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Computer modeling and simulation

alienentity

Illuminator
alienentity
Joined
Feb 21, 2009
Messages
4,325
Morning all,

Many a truther has expressed contempt for NIST's WTC7 analysis because it relied on sophisticated computer models for fire simulation, possible explosive demolition, and failure analysis. They don't think this type of work represents 'real' things, since the results can be faked or fudged to produce any outcome.

A few days ago I watched a documentary on sports car racing on Speed Channel called 'Project LMP1, Acura's next challenge 1'. The program focuses on the efforts of Acura to enter into this hyper-competitive class of racing.

What is notable about the Acura effort is that the entire design phase of the car was done using advanced computer modeling, employing 500 computers in 4 giant clusters (Dell computers) running 24/7 and dedicated directly to churning out solutions.

Instead of going to a wind tunnel to test models, this task was also performed by computers!!

Then, once the 'car' was designed, it was tested using a virtual car running on a simulator, by a professional race driver.

Using the results of the simulator the car was then fabricated, and finally, and only then, was track tested - it proved to be a successful design!

This shows how devastatingly powerful such technology can be in modeling the real world. Simulations which simply could not be achieved just a few years ago are now possible.

One could argue that NIST's job at simulating the structure and conditions of WTC buildings was a more difficult task, and I couldn't argue one way or another. But to dismiss the modeling, as many truthers do, is to deny the undeniable fact that this technology is very accurate.

The company is Wirthresearch, in the UK.

I've posted the show on my channel in five parts. Here's part one:
(the playlist link is here http://www.youtube.com/watch?v=smUikmefWNk&feature=PlayList&p=B74EB9AC2E9A6C9D&index=4)


 
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Every Vehicle you drive or ride in was Simulated through FEA before a single part was cut, a single weld made.
I know for a fact the MCII G4100 and G4500 (run by Greyhound and numerous charters) was done that way, because I did it.
Every Airplane, every Rocket, every satellite--every complex machine and many simple ones--were FEM'ed prior to production.
Amazingly enough, we actually know how materials act under load, what their properties are, and how the loads get applied.
Science. It works the same way EVERY TIME!
 
rwguinn said:
Every Vehicle you drive or ride in was Simulated through FEA before a single part was cut, a single weld made.
I know for a fact the MCII G4100 and G4500 (run by Greyhound and numerous charters) was done that way, because I did it.
Every Airplane, every Rocket, every satellite--every complex machine and many simple ones--were FEM'ed prior to production.
Amazingly enough, we actually know how materials act under load, what their properties are, and how the loads get applied.
Science. It works the same way EVERY TIME!
Click to expand...

Excellent points! Usually they use wind tunnels to test scale models of race cars. Do they still do the same for aircraft or have they gone completely digital?
 
alienentity said:
Excellent points! Usually they use wind tunnels to test scale models of race cars. Do they still do the same for aircraft or have they gone completely digital?
Click to expand...

I don't do aerodynamics myself-I'm a structures guy--so I can't answer that.
But the F-35 was put in flight test well before any actual structural testing was done.
 
alienentity said:
Usually they use wind tunnels to test scale models of race cars.
Click to expand...

This is still true in Formula One, although I don't think they scale the cars down much if at all; the few picures I see look to be a full or nearly full sized chassis. Anyway, some teams have two, not just one, wind tunnels for development; there's tons of money spent in F1, and the top teams go all out. However, in an attempt to cut costs and speed aerodynamic development, some teams are switching to CFD (rwguinn and all the engineers here will know what a "Computational Fluid Dynamics" system is) in place of wind tunnels; here's a story about the Renault team increasing their use of such "virtual" wind tunnels. And here's a different one from a few years back advertising an association with a now defunct team. Real tunnels are expensive, and do need down time for routine maintenance, although I don't read anything about any F1 team completely ditching the real world wind buildings. I don't think any of them are willing to go that far.

Oddly enough, back when Indycar's direct rival - Champ Car World Series - still existed, they actually had a rule against wind tunnel testing. What they did in place of that, I don't know. Indycar had no such restriction.

To bring this back on topic: Yes, it's true, virtual modeling for race cars at least is very advanced. If it gives a competetive advantage, you can bet F1 teams will somehow dig up cash for it, and in a racing series where fractions of a second per lap matter (yes, that's not an exaggeration; watch an F1 race or qualifying session some time), those teams will demand the utmost out of every step of their design process. CFD and FEA are important tools in the multi-hundred million dollar series (link is not to a definition, but an article about one team's integration of FEA into their design process; even though not about the Twin Towers, it's actually a good on-topic read).
 
the truthers seem to think that the physics was tweeked somehow
but that not the way those work

you build the structure from what you know (INCLUDING THE MASS OF THE PARTS PSIKY!)
then try to simulate damage that no one could see directly
and you keep tweeking until you see what happened in real life
and its not a snapshot its a movie in 3D so the right sequence matters too

its very tough work
my silly models i tweek the same way
but they are way too simple (amongst other issues) to accurately depict anything discussed in the subforum here except to point out simple concepts

other than that
like stated earlier most things you use these days was born in a virtual world
heres a video of a machine i service regularly (previously i worked at the dealer) that was computer designed and tested before the 1st part was cut

its a industry ad for it
a game you can play with this one (for you safety people):
"how many OSHA violations can you point out?"
 
Justin39640 said:
the truthers seem to think that the physics was tweeked somehow
but that not the way those work

you build the structure from what you know (INCLUDING THE MASS OF THE PARTS PSIKY!)
then try to simulate damage that no one could see directly
and you keep tweeking until you see what happened in real life
and its not a snapshot its a movie in 3D so the right sequence matters too

its very tough work
my silly models i tweek the same way
but they are way too simple (amongst other issues) to accurately depict anything discussed in the subforum here except to point out simple concepts

other than that
like stated earlier most things you use these days was born in a virtual world
heres a video of a machine i service regularly (previously i worked at the dealer) that was computer designed and tested before the 1st part was cut

its a industry ad for it
a game you can play with this one (for you safety people):
"how many OSHA violations can you point out?"
Click to expand...
.
Criminey Justin,

You were checking out THAT video for OSHA violations??

You need a slap upside the head, boy, to get your attention refocused...!

:D

Does OSHA even have regs on the height of stiletto heels? Lengths of slits up the sides of dresses??

Pretty cool vid, tho. A real shame that PC gets in the way of them getting produced over here...

Tom
 
tfk said:
.
Criminey Justin,

You were checking out THAT video for OSHA violations??

You need a slap upside the head, boy, to get your attention refocused...!

:D

Does OSHA even have regs on the height of stiletto heels? Lengths of slits up the sides of dresses??

Pretty cool vid, tho. A real shame that PC gets in the way of them getting produced over here...

Tom
Click to expand...

i meant after the 15th viewing ;) lol
 
I do wonder how NIST modelled pretty much the full collapse of WTC7, without doing the same for WTC 1 + 2. I thought that they were simply unable to 1+2 becuase of computer limitation, so how come they were able to model the collapse of WTC7 and not 1+2?
 
KJC said:
I do wonder how NIST modelled pretty much the full collapse of WTC7, without doing the same for WTC 1 + 2. I thought that they were simply unable to 1+2 becuase of computer limitation, so how come they were able to model the collapse of WTC7 and not 1+2?
Click to expand...

It's a simple matter of scale really, a single WTC7 model run took months, and the WTC towers were significantly more complex structures.
 
KJC said:
I do wonder how NIST modelled pretty much the full collapse of WTC7, without doing the same for WTC 1 + 2. I thought that they were simply unable to 1+2 becuase of computer limitation, so how come they were able to model the collapse of WTC7 and not 1+2?
Click to expand...
What ********. They did model failure of 1 and 2. They did not model post-failure of any of them.

e^n said:
It's a simple matter of scale really, a single WTC7 model run took months, and the WTC towers were significantly more complex structures.
Click to expand...
Collapse Initiation, not full collapse. Purdue U has done work post failure, but NIST did not, with ANY tower. Not 1, not 2, not 7.
"This is how it failed" is one hell of a lot different than "This is what happened after failure"
The twoofers think that the program and engineers should model every event/particle after failure. It is a useless, wasteful exercise.
You find out HOW it failed, which tells you WHY it failed. Events after that are useless
 
rwguinn said:
What ********. They did model failure of 1 and 2. They did not model post-failure of any of them.


Collapse Initiation, not full collapse. Purdue U has done work post failure, but NIST did not, with ANY tower. Not 1, not 2, not 7.
"This is how it failed" is one hell of a lot different than "This is what happened after failure"
The twoofers think that the program and engineers should model every event/particle after failure. It is a useless, wasteful exercise.
You find out HOW it failed, which tells you WHY it failed. Events after that are useless
Click to expand...

NIST ran an analysis on WTC7 that was post initial failure. It shows the entire building collapsing (and falling down). I believe it was done with LS-DYNA but don't trust my memory.
 
rwguinn said:
I stand corrected.
That is a LOT of computing power...
Click to expand...

This is the crucial point. Modelling the buildings up to and including collapse initiation is interesting and useful. Continuing beyond this consumes a lot of processor time and memory. Justifying this use, when it had already been shown that the collapse would progress to completion, is.... difficult.
 
Some of this brain-death, evil truthers really want, that NIST opens all data of their computer-simulations.

Why not just believe the former bush-government run agency?

Be a "Jref´ler".
 
bio said:
Some of this brain-death, evil truthers really want, that NIST opens all data of their computer-simulations.

Why not just believe the former bush-government run agency?

Be a "Jref´ler".
Click to expand...
why would they?
it would take a PC years to render all that data
its useless to you
then youll scream "it didnt work, INSIDE JOB"

lol @ former
i thought we were all supposed to be enslaved by now hehe

heres what the NIST
NIST said:
Improvements to Structural Models
The ANSYS and LS-DYNA structural models are highly rigorous to capture complex failure mechanisms. NIST’suse of these FEA models is advancing the state-of-the-art of computational analysis, in terms of software and hardware. Significant improvements made to the structural models include:
-Identified and incorporated possible failure mechanisms:
-Bolt shear, weld fracture, tearoutand block shear failures in connection plates or angles, beam/girder walk-off of a bearing seat, and shear stud failure
-Lateral torsionalbuckling of beams and buckling of columns
-Developed (1) 18 types of user-defined break elements for the ANSYS model on floors 8 to 14, and (2) 31 types of connection sub-models for the LSDYNA model.
-Each break element contained multiple failure mechanisms, which were modeled using beam elements, contact elements, nonlinear springs, and rigid links, for:
-3 types of shear connections for beam-to-beam framing
-7 types of bearing connections for girders framing into columns
-1 type of shear stud connection between the steel beams and concrete slab
-To include connections (1) a total of 12,866 elements were addedto the ANSYS model, and (2) 13,920 connection sub-models were added to both ends of all floor beams and girders inthe LSDYNA model from floor 4 to the roof.
-The addition of connections and identified failure beam/column failure mechanisms greatly increased computational demand, slowing down the analysis when a large number of break elements failed.
-The level of detail in the models was optimized to maintain sufficient modeling fidelity, adequately capture failure mechanisms, and minimize computational times.
Click to expand...

from: http://wtc.nist.gov/media/WTC7_Approach_Summary_18Dec07-Final.pdf
 
Justin39640 said:
why would they?
it would take a PC years to render all that data
its useless to you
then youll scream "it didnt work, INSIDE JOB"
Click to expand...


If that is indeed true, then why not just release it?

Either way - based on my understanding (please correct me if I'm wrong), we don't actually know how long it would take to run the simulation on (fill in the blank) hardware, because NIST didn't supply any specific information about the number of calculations involved.

They said they used several powerful workstations, and clusters of some sort - and it took eight months to complete. That tells us absolutely nothing.
 
deep44 said:
If that is indeed true, then why not just release it?

Either way - based on my understanding (please correct me if I'm wrong), we don't actually know how long it would take to run the simulation on (fill in the blank) hardware, because NIST didn't supply any specific information about the number of calculations involved.

They said they used several powerful workstations, and clusters of some sort - and it took eight months to complete. That tells us absolutely nothing.
Click to expand...

the numbers would crash your PC
"BSOD = inside job!"
 
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