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1)
Hi Clemens I've analysed a plate structure using Karamba and wanted to do a convergence analysis on results computed as a function of the number of elements.
Now, when strictly looking at the result magnitudes of internal energy (IE) and maximum displacement (w_max), it's acceptable, that their relative deviations are very small. But I cannot explain the tendencies of their graphs. From what I know, FEM should always compute underestimated results when compared to analytical solutions. So I don't understand why both the IE and w_max seem to be decreasing for an increasing number of elements.
But my main concern is the behaviour of the peak moment, it seems to be simply hill climbing untill suddenly a singularity kicks in. I initially wanted to use the peak moment as a fitness value for optimisation, but with this behaviour, I don't think that would make sense. I've attached my GH file as well.
It would be much appreciated if you could enlighten me on these subjects. Cheers Daniel Andersen
2)
Hi Daniel,
I could not run your definition because I have not all the plug-ins installed that you use.
You are basically right that the displacement should increase with a finer mesh. However the result of the shell analysis also depends on the shape of the triangles (well formed vs. very distorted). In order to test this, I think it would be interesting to use a very simple example (e.g. rectangular plate with one column) where you can easily control mesh generation. Would you like to start a discussion on this in the karamba group at http://www.grasshopper3d.com/group/karamba?
It is not a good idea to use the bending moment at a singularity for optimization because the result will be heavily mesh dependent. Also real columns do have a certain diameter and modeling them as point supports introduces an error.
Best,
Clemens
3)
oh, and by the way!
Here's some relevant literature on handling peak moments: https://books.google.dk/books?id=-5TvNxnVMmgC&pg=PA219&lpg=PA219&dq=blaauwendraad+plates+and+fem&source=bl&ots=SdDcwnrSA1&sig=6HulPmKNIhqKx4_rGxitteMC4CU&hl=da&sa=X&ved=0CDEQ6AEwA2oVChMIg66k0LPaxgIVgY1yCh1KPAeY#v=onepage&q=chapter%2014&f=false (Blaauwendraad, J., 2010. Plates and FEM : Surprises and Pitfalls, see Chapter 14) It would be great if a feature dealing with peak moments could be incorporated in Karamba. In my work, I ended up exporting my models to Robot in order to verify the moment values. Best, Daniel
4)
Hi Daniel,
thank you for your reply and the link to Blaauwendraads excellent book!
At some point I hope to include material nonlinearity in Karamba which will help in dealing with stress singularities.
If you want you could open a discussion with a title like 'moment peaks in shells at point-supports'. Then we could copy and paste the text of our conversation into it.
Best,
Clemens
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nside a script.
However, it should be noted that to do so introduces a significant amount of overhead, which may impact performance. This is because (to the best of my understanding) all the methods described below actually instantiate and execute a virtual Grasshopper document, with components and everything else. Whenever possible, it is advisable to simply call RhinoCommon functions - these are designed to be called in code and are more streamlined.
Python
Grasshopper's Python is unique among the scripting languages in that it has a "node-in-code" mechanism for this purpose in the form of the ghpythonlib library and its "components" class. Here is some example code:
from ghpythonlib import components as ghcomp import Rhino a = ghcomp.Circle(Rhino.Geometry.Plane.WorldXY,25.0) result = ghcomp.DeconstructBrep(b) faces = result[0] edges = result[1] vertices = result[2]
This code will call the "Circle" component with the world XY base plane and a radius of 25, and then call the "Deconstruct Brep" component on a brep (input to the script as "b").
The arguments passed to the function will correspond to the inputs of the component, and the function will return the output (the data itself in the case of a component with only one output, and a tuple of data in the case of multiple outputs, as in the second example above).
For more info on this technique, see this post by Steve Baer.
C#/VB.Net
James Ramsden has described a method for doing this in these two posts on his blog:
Run a Grasshopper Component from C# Code
Read and edit persistent data in Grasshopper components with C#
His examples are in C#, but everything he describes can also be done in VB.net with some syntax tweaks.
The core of his method is to programmatically instantiate a component, populate its inputs, and then create a virtual grasshopper document in which to execute the code. He then harvests the outputs and converts them back to simple data. Here is his example code for calling the "Circle by Normal and Radius" component:
var cs = new CurveComponents.Component_CircleCNR(); //add the circle centre (input 0) var pp = cs.Params.Input[0] as Grasshopper.Kernel.GH_PersistentGeometryParam<Grasshopper.Kernel.Types.GH_Point>; pp.PersistentData.ClearData(); pp.PersistentData.Append(new GH_Point(new Point3d(0, 0, 3))); //add the circle radius (input 2) var pn = cs.Params.Input[2] as Grasshopper.Kernel.GH_PersistentParam<Grasshopper.Kernel.Types.GH_Number>; pn.PersistentData.ClearData(); pn.PersistentData.Append(new GH_Number(y)); //y is another variable //run calculations cs.ExpireSolution(true); //add to a dummy document so we can read outputs var doc = new Grasshopper.Kernel.GH_Document(); doc.AddObject(cs, false); //read output circle cs.Params.Output[0].CollectData(); A = cs.Params.Output[0].VolatileData.get_Branch(0)[0]; //remove that component doc.RemoveObject(cs.Attributes, false);
Final notes
For a great many of the simple components, there are in fact methods in RhinoCommon that accomplish exactly the same thing. Note the complexity of the above code, and then look at the equivalent code using RhinoCommon methods:
Circle circle = new Circle(new Plane(origin, normal), radius);
In my experience it is preferable to just call or construct the methods you need using RhinoCommon rather than relying on trying to call components from inside your code.
Lastly, It is my understanding that this concept is central to David's thinking around GH2 - so that it in the next version it will be significantly more streamlined to switch between components and code representations. (I have no special knowledge of GH2 development - this is just what I have seen David say on the forums, and as usual any statements about future features are subject to change.)
Hope this is helpful!
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me of the dimensions that changed ( become Diagonal after they were Vertical or Horizontal)
I sometime use Record History in rhino for saving time, but when I change some points of curves or trim curves , I have problems with dimensions (see the two pictures below).
Problem 2 :
After trimming , only two dimensions should be changed depending on their place in changed curves . But what happens is that all the dimensions become crazy!!!!!!
I always use Aligned dimension in rhino. Now I know that dimensionsdo not exist in grasshopper. So I ask you if we have expertise in BV , C#, can we create a script for dimensions or is it impossible ??
If we can , I only need Aligned dimension.
I hope that I find or create a script that can define all points: start and end of curve ribs and create dimensions from grasshopper to rhino directly with or without the ability to change automatically .
Thank you
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mesh by an infinite plane
Namespace: Rhino.GeometryAssembly: RhinoCommon (in RhinoCommon.dll) Version: 5.0.15006.0 (5.0.20693.0)
Syntax
C#
public Mesh[] Split( Plane plane )
Visual Basic
Public Function Split ( _ plane As Plane _ ) As Mesh()
Parameters
plane
Type: Rhino.Geometry..::..Plane[Missing <param name="plane"/> documentation for "M:Rhino.Geometry.Mesh.Split(Rhino.Geometry.Plane)"]
Return Value
[Missing <returns> documentation for "M:Rhino.Geometry.Mesh.Split(Rhino.Geometry.Plane)"]
See Also
Mesh Class
Rhino.Geometry Namespace
Last updated 3 June 2011 - Robert McNeel and Associates
Send comments on this topic to steve@mcneel.com
Report wishes and bugs: https://github.com/mcneel/rhinocommon/issues
Is this the function?
I have a VB component with this:
a = rhino.Geometry.Mesh.CreateBooleanSplit(x, y)
but this is a boolean split, so I have only one mesh, with the intersection. I would like to have several splitted meshes.
Thank you in advance again.
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y anyway ;))
Since 2014 i begun to get back into the construction biz for some dozen main reasons, one of them being the highly increased availability of this kind of software "power", and robotics.
first project ended by 1stQ 2015 was focused on the development of a parametric block for construction. (almost sure the first parametric product designed in Uruguay, and probably one of the few first of this kind globally...)
Far from being a complicated model. In fact the standard model is extremely simple, key thing is that is fully parametric...
dimensions, materials, textures, colors... and so on
second key thing is that the main common component of the blocks (an EPS core) is robotically machined...
the blocks are the base of a construction system (oriented mainly - though not restricted only - to residential buildings) that
- is based on digital models, tendentially to be used in parametric models of buidings
- lab tested to prove to be 1.5 times as compression resistant than traditional bricks and blocks. (autoportability up to two stories buildings)
- has recently proved (due to size) to be 300% more efficient than the classic and 200% more efficient than steel frame in (our country official figures)
check it out here
--
https://drive.google.com/file/d/0B1TRxxgF_sEnQnZrTkZGbUx3cmM/view
--
- and it's aimed to be mass produced and handled by robots...
this project ended on 1H 2016
and i filed 4 patents in the process.
3 of them of mechanical devices designed as extensions for a cnc machine i own
and the fourth (
the patent related specifically with the blocks ) included a dozen of innovations (believe me...i have almost 15 yrs in the biz, and are coool stuff...)
along the project I've been working with inventor, even knowing in advance it will lack the kind of features I wanted to program many things... (lisp, VB, etc.... all same species of -prehistoric - animals) to leverage the tool to the sky - and far beyond... -
but was an alternative valid by that time because it allows the implementation of some form of parametric models, had a local representative and some supposedly skilled guys in the neibourhood....
but life is hard... and none of the latter two rendered me any significant help
so I had to take the tour myself...
- mind i never regret to do things that others cant -
and finish what i start
this one was a great project for many figures... and ended with more results than the ones commited to accomplish...
... some more history here ....
then because of a customer who brought a ZHA project ! to quote..., I crossed with rhino, and then met GH again to notice to my great joy and pleasure, in what kind of animal it had developed...
since money talks I'm investing hard on getting up to the expectations, and beyond as i usually do...
and thats how we met..
2017-2018 it's the time frame to build two robots. first one is a prototype to handle the k-nano blocks in the production process, delivery AND at the construction site ( a "smart crane" we nicknamed...)
the other one is the first prototype of robot to assist in the fabrication (smart blocker we called it to be creative ! ;))
then by 2018-2019 i'll be making a "kinda contour crafter" machine to complete the pie :) (you'll be interested on this..)
i guess you already know what all this has to do with GH...
i already have all the components i can imagine to do almost all i ever wanted to do in relation to this set of projects
but in almost a single tool !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
i can design, animate, render, optimize, simulate and even robotic simulate..
so, i have to ask...
is there a chance you might be interested in helping us in some projects we are starting on march and june 2017 (8 and no more than 18 months of duration respectively) ?
sent you a friend request, for the case you might be interested to continue by e-mail...
in any case many thanks for your help and inspiration !
best regards !
long happy marriage, and large figures bank account !
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,with OpenfoamV1612+ in Windows 10 64bit.The blockmesh worked good.And the snappyhexmesh crashed in the process.My computer memory is not enough? Or some settings wrong?Could you help me solve this question?/---------------------------------------------------------------------------| ========= | || \ / F ield | OpenFOAM: The Open Source CFD Toolbox || \ / O peration | Version: v1612+ || \ / A nd | Web: www.OpenFOAM.com || \/ M anipulation | |*---------------------------------------------------------------------------*/Build : v1612+Exec : snappyHexMeshDate : Aug 27 2017Time : 09:39:54Host : "default"PID : 13443Case : /home/ofuser/workingDir/butterfly/outdoor_airflownProcs : 1sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).fileModificationChecking : Monitoring run-time modified files using timeStampMaster (fileModificationSkew 10)allowSystemOperations : Allowing user-supplied system call operations
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //Create time
Create mesh for time = 0
Read mesh in = 2.14 s
Overall mesh bounding box : (-241.5472 -241.4418 0) (496.4376 536.2438 144.8633)Relative tolerance : 1e-06Absolute matching distance : 0.001081851
Reading refinement surfaces.Read refinement surfaces in = 0.01 s
Reading refinement shells.Refinement level 3 for all cells inside around_buildings_area.stlRead refinement shells in = 0 s
Setting refinement level of surface to be consistent with shells.For geometry outdoor_airflow.stl detected 0 uncached triangles out of 120Checked shell refinement in = 0 s
Reading features.Read features in = 0 s
Determining initial surface intersections
Edge intersection testing:Number of edges : 1684728Number of edges to retest : 1684728Number of intersected edges : 5583Calculated surface intersections in = 1.68 s
Initial mesh : cells:554112 faces:1684728 points:576779Cells per refinement level:0 554112
Adding patches for surface regions
Patch Type Region
outdoor_airflow:
6 wall buildings
Added patches in = 0.03 s
Edge intersection testing:Number of edges : 1684728Number of edges to retest : 0Number of intersected edges : 5583Selecting decompositionMethod none
Refinement phase
Found point (127.4452 147.401 72.43167) in cell 402042 on processor 0
Surface refinement iteration 0
Marked for refinement due to surface intersection : 8820 cells.Determined cells to refine in = 3.87 sSelected for refinement : 8820 cells (out of 554112)Edge intersection testing:Number of edges : 1883850Number of edges to retest : 250376Number of intersected edges : 21198Refined mesh in = 1.77 sAfter refinement surface refinement iteration 0 : cells:615852 faces:1883850 points:652499Cells per refinement level:0 5452921 70560
Surface refinement iteration 1
Marked for refinement due to surface intersection : 38502 cells.Determined cells to refine in = 0.04 sSelected for refinement : 40392 cells (out of 615852)Edge intersection testing:Number of edges : 2787132Number of edges to retest : 1118049Number of intersected edges : 85655Refined mesh in = 3.17 sAfter refinement surface refinement iteration 1 : cells:898596 faces:2787132 points:990317Cells per refinement level:0 5432351 486812 306680
Surface refinement iteration 2
Marked for refinement due to surface intersection : 159213 cells.Determined cells to refine in = 0.1 sSelected for refinement : 168471 cells (out of 898596)Edge intersection testing:Number of edges : 6576117Number of edges to retest : 4737635Rhino Model and GH files is in t'he zip file.Please help me solve this question!~~…
rtitions." (http://wias-berlin.de/software/index.jsp?id=TetGen&lang=1)
To continue with my wrapping career, TetRhino (or Tetrino) is a .NET wrapper for the well-known and pretty amazing TetGen mesh tetrahedralization program. It provides one new GH component for discretizing or remeshing objects using TetGen. Basic tetrahedralization functionality is exposed with a few different output types that can be controlled. At the moment, the only control for tetrahedra sizes is the minimum ratio, which is controlled by a slider. This is hardcoded to always be above 1.0-1.1, as it is very easy to generate a LOT of data (and crash)...
The libs are divided again into different modules to allow flexibility and fun with or without Rhino and GH, so have fun. All 4 libs should be placed in a folder (maybe called 'tetgen') in your GH libraries folder. Remember to unblock.
Once again, the libs are provided as-is, with no guarantee of support for now, as I use them internally and do not intend to develop this into a shiny, polished plug-in. If there is enough interest, I can tidy up the code-base and upload it somewhere if someone more savvy than me wants to play.
TetgenGH.gha - Grasshopper assembly which adds the 'Tetrahedralize' component to Mesh -> Triangulation.
TetgenRC.dll - RhinoCommon interface to the Tetgen wrapper.
TetgenSharp.dll - dotNET wrapper for Tetgen.
TetgenWrapper.dll - Actual wrapper for Tetgen.
Obviously, credit where credit is due for this excellent and tiny piece of software:
"The development of TetGen is executed at the Weierstrass Institute for Applied Analysis and Stochastics in the research group of Numerical Mathematics and Scientific Computing." See http://wias-berlin.de/software/index.jsp?id=TetGen&lang=1 for more details about TetGen.
To wrap up, some notes about the inputs:
These are the possible integer Flags (F) values and resultant outputs for the GH component:
0 - Output M yields a closed boundary mesh. Useful for simply remeshing your input mesh.
1 - Output M yields a list of tetra meshes.
2 - Output I yields a DataTree of tetra indices, grouped in lists of 4. Output P yields a list of points to which the tetra indices correspond.
3 - Output I yields a DataTree of edge indices, grouped in lists of 2. Output P yields a list of points to which the edge indices correspond. Useful for lots of things, very easy to create lines from this to plug into K2 or something for some ropey FEA (or not so ropey!) ;)
As this component can potentially create a LOT of data, especially with dense meshes, care should be taken with the MinRatio (R) input. This will try to constrain the tetra to be more or less elongated, which also means that the lower this value gets, the more tetra need to be added to satisfy this constraint. Start with very high values and lower them until satisfactory.
Hopefully shouldn't be an issue, but it's possible that you need the 2015 Microsoft C++ Redistributable.
Happy tetrahedralizing...
UPDATE: The tetgen.zip has been updated with some fixes.
UPDATE2: This is now available on Food4Rhino: http://www.food4rhino.com/app/tetrino
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Added by Tom Svilans at 1:27am on October 24, 2017
Karamba.
I am using your plug-in for normal forces evaluation in the transvere wires and spreaders of a sailboat. Mast is solved in another way, so I am not taking forces from Karamba in that case.
Basing on the forces value an adequate wire size (diameter) is choosen. Then masses of wires are being calculated. Loads (forces) on longitudinal wires are calculated without Karamba. The problem is when choosing transverse wires’ mass minimization as a criteria, the Octopus doesn’t get any results - is changing the sliders (genes) too fast for Karamba to calculate the forces (so Octopus gets only nulls):
When minimization of a e.g. longitudinal wires’ mass (calculated without Karamba) is taken as a criteria Octopus works fine.
Which suggests that the problem is in interaction of two plug-ins.
Any ideas how to avoid that problem?
Thanks,
M.
Below some screenshots of definition part with Karamba:
1675×807 200 K
image.png1680×789 398 KB
Despite the ‘orange warning’ the values are correct (double checked with other software).However I don't know why does it say that there is a part that can move freely without deformation,as the model looks like this:
image.png1239×343 55.5 KB
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