Motion analysis on the engine

Simulation Generality
1

Hello

I'm simulating an oscillating table. The oscilation is created by a motor+arm+connecting rod.

I do a simulation on 2s.

I put a circular motor at 60 RPM and created a graph to see the movement of the linkage.

Problem: the oscilation pattern in Z does not follow the engine and if I vary the speed of the engine, the frequency of the oscilations varies little and in any case do not follow the "theory".

Does anyone have a lead?

Because at the same time  I do acceleration measurements that don't follow the theory ...

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tableoscilante.jpg
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2

already do it step by step

Motion simulation

Put the motor on this axis and turn slowly to see your oscilation

already in your assembly you must be able to do it

but via the movement study it is necessary to rectify the constraints

hoping that your graphics card and the PC follow

at first

and that all your axial constraints are good

@+

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3

Good evening

Have you tried changing your constraints? Instead of putting a coaxiality, constraining cross points from sketches, it has already happened to me and I think I had done that.

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4

Hello

Thank you for your answers.

I simplified the problem, just an arm that spins at 60 RPM, and no stress error and no interference.

What I have a problem with is that I put a sensor on the end of the arm which is rotating at 60RPM and it gives me the following graph which is not coherent and if I double the speed of the motor the graph remains more or less the same.....

I can't see where I'm wrong? Is it the position of the motor, is it the position of the sensor or others?

Do you have a lead? Thank you.

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tableoscilante_2.jpg
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5

Your displacement will always have the same curves since it's an axial displacement

It's simply the rot ation time that will change

if you increase the speed X2

In theory your cycle time will be / 2

@+ ;-)

6

That's the problem, I went to 120RPM and you'll see attached that the cycle time is only slightly modified.....

I should have 2 "peaks" per second and I barely have 1.7 ...?

A+.


tableoscilante_3.jpg
7

Indeed, there is a bug in the time scale. The running distance will always be the same since it depends on the length of your connecting rod, but if you compare your graphs, the n°2 should correspond to the n°1 x2 on the time scale (frequency).   

60 rpm --> 60 rpm --> 1 rpm so 120 rpm --> 120 rpm --> 2 rpm

Have you recalculated your animation correctly? It's the icon that looks like a calculator.

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8

That's the problem, I rebuilt, I recorded... I don't see where the problem can come from.

I'll try to change the type of constraint, as you proposed to me....

9

A yes but I'm not sure if there is a link with this constraint for this problem.

10

You're right, the modification of the constraint didn't change anything.

On the other hand I started the study of the "valve_cam" tutorial with the default values and there it works on the other hand when I started to modify the speeds, and passed the test from 0.1s to 2s, it started to put me alert messages and the results became wrong.

So I think I need to dig deeper into Motion's preferences.

If anyone has any recommendations, I'm interested.

Thank you.

A+

1 Like
11

Found an answer, maybe there are others....

The constant speed motor is not at all constant speed!!

I did the test over 10s and the speed is not constant at all!!

The solution is to take the movement by segement by managing an acceleration and deceleration ramp.

Here is attached a nice regular curve at 120 RPM

If you have any comments, I'm all for it.

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tableoscilante_4.jpg
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12

Indeed it's much better, maybe  the constraints were struggling to keep up.

13

Hello

I don't think it's due to constraints, I'd lean more towards a solidworks bug because I have the same phenomenon if I start from the tutorial file...

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14

Hello

Do not use the constant function because it is not constant at all, but use  the speed per segment.

A+

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15

Out of curiosity, I made a quick little anime, and how do you get a graph? The only graph I can get is the one of the parameters of the engine that can be modified, but not a graph of results. 

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16

Hello

I select a point on the outside of the arm and then the attached icon and it asks for a reference object, often I take the origin point of the assembly.

Then restart the calculation and normally the graph appears, on the other hand not find a report generator as under the material resistance  simulation (?) .

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34312_capture.jpg
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17

But you are positioning a sensor? If so, what do you use as parameters? I tried, but I can't get this graph.

Edit: in fact it's because I don't have the simulation module, when I point my cursor at the sensor it informs me that the information is not available, even for a speed reading...; (


2017-03-06_at_15-43-36.mp4
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18

In fact, I start by selecting the plane in the graphics window and then I select the "graph" tool, (icon in capture) and then a fixed point. The 2 dots are in the same dialog box. Of course you have to select displacement and the axis.

Then you just have to restart the calculation.

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19

Oh well, I don't think it must be the right catch!