I've been putting up soundproofed sheds at the 100 acre property I purchased for static tests. One area will be put aside for weight testing shock absorber systems. Various systems from pistons to low pressure gas bags will have heavy weights dropped on them and the impact reaction will be measured. The more explosive tests will largely be conducted to determine the shock rersistance of different plates. Aluminum looks to be a good material. Later when fully fledged models have been completed I'll be hauling them out into the desert for launch tests. Such chemical experiments have limited value for proving Orion's feasibility but will certainly be a lot of fun. I will ofcourse be posting pictures of any successful take-offs.
Hmmm. Impact testing a pusher plate seems like an interesting idea. It couldn't duplicate the brisance (pulse width) of a high explosive shock, but it might be able to simulate the reasonably slower 'push' from the primary shock absorbing system to the secondary.
Am I to understand that you are actually looking at doing some ground tests with high explosives? This sounds like an exciting project that harkens back to the days when Orion was first explored in San Diego. Have you obtained the proper BATF Explosive Ordnance Permits? It sounds to me like you might actually be able to get some funding grants for your research...
Jaro, I did a google search on LS-DYNA and came up with dozens of links. LS-DYNA is a multipurpose cumputational engineering tool with full three dimensional visualization (well, 4-D if you consider the animation overlays!)
It looks like an awesome package--with probably an awesome price (atleast for us folks who work at grocery stores!)
I think you're right--you probably could do a high-definition simulation of the impact dynamics of Orion with it. If one were to run it on a relatively small, but high end network with 10/100/1000 Base-T LAN switches, I think a nearly realtime simulation could be created. The impulse dynamics of the plasma jet interacting with the pusher plate as the jet spreads and splashes along the edges; the dynamic vibration modes of the pusher plate itself (it ought to 'ring' like a big cymbal!); the dynamic coupling of the pusher to the primary shock absorber system; and the momentum coupling to the secondary shock absorber system.
However, I suspect that this perhaps could be one of the most dynamic models ever created on a computer. As it would literally encompass the full range of cumputational fluid dynamics (the plasma jet,) structural deformation from impulse loading (pusher plate dynamics,) structural deformation/vibration modes from momentum 'handoff' from one conditioning system to the next; and of course, non-compressible fluid dynamics simulating the flowes of hydraulic fluids in the secondary shock absorbers. Throw in compressibility of gasses, damping and turbulent flow in non-compressible fluids, with just a smidgeon of friction, and you might even be able to identify hot-spots in the structure that will need active cooling!
Wow! I wish I had about hundred grand--maybe a little more--to play with. I think a reanalysis with modern engineering methods could go light-years to forwarding Orion technology.
Yes, I agree that an Orion simulation could get awfully complicated.
But I think its possible, with a few cleverly selected assumptions, to do some interesting amateur work (remember that this is the AMATEUR ROCKETRY page !) even on a single high-end PC.
I'm thinking in particular about basic structural design of the ship, and the way it performs when hit by a pre-defined shock. An under-designed Orion would be especially fun to model -- to watch it deform plastically in various weak spots. Then you adjust your design, reinforcing those same weak spots, or making other adjustments. Its the iterative aspect of the design process that's so fun.....
As for the price of LS DYNA, I forget the exact figure that was mentioned (a colleague is using it for spent nuke fuel can drop analysis), but it was something like a few thousand dollars. Everyone was quite surprised by that, after having seen some of the sims.... Maybe even low enough for folks who work at grocery stores! ....besides, becoming an "expert" in using the software might open up a new career
O.K., Jaro, the wheels of my mind are spinning. I saw some of the websites and the simulations were impressive. It looks like LS-DYNA has been used in the automotive industry for some time to digitally 'crash test' various designs long before metal is cut and welded.
Pretty cool idea about under designing something, and then building the model up in an iterative process. Iterative evolution of a design is a hallmakrk of modern engineering as it is exceedingly rare for a proper design to 'just happen.'
O.K., I guess I'll e-mail them for a price quote!
You know, it makes me wonder if it could be possible to design a pulse unit with a 'double gaussian' or offset 'gaussian' distribution of momentum. A toroidal distribution would tend to preferentially couple momentum to a locus of points on a circle perhaps midway along the radius of the pusher plate. That way momentum tends to be less concentrated at the edge and at the center where the pulse units feed through the pusher plate. This ought to significantly cut down erosion problems for the lip of the pusher plate and the central 'feed tube.' This would also tend to make it easier to steer Orion without causing massive tangential torques normally associated with gimballing a rocket motor.
GoogleNaut wrote: Jaro, I did a google search on LS-DYNA and came up with dozens of links. LS-DYNA is a multipurpose cumputational engineering tool with full three dimensional visualization (well, 4-D if you consider the animation overlays!) It looks like an awesome package--with probably an awesome price (atleast for us folks who work at grocery stores!) I think you're right--you probably could do a high-definition simulation of the impact dynamics of Orion with it. If one were to run it on a relatively small, but high end network with 10/100/1000 Base-T LAN switches, I think a nearly realtime simulation could be created. The impulse dynamics of the plasma jet interacting with the pusher plate as the jet spreads and splashes along the edges; the dynamic vibration modes of the pusher plate itself (it ought to 'ring' like a big cymbal!); the dynamic coupling of the pusher to the primary shock absorber system; and the momentum coupling to the secondary shock absorber system. However, I suspect that this perhaps could be one of the most dynamic models ever created on a computer. As it would literally encompass the full range of cumputational fluid dynamics (the plasma jet,) structural deformation from impulse loading (pusher plate dynamics,) structural deformation/vibration modes from momentum 'handoff' from one conditioning system to the next; and of course, non-compressible fluid dynamics simulating the flowes of hydraulic fluids in the secondary shock absorbers. Throw in compressibility of gasses, damping and turbulent flow in non-compressible fluids, with just a smidgeon of friction, and you might even be able to identify hot-spots in the structure that will need active cooling! Wow! I wish I had about hundred grand--maybe a little more--to play with. I think a reanalysis with modern engineering methods could go light-years to forwarding Orion technology.
FYI, today I installed ANSYS with LS-DYNA on my PC at the office. Now all I need to do is figure out how to use it !
For starters, I printed out just three small parts of the user's manual CD -- over a thousand pages -- about some of the basics of using ANSYS for static stress analysis of solid objects.
A colleague who took an ANSYS course not too long ago, said that creating a model in ANSYS is not recommended for anything but the simplest objects -- the preferred method being importing 3-D models from Solid-Edge drafting software. Although we have Solid-Edge at the office, I know even less about it than about ANSYS.
Sooooooo..... it looks like its going to be a while before I'll be modeling Orion launches
I just came back from a two-day LS-DYNA course in Toronto this week. The instructor was one of the code writers from the California-based company.
As part of the course, we did a few simple, but nevertheless impressive examples of dynamic stress analysis. The FE models were already prepared for us, since modeling was not part of the course.
That other part is coming at the end of the month, when we do a week-long course in Hypermesh -- supposedly the most user-friendly FE meshing software available for creating models for analysis using LS-DYNA (the others being ANSYS and FEMAP).
Anyway, with a bit of luck, we'll get to practice regularly in both modeling and analysis software, and eventually get reasonably proficient in it to possibly attempt problems such as the pulse rocket. It is definitely in the category of the more advanced simulation problems, since it involves interaction of fluids with solids, but LS-DYNA is uniquely suited for handling just such problems.
As a point of interest to others, the instructor mentioned that a student version of LS-DYNA is available relatively cheap (he didn't mention a specific figure, but I imagine its no more than a couple hundred bucks). Furthermore, he said that it has all the features of the pro version -- only the number of elements in the model is limited to 10,000 -- which is still pretty substacial.
So if any of you folks are interested in getting into this virtual reality modeling, it appears there is a way to get started.....
Thanks for information, Jaro. If you can get your instructor's contact info or even a price quote for the student version, I would really appreciate that. Please feel free to email me.
