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Train load

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Hi, I need to apply moving train load which have different spacing between adjacent axles. Can u suggest any method for load application. I have attached the loading diagram of train loads. I am using 5.2version.

Regards Varsha



5 Replies Last Post 8 mars 2018, 10:40 UTC−5
Henrik Sönnerlind COMSOL Employee

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Posted: 7 years ago 26 févr. 2018, 08:47 UTC−5
Updated: 7 years ago 26 févr. 2018, 08:48 UTC−5

Hi Varsha,

This example (which is also distributed with the product in Application Libraries) shows how to model a traveling load:

https://www.comsol.com/model/beam-subjected-to-traveling-load-22251

In this blog post, you will find another example:

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

Regards,

Henrik

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Henrik Sönnerlind
COMSOL
Hi Varsha, This example (which is also distributed with the product in Application Libraries) shows how to model a traveling load: In this blog post, you will find another example: Regards, Henrik

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Posted: 7 years ago 26 févr. 2018, 19:45 UTC−5

Hi Henrik, Thank you for your help. I have already gone through the travelling load example given in comsol. But the problem here is as shown in the attached screenshot of loading diagram the spacing between the loads varies. So I cannot make a single load travelling as periodic with some spacing.

Hi Henrik, Thank you for your help. I have already gone through the travelling load example given in comsol. But the problem here is as shown in the attached screenshot of loading diagram the spacing between the loads varies. So I cannot make a single load travelling as periodic with some spacing.

Henrik Sönnerlind COMSOL Employee

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Posted: 7 years ago 27 févr. 2018, 01:58 UTC−5

Hi Varsha,

You have to add several such loads, with a shift between them. You can still use one single loading function, you just have to call it with arguments which is shifted in space or time from the different load features.

Regards,

Henrik

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Henrik Sönnerlind
COMSOL
Hi Varsha, You have to add several such loads, with a shift between them. You can still use one single loading function, you just have to call it with arguments which is shifted in space or time from the different load features. Regards, Henrik

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Posted: 7 years ago 8 mars 2018, 00:31 UTC−5

Hi Henrik, Thank you for your suggestion. But the example u have suggested (travelling load on beam) has a pulse width load of 2m which cannot be treated as point load which is required in my case. I tried reducing the pulse width but the results are not appropriate. So how can I apply moving point load.

Hi Henrik, Thank you for your suggestion. But the example u have suggested (travelling load on beam) has a pulse width load of 2m which cannot be treated as point load which is required in my case. I tried reducing the pulse width but the results are not appropriate. So how can I apply moving point load.

Henrik Sönnerlind COMSOL Employee

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Posted: 7 years ago 8 mars 2018, 10:40 UTC−5

Hi Varsha,

Applying a point load at a general position (which is not a point, and possibly not even a mesh node) is bit tricky. There is no built-in feature which can do that, not even for a non-moving load.

You can however do this, using a General Extrusion coupling operator to pick out the displacement at an arbitrary location (which changes as the load moves), and then add your own weak contribution for the load using an expression like 1[kN]*test(genext1(v)) .

Regards,

Henrik

-------------------
Henrik Sönnerlind
COMSOL
Hi Varsha, Applying a point load at a general position (which is not a point, and possibly not even a mesh node) is bit tricky. There is no built-in feature which can do that, not even for a non-moving load. You can however do this, using a General Extrusion coupling operator to pick out the displacement at an arbitrary location (which changes as the load moves), and then add your own weak contribution for the load using an expression like 1[kN]\*test(genext1(v)) . Regards, Henrik

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