Hello, I'm learning FEA, and have worked my way through the first six lessons of the DEAL II tutorial. Nice. :) I am not seeing, though, how to do mixed dimensional problems.
The simplest example I can think of: I want to model a piece of netting woven in a certain way. The cloth/net itself is a 2D object. But the problem I am interested in solving is 3D, >From the Deal II tutorials, I get the impression that Deal II is based on a paradigm that the dimensionality of the object determines the space that the object is simulated in. So, this is a little puzzling to me. Before Deal II, I was attempting this problem using Calculix CCX. The project's been stalled for four years because of bugs in Calculix. SInce the problem is large ( A typical piece of cloth has a half million nodes); I wrote a python script to create a piece of 2D netting using a low computational cost three point beam element: https://web.mit.edu/calculix_v2.7/CalculiX/ccx_2.7/doc/ccx/node53.html The python script handled node numbering, degrees of freedom, and all of that to create a piece of cloth with hexagon type weave and fixed at end two nodes. (Essentially a Hammock, hanging between two fixed points. ) I only wanted to do a static analysis of how such a hammock would SAG under weight/gravity. I'm not seeing examples of how to do similar things in DEAL II; and Calculix crashes so I'm trying other FEA systems. . I've been able to complile DealII from source, and paraview, and install and run the demos. (I'm good at Linux and problem solving, and post before now!!!) Although my laptop is not a supercluster, just an 8 core Ryzen, the performance is plenty good. These are problems that I can let run a week or a month to solve, if necessary. To give a very clear example of what I was trying to do, here is the output from the python program, truncated, so the problem's outline can be seen easily. Comments, suggestions, links to tutorial(s) I missed, appreciated. Thanks. --Andrew Robinson. [ START CALCULIX CCX PROGRAM ] *HEADING Model: hammock Date 24-Jul-2019 *NODE 1 , 0.0, 0.0, 661.9 2 , 399.7, -140.3, 431.3 3 , 400.3, -138.6, 430.6 4 , 399.7, -136.8, 431.3 ... SNIP ... 353661, 3017.6, 142.0, 431.7 353662, 3424.0, 0.0, 661.9 *NSET , NSET=Nall, GENERATE 1,353662 *NSET, NSET=FIX 1, 353662 *ELEMENT, TYPE=B31 , ELSET=Estring 1 , 1 , 2 2 , 1 , 164 246 , 2 , 165 ... SNIP ... *ELEMENT, TYPE=B32 , ELSET=Ebar 101072 , 54544 , 54945 , 54944 466785 , 298353 , 298754 , 298753 *ELSET,ELSET=Eall Estring,Enet,Ebar *BOUNDARY FIX,1 FIX,2 FIX,3 ** Polyester netting material defintion, simple. *MATERIAL, NAME=PolyEster ** N/mm^2 Youngs, Poisson, (warp) diagonal 1/3 that value other dirs *ELASTIC, TYPE=ISO 3600, 0.16 ** Density 1.385g/cc (1385kg/m^3) *DENSITY 1385 ** BEAM SECTION ... ; thickness local tangent/x, thickness local tangent/y. ** Thickness from square estimate= ( 0.37mm * 0.37mm / pi )**0.5 * 2. ~= 0.42mm *BEAM SECTION, MATERIAL=PolyEster, ELSET=Enet, SECTION=RECT 0.37,0.74 *BEAM SECTION, MATERIAL=PolyEster, ELSET=Estring, SECTION=RECT 2.0,2.0 *MATERIAL, NAME=Aluminum ** N/mm^2(AKA MPa) Youngs, Poisson ratio, ?? (warp) diagonal 1/3 ?? *ELASTIC, TYPE=ISO 100000, 0.32 **DENSITY *DENSITY 2710 ** BEAM SECTION ... ; thickness local tangent/x, thickness local tangent/y. ** Thickness-- Assume 5/8 inch. (~16mm) *BEAM SECTION, MATERIAL=Aluminum, ELSET=Ebar, SECTION=CIRC 16.,16. ****************************************************** *STEP *STATIC *DLOAD Eall,GRAV,9.81,0,0,-1 **DLOAD **LoadNodes,GRAV,9.81,0,0,-1 *NODE PRINT, NSET=Nall U *EL PRINT,ELSET=Eall S *NODE FILE U *EL FILE S *END STEP [END PROGRAM] -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/CAAOASGtGvcPw9y0bA%3DyLUHMD97A5hGqrV%3DNf2cCv9g_CWpNTrA%40mail.gmail.com.
