Re: [NSW] Cityrail Millennium Train

["Adam Dunning" <adamdunning@start.com.au>]

For a mechanical engineer, you sure do sound like a structural engineer.  A
mechanical engineer would work on the motion components (possibly cab
controls as well) while a civil or structural engineer would do the body.
I've completed one year of general engineering, and start tomrrow studying
mechanical engineering, and this above fact (mech does this, civil does
that) was made quite clear to all of us (studying eng that is).  While a
mech engineer would have some knowledge of structural behaviours of bodys
etc., the majority of the body would have been built and tested by
civil/structural engineers.

Adam

"Al" <alpout@optusnet.com.au> wrote in message
3a973f67$0$25490$7f31c96c@news01.syd.optusnet.com.au">news:3a973f67$0$25490$7f31c96c@news01.syd.optusnet.com.au...
>
> Geoff Lillico <glillic@msn.com.au> wrote in message
> JApl6.1603$v5.5993@newsfeeds.bigpond.com">news:JApl6.1603$v5.5993@newsfeeds.bigpond.com...
> > Yes there are standards in place.
> >
> > I would hazard a guess and say that not one correspondant to this thread
is
> > a structural engineer and nor am I, but unless you have substantiated
> > evidence to the contrary, I believe it is unwise to suggest that these
new
> > trains do NOT comply to the standards set for the Bureau of Rail Safety
of
> > D.O.T. or those of the Australian Standards Authority.
> >
>
> You could be right there, but anyway it's not a structural engineer you're
> after, but a mechanical, which I'm starting my final year in on Monday, so
> here's my probably totally flawed thoughts about it.  Don't take it as
gospel,
> but rather as a guide to what the designers are considering.
>
> I also work for a company which makes fire trucks, and has done work for
> Goninan on train bodies, bogies etc.  Actually, half the people on the
floor
> there worked for Goninans when they were making the Tangaras and NRs, but
> that's another story.
>
> One thing to consider is that the trains could be built as a monocoque or
> unitary construction, similar to a passenger car such as a Commodore or
> Falcon.  They do not have a fixed chassis such as a truck, but rather the
load
> is taken by the panels all over the vehicle.  This could explain why it
looks
> flimsy, where it could actually have a very strong rigidity (essentially
one
> big box section).  Advantages to this are light weight and high strength,
> which is one reason why most passenger cars are made this way now.  It
also
> gives better energy absorption in a crash, which is why newer cars are
more
> survivable than older ones in crashes.
>
> Also, the material used can affect the standards.  Judging by the colour
of
> the metal in the photos, it's either aluminium or steel sheeting, probably
> aluminium, cause it can be made extremely strong but remains lightweight,
with
> a steel framework as a cheap, but effective backbone.  People, by and
large,
> aren't all that heavy (2000 people on an 8-car train ~ approx 180 - 200
tonnes
> to give a comparison to freight trains), so most of the structural
strength is
> required for the shock loadings that the trains experience, such as going
over
> gaps in the track at points, wind blast from passing trains at high speed,
and
> full throttle-full brake scenarios, such as an uphill into a station.
>
> Finally, the type of accident or load that you consider can make the shape
> substantially different to what you expect.  Passenger cars are designed
for
> accidents coming into the car from the plane of the road (ie front and
sides).
> What are the kinds of accidents a train can expect?  You could possibly
design
> the cab as a crumple zone, on the assumption the driver can get out in
time
> (re Glenbrook).  This also works both ways for front and rear end
collisions.
> You don't have to worry about T-bones, but rolling is another possibility,
> where you don't want the structure to collapse onto people inside it,
which is
> where a monocoque has another advantage.
>
> Hope that helps,
>
> Al
>
>