Science method

Question
I might have in my design on CST some overlaps but I couldn't find where it is , so is there any way to know exactly where is it? my design waveguide and metamaterial
Question
Are its faces polytopes?
Is there any information in the literature on the geometry and topology of saddle polyhedra?
Can we use them to construct structural triply periodic minimal surfaces?
An attempt to answer some of these questions in:
José Luis Junquera, Saddle polyhedra are three-dimensional objects with curved faces. They are not polyhedra in the traditional sense, because polyhedra must have flat faces. However, saddle polyhedra do have some properties that are similar to those of polyhedra. For example, they have an Euler characteristic, which is a topological invariant that is defined for all three-dimensional objects. addle polyhedra are the only other three-dimensional objects known to have an Euler characteristic of 2. This is an interesting fact, because it suggests that saddle polyhedra have some topological similarities to spheres and flat-faced polyhedra. The two saddle polyhedra that are known to exist are the saddle tetrahedron and its tessellation. The saddle tetrahedron has four curved faces, six edges, and four vertices. Its tessellation is a three-dimensional tiling that fills all of space. Saddle polyhedra are a relatively new area of research, and there is still much to learn about their geometry and topology. However, the fact that they have an Euler characteristic of 2 is a significant discovery, and it suggests that these objects have some interesting properties.
Question
Dear commubity,
I have a question concernig the geometrical modeling. My question is as follows:
May i create my geometry in ANSYS Design modeler and save it as a CAD model, and then import it in the ANSYS APDL as any CAD file which is imported from a CAD software like Autocad, Solidworks, Catia?
Sincerly,
Hajar
sir Josnier Ramos Guardarrama , thank you so much. I tested this solution and it worked for me. Thank you so much
Question
I have a solid CAD model geometry (complex shape). I want to generate random spherical pores within that geometry with desired porosity and pores size.
Ankush Pratap Singh, you can do this by using the following steps:
1. Generate random points within the geometry. Rhino is an efficient tool to perform this step.
2. Assign random pore size to each point.
3. Generate desired pore shape at each point with assigned pore size.
4. Subtract the pore shapes from the geometry.
To generate a geometry with a desired porosity, you have to play with the range of assigned pore sizes.
Question
Instead of SI units, I would like to use millimetres. How can I achieve this with pythonocc?
To change the unit system in OpenCascade using pythonocc, you can modify the system of units used by the TopoDS_Shape object Nils Wagner
Question
I am doing some simulation for stiffness identification of ABB irb 7600/500kg serial robot links. The CAD model provided in the ABB library is a solid model, but the actual robot is a shell model. Can anyone help to identify the shell model of the ABB irb 7600 robot?
Thanks, Dmitrii for the reply. I need a hollow model of this with 12 mm thickness. I tried in solid works but its difficult to convert a (.step file) into a hollow model of 12mm thickness.
Question
Hi
I wrote the codes blow for a minimal surface as a part of gyroid, but after running them, I got some errors. Could you possibly explain either what I should do in order to correct them or how I can convert a surface created in MATLAB to iges CAD model?
______________________
This is the link of iges MATLAB codes:
______________________
These are the written codes:
[x, y, z] = meshgrid (-pi/2:pi/32:pi/2); % 3D coordinates defined by x, y, z
v = sin(x).*cos(y)+sin(y).*cos(z)+sin(z).*cos(x); %gyroid formula
figure(1);
fv=isosurface (x, y, z, v, 0);
hold on;
figure(1);
igesout(fv,'gyroid.iges');
______________________
and these are two errors:
Reference to non-existent field 'knots'.
Error in igesout>getEntities (line 256)
if iscell(obj{i}.knots)
Error in igesout (line 91)
[obj,Entity,Num] = getEntities(obj);
We can convert a surface from MATLAB to STL file by using the codes below.
The STLWRITE codes are also attached.
____________________________
These are an example:
[x, y, z] = meshgrid (-pi:pi/16:pi); % 3D coordinates defined by x, y, z
v = sin(x).*cos(y)+sin(y).*cos(z)+sin(z).*cos(x); %gyroid formula
figure(1);
fv=isosurface (x, y, z, v, 0);
hold on;
figure(1);
stlwrite('test.stl',fv);
Question
usually we use CAD softwares to design a specific part then we convert it to STL to be able to 3D print it using any of the additive manufacturing techniques. I want to know if there is a smart simple way to convert a STL file into one of the CAD forms (step, parasolid .. etc.) so I can modify it (say using solidworks or so) or perform numerical simulations using Abaqus or the same.
Question
I would like to create 3D models from CT/MR image data sets to be used in FEM software (COMSOL). Does anyone have experience with Materialise Mimics and Simpleware ScanIP? Which one is best in terms of being user-friendly and generating smooth CAD models for FEM numerical modeling (electric field and temperature)?
Thank you
Both are good in what they are designed for, but I will lean towards Simpleware ScanIP due to ease of integration of its output with downstream finite element analysis tool.
Question
Dear all,
I have a Abaqus script that repeats a lattice structure in two dimension. I am modeling lattice cells as solids with their wall thickness. And geometry is a plate-like structure with a smaller out of plane thickness compared to other lengths.
However, i want to roll this structure into a tube like geometry. The result I'm trying to achieve is actually a tube with lattice walls. I want to write this Abaqus script parametrically in terms of mesh repetitions and relative density.
If anyone has any ideas on how to do this and can help I'd be very happy.
Dear Prof. Osman Eroğlu,
It can be modeled with each ring. Also, the lattice of the rings can be 0-360.
I wish you good studies.
Best regards
Question
We need to capture the 3 D image of a body part and get a CAD model of it. Which we want to analyze for application in a specific domain.
Kindly help
If you want to answer privately. Then you can mail me at kohli.anirudh03@gmail.com
Ross James Friel thank you, I will do that as well as explore further. I was using a 3D scanner previously to do the same but couldn't get the desired output
Question
I am trying to make simplified human cell CAD model. It will have plasma membrane, viscoelastic fluids within, nuclear membrane, nucleolus and fluid within nucleus.
Problem is, the plasma membrane and nuclear membrane are very thin approx. 10-20 nm. I don't find any cad software to model this. can you please suggest how to do that.
Question
Hi
I have generated a STL file of a skull using 3D slicer. I would like to convert my STL file into a cad model, so I could split it up into smaller pieces so that it can be printed piece by piece. My initial attempt was using Geomagic Design X where I had imported the STL file. However it seemed as if the skull was too organic/complex for the software.
Does anyone know how I can convert the STL file into a CAD model, or maybe another technique as to split the slit in parts?
Hey Naveshin,
Maybe using Fusion 360 may be the easiest, haven't tried my self but seems to be a lot of tutorials online: https://www.youtube.com/watch?v=KFQ4-1GH0wg
-Chris
Question
for a project I want to create a 3D CAD model of the child's chest.
Question
Hello,
I would like to extract all the walls from complex .DWG files that comes from the conversion from a .PDF by AutoDWG software. In these big multi-floor plans, there are multiple types of walls (exterior, office, corridors, etc) that have their own thickness and interior composition (trusts, insulation, etc.) and it's not even always clear to the eye where one type of wall ends and another starts. To give you an idea of the problem, here are two examples of very small regions of these kind of plans.
Note that I'm NOT interested in starting from a high resolution image of a scanned floor plan as the information is already vectorial in the DWG file. Also, I must do it by programming and as little user intervention as possible as this must be part of a bigger software solution.
I would be glad if anybody could propose software, libraries or papers describing methods to extract wall information from such a .DWG file. I guess OpenDWG seems to be part of the solution but if someone has more first hand experience with this problem, I would like to know about that!
In AutoLISP or ObjectARX C#/C
- Disable all layers except envelopes, partitions, doors and space labels.
- With each space label: Zoom centre then zoom out to a common zoom factor: You'll be able to figure out a factor by zoom extents on the largest space's boundary.
- Use the space label's insertion point (assumption that label insertion points are within their space's boundary.
- Run boundary poly command "_bp" (I think)
- With each space boundary, get the selection set of intersecting envelopes.
- Finally, for each bpoly line segment, match the points from the segment to the adjacent envelope/partition/door.
Question
some of the researches carried on porous media by using the ultra CT-scan method. they have been scanned in an actual porous metal form, and using some binary conversion methods, the scanned image converted into a 3D model. if anyone has a link for that sort of 3D model please comment below.
thank you
Hello! We are engaged in modeling and creating materials with ordered porosity - https://www.scopus.com/record/display.uri?eid=2-s2.0-85013168155&origin=resultslist. To model an unordered porous structure, we created our own macro program.
Question
How to define quarter-point element at the crack front, in a Static Structural analysis with a 3D CAD model in Ansys Workbench? Is there an APDL command that can be used in WB do to so?
On my research thesis, I used Ansys Workbench but at entry level only. Some researcher are discussing your issue too. Sometimes in Ansys you have to use some techniques to solve the issue. because it is not "straightforward software". It is like doing research, putting other people answer together and solving puzzles... then see if you can find your answer (Up)
By the way, maybe this link of website below is useful for you.
Question
I would like to learn drawing or getting centerline of a surface in Solidworks. I search on internet but I found limited information. I found a programs like VMTKLab.There is a section for centerline computing.
Ex: http://www.vmtk.org/index.html - computing centerlines.
Probably there is a method to get by using Solidworks.I will work on 3D modelled human leg, I want to get centerline of it to use in analysis as reference. Any ideas? Thanks.
The answer of M.Sc Eoghan McNamara is very correct. He shared his aponion and recommended it.
Question
To my limited understanding, FEA gives me part deformation under certain boundary conditions. So if I have the CAD model, I will know how much it will bend (for example) if I press my finger on it , or simply due to earth's gravity.
Now if I only know the shape of a part under gravity (and boundary conditions about how it is supported), can I find out the part shape in zero-gravity space? Is there a way to solve this kind of problem?
Thanks, Victor. Could you please elaborate on when (which step) is least mean squares or Tikhonov regularization used?
So far I've found that due to the differences between the meshing of the loaded and load-free part, there is about 5-10% error in recovered shape (even after re-doing the meshing completely). If the part geometry gets more complex, the error gets bigger. Is there a way to reduce this error?
Question
Can anyone help me find the find the Pelvis CAD model or Sawbone model with Peprosky type 3A or 3B defect.
What an odd request. First, you might try some calories looking in the literature and contacting labs that might already have a CAD file to work with. However I would not hold my breath. Secondly, you might want to try making one. Have you ever heard of the "Visible Human Project?" Look it up. I was part of a group that did some similar type of work. Where the VHP took a man and literally sliced him up and took pictures to be able to make a reconstruction of the human body to make an incredible 3D module, I was part of some work where we looked at cellular and dendritic alloy micro-structure and we sliced up the alloy in a directional manor and made a 3D model of the alloy structure (see linked articles in my profile at Researchgate). Anway, you could try getting a model of a joint from https://www.sawbones.com. It looks like you can order models of bones and joints... all sorts of cool models. Then per some nice images I see on
You could modify the model to create the type of defect you are after. Now for the fun part. You put this point into an epoxy in a nice flat edge mold container. Then say at approx. 0.1 mm at a time you grind/polish a layer off and take a digital images of the cross section each time. You do this for the entire joint creating a database of 2D layers of the 3D model. For the alloy samples we cut those with a Leica Ultamiller. The VHP used a big version of that in a freezer. I am sure you can find documentaries on Youtube about that, here is an overview (https://www.youtube.com/watch?v=7GPB1sjEhIQ ). Now maybe you could get your hands on this software and use it to generate your joint where you could also modify a model to introduce the 3A and 3B defects? Who knows maybe contacts with that VHP might be helpful?
Now depending on some coding ability or connections and collaboration you could create a 3D module of this. So, I don't know you if you are doing a MS or PhD, but I have a feeling if you want to do some FEA and or use something like Solidworks or some other cool software to analyze the joint and defects then you have an idea here where one could go to generate a model from scratch. Are you trying to correct the defect, replace the defect???
I mentioned the alloy work, well I also once supplied a turkey leg to my mentor at the time Dr. S.N. Tewari who as I recall used that turkey bone and the same general technique on the alloys (seem citations in my profile) to generate a model on the pore structure of a load bearing turkey bone. That went towards some other graduate students work. I was at this time an undergraduate in a cool and fun lab. Well, I just went and found you that link to the turkey bone project: https://link.springer.com/article/10.1023%2FB%3AJMSC.0000007746.00517.ba
So
You will be in a hunt for that CAD file that may or may not exist. Maybe the sawbones.com company might have some sort of file to share? Again, I had a hoot of a time working with Dr. S.N. Tewari. He is a top notch man and engineer/scientist. He likely has other papers beyond what I contributed to so if you like anything I am saying he is a source in the literature.
On the other hand if you can get an animal joint... (non-human) you could do the same thing where you put into a mold. Now with an animal source you could also grind/build the defects into those joints. After that is done you can put the Type 3A and Type 3B defect models into epoxy and make the 3D models slice by slice. I like that version. I used Sigma Scan Pro at the time to draw the layer by layer boundaries. A PhD student at that time (Lu Yu) who is in the articles was the one making the 3D models of the alloy structures. That was a while ago and computers and software have gotten better but the Sun Work Station type and any software used should be in the articles.
Now that was some rambled brain storming but I hope it might help. Good Luck no matter how your path goes.
Question
Hall scan data can consist of point clouds, (3D) images and videos...
I'm curious if you know about any projects or ongoing research in this area.
The aim of the object detection could be the creation of a map or a CAD model.
I suggest you to use the OpenCv library is very powerful in detecting the object whit new algorithms and methods. I was use in my article in sector automotive , we can see you my article in profile , I applied in real-time.
I hope that be Clair for you. @Carina Mieth
Question
I'm researching the use of PMI data in a MBD model for use in manufacturing.
I wasn't able to find any information about how threads (e.g. M10) and the ISO system of Limits and Fits (e.g. 20 H5) are handled within STEP AP242. In most CAD systems these are handled very well within the 3D annotations of the native model but once you export them to STEP AP242 you lose a lot of information. This limits the automated use of PMI data when exchanging this data. So I'm wondering whether I'm missing something or whether this is lacking within the STEP AP242 definition or the way it is implemented.
Any help to help me understand this is very much appreciated.
Thank you, I'll check it out.
Question
I plan to use V-REP together with python for the development of trajectories in 3D CAD models, the path I will trace on the CAD file and generate a DXF file of it, Python would process it to enter the trajectory in V-REP.
Would someone recommend me any resources to learn how to program V-REP? Or how could I link between the DXF file, Python and V-REP?
A nice library that helps to generate DXF files
Question
For get length and number of crack increase in the crack propagation problem.
+1
Question
I am currently working as a supervisor on a project related to Automotive Aerodynamics. My students are suppose to make a CAD model of a passenger vehicle. The geometry for the CAD model is obtained by taking the blueprints of the vehicle. Then in the next step there will be CFD Aerodynamic analysis and optimization of the vehicle shape ( in some areas) .
So my question is that after doing research work is it possible to be published or it is necessary to take consent of the automotive manufacturer for we used their vehicle as a test vehicle. Kindly give your answers on this issue.
Hello. You can do this to a large extent using: wizfds
Question
Actually for a project of FEA class, I need to perform FEA analysis for braces application. Please guide from where could I get the CT scans files. Because CT scan files can be converted to CAD model.
1. Wallner, J. et al. Computed tomography data collection of the complete human mandible and valid clinical ground truth models. Sci. Data. 6:190003 https://doi.org/10.1038/sdata.2019.3 (2019).
2. Aki Hasegawa, Akikazu Shinya, Yuji Nakasone, Lippo V. J. Lassila, Pekka K. Vallittu, and Akiyoshi Shinya, “Development of 3D CAD/FEM Analysis System for Natural Teeth and Jaw Bone Constructed from X-Ray CT Images,” International Journal of Biomaterials, vol. 2010, Article ID 659802, 7 pages, 2010. https://doi.org/10.1155/2010/659802.
Question
My question is, in principle, quite simple. I have the necessity to extrapolate the geometry from a mesh I'm using in Fluent. As a consequence, the extension of the mesh file is .msh (I should also be having the OpenFoam version of the same case). Is there any way I can extract the geometry into, i.e., stl, obj, 3ds, svg (and so on..) formats that I can later open in Blender for rendering? I tried using ICEM, without succeeding. Does FLUENT or ANSYS allow doing such an operation?
Is it possible to export geometry from Paraview to ANSYS or any meshing software for generating meshing.
Thanks,
Question
How to do simulation in PMC to get mass fraction of hydrogen from Biomass combustion using FLUENT or CFX with cad model of combustor??
Is there any specif papers available.. help me
is there any reliable journal papers to refer regarding the geometry of the combustor.
Question
I am running a sliding mesh simulation for a wind turbine in a nozzle (i.e. a ducted turbine), but at the moment I am having the problem that my solution just blows up after a few time steps - continuity and some of the other residuals diverge and become exceedingly large. I have been running my simulation in ANSYS Fluent, but I do my CAD modeling in SolidWorks the import it over. This method worked fine for the other sliding mesh work I did.
I tried reducing my time step, and that seemed to help get to a later time, but I'm still seeing some significant instability eventually. I heard there was some way to improve the mesh matching between my rotating section and the stable section that would help fix the problem, but I haven't been able to track down how to do that.
Does anyone have advice on getting better connection between a rotating mesh and a stationary one? It seemed like it was a common problem when I was searching online, but I wasn't finding a solution to it. I'm still trying to make adjustments to get the system to work properly.
Thank you for the offer, Poul, but I think I have resolved my problem for now.
For posterity sake, it seems my problem was that the space between my sliding mesh and the tip of my turbine blade was too small, and the mesher was not automatically making the mesh smaller to work in that space; specifically, I had set a 1 cm gap while using a 2.5 cm element maximum size. I had also defined my inflation layer such that 1 cm was not enough space to fill it out, which exacerbated the problem.
I fixed the problem by increasing the space between the blade tip and the rotating zone to 10 cm; I think there was probably a way to make the mesh much finer instead. That would have taken much longer to resolve, but I suspect it would have worked.
Question
I opened it in assembly design and then in DMUoptimizer saved it as model and reopened it but couldnt paste its copy in part design ;I faced this error:'"paste is not possible""
I think that copying may have gone wrong. I have already imported several STL files in catia in this way. There is also a rapid prototyping tool in catia. But currentl i use blender for such problems.
Question
The artery models are not patient specific CT models, rather, CAD models based on previous knowledge of human body.
Blood flow is an non-Newtonian fluid so you can use a fluid that near to blood properties and make numerical simulation representing the actual case study.So the mechanism including the non-Newtonian fluid case can be used in validating the actual case study.
Question
I am currently working with Solidworks.
Solidworks s good for modeling assembly parts but it isn't strong with mechanical analysis.
I worked with ANSYS and Abaqus but both of them are difficult for modeling and running for analysis. I am looking for software that is suitable for enclosure that is easy to run for analysis.
Ansys workbench will be the best option
Question
Which one is most suitable software (Solidworks Cosmosmotion vs Adams-MSC) for analysis & motion simulation of mobile robot platform mainly focus on obstacle negotiation??
I am well-versed with Solidworks CAD modeling software so kindly advise me about Solidworks Cosmosmotion for dynamic simulation and analysis of mobile robot platform (multi-body) .
ADAMS is a multibody dynamics simulation software equipped with Fortran and C++ numerical solvers. ADAMS was originally developed by Mechanical Dynamics Incorporation which then was acquired by MSC Software Corporation. So it is specifically designed to solve the problem.
Question
Dear all,
In order to simulate CAD model in MATLAB, I need to using this code. If anyone has the MATLAB code in this regard please share it to me.
Regards.
Regards.
Question
Hello Everyone,
Can someone suggest me how can i create tetrakaidecahedron model in ansys design modeler or ansys space claim? I have attached the image file below. The model is composed of 6 squares and 8 hexagonal faces and it is closed cell aluminium foam. Please help me to design this CAD model in either ansys design modeler or in ansys space claim. I am looking forward for your suggestions. Thanks in advance.
Kind Regards,
Karthikkumar
while building parts and products in 2D views is sufficient for some, many users need a 3D model for mass properties, interference-checking and visualization.
With SpaceClaim it is comfortable using 2D can now make an easy transition to 3D. As continue to work in 2D views while the system automatically provides the benefits of 3D modeling. The software lets engineers create and edit in “live” cross sections (both in a solid model and in the drawing space), taking advantage of SpaceClaim’s major modeling tools:
Pull
Move
Fill
Combine.
Question
Hello, everyone!
I need a software that could pack the arbitrary shaped particles (random packing).
Particle models are prepared in CAD software (see figure for example). Now I need to fill the column (cylinder) with them.
The software is highly preferrable to be free, maybe even open-source.
I heard about Blender could pack spheres, and how about user-defined particles?
Dear Ivan,
You're right. I forgot that YADE only uses spherical particles. Best regards,
Question
I need to export GD&T information from a CAD model into STEP 242. I tried to do that using SOLIDWORKS and Creo, but saving the design as a STEP file 242 means the GD&T information will be lost even if they have been added as annotations in Creo. However, I read a solution that suggest the use of Constraint Tolerance Feature (CTF) graph files. I could not find a reference that explains what is exactly the CTF file? and how can I generate it?
I will be more than thankful if anyone can help me to understand how can I generate this file by giving me an example.
Thank you very much.
Actually, the STEP AP242 was developed to support GD&T information; however, the CAD venders didn't use this facility yet. This is kind of a shortcoming in CAD systems since their inner translators don't extract GD&T information from the presentation level and add them as semantics via the STEP AP242 in the representation level.
Question
Rocket mass is changing due to burning of the propellant and this means that moment of inertia is changing too. Moment of inertia is mass X radius of gyration squared. I currently have a simulink model that caters for the varying mass of the engine and rocket. However, I am still having difficulties in determining the changing moment of inertia. I already have the moment of inertia of the rocket without the propellant using my CAD model. Questions are
1.Is there a mathematical formula of determining moment of inertia of the solid propellant?
2. Is radius of gyration constant or it keeps changing? (Assumption is that rocket body axes originate from the center of gravity which coincides with the center of mass)
Sorry my question is long but I would like to hear your views and answers. Thank you
If u are using solidworks..then...u can make configuration and set the level of burning fule and evluate moi from evaluation toolbar
Question
Hello,
In a new project I'm about to start in the garment design industry, I will need to extract some surfaces from the scanned body of a person in order to customize parametrized pieces of clothing based on these surface measurements.
I already used Rhino on another manufacturing project. All its algorithms can be called from Python scripts and reusing its visualization, object creation, geometric algorithms was a big time saver.  The problems I encountered were the following:
- Non standard Python 2.7 version (Iron Python) not compatible with lots of recent libraries (difficult to use NumPy, SciPy, etc).
- Non robust mesh algorithms (intersections, boolean operations, etc.)
I would like to get advices from people using other CAD like CATIA, SolidWorks, Pro-E, etc about the ease with which one can extend and customize these software to serve as "frameworks" for custom applications.  Which language can be used? Can it call standard C/C++ code or Python code?  Are they offering advanced and robust algorithms on triangular meshes?
Thanks
not sure you should be looking at CAD apps then ... sounds like you're better off with CGI apps like Blender, Maya, & 3DSMax. Those apps have solid mesh implementations and rich APIs.
Question
I am trying to get the simulated data for Mechanical properties of (Stress/strain/ fatigue failure) a CAD speciment made of Nitinol (Nickel titanium alloy) after & before cryogenic treatment.
You can perform a transient Structural-thermal multiphysics simulation in ANSYS mechanical to see the effect of cryogenic temprature on your maerial. However you need to define temperature dependent material first (If there is published data available for this material of course). If this is somthing you want to do. Ask me to provide more info for performing a multiphysics simulation for you.
Question
Hello, for my final year project i'm required to produce a finite element analysis on abaqus of the human knee joint. Im starting off by producing an FEA on a simplified CAD model but unfortunately ive been receiving the following error: "Time increment required is less than the minimum specified" and "Too many increments needed to complete the step" after decreasing the minimum increment size.
I would really appreciate if someone could help me get over this problem. I've attached my CAE file.
Thank you
So I looked at the model and found the following problems:
Your units are probably wrong: You give density as 1600 (probably in kg/m^3), but your geometric unit seems to be millimeter so your units are not consistent.
You should specifiy NLGEOM=ON in a contact problem unless you do small sliding
The displacement bc on the top is strange: You apply it so some points (or a RP? or both?)and then do some kind of kinematic coupling to transfer it to other points. And then in step 3 you add a concentrated load to the RP?
The BC on the tibia is wrong - you should not specify a bc on a contact surface, but on the bottom surface, I suppose.
It is also very wasteful to start with such alarge gap between the parts.
Also note that you are dealing with a Hertzian contact (sphere with a plane), this requires a much finer mesh to be resolved correctly.
Since I could not really make sense of your three loading steps. I deactivated them and changed the model so that the first step runs (was fun, actually). Hope you can take it from there.
PS: Please also note that if you actually want to model a knee joint, you will have to account for synovial fluid, cartilage etc., which will be very difficult to model (and to get material parameters for...)
Question
Hi all,
Please suggest me different CAD tools available for MEMS that will allow me to integrate other devices with MEMS (device description is based on differential equations) to study the system behaviour as a whole.
Regards,
Raghu
Hi Raghuram,
COMSOL Multiphysics is one software that involves equation based modeling. You can check those links if could help: https://goo.gl/YGJDN1 .
Also, a better and more time convenient method is to develop a Verilog-A model that characterize your whole system. Given that you already have one device described in differential equations you can model the other device also and write a complete model for the system and thus you can simulate them easily using any circuit simulation tools (e.g., Cadence Virtuoso).
Question
Hi all,
I want to model the following in Abaqus (just the reinforcement for the rubber hose) : (See figure 1)
I want to do this in order to identify the value of the force at the contact region of the thread knots. (See figure 2)
These are very thin, membrane like structures made of Aramid. They will expand with the rubber hose under internal pressure. I would want to identify the force at the contact under tension/ expansion of the hose.
I am confused as to what is the best way to model these thread reinforcement structures. I would think that Rhino3D is a good option since it uses NURBS. I have a fairly good knowledge of Rhino.
However, I do not know what properties (section/ contact interaction) to give these reinforcements in Abaqus.
Dear Jonah
To give reinforcements in Abaqus. you have to define the contact, try to do Face to face contact by layers with nonlinear-elastic behavior
Hakim
Question
I need DICOM format of femoral shaft fracture to convert them into CAD model. i need them for my research.
If you are doing research - I would suggest that you liaise with your local radiologist and ethics to use the CT unit database.
Question
Could you please tell me that how one can plot the deformed CAD model in Isogeometric analysis after getting the displacement of x and y dofs of each control points.
Litrature directs that, post-processing in IGA  is similar to finite elemenet analysis. I tried to do so but facing the problem while plotting the deformed shape of an objet (e.g. beam of plate). GeoPDE utilizes the Paraview to get the deformed shape. Isn't there a conventional way to do so as we do in finite element analysis.
Thanks
Dear Vishal Agrawal,
if you have a tool to visualize your initial CAD model, or geometry, than you could do the following: produce a new geometry by using the original B-Spline basis (or NURBS, or whatever kind of splines you are using) with the new control points. Those control points you get by adding displcament DoFs to the corresponding control points of the initial geometry. The resulting geometry you can visualize in the same way as your initial one.
That would be "the true IGA way". But of course you could also just sample your geometry and the displacement field and send it to Paraview to do the job.
Question
currently some colleagues and I have been working on these issues and the curious thing is that we do not find articles or works that are not more than 10 years, it is as if the enthusiasm for this subject would have died.
thanks for any help.
What exactly you are interested in?
Question
Hi,
Does anyone know about any website where I can purchase human CAD model which has the option of movable limbs?
Thanks.
Thanks Alex! I searched earlier on Zygote but did not find any CAD with movable limbs.
Question
Design of composite materials is crusial for material engineers. Accordingly, I would like to utilize the capability of some softwares as autodesk to simulate the compoisites parameters under various conditions of work.
Hi,
May be you should try this Helius Composite Case Study Demo from YouTube
Question
I am importing an .iges file in ANSYS workbench. After importing beam tool is not highlighting. What is the solution for this? please help.
Thank you all for your quick response.
Question
Hello. I just finished my degree and Im thinking of embarking on Masters but im perplexed on a topic and need help. Does anyone have any suggestion on research topic based on my interests below:
"Augmented reality in teaching and learning models"
"Effectiveness of augmented reality in 3D CAD models"
There are more but cant seem to figure which is ideal for me. I enjoyed using the occulus rift during my final year game exhibition thereon Ive picked interest.
I'd be grateful for any form of help to begin.
One very relevant topic (and surprisingly not that well researched) is the issue of on boarding the augmented reality application in the first place. To pick up the phone from your pocket, turn it on, find and/or download the application, find the correct place to use the app, and to experience the augmented reality content is a long list of interactions for the user to take - prone to many break downs in the action cycle. This problem is more immediate in context like in un-faciliated private use cases, such as when using AR in private, at an exhibition ect.
We touch a bit upon the issues in this paper http://vbn.aau.dk/en/publications/adopting-the-unknown-through-the-known(5ad7fa54-c683-4695-ae0a-847620598aed).html but there are definitely more work to be done in this arena for HCI research.
Question
our research group want to focus on 3D Bioprinted scaffolds, hence i want to know regarding commercially available 3D printers.
like PROs and CONs of following printers
1. BioBots
2. Regenova
3. NovoGen
4. Fabion
5. RoKitINVIVO
Hello,
I have some experience in 3D printing, but bioprinters are a bit different. I have knowledge about a few:
1. EnvisionTEC 3D Bioplotter (Manufacturer and Developer Series), uses syringe-based extrusion with materials like hydrogels, silicone, hydroxipatite, titanium, chitosan. Price could be around \$200,000 or more
1. Organovo NovoGen MMX, uses the same technology like the previous one but with cellular hydrogels only. I don't know if it is for sale, because Organovo uses it to produce bioficial tissues and sell those to drug manufacturers.
1. RegenHU 3D Discovery and 3D Biofactory, uses the same process as the two above but with materials like bioink and osteoink. Price could be around \$200,000.
1. FABION 3D Bioprinting Solution, uses multiple technology like photocuring, electromagnetic and exrtrusion with material of type hydrogels and organoids. I'm not sure whether it is for sale. It is a Russian-based 3D Bioprinting Solution develped by Skolkovo.
1. Biobots BioBot1, uses syringe-based exrtrusion and blue light technology with materials such as agarose, collagen, alginate, polyethylene glycol. Price is around \$10,000
1. CELLINK Incredible, uses syringe-based extrusion with it's own materials (CELLINK+, CELLINK A). Price is around €5,000-€9,000
1. Ourobotics Revolution, uses syringe-based extrusion with collagen, gelatin, alginates, chitosan and other. Price is around €12,500
1. Advanced Solutions BioAssemblyBot, uses six-axes syringe-based extrusion and cost around \$160,000
1. GeSim Bioscaffolder 2.1, uses syringe-based extrusion and piezoelectric nanoliter pipetting with materials such as polymers, high viscosity paste materials, alginate, calcium phosphate, silicon, cell and protein solutions. Price is around \$180,000
2. 3Dynamic System - Alpha & Omega, uses syringe-based extrusion with bone tissue from PCL, PLA, PGA, PEG, fibrin elastin, collagen, calcium phosphate and hydrogel mixtures. Price is at least £12,000
3. Bio3D SYN and Explorer, uses syringe-based extrusion with polymers and hydrogels
4. n3Dbio Bioassembler, uses magnetic levitation with cells. They deliver it in kits with a price range from \$500 - \$750
Question
Hi
I'm running a 3d bioprinter which runs via air pressure. Presently all control of air pressure is manual via a valve set in between the printer and the wall. The printer itself actually also has a valve, where you can set the pressure for the individual print heads. I can change the speed at which the printer prints but using g-code, but would also like to be able to do this for the air pressure. There is, in fact, an M-code dedicated to changing pressure, though I've never seen it used for normal 3d printers. Is there an electronic actuator/valve I can buy which is controlled via the computer?
If you need to control the flow you will need a electronic controlled valve, but they are expensive
if it was just on/off you would be good with a solenoid valve.
You can make your own valve by hacking a manual flow valve and adding to it a servo or a stepper, but you would have to program the software on your printer board to actuate the servo on recieving the M code.
By the way you can cook up your own M-codes, there is a list of reserved M-codes you can use for your own implementations
Question
This is a question to colleagues who ever developed CAD modeling algorithms on B-Rep. Examples are Boolean Operations, fillets, Euler operators, etc. All such algorithms are quite complex in nature, and I wonder if there are any "conventional" tools which a researcher could use to ease his life while holding CAD-neutral position (e.g. not being sticked to Catia, whatever). I have heard about Djinn and the idea looks pretty good to me. Though, I don't know if it has found a real use in academia. To be more specific, let's say I want to implement feature suppression algorithm, e.g. defeaturing of fillet chains. I can start with OpenCascade as a kernel, but it does not offer a convenient SDK for visual profiling of my algorithms. I will want to see the intermediate results of Euler ops., to check curvatures at surface points, to query neighbor faces, to check their surfaces, and many other things which are quite tedious without a good tool at hand. Is there any SDK like this?
To put it short, if I am about to start my own geometric kernel, which tools should I have in my tool box?
Thanks.
Dear Sergey,
Please have in mind that if you are considering a parametric CAD environment, introducing suppression will impact on other features that rely on that very one you tend to suppress.  I'm not sure how to help you here, but I thought I had to point this out.
Question
I'm in possession of an FDM 3D Printer (Robo R1+) and just came across the Taulman Nylon 680 which is FDA certified. I also have a stainless steel nozzle for printing the parts.
My question is: Do I need to take any further steps to be able to defensibly use 3D printed parts for product contact?
What you have identified potentially is a safe starting material - not knowing what you are manufacturing it is hard to answer the question.
If this is a medical device or pharmaceutical product you would still have requirements for traceability on the design of the parts you are printing (i.e. drawings, manufacturing records of such, cleaning) to make final products.  Additionally, you may want to provide some justification or testing to demonstrate that the safe material you started with is still safe; thus locking in your printing parameters for future justifications of parts and purchase specification / release requirements for the Nylon filament.
It is a tricky question without all the details, although it is certainly a lower bar to 3d print a production aid than say a component of an implant.  Documentation is key - remember to err on the side of caution and CYA; get your QA group involved, maybe they can help.
Question
For 3D Printing by which software we can design ? Pro-E Or Solidworks ?
For single part without complex surfaces "Parasolid" kernel i sufficient. But when it comes to large assemblies or complex surface geometry and multiple branches, CATIA in my opinion is still a winner of competition due to independecy of surfacing and solid modelling but still in integrated environment.
Question
I am doing in cylinder flow analysis of piston bowl.
How do i model a grid electrode in ANSYS Maxwell? I would like to place a curved grid electrode below a suspended tip electrode to simulate charge distribution on it.
Question
Hello,
I'm working on a commercial product where I need to estimate the 6DOF pose of a known 3D CAD (closed 2-manifold triangular mesh) in a single 2D image (see attached picture).
In general, this a difficult problem but under our operational conditions, we can impose the following constraints simplifying the problem:
1. The CAD object is known and we do NOT aim for generality like recognizing the class of all chairs.
2. We could get the user to position the camera approximately to a specific pose (distance from the object, general orientation +/-15deg, etc.)
3. If possible, we would use only the edges of the image (like Canny) to find and match against the object viewed from a given position.
4. This would be used in an industrial environment with manmade objects (pipes, valves, junctions, etc) without much texture.
All these constraints lead me to think that even relatively old and somewhat basic techniques could work.  For example, in the Sonka and al. book (see link below), section 12.3.2 Goad's algorithm explains a 1986 paper from Goad C. "Fast 3D model-based vision" which could work relatively well under our assumptions with its top-down "hypothesize-and-verify" approach.
I also know that the industrial vision and robotics community have tackled this problem and its generalization for a long time so there is bound to be something usable out there.
My question is the following: Would somebody know of a commercially usable implementation (like OpenCV, etc.) solving this problem?  More specifically:
• I'm NOT looking for deep learning stuff needing an offline learning phase with thousands of viewpoints from our CAD models.
• I'm NOT looking for RGB-D techniques relying on depth sensors. The color is also irrelevant as the CAD is colorless.
• "Old" techniques out of research fashion are OK, even preferred as we will be running on a low performance computer.
• Ideally, using C or C++ (may depend on OpenCV for example).
• Usable commercially (licensed under BSD, MIT, BOOST, etc.), not GPL.
Bruno
Thanks Max!  That's a very awesome answer!
I also had other answers from Alberto Pretto about code implementing his paper "D2CO: Fast and Robust Registration of 3D Textureless Objects using the Directional Chamfer Distance".  Mister Pretto said that his group will release the refactored version of the code under BSD license!
There is also a paper named "Fast 6D pose estimation for texture-less objects
from a single RGB image" which works on the same kind of problem.
Again, thanks for having taken so much time to explain the work you did on the problem.  I hope you will find the following links interesting!
Bruno
Question
Suppose I take a pole (hollow, length>>width) and convert the CAD model into a surface model specifying a certain thickness and mesh it in a commercial CAE package such as ANSYS (in this case it'll be a surface mesh-quad)
Compare the results of the above analysis, with a similar ribbed model (not surface, solid) and do 3D meshing-hexa, tetra
Will the results be in 99.999% conformity?
Hi,
You must make a study of sensitivity to the mesh size and the elements type on your numerical model.
you take three types : fine mashed, Medium and coarse . and see who offers a good results.
Question
I have coordinate information of irregular shapes in excel file, the irregular shapes are within a rectangular plate and origin of coordinate system lying on one corner of rectangle. There are around 20 such irregular shape. I need to generate part drawing of the system so that I will be able to mesh the part and perform FEA. What are the possible ways to do it and which software to use??
The solution is to create a script file in python as shown here in page 3:
Question
I have tested the SolidWorks Flow Simulation package. It is quite handy to use with CAD models and results seems very nice, but I haven't been able to find theoretical background on it. I mean, it must be some version of Navier-Stokes equations, but which version, what approximations it uses?
Moreover, the turbulence parameters "intensity" and "length", any knowledge about their theoretical background? My guess is the "length" refers either to Kolmogorov length or Taylor microscale, but would like to know more about it.
Generally, it is a very useful pacjage with many featyres. I have made many studies and the solaver is tested and the results reliable.
Question
Hi all,
I'm trying actually to improve my method of recognizing from STEP file of CAD models, manufacturing features using rule-based and entity growing approaches. Anyone interested to chare ideas?
Jaider: You mean automatic manufacturing features extraction using rule-based? Not quite. I have employed rule-based techniques to extract parameters and geometric attributes from CAD models,
Take  a look...
Question
hello, I want to simulate a vehicle in fluent , I have the cad model of my car with it's actual dimensions. generating the vehicle mesh is very Time-consuming for my computer system , so can I scale my model in smaller dimensions and then achieve true  results as well as actual dimensions ?
I am not sure if scaling the mesh will reduce the strain on your computer. The number of cells in your mesh will still be the same. You can reduce the mesh density, but this will likely effect your results. You could run a mesh independence study to determine what mesh density is needed for accurate results.
Question
This book contains Feature Based Manufacturing.
Which I am unable to find in other CAM related books.
Hello sir,  welcome
Question
Hello!
CST studio offers many voxel models, CAD models that are voxelized when imported, and only one full-usable CAD model. CAD models have smooth components with continuous shapes, whereas voxel models are conformed by cubes with limited spacial resolutions (around 1mm x 1mm x 1mm per cube).
I'm wondering if the resolution of the voxel models is good enough for simulating the performance of small implantable devices (on the order of a few voxel cubes), or if a CAD model is always more adequate at any frequency band (without considering the meshing part still).
Thank you.
Hi Alejandro,
There are two types of models you can use. One is Voxel model and other is normal CAD. Both of them have some resolution. Contrary to what you may believe that CAD models are smooth with infinite resolution, this is not the case. Also, resolution of CAD/Voxel model and meshing are two different things. Let me explain both these issues.
These models whether Voxel or CAD, are generated from the MRI or CT scan images of the real people /dead bodies. These images themselves have the resolution limitation. For example, for an MRI scan with 1.5T machine may have the maximum resolution of 1mm (as a general case ). Naturally, any model which is generated from these images can have the maximum resolution of 1mm. What this means is that the positional /spatial accuracy of the model is 1mm. Any changes in the physical arrangement of various body parts can have the maximum deviation of 1mm. Now you can very well see that this resolution is practically sufficient for all the purposes. After all, from person to person, this 1mm deviation can easily occur. For example, one of my teeth can easily differ from yours by 1mm and you may have more muscle than an average person. So there is no point in having a higher accuracy of the model. So you see, the resolution of model means how closely the model represents actual human being. Thus, this has got nothing to do with meshing accuracy.
Now meshing for both CAD/Voxel model is done based on the frequency of operation. In meshing, what we are interested in knowing the E and H fields at different locations. For the implantable antenna, we are also interested in knowing SAR values. Now, if you are working at very low frequencies,.the number of mesh cells will be small and for the higher frequency, they will be large, just as with any other model. That being said, you may also like to know that meshing is always done such that you have mesh cells where the material boundary changes. Naturally, if you have more boundaries, which means more types of tissues in a small space, you will have more elements. I would conclude by saying that you do have the infinite resolution in terms of meshing. Theoretically, there is no limitation on this. The mesh for which your solution converges is the best value for you.
Now answering your main question, What are advantages of Voxel over CAD. Immediately I can say that it is more compatible with time domain method used by CST. In the frequency domain , CAD model is good. Secondly, If you have the large number of meshcells for Voxel model, your simulation will take a very long time or you can also use GPU to reduce time. However, in CAD model, if the number of tetrahedrons increases beyond your RAM limitations, there is no way you can simulate your design without increasing RAM.
That's All Folks. Have a good time simulating :)
Question
2012, ASTM accepted a standard format called Additive Manufacturing Format (AMF), capable of storing color, materials, lattices, and constellations , unlike STL format contain only surface mesh information of CAD model. I see that AMF fits nicely for the needs of additive manufacturing for gradient component or multi-material fabrications and is better than STL. But, I don't know why this format is not widely accepted.
STL file structure was developed many years ago, additive manufacturing is a recently new process. The multi color printing heads are just now becoming common. It's easier to write a slicing program that can incorporate multifunctional data. That, being based on a machine capable of reading the code.  G-code is still the language of the machine processor, I program multi-axis 3-D milling projects using 2-D data. The skin of an STL file is truly the only data necessary for both additive and subtractive processing.  My biggest interest would be in having an affordable application that can fully manipulate and repair an STL model, closing the manafold is tiresome. It's a legacie thing really, not many CADD programs can translate to STL
Its all about interfacing the mind and the machine. We can imagine complex structures, but telling a machine how to create it in binary code is a completely new ball game. I see a big future in additive processing, when we can "print" using molecularly bonded (welded) metal within .0001" tolarance, the Art will have been perfected. Until then
Question
could someone provide me a 3D CAD model of right ventricle?
I want to simulate the blood flow into the right ventricle and then investigate the effect of omentum layer on the behavior of ventricle and blood flow.
Thank you
What you can do is get hold of some online CT data, import it into OsiriX or a similar DICOM reader. Then export the volume rendered scan as a STL file. That'll give you a very rough file, but it's a starting point. Another method is to import the CT DICOM files into Slicer, it's a free an open source app that let's you fine tune the part of the CT image series that you want to convert to a 3D STL file. You'll still need to refine and simplify the STL file in Solidworks before you can mesh it in Ansys.
Question
suggest any solution so that CAD model imported to abaqus software
Dear Sumit,
In the past I've done exactly this for micro-CT captured 3D reconstructions using both free software and academic licensed CAD software so very low cost. I imported the final geometry into COMSOL FEA software and ran models which were then successfully validated using data from acoustic tests and previous simulations of similar 3D geometry captured using optical methods.
To try and help answer your question I require some more information please, specifically, what software was used to reconstruct the SEM images, what format are the 3D files currently in and, finally, on average, what size are the 3D recon files?
Best,
David
Question
How we can determine the control points and knot vectors required to represent the geometry of a structural member such as a square plate, a circular plate etc .
For simple geometries such as circles, squares etc., the control points and weights can be found in any CAD books such as:
L.A. Piegl, W. Tiller, The NURBS Book, Springer, 1996. Or you can find them in the paper on Isogeometric Analysis:
T.J.R. Hughes, J.A. Cottrell, Y. Bazilevs, Isogeometric analysis: CAD, nite elements, NURBS, exact geometry and mesh re nement, Comput. Methods Appl. Mech. Engrg. 194 (39–41) (2005) 4135–4195.
For other geometries, you can use a software such Rhino.
Best regards,
Phu
Question
I’m looking for an approach to reconstruct a 3D model of eye glasses (without lenses) in a fast and accurate way with as little as possible manual post-processing (as in no Meshlab if possible!).
One difficulty for laser, structured light or traditional photogrammetric approaches is the diversity of the material (from highly specular metal to very diffuse black plastic), the impossibility to apply powder (could not resell the product afterward), the geometrically thin structures without texture, etc.  I also want to capture the texture of the glasses to have a good rendering of “the real thing”.
One aspect of this particular problem that might help is the very constrained geometry/topology of eye glasses.  Is this something that could be exploited by some kind of synthesis image-to-CAD algorithm that could use the information contained in a few images to generate a faithful 3D model?
Thanks
Regarding the library side, if you wanna do SfM or Multiple View Geometry computation => You can take a look to https://github.com/openMVG/openMVG
Question
So, the matter is that I've modeled a system that deals with 9 transmission lines in Power System Computer Aid (PSCAD) Program.
but, when I put Multi-meters between two sides of transmission lines the calculated P,Q and V differs from each other far behind the desired amounts comparing between putting a Wire between the buses instead.
I've tried PI and Overhead Transmission lines(Bergeron Model & Frequency dependent) but no differences.
The Question is that What should I do in order of getting the same values before and after the transmission lines.
Thanks a lot.
Note: I have 4 Generators, 3 of them supplies the load with appropriate generation but the smallest generator goes to the motor mode( the generation amount of power is negative p.u and is very small compare to others, 0.3 p.u for instance.)
I can't figure out the problem.
Question
I have a model that created by multi surfaces in Catia software. but, i want to make one surface by using multi surfaces.
Dear Kazem:
Any powders of nanoparticles, microparticles compared parameters characterize a specific surface area in units of cm2 / cm3.
Regards
Question
We can ask a very similar question about when the industry moved from drawing boards and typewriters to the first CAD and word processing systems in the 1980s. The answer is everyone made money because the work processes became more efficient and accurate. If you made a mistake you could undo it. If you had to draw the same window 100 times, each copy was exactly the same as the first. If you wanted to find a particular word or phrase within a 100 page document, you could search for it in seconds.
Now it is time for the industry to move to the next stage of technology and structured data.
The designer will no longer spend time retyping the data from a 2D CAD model into Microsoft Excel to produce a 200 instance door schedule, and they will not spend time going through a 150 page specification looking for each place they have requested the contractor to submit proposals or samples. The contractor will no longer be informed about clashes in the design by the structural and M&E engineers on site during construction, and they will be able to more efficiently price projects by getting more competitive prices when purchasing in bulk, with less waste. And finally, the building owner will be able to manage and alter their facility using an accurate digital model of the physical building.
Clients are the most beneficent in BIM implementation process. While clients get benefits after completions that is much more valuable than the others in design and construction face.
Question
Please show models for which extracting correct mid-surface (midsurface, medial) is difficult? Situations for which mid-surface shows gaps, overlaps etc.
One example of application for extraction of mid-surfaces is the preparation of geometry data for finite-elements simulation of automotive body in white. Here, challenges can be found in complex curved surfaces (including holes, beads and seams), different sheet metal wall thicknesses, connection technology (overlapping weld spot flanges and bonding flanges). In addition, multi-material componentes and components with variable wall thickness (e.g. casted  junction plate) require more effort to extract the mid surfaces.
Kind regards,
Mario