High Speed Sampling to Catch Vibration in Structures

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High Speed Sampling to Catch Vibration in
Structures
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The Problem

• Impact or Rattle In a Structure
• spreads rapidly through structure
• speed of sound in metal circa 5000m/s compared to
  air at circa 250m/s
• difficult to identify point of origin
• subsequent rattle or ticking noise hard to locate
• Step by Step part modification
• is time consuming
• sometimes results in multiple simultaneous
  parameter changes
• requires skilled operator assessments

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The Solution

• Measure vibration simultaneously around structure
• requires phase matched transducers and parallel
  sampling
• Use high sample rates to find point of origin
• 100kHz sampling will resolve circa 4cm spatially
• 400kHz will resolve about 1cm

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Prove out on simple structure

• Test Parameters
• 100.000Hz Sampling Rate
• 8 Channels Simultaneously Sampled
• Pre-Trigger 0.1s
• Sampled 1s

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Prove out Results
Mounted as shown in photo
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Prove out Results
All mounted in one plane at tube end
Impact at this end
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Example Steering gear ticking

• Ticking or Rattling noise audible in vehicle
  during light steering over small bumps
• Needed to localise ticking source
• 8 accelerometers placed around steering gear

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Ticking Measurements
Accel 2 starts first and shows largest amplitude
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Result- Origin Located

• Ticking originates at upper tower bearing
• plots clearly show origin at pt2 and spread to
  further away locations according to distance

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Further Applications

• Location of Rattles in Structures
• e.g. car seats, dashboards roof liners etc.
• Locating Intermittent Noise sources in complex
  systems
• e.g. Powertrain structures, Gearboxes, Radiators,
  Climate Systems etc.

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End