Crash helmets, how long do they last??

[Deon]

would you class this as a shatter ?

Mmmmm.... very interesting !

@Winston,
You might have convinced yourself mate, but you will never convince me. Anyway, that is what makes life interesting. We all have our different views.

Deon

[mecki]

You are not trying to tell us that ther was actually a head in that helmet when it was destroyed. 
I don't think anybody would have survived that and furthermore there is no blood and/or brain matter on it.
Therefore it looks more like an axe than an accident to me.
And I guess painting a helmet helps to make it shatter too. 

[Winston Smith]

With you there Mecki.

I would not say shattered in any case, that has had severe impact and it has cracked/broken/split.

Shatter would imply like glass into shards or numerous small pieces.

[routemaster]

It would interesting to know what caused that sort of damage, particularly given there is a fairly long relatively straight/clean cut edge to some of it?

Kind regards

Steve

[Lonewolf]

Steve if I were to hazard a guess, I'd say a Dewalt Stihl saw! 

[Winston Smith]

Well, lets agree to disagree. Plastic does not shatter like a composite lid would on impact and plastic does not have a "memory".

Not here to agree, disagree or otherwise.  Plastic would have a memory.  It will return to it's original shape or break, although the type of plastics used in helmet construction are designed not to break.  A composite shell is more likely to delaminate, but in doing so will become malleable.  Such design is to prevent continued pressure on skull in a severe crush impact.

So, if impact "crushes" helmet it will stay in that shape putting pressure on the brain.

The polystyrene inner absorbs the impact and crushes to save the skull.  This stuff has no memory and will remain crushed once its job is done.  One reason for not wearing a helmet that has been dropped is that the outer shell may have bent on impact then returned to it's original shape having crushed the inner polystyrene liner.  Visual inspection would not show any signs, but if another impact occurred at the same point on the helmet there would be no protection afforded to the skull

I for one, will never wear a plastic lid - because I don't have a plastic brain !! 
But, it is your life, so wear what you like I suppose

All helmets on sale in the UK are to the required EEC standard and will do their job.  Plastic or composite they are OK.
Biggest difference is finish, inner lining quality and QC in respect of construction aligned to development and research.

I am personally a fan of composite lids, lighter and usually better constructed, however plastic lids are more likely to have a consistent thickness of shell due to the more automated injection processes utilised, opposed to 'hand laid' composite layers of kevlar/fibre glass and resin etc.

I do value my head, I would always go mid to high end, but fit is more important than cost or construction bearing in mind the standards are the same whether you buy a Box or an Arai