WM2D

[wheelmaster]

For those of you that are tired of setting up your grand plan in WM2D only to have a GPF pop up and kick you out of the program.

Try this goto edit - select all - copy.
If WM2D kicks you out just relaunch the program and click on paste.

[epistemologicide]

Just put 'working model' in e mule, and you will find it.

[graham]

Hi Jim, I have a question about giving a wheel an initial "push" to get it moving.

If you look at the screenshot you will see that I have entered "500" in the velocity "rad/sec" box.

Is this just applied as an initial starting velocity or is it applied constantly as a continual force?

Probably a dumb question for someone who has been using the program for a couple of years.

Thankyou.

Graham

[jim_mich]

Graham,

That's one way to give the wheel an intial starting velocity. If the wheel has components attached they will get jerked around at the begining since the program will think that the wheel is already turning and the components are sitting still.

The method I like to use is to add a torque force (or a motor) that gives the wheel torque until a preset time has elapsed. This would be more like Bessler's wheel being given that intial push.

[Gregory]

I have a question regarding CF related experiments in Wm2d:
Does Wm2d figure CF correctly in the simulations? And how accurate it does?

Thanks in advance.

[graham]

Gregory I have found it not to be trusted in my sims that try to demonstrate CF.

If you want to have a go at it you might want to turn "gravity" off so that CF is the only force at work . If you need to get things moving you can either use a motor or give the whole thing an initial starting velocity.

The reason I don't trust it, is because differs from my real life experiences with CF.

Graham

[Gregory]

Thanks, Graham.

The reason I don't trust it, is because differs from my real life experiences with CF.

Hhhm... I suspected something like this. Could you go into detail please, what's the difference? Does the effect weaker in the real world, or less stable?


Anyone with an other experience / opinion?

[Deven]

The program makes it impossible for me to get my best ideas down. I wouldn't even call them all that complicated. Anything where I try to get weights to move in pairs in a non direct way causes the wheel to explode or simply stop moving. I also notice that it will randomly change the lengths on my pulley systems mid motion.

I thought maybe putting the wheel into sections connected by gears could help, but not much change so far.

Are there any files where you can go in and edit the more advanced settings? I tried to look on Google for any help and there doesn't seem to be any.

[graham]

I think many problems are a result of a lack of knowledge of the advanced options and how to set the properties of constraints.

Jim if you read this can you tell me if there is a way to have a rigid joint "active" for a certain number of seconds and then become "inactive" thereafter ?

In the properties menu there is a checkmark in the "always active" box.
If I remove the checkmark then I have the box available to enter something. But I haven't a clue what kind of value to enter there.

Graham

[Fletcher]

Hi Graham .. not exactly jim but never mind ;)

Put something like .... t<2 ... in the box. That means the rigid joint is active for the first 2 seconds of the sim run then it deactivates itself.

If you put a rotational joint beneath it it will then be free to swing etc.

t means time.

[graham]

Thanks a lot Fletcher. Might I ask you where this sort of information is to be found ? I looked everywhere I could think of in "help" but came up empty.

Graham

[Gregory]

Hi Graham and Deven,

You can find the complete formula reference here:
http://www.overunity.com/index.php/topi ... 13999.html

Thanks for Rainer.


Graham,
you can use the 'active when' option anywhere you find it, but don't forget, it easily can be a kind of cheat in lots of cases. But sometimes very useful. You can use other values not just time to control something.

For example: body[1].v.r < 20
Which means: when the rotational velocity of body[1] less than +20 Rpm. (anti-clockwise rotation)

Read the formula language reference, you can find much more. Also you can click on measure displays and check what formulas they use in the properties window. Very useful...


Deven,
Pulleys are not easy to simulate in some cases. You must use the right formulas, and as well as right accuracy settings for the simulation. Formulas dependent on more thing, and can be more complex in cases. And also they allow you to cheat, so you must know what you do, otherwise the simulation can be false, or simply doesn't work if you don't use the correct formula for a given situation.


If you ask questions here, I might can help.

[graham]

Thanks for the formula ref link Gregory. Very useful .

The reason I said I didn't trust my CF results were due to my own lack of competence with the program.

I knew that CF always pulls at 90 deg to the axis 0f rotation ,so when my sim gave different results I was stumped.
Then I realized that the initial startup of the sim would have to overcome the inertia of the mass I was attempting to study.

Now If I can lock the mass I am studying with a rigid joint during startup then unlock it once it has got moving ,I should get a correct simulation of the effects produced by CF.

I can't wait to try it later, when I have the time.

I'll let you know if my trust will be restored in good ole WM2D.

Graham

[Jon J Hutton]

Here is an obvious glitch not reported here before. Please be carefull any time you attach a weight to a crossbar...it can give pm results.

JJH

[Gregory]

Hi JJH,

After treating the accuracy settings, It works correctly. No glitch !!

Be sure what accuracy settings you use for what action!
It is highly recommended to not use the default low settings. Always use custom ---> accurate settings if possible, and not fast. And it is good to use always 100 Hz or more steps, so 0.01 sec / step, if it works correctly with the sim.

I attached the accuracy settings I usually use by default. It can slow down some models, but it's more accurate. At times I use even more accurate settings...