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Help program

 
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oggyogg
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PostPosted: Mon Jun 22, 2015 11:31 pm    Post subject: Help program Reply with quote

Hello everybody,
I'm a mechanical engineer & i'm a beginner in Fortran 77.
plz i need to write a program in .txt file in order to put it in my main program any help:

the input file is :
4
1 0,0
2 0,5
3 10,5
4 10,0
3
1 1,2 1000,2,5
2 2,3 1000,4,20
3 3,4 1000,2,5
1 1,1,1 0,0,0, 0,0,0
2 0,0,0 5,0,0, 0,0,0
3 0,0,0 5,0,0, 0,0,0
4 1,1,1 0,0,0, 0,0,0

Running this with input file produces the following output.
--- Node coordinate data ---
Node x-coord y-coord
1 0.000000 0.000000
2 0.000000 5.000000
3 10.000000 5.000000
4 10.000000 0.000000
------ Element data -------------
Element i-node j-node Modulus Area Iner-zz
1 1 2 1000.0000 2.0000 5.0000
2 2 3 1000.0000 4.0000 20.0000
3 3 4 1000.0000 2.0000 5.0000
--------------------- Degree-of-freedom data ----------------------
Node BCtags x-force y-force z-momen x-displ y-displ z-rotat
1 1 1 1 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000
2 0 0 0 5.000000 0.000000 0.000000 0.000000 0.000000 0.000000
3 0 0 0 5.000000 0.000000 0.000000 0.000000 0.000000 0.000000
4 1 1 1 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000
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LitusSaxonicum



Joined: 23 Aug 2005
Posts: 1599
Location: Yateley, Hants, UK

PostPosted: Wed Jun 24, 2015 10:40 pm    Post subject: Reply with quote

You aren't going to get many replies with this post, as (a) it isn't clear what you want, but (b) it looks like you are asking someone to do a coursework exercise for you (which most people won't).

There are plenty of plane-frame stiffness-method structural analysis programs in books that you could use even if you can't program it yourself.

My advice to you is to remember the units for every one of the inputs: the values for 'length' and 'area' and 'modulus' are probably not a consistent set.

Eddie
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John-Silver



Joined: 30 Jul 2013
Posts: 495

PostPosted: Fri Sep 04, 2015 6:57 pm    Post subject: Reply with quote

... I read this post while catching up with posts missed and wished I hadn't.
Input data given, output results given, no sign of any program !
completely befuddled me.
I'm amazed how you deduced that it may be a units problem Eddie !!!

Interesting how the reasults have zero loads and zero displacements - obviously not applied any restraints ! ... or more likely, since results are exact zeros and not high precision computer zeros Wink , not even applied any loads !!!
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JohnCampbell



Joined: 16 Feb 2006
Posts: 1726
Location: Sydney

PostPosted: Sat Sep 05, 2015 12:41 am    Post subject: Reply with quote

Eddie,

The example data is for a plane frame. This was the first structure that was analysed using a computer, by John Bennett in 1950's, who taught me numerical methods in 1974. He used EDSAC at Cambridge University to carry out the first ever structural engineering calculations on a computer.

I coded up this problem in my FE program and it would not run !! The bandwidth optimiser can't handle a problem with only 2 active nodes.
So I included an extra node "6" midway between nodes 2 and 3 and got the following displacements at nodes as:
Code:
 .......NODE DISPLACEMENTS AND ROTATIONS

  NODE  LOAD         X              Y              Z             XX             YY             ZZ

     2    1     0.01525822     0.00528169     0.00000000     0.00000000     0.00000000    -0.00193662

     3    1     0.01525822    -0.00528169     0.00000000     0.00000000     0.00000000    -0.00193662

     6    1     0.01525822    -0.00000000     0.00000000     0.00000000     0.00000000    -0.00061620

Although the section properties that have been selected don't look realistic, the problem does have a solution. They definitely look like a mixture of units as the ratio of Inertia/length is unusual.

John
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LitusSaxonicum



Joined: 23 Aug 2005
Posts: 1599
Location: Yateley, Hants, UK

PostPosted: Sat Sep 05, 2015 1:17 pm    Post subject: Reply with quote

Hi Guys, Odd that this should come alive again after some months.

JS: It's a portal frame, and although I'm a geotechnical engineer, I'm enough of a structural engineer through experience past to recognize it, and also that the units are inconsistent.

I've been through lots of data files to work out from raw lists of numbers and vague hints how the dataset is structured!

JC: Yes, it is a plane frame, and you probably can't optimise it because it's too simple.

Eddie
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mecej4



Joined: 31 Oct 2006
Posts: 653

PostPosted: Wed Sep 09, 2015 5:30 pm    Post subject: Re: Reply with quote

LitusSaxonicum wrote:

JS: It's a portal frame, and although I'm a geotechnical engineer, I'm enough of a structural engineer through experience past to recognize it, and also that the units are inconsistent.
Eddie

Years ago, I ran into an engineer who used to report his program execution times in ohm-farads, just to enable him distinguish the engineers from the non-engineers among the readers when he had to field questions about the report.
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LitusSaxonicum



Joined: 23 Aug 2005
Posts: 1599
Location: Yateley, Hants, UK

PostPosted: Wed Sep 09, 2015 10:27 pm    Post subject: Reply with quote

Mecej4,

I was once told that the units of kinetic energy were Newton-pounds! But then it was just one item of twaddle in a wasted afternoon.

Your chum was lucky: I remember execution times in hours, and sometimes days. So what is an ohm-farad per second? A Mecej4 number?

Eddie
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mecej4



Joined: 31 Oct 2006
Posts: 653

PostPosted: Wed Sep 09, 2015 11:09 pm    Post subject: Reply with quote

Eddie, you may be pulling my leg, but I don't mind. I'll answer without pulling the shroud down completely.

Remember the good old R-C circuit with a battery and switch, with the solution V/V0 = exp(-t/RC) ? See, for example, https://en.wikipedia.org/wiki/RC_circuit . If R and C are expressed in ohms and farads, which are the standard SI units, what can the units of t be? Coulombs/ampere, of course! Or is it joules/watt?

One of my physics teachers amused us by trying to explain to us the difference between metre-newtons (for torque) and newton-metres (for energy). By the way, "Newton-pounds" is wrong, both in the sense of "the English Italianate is the ... Incarnate" and in the sense of energy having to equal force X distance, not force X mass or force X force -- unless we have cooked up a unit system in which mass and distance are equivalent.
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JohnCampbell



Joined: 16 Feb 2006
Posts: 1726
Location: Sydney

PostPosted: Thu Sep 10, 2015 4:26 am    Post subject: Reply with quote

This is a structural engineering problem, so electric circuit theory was not a favourite of mine.
I first "learnt" structural dynamics using the imperial unit system. ouch! Mixing "psi" and "kPa" as a pressure unit was an early problem, then when poundals and I recall slugs as mass units, when the Elastic modulus unit for pressure was psi was never easy to understand. There were some horrible factors to apply, plus remembering what g constant was to be applied. Mixing feet and inches for length or poundals, slugs, tons or others for mass and lb_force for force was a nightmare.
When SI units came along with metres, seconds, kN:force, tonne:mass (about a ton) and g = 9.8 metres/sec^2 it all got a lot easier. I never went back to imperial and the understanding was quickly forgotten.

On the test above, I must be a non-engineer !

John
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LitusSaxonicum



Joined: 23 Aug 2005
Posts: 1599
Location: Yateley, Hants, UK

PostPosted: Thu Sep 10, 2015 4:17 pm    Post subject: Reply with quote

I don't usually use electrical units, so I went for their dimensions, and on the basis of a crude dimensional analysis came to the conclusion that the answer was seconds. Dimensionless numbers are a passing interest of mine, and I've been above Mach 2 in a Concorde, which I reckon is Warp Factor 0.000002 or thereabouts.

The problem with SI is that across Europe (where the limits of my knowledge show) it isn't widely used, as they use older variants of the metric system, without the clear distinction between mass and force that enables electrical units to be part of SI in a rational way. John's poundals, slugs et al. are an effort to bring the distinction into the Imperial system only ever intended to function in one gravitational environment.

Moreover, SI isn't a decimal system, it has preferred intervals of thousands. It irritated me like mad that my kids came home from school having been taught centimetres, because the millimetre is too small to be useful, and the metre too large, yet those are the preferred units in SI.

The Newton-pound nonsense is a lasting memory of a wasted afternoon attending a 'speed awareness' course having been clocked at 35 in a 30 mph area. Not only was the course filled with similar drivel, but on travelling that route again some weeks afterwards, I discovered that the speed limit was actually 40, and I'd been trapped by policemen who were, shall we say, economic with the actualitée. Thus was insult added to injury.

Eddie
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