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Simulation of a lifting CE

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Level 9

Simulation of a lifting CE

Hello,
To calculate a hoist as in the attached image, how do you define the crane attachment point at the top and the motor attachment point at the bottom.
In Simulate you can not leave two parts free.
Blocking for example the point of the crane will give a false representation of the deformation.
Cordially.
Denis.

 

27 REPLIES 27

Re: Simulation of a lifting CE

Simulate can leave two parts free.  (some degrees of freedom (d.o.f.) free)

IF you have applied all loads from a Free Body Diagram (FBD) and determinate Static case.

This means you are in static equilibrium.

Then turn on inertia relief check box at static Analysis Definition. (this resolves any numerical rounding errors that make the part move and not be static)

Probably best load type is BEARING Load. for hoist pin and mass pin (motor)

 

Another way may be cut in half and use planar symmetry since the hoist rig appears symmetric from top to bottom.  Again inertia relief.

 

Another way instead of inertia relief for any case is to hold some area where stress is insignificant in the missing DOF.  If FBD and loads are accurate then the stress will not be very much.  There is a specific technique from PTC on constraining parts  in static equilibrium.  I could not find it in their knowledge base so it is attached here.

 

I found a related article at PTC support.

 Article - CS59477

 

And here is the static equilibrium technique.  It was redone for a thermal study but it is the same method.

Suggested Technique for Modeling Free Thermal Expansion

http://support.ptc.com/cs/cs_25/howto/mst728/mst728.htm#_ga=2.258133832.398535393.1523881733-1278185...

 

Re: Simulation of a lifting CE

Hello,
Thank you for these explanations.
I will try to apply them.
Cordially.
Denis

Re: Simulation of a lifting CE

 

Re: Simulation of a lifting CE

Hello,
Thank you for your model.
But in the case of my Cé, the fixation is in a circle, how can I put points there to fix the degrees of freedom as on your bridge?
Cordially.
Denis.

Re: Simulation of a lifting CE

maybe this?

Lift2.JPG

 

Re: Simulation of a lifting CE

Hello Denis,

 

I recommend rigid links.

Re: Simulation of a lifting CE

Hello Denis,

 

better example test_d_new.zip

Re: Simulation of a lifting CE

Unable to play video. Please try again later.
(view in My Videos)

Re: Simulation of a lifting CE

Hello,
I thank you for your very detailed explanations and your models.
On the other hand I did not understand the utility of the spring in the model test_d_new.
(Can not read the video)
Cordially.
Denis