structure moves while in operation. It helps identify abnormal or excessive motion, uncovering hidden faults that static inspections can miss.
ODS (a little more info)
⚙️ What is ODS (Operational Deflection Shape)?
Operational Deflection Shape (ODS) analysis is a dynamic testing method used to visualize how a machine or structure moves (deflects) while it's operating. It helps you see the actual vibratory motion of equipment under running conditions—something that can’t be captured with static inspection or idle modal testing.
Think of it like slow-motion x-ray vision for vibration: you’re not just looking at numbers on a spectrum, you’re seeing how parts of a machine actually move in space.
🧠 What Does It Do?
ODS tells you:
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Which parts of a machine or structure are moving the most
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Where vibration energy is being amplified or transferred
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How forces travel through a system
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Where support or stiffness may be lacking
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If any components are flexing, resonating, or out-of-phase with others
🛠️ What Is ODS Used For?
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Diagnosing resonance or structural amplification
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Visualizing vibrational modes in rotating equipment, piping, beams, and frames
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Identifying loose parts, frame soft spots, or flex points
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Verifying that repairs (like adding supports or braces) actually change the dynamic response
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Troubleshooting unexpected vibration that doesn’t show clear fault frequencies
🔍 How Does ODS Work (Step by Step)?
1. Sensor Placement
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Accelerometers or laser vibrometers are placed on multiple points of the machine or structure (usually in a grid pattern).
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Sensors can measure motion in 1, 2, or 3 axes (X, Y, Z).
2. Data Collection
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Vibration data is collected while the machine is running under normal load.
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All points must be measured either simultaneously (with multiple channels) or in sequence with a reference sensor fixed at one location.
3. Synchronized Phase Measurement
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ODS is not just about amplitude—it also measures the phase of the vibration at each point.
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This phase data allows you to understand how different parts move relative to each other (e.g., in-phase vs out-of-phase motion).
4. Data Processing
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The collected time-domain signals are transformed using FFT to get spectral information.
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The analyst selects one or more frequencies of interest (usually peaks from spectrum).
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The software then uses the phase and amplitude at each point to reconstruct a motion map.
5. 3D Animation
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Using a model of the structure (or imported CAD model), the system animates the machine’s motion at that frequency.
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The result is a visualization of the deflected shape—you can watch how the structure moves, bends, twists, or vibrates at specific frequencies.
🧭 Example Use Case (Real-World Style):
A paper mill had high vibration on a fan motor. Spectrum analysis didn't point to any classic faults. ODS was performed and revealed that the frame supporting the fan was flexing at ~120 Hz. Adding steel bracing in specific spots eliminated the flexing and reduced vibration by 60%. Traditional analysis couldn’t have shown this—it was a structural resonance problem, not a bearing or balance issue.
🧪 Important Notes:
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ODS is not Modal Analysis:
ODS shows how a structure moves while operating. Modal analysis shows natural frequencies under controlled excitation (usually offline). -
ODS doesn’t identify root cause by itself, but it shows where to look.
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It’s a powerful visual complement to frequency and waveform analysis.