Another engineering design failure - this time for high speed trains

[studiot]

The preliminary report on why the UK's most recent high speed trains had to be withdrawn from service has been published.

Apparently metal fatigue and stress-corrosion cracking were the causes of cracking in different components.

Amazing that such design mistakes can still occur.

What a good job they were found before any accidnets were caused.

https://www.bbc.co.uk/news/uk-england-58494275

Hitachi train cracks due to fatigue and corrosion, report says

[MigL]

Maybe train designers don't think trains are subjected to extreme stesses.
Aircraft designers learned their lesson a long time ago.
Again in Britain; read up on the de Havilland Comet.
Turns out square windows in a stressed tubular structure are a no-no.

de Havilland Comet - Wikipedia

[exchemist]

1 hour ago, studiot said:

The preliminary report on why the UK's most recent high speed trains had to be withdrawn from service has been published.

Apparently metal fatigue and stress-corrosion cracking were the causes of cracking in different components.

Amazing that such design mistakes can still occur.

What a good job they were found before any accidnets were caused.

https://www.bbc.co.uk/news/uk-england-58494275

Hitachi train cracks due to fatigue and corrosion, report says

 

From the article it appears the trains have been returned to service, without being repaired first, subject to careful monitoring to see if the cracks develop further, which they have not. So it does not look as if there is judged to be a risk of accidents due to these cracks. (The "yaw dampers" will, I presume, be the dampers that prevent the bogies from hunting at high speed.)

[studiot]

45 minutes ago, MigL said:

Maybe train designers don't think trains are subjected to extreme stesses.
Aircraft designers learned their lesson a long time ago.
Again in Britain; read up on the de Havilland Comet.
Turns out square windows in a stressed tubular structure are a no-no.

de Havilland Comet - Wikipedia

 

28 minutes ago, exchemist said:

From the article it appears the trains have been returned to service, without being repaired first, subject to careful monitoring to see if the cracks develop further, which they have not. So it does not look as if there is judged to be a risk of accidents due to these cracks. (The "yaw dampers" will, I presume, be the dampers that prevent the bogies from hunting at high speed.)

 

Thank you both for your thoughts.

Yes, we have discussed deHavilland before. Geoffrey was one of the most talented aircraft designers ever. But he obviously worked without the benefit of Roark or Klein-Logel.
And for fatigue, stresses don't have to be extreme, they just need sufficient repetition. I had always understood that the worst comet failures were fatigue at the root of the alloy wings.

 

I can't say I am keen on knowing that our most advanced and recent trains were designed in such a way as too need 'monitoring' well before much more elderly trains have been withdrawn from service.