AKISPL Function....

[fayed175]

Hallo,

I really need your help here.

I want to run my crankshaft using the spline data as in graph( the red line).
So i use AKISPL function for the motion(highlight in turqoise) in 360 degree using the velocity data (spline).

However, i did not get the good result for the forces at the joints at the machine.

Can anyone help me, how to move the crankshaft using my spline data as in the graph?

Thanks.

 

[fayed175]

attachment for crankshaft....

 

[GregLocock]

Yes you need to apply a motion to a part. Typically in your case add a motor to a revolute joint. Having got the banalities out of the way, what is going wrong, what does the data from your model look like, etc etc?



Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[fayed175]

yes i already applied a motion using AKISPL for my spline data. what do u mean by add motor to a revolute joint?
FYI, i used cyclindrical joint at the crankschaft as u seen in 2nd attachment...

the problem is:

when i measured the angular velocity at motion, the values are so high compared to the original values(red line in the 1st attachment)

the measured values of angular velocity should be the same with the original values.

when i measured the forces at the joints, the values are also irrelevant; more than 10000000

 

[GregLocock]

Well, without being a mind reader I can't possibly tell what is going wrong.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[GregLocock]

Here's bits of adm code that moves one part correctly

SPLINE/510,
,X=0,0.04 (etc)


MOTION/735,JOINT=10,ROT
,FUNC=DTOR*AKISPL(TIME,0,510)

Joint 10 is a revolute joint, and the spline is in degrees

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[fayed175]

Hello,

Sorry i`m new to ADAMS....

what is adm code?

 

[fayed175]

what is the meaning of DTOR?

 

[GregLocock]

DTOR is a constant degrees to radians, ie 1/57.3 approx. The adams solver uses radians. ADM is the language the solver actually uses, so your pretty picture in the View GUI is reduced to adm language which you can examine if you export it as adm.

Typical problems with using splines to drive motions are that the spline does not allow for a smooth acceleration up to the initial condition, and that the data is spiky.

Here is a succesful run where a vehicle model is being driven by the above method showing the overlay betwen the drive splines and the model behaviour





Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[fayed175]

where to put that adm code?

Is it same when i write this function: DTOR*AKISPL(time,0,v_spline, 0) to the Motion?

Then the result for the forces of 1 spherical Joint is shown in the attachment....

 

[GregLocock]

Where do you need a spherical jint in an engine model? Have you tried to run your model with a gently accelerating signal rather thn a real one?

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[fayed175]

Oppsss sory....
i use the cyclindrical Joint at the crankshaft as shown in my 2nd attachment...

yes i already try it with gently accelerating. So the result(smoother) are shown in the attachment...

 

[GregLocock]

so what's the issue ? Look back through the data and descriptions you have given me and see if you think that is enough to deduce what is going on.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[fayed175]

do you know how to make my result smoother??

i mean no more spiky graph as shown before...

what cause this spiky results actually??

 

[GregLocock]

spiky input data, insufficient compliances, incorrect kinematics. How about putting a compliantly mounted flywheel on the nose of the shaft and driving that with your angle spline?

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[fayed175]

what do u mean by "mounted flywheel on the nose of the shaft"?

i cannot get it....

 

[GregLocock]

Instead of driving the saft directly with a motion at the bearing, drive it via an inertia/compliance system. this will low pass filter the input signal.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[fayed175]

thank you i willl to do it...

but this is something new for me...can you show me example?

Thank!

 

[GregLocock]

Not cheaply.



Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[fayed175]

btw thank