element type

Are you using Radioss solver for analysis?

yes

I just read about this in some literature.

Also, i need some guidance in 1d elements,i.e. when to select which type of element as a connector, as rotating support. considering the practical practice followed by experts.

Please download Free eBook: Crash Analysis With RADIOSS – A Study Guide using beow link.

http://www.altairuniversity.com/free-ebooks-2/free-ebook-crash-analysis-with-radioss-a-study-guide/

Page 280 & 281 we talk about commonly 1d element used in Radioss.PFA screenshot for same.

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PFB relevant vistia link for all above topics.

https://altair-2.wistia.com/medias/6fm5g2vpl0
https://altair-2.wistia.com/medias/d0rk2lpidy
https://altair-2.wistia.com/medias/q5ax6k868p
https://altair-2.wistia.com/medias/bsf1x7k3rd
https://altair-2.wistia.com/medias/vcidbz42ah
https://altair-2.wistia.com/medias/bqi5wmhxma
 

Is it bad to use tetra elements for stress analysis in explicit solver?

You can use tetra elements also.

A small comparison on brick vs tetra elements:

 • The number of elements and nodes generated by a brick mesh are of the order of 1/2 to 1/50 in comparison to a tetra mesh. A brick mesh reduces the solution time and results in       the ease of handling the model on a workstation

 • Analysis types like crash or nonlinear give preference to brick mesh due to the number of nodes and mesh flow lines.

 • The time consumed in brick meshing is more and requires experience, hard work, and a lot of patience too.

 •  Over the years, the algorithm for tetra meshing has improved and accuracy wise there is not much difference in tetra and brick elements.

For more details on the same please download our free ebook on Practical Aspects of Finite Element Simulation (A Study Guide) which covers every basic aspects on Finite Element Analysis.

how to check the stability of element after meshing in the model ?

Hi,

Can you please be more clear on the query, that is what your referring with element stability?.

As a general note:

After meshing, check the model connectivity. Also, make sure the material values, material curve values are correct and also ensure that the proper material card image has been selected. Any unclear or illogical data provided during material characterization will lead to weird model behavior and uncertain results.

element length and time step value in explicit analysis.

Hi,

From the  Check Elems (F10) panel user can know the basic quality of  the elements. Use the Time subpanel to determine the approximate minimum time step for explicit solvers based on element dimensions. Please go through the Help Menu on the same which explains about this in detail.

I would recommend you to go through the starter out (_0000.out) file which will show the minimum time step in the model. So that user can also decide on the added mass required to achieve the desired minimum time step.

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while using mixed meshing type what property we need to give?

Hi,

Based on the element type you have to provide the property in a model.

small thickness parts in an assembly is converted to midsurface which creates gaps between parts for that I extended the surfaces which makes parts to intersect and share common nodes is it required to define welding in this case ?

Hi,

Please check the model connectivity. If its fine there is no need to model any connectors in this case.

How to mesh fillets of smaller radius with hex meshing ?If the fillet is in critical region ?In case of explicit analysis when we are trying to have large elements.

Hi, 

Please go through http://www.altairuniversity.com/wp-content/uploads/2014/02/3DMeshing.pdf which covers these aspects.

If the elements are much smaller, this can terminate the run with Negative Volume error. 

the reason for intersection and penetration ?

how to check whether the tetra elements are 10 noded or 4 noded?and how to change it ?

Hi,

Penetration is the overlap of the material thickness of shell elements, while Intersection is defined as elements that actually pass completely through one another .User has to recheck the model thickness for removing penetrations and for intersections user has to check whether the components in the model are properly placed, else elements can pass through,

10 noded tetrahedral elements are second order tetra elements and user can change the order of elements from 3D panel>order change option.

You can check this by selecting card edit option, and select the nodes. If they are second order elements mid nodes will be selected. Please check the image below.

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How to remove intersection in  3d elements as they do not move in normal direction ?

Hi,

From the manual penetration fixing tool (Tools>Penetration Check) user can determine the direction that he wish to manually move the selected nodes or elements and thereby the intersections can be fixed. Move along nodes option is also available in  which the nodes selected in the model will define the direction vector. If user pick two nodes, they define the direction. If you pick three nodes, the direction is the normal of the plane that these three nodes define.

Please note: For new technical queries please create a new topic. Please don't continue on this thread.
 

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8 noded hex element with Isolid 24 and 10 noded tera element for stress analysis?

Hi,

You can use these element types. 10 noded tetrahedron elements may consume more formulation time.