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propogation of shear bands or dislocations

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Hi all,

Can I use COMSOL program for discribing compession test of metallic glasses (amorphous material).
Does this program take into account an initiation and propogation of shear bands in metallic glasses during compression (or propagations of dislocstions in crystalline materials during load)?

Regards,
Alex

2 Replies Last Post 05.04.2010, 10:46 GMT-4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 06.02.2010, 04:52 GMT-5
Hi
You have a very interesting subject there. I do not believe its "in there" by default, but there are good chances that you can build up some equations to study disclocations quite well, just as the crack propagation in material can be studied, with some extra equations (I have seen that somewhere, probably in one of the conference papers or the web model gallery, or both).

So ask youself how you could describe the trigger selection for a dislocation skip, and try to add it in the equations. It should be equivalent to have some elements that changes their properties depending on the values of some of the parameters of their neighbours, as such this I do not beleive exist ready made in COMSOL. It is with some similarity to other person here looking for elements that could "disapear" under certain conditions to model air/vacuum gaps that collaps when mixing ACDC and Structural.

For me this is typical a subject to ask COMSOL support too, if it's not included they can often give some refeences or ideas where/how to start.

Good luck, and pls keep us informed
Ivar
Hi You have a very interesting subject there. I do not believe its "in there" by default, but there are good chances that you can build up some equations to study disclocations quite well, just as the crack propagation in material can be studied, with some extra equations (I have seen that somewhere, probably in one of the conference papers or the web model gallery, or both). So ask youself how you could describe the trigger selection for a dislocation skip, and try to add it in the equations. It should be equivalent to have some elements that changes their properties depending on the values of some of the parameters of their neighbours, as such this I do not beleive exist ready made in COMSOL. It is with some similarity to other person here looking for elements that could "disapear" under certain conditions to model air/vacuum gaps that collaps when mixing ACDC and Structural. For me this is typical a subject to ask COMSOL support too, if it's not included they can often give some refeences or ideas where/how to start. Good luck, and pls keep us informed Ivar

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Posted: 1 decade ago 05.04.2010, 10:46 GMT-4
Hi all,

I am trying to simulate compression tests using Comsol. The feature of material, which I would like to compress is that this material has many shear bands (10 nm in thickness) or nm- sized gaps. Is it possible to build this model in Comsol? To simulate compression, I need these inhomogenities (gaps, shear bands) to be interacted with each others. Will these gaps to propagate or to nucleate during simulation of compression ?

Also when I am doing compression with for example 20-30 small gaps, resolving is going well but when there are a lot of gaps for example more 100 - 1000 any errors is appearing (although geometry of sample recognizes in Comsol quite well (but not always))

Also error is appear with the meshing of gaps, if they has large difference in size). How to mesh in other way, or what do I need to avoid in geometry of my sample for avoiding mesh problem?

Best Regards,
Oleksii
Hi all, I am trying to simulate compression tests using Comsol. The feature of material, which I would like to compress is that this material has many shear bands (10 nm in thickness) or nm- sized gaps. Is it possible to build this model in Comsol? To simulate compression, I need these inhomogenities (gaps, shear bands) to be interacted with each others. Will these gaps to propagate or to nucleate during simulation of compression ? Also when I am doing compression with for example 20-30 small gaps, resolving is going well but when there are a lot of gaps for example more 100 - 1000 any errors is appearing (although geometry of sample recognizes in Comsol quite well (but not always)) Also error is appear with the meshing of gaps, if they has large difference in size). How to mesh in other way, or what do I need to avoid in geometry of my sample for avoiding mesh problem? Best Regards, Oleksii

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