Linear Elasticity: Normal Force depending on displacement?

Numerical methods and mathematical models of Elmer
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Takala
Posts: 186
Joined: 23 Aug 2009, 23:59

Linear Elasticity: Normal Force depending on displacement?

Post by Takala »

Hi Guys,

I'm wondering whether the "normal force" changes due to the displacements in the linear elasticity solver? For example if one analyzes the effect of hydrostatic pressure on mechanical structures, it is important to know (in case of big displacements, one might get wrong result).

Best Regards,

Eelis
raback
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Re: Linear Elasticity: Normal Force depending on displacement?

Post by raback »

Hi Eelis

I think that the reference mesh is the initial mesh. Upon request the displacement field is applied after solution but the assembly and hence the normal force are in the referecence configuration. For the nonlinear ElasticSolver the solution affects the direction of the normal.

-Peter
Takala
Posts: 186
Joined: 23 Aug 2009, 23:59

Re: Linear Elasticity: Normal Force depending on displacement?

Post by Takala »

Thanks Peter!

It seems that in the ElasticSolver only tetraeders and octaeders are available. Are there any richer basis functions for those than linear ones? Is there any way to use the LinearElasticity with the correct orientation of normal force? Or what is the easiest way (since there always is a way ;) )?

Cheers,

Eelis
mika
Posts: 230
Joined: 15 Sep 2009, 07:44

Re: Linear Elasticity: Normal Force depending on displacement?

Post by mika »

Hi,

I just committed a new version of ElasticSolve.src which should enable the use of all classic element types. I think the nonlinear elasticity is the only way to go if the change in the orientation of the surface force vector has to be taken into account.

Best regards,
Mika
Takala
Posts: 186
Joined: 23 Aug 2009, 23:59

Re: Linear Elasticity: Normal Force depending on displacement?

Post by Takala »

Thanks a lot Mika! Works like a charm.

Cheers,

Eelis
Will01
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Re: Linear Elasticity: Normal Force depending on displacement?

Post by Will01 »

mika wrote:Hi,

I just committed a new version of ElasticSolve.src which should enable the use of all classic element types. I think the nonlinear elasticity is the only way to go if the change in the orientation of the surface force vector has to be taken into account.

Best regards,
Mika
Hi Mika,

Is it possible to handle the plate or shell model in the nonlinear elasticity analysis in elmer?

thanks,

will
mika
Posts: 230
Joined: 15 Sep 2009, 07:44

Re: Linear Elasticity: Normal Force depending on displacement?

Post by mika »

Hi,

If the finite element approximation is based on using piecewise polynomials of degree 2 or higher, the nonlinear elasticity solver could in principle be used for handling shells and plates. However, for very thin bodies the accuracy is expected to be far from optimal. There are certainly better finite element formulations for nonlinear shell problems, but they have not yet been implemented into Elmer.

Best regards,
Mika
Will01
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Joined: 03 Sep 2013, 05:20
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Re: Linear Elasticity: Normal Force depending on displacement?

Post by Will01 »

I see, thanks.
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