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Asked by edison to Rachel E on 14 Mar 2024.
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Rachel Edwards answered on 14 Mar 2024:
If sound was really REALLY loud, it might shake the track enough to break it. We see that sometimes with earthquakes, when they move the ground and that breaks roads and railway tracks.
Instead… we use much quieter sounds to try and find problems like cracks that happen because the tracks have to carry such heavy trains. We send sound along the railway track, and we can either listen for echoes which bounce off any cracks, or we can listen to see how the sound changes at different positions along the track. If there are any cracks it changes how the sound travels along the railway tracks.
Railway tracks were designed with such a clever shape that they can carry really heavy trains without problems most of the time!
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Comments
Steve P commented on :
1) impact: sound as a pressure wave carries energy. If the wave front is strong enough it may break a solid object it impacts (but this is exceptionally unlikely for something as strong as a railway line)
2) resonance: the sound with resonant frequency of a structure hits that structure then the size of vibration within that structure can increase to the point at which it breaks.
3) fatigue: dislocations in the crystal structures can be moved around by vibration and impact. Over time / repeated dislocations a matierial can ‘fail’ or lose it’s strength.
Such fatigue and resonance vulnerabilities are rigorously designed out / minimised in the transport (eg rail, air) industries so the chance of a properly designed / maintained / inspected component failing is very small.