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First, I disagree with everything you've said here - quite strongly. The issue can most definitely be discussed and even brought to a rigorous conclusion without EVER considering output graphs from ANY ONE particular simulation. This is down to general mechanical principles, not beholden to the appearance of a single graph. Furthermore, specification of the fact that connections are massless is REDUNDANT and UNNECESSARY with a discrete mass model because that's the very definition of a discrete model!Well the thread does not make any sense without the graph from the simulation which contained the SIMULATED massless compression springs. What was the date the graph was first posted and what was the date that the massless springs were specified?
psik
First, I disagree with everything you've said here - quite strongly. The issue can most definitely be discussed and even brought to a rigorous conclusion without EVER considering output graphs from ANY ONE particular simulation.
Second, I know you and your tactics:
Now, it is possible to also incorporate mass elements with finite extent and modulus properties in one of the environments, and possible to distribute discrete masses along the line in another. These function as connections with mass, like real supports. I have done this on a limited basis, but there many reasons to avoid it:
- it adds complexity
- greatly increases the time to run the simulation
- like FEA, the possibility of error or unphysical artifact is increased
- accuracy increase in error-free runs is insignificant
- most (cheap) deformable elements only cover elastic range and do not function well in non-linear or far-from-equilibrium conditions
I said:So if you are not going to supply the graph then forget it.
Third, I'll oblige you by supplying the information, anyway. Shortly. I will NOT let you distract from the central issue before I've even had a chance to make my case.
... I'm damn straight not going to post any graphs until you provide at least a sentence or two WHY you believe massless connections to be absurd.
So, are you saying you accept massless springs in compression in all other simulations? Some? Including all the other simulations I've done in other environments with massless connections? Are those okay or not? This is not a rhetorical question.It has everything to do with one particular simulation.
I just went a long ways towards doing that right above your post. Went completely over your head, did it?Let's see YOU explain it to anyone.
I've dealt with that long ago. WHO CARES? You've known for a long time, when are YOU going to deal with it?And then deal with the fact that you did not tell everyone ...
So what? I just showed above it's not only NOT a problem, it's SOP....it was the result of ridiculously long massless compression springs holding 1 kg that no one knew were there until two years later.
You're tapdancing and dodging as usual. You're not showing that use of massless connections* is ridiculous.
Actually, when you first started complaining about this, you most certainly did. Then I trotted out a half dozen examples of the very same thing being done in the research literature, and you completely ignored all of them but one: The one with NASA using massless springs to simulate a parachute line in tension. Somehow, you managed to wrap your mind around that one but completely ignored the others like they didn't exist. That's when you switched your complaints to springs in compression, like somehow that matters. No comments from you on the approximation of large steel columns by massless compression springs!I never said ALL massless connections were ridiculous.
Are you saying it is ONLY that simulation you have problem with?I made derogatory remarks about your using 3.7 meter massless compression springs in THAT PARTICULAR SIMULATION...
How long are you going to beat that dead horse? There's no shame in following SOP, and nothing odd about not explaining that it's SOP....and NOT TELLING everyone that you were doing it.
I said I would - AFTER you provide at least one sentence of explanation WHY you think massless connections are ridiculous. So far you have not. Only reiterated your complaint that it is ridiculous and I didn't tell you.Now you want to TAP DANCE by accusing me of making some blanket accusation and not providing the graph on the particular case in question.
I told you already the image host (TinyPic) deletes them after a period of inactivity. You don't believe that? Look at their stated policy. I don't even have the ability to delete them once uploaded. So, give this BS a rest.Surprise, surprise! But your other graphs were there. Curiouser and curiouser. Tactics, tactics.
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