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Freewheel Mechanism

JZ_8428090
3-Visitor

Freewheel Mechanism

Hello everyone, 

 

As part of one of my projects, I need to simulate a mechanism, using Creo. This mechanism contains a freewheel, which is not made with ratchets, but with a specific bearing and I don't have the CAD model. 

 

My question is : is it possible to create a freewheel constraint on a pin connection in Creo Mechanism ? 

 

Thank you 

 

Julie 

French mechanical engineering student 

1 ACCEPTED SOLUTION

Accepted Solutions

Here is how (two different ways) to put the conditional torque.  Be sure to include all the possible input range (I used -1E12 to 1E12 deg/s)

 

First way is user defined function. (key change primary variable from t to your measure)

 

Condition1Condition1

 

Condition2Condition2

 

Second way is by table. (key change primary variable from t to your measure)

Screenshot 2021-11-16 112854.png

 

 

View solution in original post

4 REPLIES 4
tbraxton
19-Tanzanite
(To:JZ_8428090)

There is no predefined freewheel constraint in Creo. I presume you are referring to sprag clutch mechanism in the bearing.

 

If it is just a kinematic simulation then you just need to accurately represent the degrees of freedom.

 

One option is to use a conditional torque.

The torque will act on the rotating body only if the rotational velocity is either negative or positive, depending on which way you wish your clutch to freely rotate.

 

Create a measure of the rotating DOF joint rotational velocity (conditional test to transfer torque)

Create a torque on the rotational DOF joint which is only applied when the rotational velocity condition is true (direction of rotation for clutch engagement)

This will enable rotation freely in one direction and "lock-up" in the other

 

 

Hi Tbraxton,

 

Thank you for your quick answer.

I created a measure of the rotating joint rotational velocity, but I don't know how to use this measure in a condition to apply the torque. In the torque function, I selected "user defined" and Creo does not accept only conditions. In other words, I don't know how to translate "If measure1>0; torque=1000; Endif" for Creo.

 

Have a nice day and thanks again

 

 

tbraxton
19-Tanzanite
(To:JZ_8428090)

I do not currently have access to mechanism module and I do not know the UI interface from memory applicable to this.

 

The logic of the condition is implemented by specifying an Expression Domain for the torque to be applied.

 

Review this help link. Step 5 addresses how to define the domain on which the torque is applied.

 

http://support.ptc.com/help/creo/creo_pma/usascii/index.html#page/simulate%2Fmech_des%2Fmotors%2FTo_... 

Here is how (two different ways) to put the conditional torque.  Be sure to include all the possible input range (I used -1E12 to 1E12 deg/s)

 

First way is user defined function. (key change primary variable from t to your measure)

 

Condition1Condition1

 

Condition2Condition2

 

Second way is by table. (key change primary variable from t to your measure)

Screenshot 2021-11-16 112854.png

 

 

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