Polytec’s non-contact scanning laser vibrometers have proved an invaluable tool in surface wave measurement. Using a scanning laser vibrometer allows the propagation of such waves across the surface of metal or composite structures to be seen. Work on composite materials can highlight the sub-surface failure region caused by the stress resulting from a localised impact. Different instruments are available to measure and study out-of-plane (1D) or full tri-axis (3D) waveforms.
Surface Wave Measurement On Metal or Composite Using Polytec Laser Vibrometers
The phenomenon of surface wave measurement has attracted high interest in pure and applied research in recent years, the most recent relating to potential issues with HS2 (High Speed Rail Link). Lamb and Rayleigh waves travel rapidly across a structure in the region close to the surface.
They present as a ‘rippling’ effect that can, at low amplitudes, tell the observer much about the integrity of that structure. For example, whether there are cracks or stress failures in an airframe or rail track. At higher amplitudes, such as are seen when waves travel rapidly across the ground during an earthquake, they can cause major damage. This is a characteristic that is causing concern in some quarters for the new high speed rail link.