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Mapped mesh in 3D

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Dear all,

1-I trying to mapped mesh a solid in 3D, but it sends me an error message "Error: 7161:The mass matrix is zero" when i try the eigenfrequency, and yet if the default mesh does not send it.

2-how can I set a damping coefficient?

Achraf

3 Replies Last Post 2013年4月14日 GMT-4 17:18

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Posted: 1 decade ago 2010年4月26日 GMT-4 12:09

Dear all,

1- I'm trying to mapped mesh a solid in 3D, but it sends me an error message "Error: 7161:The mass matrix is zero" when I try the eigenfrequency, and yet if the default mesh does not send it.

2-how can I set a damping coefficient?

Achraf


[QUOTE] Dear all, 1- I'm trying to mapped mesh a solid in 3D, but it sends me an error message "Error: 7161:The mass matrix is zero" when I try the eigenfrequency, and yet if the default mesh does not send it. 2-how can I set a damping coefficient? Achraf [/QUOTE]

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 2010年4月26日 GMT-4 14:21
Hi

for me the mapped mesh is mot pobably not the reason for mass matrix is zero (except perhaps if part of the volume is stilll not fully meshed, try to hit the "select remaining" noting should light up), incomplete BC are also potential causes.

For the damping you have the volumic ones and, depending on the application mode therr might be also on the boundary conditons, pick what corresponds to your case. For 3D structural, there are a couple of section related to how to select the damping, as this as a great influence on the resonant peaks, and these are often frequency dependet too, check the doc, in particular the structural

Good luck
Ivar


Hi for me the mapped mesh is mot pobably not the reason for mass matrix is zero (except perhaps if part of the volume is stilll not fully meshed, try to hit the "select remaining" noting should light up), incomplete BC are also potential causes. For the damping you have the volumic ones and, depending on the application mode therr might be also on the boundary conditons, pick what corresponds to your case. For 3D structural, there are a couple of section related to how to select the damping, as this as a great influence on the resonant peaks, and these are often frequency dependet too, check the doc, in particular the structural Good luck Ivar

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Posted: 1 decade ago 2013年4月14日 GMT-4 17:18
Hi

This problem arises when you have a model with sharp edges. Try filing your edges with reasonable fillet radii.

Then apply a mapped mesh to one end face of your model and sweep that mesh along your model.

Problem will be resolved.

Have fun!
Hi This problem arises when you have a model with sharp edges. Try filing your edges with reasonable fillet radii. Then apply a mapped mesh to one end face of your model and sweep that mesh along your model. Problem will be resolved. Have fun!

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