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Moving Point Load

Posted Jul 22, 2011, 6:32 a.m. EDT Structural Mechanics Version 4.2 5 Replies

Itxaso
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Hello,

I am doing a solid mechanics model and I want to represent a Point Load that is moving with time. It follows an helicoidal path.
In the Point Load's settings window, you can enter the magnitudes of the force in each direction. But the only option to define where you want to apply this force is choosing points of the geometry. It's not possible to apply it in a different point.
Is it possible to create a point that moves with an helicoidal path? I have tried to define it as Geometry -> Point -> and entering in x y and z the ecuations of the helice (time dependent), but I get an error message because it doesn´t recognize any variable ( time).

Please, help me with the moving point force! I don´t know how to define it! Thanks in advance.

Itxaso
5 Replies Last Post Oct 23, 2016, 4:37 p.m. EDT
Nagi Elabbasi Facebook Reality Labs
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Posted: 1 decade ago Jul 24, 2011, 9:59 p.m. EDT
You can define a boundary load instead of a point load and make that load non-zero only over a small area to emulate the point load (use Gaussian function or ramp for example). To simulate the movement of the force, change the location of the peak/center of the load with time.

Nagi Elabbasi
Veryst Engineering
You can define a boundary load instead of a point load and make that load non-zero only over a small area to emulate the point load (use Gaussian function or ramp for example). To simulate the movement of the force, change the location of the peak/center of the load with time. Nagi Elabbasi Veryst Engineering
Ahmad Gad
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Posted: 8 years ago Oct 19, 2016, 1:39 p.m. EDT
Hello Nagi Elabbasi,

Can you please post a file including an example showing what you said? This will help me a lot as I am a beginner to using COMSOL

Thanks and best
A. I. Gad
Hello Nagi Elabbasi, Can you please post a file including an example showing what you said? This will help me a lot as I am a beginner to using COMSOL Thanks and best A. I. Gad
Henrik Sönnerlind COMSOL Employee

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Posted: 8 years ago Oct 20, 2016, 1:02 a.m. EDT
Hi,

This blog post shows how you can create traveling loads:

www.comsol.com/blogs/how-to-make-boundary-conditions-conditional-in-your-simulation

Regards,
Henrik

Hi, This blog post shows how you can create traveling loads: www.comsol.com/blogs/how-to-make-boundary-conditions-conditional-in-your-simulation Regards, Henrik
Ahmad Gad
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Posted: 8 years ago Oct 20, 2016, 8:49 p.m. EDT
Hello Henrik.

Thanks for the reply and thanks again for the very detailed article. It ended up with solving my problem in simulation a moving energy source on the specimen.

I am wishing if you can guide me through another answer for the next key question. I am trying to simulate a welding operation. And I am really interested into doing it using COMSOL through the process similar to "birth and death" of elements. I need to know how to do this, or you can push some articles to me, so I can dig through them to get the details.

Some people replied to me by making the material constants as function of temperature, so when the element's temperature exceeds the melting point, I can tremendously reduce the Elasticity modulus (not zero) and make Poisson's ratio close to 0.5. to simulate a "kind" of liquid.

However, this may help in melting, but what about the birth of element? Is there an explicit technique to do so, or even some workarounds that guarantee a convergent and accurate solution?

Thanks and best,
----------
A. I. Gad
Hello Henrik. Thanks for the reply and thanks again for the very detailed article. It ended up with solving my problem in simulation a moving energy source on the specimen. I am wishing if you can guide me through another answer for the next key question. I am trying to simulate a welding operation. And I am really interested into doing it using COMSOL through the process similar to "birth and death" of elements. I need to know how to do this, or you can push some articles to me, so I can dig through them to get the details. Some people replied to me by making the material constants as function of temperature, so when the element's temperature exceeds the melting point, I can tremendously reduce the Elasticity modulus (not zero) and make Poisson's ratio close to 0.5. to simulate a "kind" of liquid. However, this may help in melting, but what about the birth of element? Is there an explicit technique to do so, or even some workarounds that guarantee a convergent and accurate solution? Thanks and best, ---------- A. I. Gad
Henrik Sönnerlind COMSOL Employee

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Posted: 8 years ago Oct 23, 2016, 4:37 p.m. EDT
Hi,

The last question is off topic for this thread. Please start a new thread if you want to discuss element death and birth, so that any forum member who is interested can find it,

Regards,
Henrik
Hi, The last question is off topic for this thread. Please start a new thread if you want to discuss element death and birth, so that any forum member who is interested can find it, Regards, Henrik

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