#1 2016-03-05 00:26:52

Humberto

Member

From: Ensenada, Mexico

Registered: 2012-10-15

Posts: 108

Website

How to add mass per unit of area on a DKT plate?

Is there a simple way to model mass acting on a DKT mesh?  Like the live loads of a building.

I want to assign mass/unit of area  on a DKT mesh, I saw Jean's book where he applies a mass of 10kg on a single node, but keeping track of how many nodes there are on a certain flat element would be overkill.

Is there an easy way to do this?

Humberto

jeanpierreaubry

Guru

From: nantes (france)

Registered: 2009-03-12

Posts: 4,049

Re: How to add mass per unit of area on a DKT plate?

hello

there are several ways

1- FORCE_COQUE apply a force, not a mass" on the element
2- modify the mass density of the element as suited
3- makes POI1 on all the nodes implied give, them an adequat mass
to get the number of implied node is faily easy in Python (ch 17.4)
and the search and assignement is a matter of a few lines of code

only 2 and 3 allow dynamic calculation

jean pierre aubry

---

consider reading my book
freely available here https://framabook.org/beginning-with-code_aster/

jlf

Member

Registered: 2007-11-22

Posts: 256

Re: How to add mass per unit of area on a DKT plate?

hello,

You could try AFFE_CARA_ELEM/MASS_REP on GROUP_MA
You must define a group of POI1 in your AFFE_MODELE with DIS_T model

You need 2 groups :
- a GROUP_MA of DKT elements (you have already it)
- a GROUP_MA_POI1  (affect with DIS_T model) on all the nodes of your DKT GROUP_MA element.

You can applied 2 sort of load:
- a global load.
- a mass per surface.
In each case Code_Aster compute the elementary mass on each node relative of the surface of the element connected to the node.

You can also use a function of (X,Y,Z) to have a space repartition of the load
JLF

Humberto

Member

From: Ensenada, Mexico

Registered: 2012-10-15

Posts: 108

Website

Re: How to add mass per unit of area on a DKT plate?

hello,

You could try AFFE_CARA_ELEM/MASS_REP on GROUP_MA
You must define a group of POI1 in your AFFE_MODELE with DIS_T model

Couldn't find MASS_REP in AFFE_CARA_ELEM,

You need 2 groups :
- a GROUP_MA of DKT elements (you have already it)
- a GROUP_MA_POI1  (affect with DIS_T model) on all the nodes of your DKT GROUP_MA element.

I guess you meant GROUP_NO for the POI1 right?

Thank you so much for the reply.

Humberto

reiteres

Member

Registered: 2013-06-03

Posts: 560

Re: How to add mass per unit of area on a DKT plate?

I guess you meant GROUP_NO for the POI1 right?

No he meant GROUP_MA correctly. If you create a discrete Element on a node it is contained in a GROUP_MA
(try to add a 0D Element in Salome with Modification->Add->0D Elements on Element Node; This will create a GROUP_MA containing the 0D Elements)

jlf

Member

Registered: 2007-11-22

Posts: 256

Re: How to add mass per unit of area on a DKT plate?

Hi,

I confirm is AFFE_CARA_ELEM/MASS_REP, and you need 2 groups :
- a GROUP_MA of DKT elements (you have already it)
- a GROUP_MA_POI1  (affect with DIS_T model) on all the nodes of your DKT GROUP_MA element.

If you don't find AFFE_CARA_ELEM/MASS_REP you don't have a recent version of Code_Aster.
You need >= 13.0.1 (30/07/2015)

JLF