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Finite Element Method - Science method

Discussion forum about Finite Element Method and its applications
Questions related to Finite Element Method
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The idea es share open-source finite element experience?
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I wasn't aware about distributed and parallel computing and advantages they had, but now I have been informed. Hence, I would like to build a new cluster to perform heavy mathematical calculations in Matlab and Abaqus. I have never clustered before and that's why I need assistance to setup.
Current workstation I own:
Dell Precision T5400
2 x Intel Xeon 2.5 GHz
16 GB RAM (2GB x 8)
1 x Western Digital 1TB HDD 7200 rpm
1 x nVidia Quadro FX4600 768MB GPU
1 x 870W PSU
OS: Windows 7 Ultimate 64-bit
2nd WS: I can buy another WS similar configuration to the one I own
I am not bothered about OS, I am willing to cluster with either Windows or Linux. However, my software are compatible with windows 64-bit only.
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I have positive experiences with Amazon Web Services (AWS) EC2.
I have also identified sabalcore.com as potentially good (or maybe even better), but as AWS worked immediately I did not discover it.
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deform 3D simulation with subroutine
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Sir can you please tell me how to write subroutine in Deform 3D if you are able to do so.
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In Abaqus, you have the option to import your assemblies made in Creo (formerly Pro/E) as one single part or as an assembly. The difference is that, when imported as a single part, no interactions are required because Abaqus treats it as a single part no matter how complex the geometry is.
But when imported as an assembly, individual parts are imported which can be assembled later on. But with this kind of import, interactions are required. However my contacts (interactions) would be defined as 'TIE" which means it is a fixed part.
My question is that for a same assembly, should my results differ from each other in different import methods? If so, then which is an ideal way to do your analysis considering importing in part mode, it is very easy to run the analysis with minimum errors?
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Hi
The two methods you described for importing a model would generally obtain different meshes when you mesh your structure, which might affect the results slightly.
Hope this helped
Best regards
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In Abaqus when we want to define a concentrated force (CF) at a certain point but it is coupled with other surfaces/ nodes so the force is transfered to those surfaces or nodes.
Once you made a reference point (RP) and then under interactions module, you define kinematic coupling. In coupling option, when the surface is selected, the analysis solves without any problems. When edges are selected, again it solves. But when the nodes are selected, the error pops up 'too many attempts made for this increment'. Why?
Any ideas or suggestions?
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The problem happens all the time in the cases where you have surface contact/couplings. This is a common error happening most of the times dealing with surface tied couplings. I suggest most of the times to use nodal/edge connections to avoid the errors with mostly no considerable loss of accuracy. As you asked why, and it is a bit imaginable there are less conditions and equations to satisfy in the case of edge constraints than surface, and the analysis converges in way less steps and attempts.
However if you insist on using surface to surface interactions, I suggest you use simpler models, as it is very hard to satisfy no-slip conditions for to surfaces with a concentrate load applied at the boundaries. I believe it will never converge in the case of having highly deformable materials in excessive loading.
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In Abaqus there is something called 'Global CSys' and then the user is allowed to make several others according to the model and requirements to define forces and other things. However, whenever you solve an analysis, the default result shown in Visualization Module is according to the Global CSys even though your BCs and Materials and other things defined using the new or custom csys. We need to change the csys from Results > Options.
Is this correct? Or there is no need to change the CSys from results > options. The results vary very slightly but it's a bit confusing.
Any advise or comment?
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Following
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Because fillet reduce stress concentration in shaft without changing its profile.?
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It is too early to suggest a title to your work......It depends on the results and success of the work....The temporary title can be "Reduction of stress concentration in gear tooth".....
First a literature survey of the problem is required - whether somebody has attempted it or not. If not ,I would strongly recommend a theoretical and mathematical check for the problem before jumping to any simulation software like Ansys or Abaqus.
Study some books on Design of machine elements to strengthen your basics and then search for journal articles to assess the improvements in this field.
U can then switch to the simulation softwares to verify your results or suggest some improvements to it.
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I am using Matlab to solve some finite element problems and I want to accelerate my codes using GPU. I want to use the Cusp library using Matlab but I don´t know how can I do it. I know that creating .cu files I can use Cusp, but I want to use Matlab to not lose my previous code made in Matlab.
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you probably need to write a C-programming calling your GPU kernels and interface that with Matlab. Take a look at http://www.mathworks.de/support/compilers/interface.html for more information
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Finite element of welding process
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I think this book may be sutable for You
COMPUTATIONAL WELDING MECHANICS by John A. Goldak , Springer 2005
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I am unable to find elastic constants of Glass Fiber and Epoxy Laminate. Can anyone list them WITH REFERENCE please. I require all 9 constants which include elastic moduli (E1, E2, E3), Poisson's ratios (v12, v13, v23) and shear moduli (G12, G13, G23).
The laminate can be manufactured either from hand layup process or vacuum assisted resin transfer molding technique.
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Download the micromechanics tool from
It's a micromechanics toolbox to predict the elastic constants for various structures.
Note: the additional "theoretical background" file is a pdf so you need to add the extension after downloading that one.
Hope this helps you out for the moment.
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Abaqus, Ansys and Patran/ Nastran
I have used a lot of software during my degree and professional work and I know it depends on what you are trying to solve determines the advantages of a particular software. Hence, this question is not about which software is better.
I am trying to solve a very simple composite problem. I have a circular plate subjected to 70 bar of pressure. The plate is made of E-Glass and Epoxy through hand layup process. 50 plies of 0.5mm are used to make up the thickness of about 25mm. The plate is bolted (25 bolts equally divided).
Model: shell
Boundary Conditions: Pressure applied on the face, bolts = encastre.
Mesh: Tet/ sweep fine mesh
Why am I getting different results in Ansys Multiphysics 14.0, Abaqus 6.12 and Patran/ Nastran 2012? Am I doing something wrong?
For example: Max. Disp. in Abaqus 6.12 = 1200mm where as Max. Disp. in Patran/ Nastran 2012 = 3400mm
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I suggest to solve first a problem with analytical solution, a circular plate --with axisymmetric loading, for example-- or a beam. Once you have obtained this results you could proceed with your problem.
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I have to model a semi-elliptical crack with singular meshing in 3D.
I am able to create half model. But I want a full model with the crack (as my loading is antisymmetric). Hence, I use the reflect command and reflect the volumes with mesh.
After reflecting, I am trying to merge the common nodes in the crack plane, leaving the nodes from the crack region, so as to get a crack.
While merging, I get error- data corrupted, Negative jacobian matrix error. When I plot the error elements, I see the singular elements along the crack front.
Experts I am a novice and not sure if this is the correct procedure.
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It all depends on what you are trying to do. If this is a one off analysis where you are only attemptimg to model a single crack configuration then persist with the problem. If you are trying to determine the stress intensity solutions for a family of cracks then using Ansys or Abaqus is not the way to go. (As ana side both use outdated 3D element formulations and you would be better off using NEi-NASTRAN which uses a much more modern element formulation.)
In this case, i.e. where you are seeking to solve for a family of cracks, the whole process is just far too man power intensive and the time taken in redoing the mesh each time far outweighs the compute time. The best way forward to solve 3D fracture mechanics problems is using 3D weight functions. This does not require remeshing for each new geometry. The down side is that you need to have a strong maths background to follow the derivation of the 3D weight functions.
Best of luck.
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Do you know anybody who works on a flexible beam with moving mass by using matlab program or simulates this problem in a finite element software such as ansys, abaqus or patran?
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Catania, Sorrentino, Dynamic analysis of railway bridges by means of the spectral method. They worked on a plate model in order to simulate a bridge crossed by a train. It is more complicated than a beam model. However they used a tensor product of beam eigenfunctions to model the plate behavior and the numerical tests were coded in matlab.I hope this will be useful.
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What are the likely problems if we leave the large deformation option ON while using FEA tools?
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Which FEA tool you are using?
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I am trying to develop a 5 sided element as a part of my Masters thesis. Works are going on. But I don't know will it be an useful work for the science society.
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Counterquestion: Why are you developing it, if you don't know what it can be used for?
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Micropolar fluid
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In Boundary layer theory we can simulate that type of every model by FDM Keller box method using MATLAB
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Numerical simulation
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Good question.. Please share me the best answer might you trust...
Regards…
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Numerical modeling of super conductor
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Dear friend
The easiest way is searching the related document by typing the keywords into google scholar. You will find some related articles.
If yet to find the articles, do not hasitate to let me know. I will help you in detail.
Good luck. Dr Zol Bahri - Universiti Malaysia Perlis
Is it possible to get the coordinates of all integration points in an element in ABAQUS UMAT?
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I know that it is possible to get the COORDS of one integration point, but my UMAT (based upon mechanism based strain gradient crystal plasticity) requires that I must have the COORDS of other integration points as well in the same element.
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@Mubeen: You have to creat user defined variables to store coordinates of other integration points. The only problem is you can't use these coordinates until next step
Wanted to analyze the track system of a vehicle, can anyone suggest a method to use?
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Wanted to analyze the track system of a vehicle, can anyone suggest a method to use?
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Please check references below.. hope it will be helpful for you… Regards… http://www.jvejournals.com/article/17947/pdf http://www.dtic.mil/dtic/tr/fulltext/u2/743464.pdf
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I am using DSPI (Q-100 Dantec Dynamics) to validate an FE model of bone. I get similar strain patterns with both methods, but the strain values differ by several orders of magnitude. Values from DSPI are within 1 microstrain of range. Could these values be within DSPI error and not be reliable to perform the validation?
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Hi Viviana,
I guess the problem is with the way you use powers of 10. For example, Young's modulus is 17GPa which is = 17 * 10^9 N/m^2. But if you input it as 17*10E9 then it becomes 17*10^10. So, actually the stiffness is higher by a factor of 10 which must be reflecting in lower strain values.
Strain from DSPI is 0.2 μm/mm that is = 0.2 * 10^(-3) m/m = 2* 10^(-4) m/m and from FE you are getting 2*10^(-5), which is lower from that of DSPI by a factor of 10. So, I think, if you input the correct value of Young's modulus, stains should match.
Apart from this, I don't see any other thing that could go wrong, based on the information provided. Adjust the Young's modulus and perform the analysis once again and check for the strain. Let me know about the outcome.
Regards,
Chenna.
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It is said in the conducting region, the solution of A and phi is unique. However, in the non-conducting region where the control equaiton is the double-curl equation whose kernel is non-trivial and thus the solution of A is not unique. As a result, how to make A unique there?
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It would be nice if you could later report your achievements in a paper. I am very interested in your findings.
Regards,
Renato.
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Fixture design parameters
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I believe GA means "Genetic Algorithm" and FEM "Finite Element Methods".......first of all start by getting all your nodes ready for proper design analysis, the more the number of nodes, the more accurate your results will be. MATLAB has a tool GA which could be used to get design results needed for your design analysis.
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I would like to ask the users of FEM/ FEA about the topics that they believe are missing and if not missing, topics that are not discussed in great detail. Also the topics on which FEM/ FEA users would like to see books or research on?
Are the users of FEA packages happy to get help from 'Help' integrated in the software or would like a summarized version of that help so they can find what they need instead of clicking links upon links just to find out a simple definition?
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Thanks Nicolas. I will look into that.
Any other topics?
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When we are solving any problem in FEM and we end up with either positive or negative eigenvalue. Is positive eigenvalue representing a stable system and a negative eigenvalue representing an unstable system? Or can even a stable system consist of negative eigenvalues? Or vice versa?
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I think in the modal analysis you are invoking, FEM is a possibility but not the only way to make it. I mean, FEM is of course good for arbitrary shapes, which might even be not connected, or at least non-simply connected (non-trivial topologies); other numerical methods can be used for studying eigenmodes, namely, Fourier analysis, although is not as flexible as FEM for complicated topologies. Having said that, usually negative eigenvalues imply a "shrinkage" and therefore stability, with few exceptions, which are those on which a system actually implodes (the instability is exhibited inwards and not outwards as could be implied by positive eigenvalues). Now, you can have a mixture of eigenvalues, but which mode dominates usually depends on the highest (absolute) eigenvalue, which in some systems this is connected with the lowest frequencies.
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I am working with structure meshes in Matlab and I want to check if my program is ok, then I select Comsol because is't easy to learn, but I can't find how to built a structrure mesh in this software.
Does any know how to built 3D structrure mesh in Comsol 4.2a?
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Ok. That can be controlled. Therefore you have to go into the properties of your mesh. In the modeltree go to mesh when you have built it and there you can add specific properties like quadratic meshing etc...
Best,
alex
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I want to use capillary heat exchangers as heat exchangers for cooling a greenhouse.
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Comsol looks best to serve your purpose, unless you want to write your own code.
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I performed a simple 3d analysis of a beam (5x5x50) with steel properties (E=206e3 and v=0.33). As I decreased the element size, the results drastically changed. The changes are recorded in the excel sheet.
Why is the stress increasing exponentially?
Which region should we label 'safe or acceptable'?
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Using 3D elements is non consistent with concentrated load. This generates a singularity because stress tends to infinty. Using finite element in that specific will give a stress that rises to infinity as element size becomes smaller and smaller... this is what you observe.
The solution is to distribute your load on the entire face or, if you want it concentrated, define a small area to distribute your load that become surfacic then (on a small surface). There will be no more singularity and convergence will then be observed.
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Given metal electrodes contacted with weak concentrations of bulk ionic fluids, I am searching for a finite element code proven to be capable of 3D modeling of the electrochemical double layer presented with low amplitude multi-frequency electrode excitation and extracting both real and imaginary components of impedance. 1D and 2D solutions would have very limited usefulness. Analyses may exceed 2 million elements in domains that are geometrically complex.
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Bill,
I don't have any experience on that topic; however, I would suggest you to check out COMSOL Multiphysics. It has modules for modeling different kind of physics, which can be fully coupled. I am mostly working on heat transfer, fluid dynamics and structural mechanics. The most powerful feature of this FEA code is, you can manually enter your ODEs and PDEs. In this way, you can create your own physics node, if needed.
Good luck.
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I am using axisymmetric modeling to simulate indentation and the indentor is an analytic rigid body while the workpiece is a 2D deformable body. I am using ABAQUS 6.12 version and did displacement controlled test. Both indentor and work piece are modeled as axi symmetric. When I do the indentation, I get an unwanted reaction force along the perpendicular direction to the loading axis (RF1) which is high compared with the reaction force along the loading axis. I imposed encastre boundary condition for the bottom of the work piece and Y axis symmetric boundry condition for the workpiece axis as well as to the indentor. Could you please help me whether there are other things to be satisfied to get rid of that RF1 component?
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Hi, that reaction force is the consequence of the symmetry conditions imposed along the axis of symmetry, in some way it represents the internal forces "on the other half of the part" in order to keep it together. If you performed and overall 3D model you would see that RF1 stays equals to zero.
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How do I find the frequency.
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eig is used to solve generalized eigenvalue problems A x = \lambda B x, whereas
polyeig is used to solve arbitrary polynomial eigenvalue problems.
In case of rotordynamics you have to solve a quadratic eigenvalue problem.
( \lambda^2 M + \lambda D + K ) x = 0
You might use PERMAS.
I guess you are interested in the Campbell diagram.
Please feel free to visit
for further information.
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I am trying to model this region using the finite element method, since I have done this for a cavity in a pipe. I mainly want to promote my modeling skills but I have really serious problems with the mentioned equations. I would appreciate it if someone could help me with them? Is there anyone out there?
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You can get the similar or apropriate answer by searching the keyword in the GOOGLE SCHOLAR page. Usually you will get the first paper similar to your keyword.
From my experience, this way will help you a lot. If you still have a problem, do not hasitate to let me know.
Kind regards, Dr ZOL BAHRI - Universiti Malaysia Perlis, MALAYSIA
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Want to compare FEM results to gain confidence.
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Thank you for the link given above.
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engineering strain
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ANSYS CFX is a commercial Computational Fluid Dynamics (CFD) program, used to simulate fluid flow in a variety of applications.
Vector Fields from Cobham, used to simulate electromagnetic vector field .
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Good question.. Please share me the best answer might you trust...
Regards…
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Give your personal opinion for others to read.
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I did not elaborate in my earlier comment because I thought most people are aware of h index and impact factor. But it seems it is necessary to say a few things.
By and large, impact factor relates to quantification of the quality of a Journal whereas h factor to that of an author. A journal has higher impact factor if it has more readership and thus popular. Now we know all over the world the number of scientific community is much more in biological and medical sciences. In physics it is not that big. In chemistry still there is large community. Therefore the impact factors f journals in physics remain low as compared to those in medical and biology fields. Now a days there is a tendency to have broad based generals like "biomedical and materials" having high impact factors because the audience they cater to is very large. Anyway this has become a technique to increase impact factor o a journal. The classical journals in physics who are well rated like Physical Review do not get their impact factors increased very much above 3. Still they have their place in the society of physicists.
As regards h index, it has not much to do with impact factor of a journal directly. It only is an indicator how many of your papers are cited how many times. It does not depend on the quality of who cites them or which journal cites them. In big groups this h index tends to rise enormously because all collaborators refer invariably the group citations and continues endlessly.
Of course there is a problem for a relatively new entrant to establish and find ppl who can cite his/her work. It seems one has also to be smart in addition to good worker.
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We consider the order of cycle or transpotion but is there any book that will give idea of order of permutation.
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I think in any book of algebraic structures you can find it.
Basically the idea is that any permutation can be unique represented into cycles operating on disjoint sets.
So we may write a given permutation P=C_1C_2...C_n where the C_i are disjoint cycles, so P^m=C_1^mC_2^m...C_n^m and we see that the order of a permutation is the lowest common multiple of the orders of its component cycles
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When we are specifying the transient analysis method in ansys mechanical Apdl using 'TRNOPT' we are specifying the methods FULL, reduced,mode superposition and variational technology method.
Can any one help me in under standing what this means.And what is the difference between these methods
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In Full method, the equations of motion are solved using the full mass and stiffness matrices.
Reduced method: Reduces the size of mass and stiffness matrices. There are many methods to reduce mass and stiffness matrices. I am not sure which one Ansys uses.
In superposition, first modal analysis is done. Next, the response for each of the first few modes is calculated and then they are superiposed.
Clearly, the first method is naturally more accurate. But, it is by far more time consuming.
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I am working on vibration suppression of cantilever beams using Eddy Current Dampers. I want to model it with any Finite Element software, so that I can compare my experimental results with it. Which software is best to use for such an analysis? Where do I begin?
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Ansoft maxwell 2d/3d can do it.
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I am working now on the grain drying with CFD simulation using Comsol and I need to start with one kernel simulation for moisture transfer during drying. This is the first time for me to use the Comsol. So, How can I start?
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We can coupling CFD and diffusion models in COMSOL to simulate the heat and mass transfer during drying.
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How can I simulate an infinite tip and what is the length of your model?
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You can get the similar or apropriate answer by searching the keyword in the GOOGLE SCHOLAR page. Usually you will get the first paper similar to your keyword.
From my experience, this way will help you a lot. If you still have a problem, do not hasitate to let me know.
Kind regards, Dr ZOL BAHRI - Universiti Malaysia Perlis, MALAYSIA
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When working with hyperelasatic materials in any FEA software, we need to select FE models such as Ogden, Van der Waals, Yeoh, Mooney-Rivlin, etc. And I also assume that you know that hyperelastic materials can handle 600-700% strains when stretched. FE Models are required to match the experimental results with minimum errors. In my case, the Yeoh 3rd degree model fits reasonably well.
I am trying to identify that the YEOH (3rd Degree) FE model falls in to which category of strain percentage. What I mean is that the 3rd Degree Yeoh Model is acceptable in which strain ranges?
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The simple truth is that the hyperelastic behaviour of different materials are not exactly the same. Hence the practice is to find which material model (Yeoh, Ogden etc.) best fits your experimental data. I assume you have done a uniaxial test. Make sure that your test data covers the range of strain that your material will be subjected to in your simulations and use the material model that best fits your data. We have found the Yeoh model is a good fit for rubber compounds for up to 1000%.
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I just started to work on a human brain activity modeling in order to find a new model of sources, in order to solve the forward problem in EEG/MEG with a finite element method. Do you know the recent news in this field?
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Thank you for your response,
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In fluent, I always used to get the error of Divergence with AMG solver. Can anyone please let me know what is the pecularity of AMG solver & settings
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If you are simulating for an unsteady case, e.g, by means of VOF technique, it is usually dependent to the time step size and transient algorithm. Try to decrease the time step to half and always use the Iterative method instead of Non-Iterative method. Hope it works!
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On a system.
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You can get the similar or apropriate answer by searching the keyword in the GOOGLE SCHOLAR page. Usually you will get the first paper similar to your keyword.
From my experience, InsyaAllah this way will help you a lot. If you still have a problem, do not hasitate to let me know.
Kind regards, Dr ZOL BAHRI - Universiti Malaysia Perlis, MALAYSIA
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The sequences are as follows:
A. Do the estimation using FEM analysis and validate with experiments
B. Do the experiments and validate with FEM analysis
Most of the studies I read show that the 'A' sequence is usually practiced. I did a study, however, on validating previous experiments, which had been done by previous researchers using FEM. When I did that, I encountered large errors/differences between the FEM and the experiment. What judgement I should make? Are the FEM models the problem or must the experiment be done again to ensure it is following what the FEM analysis estimated? This is a general question related to research ethics and an inquiry about what has been missed during the experimental tests.
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To increase the reliability in your simulation results, you should consider the following steps:
1. Perform experiments
2. Establish a simulation model and calibrate material parameters etc. to make the simulation results comply with the experimental results of step 1.
3. Consider a different set of experimental data, obtained under slightly different conditions, and verify that your simulation model from step 2 also predicts the experimental results in this second set, without re-calibration.
The bottom line is that you should do both a validation and a verification of your model. Naturally, it can also in some cases be of interest to do some preliminary simulations, prior to the experiments, just to get a general feel for what experimental conditions (loads, temperatures, velocities etc.) could be of interest.
The usual cliché holds: "All models are wrong, but some of them are useful".
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How can we raise the limits of integration for a triangular element in cylindrical coordinates in FEA? How are the limits in the radial and tangential direction?
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I don't really understand your question. If you could phrase it better and/or in a different way...
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What kind of special module is to be required for this and how can I model this?
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Steps:
1. Generate the structural model of CNT using relevant sofware, e.g. Nanotube Modeller, Material studio, etc. Note free version of Nanotube modeller is available with limitations, download from: http://www.jcrystal.com/products/wincnt/.
2. Export the model generated in (1) as a PDB file, remember to accept the option to include the connection table(bonds).
3. Convert the PDB file into Ansys nodes, keypoints and lines. You need Python and Wingware IDE to achieve this task. For more details, visit http: //machine-phase.blogspot.com/2009/11/convert-protein-data-bank-files-into.html.
4. The output file will be in the xyz directory, as created in (3). To load them in Ansys: File > Read input from...
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In COMSOL, there is a database that includes properties of common materials. What if my material is not in it?
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Dear Dr. T.Liu,
Could you describe little bit exactly - what kind of material properties you need to calculate. Our company realizing some calculations using COMSOL.
Best,
Vitaly
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Hello,
I would like to know if somebody is dealing with this kind of simulation. I did not find any studies concerning this particular subject in CFD. My main issue is to know the forces acting in the human body when it impacts the water. Since I did not find anything more similar, I'm just trying to make a correlation with the slamming studies for boats, but too many assumptions must be made, and I'm afraid I'm not being too precise...
Can anyone help me by telling me some reference or ideas?
Thank you very much
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Thank you very much for your useful answer,
Actually, I use (and it's the objective to use) just a finite elements software developped by my supervisor. It allows both implicit and explicit time integration schemes, and virtually any algorithm could be implemented.
The human model that I use was entirely made by me (programming in C++, I made a parameterized human body mesh), by using the smallest possible number of finite elements (I particularly use complex elements, 27-node hexaedric elements). The final objective is to make the simulation as fast as possible.
So finally, what I would need is some expression which could be implemented in the simulation software. I don't really need an expression 100% precise with a high calculation cost, but an expression with gives a correct order of magnitude of the body's deceleration at the water entry. And that kind of study is what is difficult to find.
I thank you again, and specially for the reference. I'll try to see more examples like yours or even look in the LS-DYNA theory documentation for some ideas.
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Hi friends,
What is the element formulation used for PLANE42 element in ANSYS software? Please let me know if anybody of you know about this. Thanks in advance.
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Hi Fatih,
Thanks a lot for the information.
Actually I know the theory behind dealing with incompressible materials, advanced element formulations like different mixed u-p formulations, Bbar, Fbar methods.
I did not find any information in ANSYS help mentioning the formulation of PLANE42. It says PLANE42 is a legacy element. I know that there are advanced elements like PLANE182 which explicitly support mixed u-p formulation and used them in the past.
My problem is that when I simulated a problem in ANSYS using PLANE42 elements with nearly incompressible Elasto-Plastic material (nu = 0.48) I could see slip lines clearly. But when I simulated the same problem(with same mesh) using the code developed here in the university with simple 4noded elements, I did not get the same result. We obviously needed to go for enhanced formulation because of locking, to get the correct results. I cant suspect the code here because it was developed by the pioneers of FEM. And I don't suspect ANSYS either. ANSYS might have some means of dealing with locking. That is the missing information I want to know.
Hope someone knows about it.
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In CFD while analysing a problem ,adequate knowledge of these softwares is essential.
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Go through Tutorials. it is really helpful.
Optimization
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hello friends, i have following optimization problem; c1-f1(x1,x2,....,xn)=0 c2-f2(x1,x2,....,xn)=0 ..... cn-fn(x1,x2,....,xn)=0 c1, c2,..., cn are constants. x1,x2,...,xn are variables. and f1, f2,...,fn are outputs of a sutructural system (let's say displacements at some points). I want to find the values of x1, x2, .., xn providing the equations listed above. I use matlab. is there any algorithm or example which i can use? can optimization toolbox of the matlab provide this? thank you
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you can use multi function PSO for this type of problem.
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Hello everyone I wish to do research work in the variational formulation of annular fins..
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Daad
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Dear Nilanjan Chaudhuri ... If you need any help with FEM .. check my articles..
Regards..
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Hey,
I'm modelling a tall stack (37.5 m high) and the main loading on it is wind load, as shown here : http://courses.cit.cornell.edu/arch264/calculators/example2.4/02.jpg . I want to model the acting wind pressure but my problem is that when I apply Pressure acting on Area in Ansys it applies it normal to the area of the stack and this is not right, the wind pressure acts in one direction only on the cylindrical surface of the stack as shown in attached picture.
I wanna know how to apply this type of load in Ansys 13.0 .
Thank you very much for your help.
Best Regards,
Omar Eladel
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I have nor used it, but using surf 154 elements seems to be your solution; http://www.kxcad.net/ansys/ANSYS/ansyshelp/Hlp_E_SURF154.html
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I'm doing my master's thesis and I need some information on how to model a wall-slab connection. I need to model reinforced concrete with the connecting reinforcement. Are there any tutorials on how to do this? I've never used ANSYS before, but I'm familiar with other FEM software. Thank you!
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Oh, forgot to mention that i also need to do a time-history analysis in order to investigate how the connection behaves under an earthquake.
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I am a final year student of mechanical engineering. I am pursuing a project in fem analysis of annular fins considering both thermal stresses and loading conditions by considering it as a cantilever. I want to have a variational formulation for this case. Can anyone please help me out??
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Are you using abaqus?
ANSYS and PYTHON TKINTER
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Hello Friends, Is it possible to implement GUI applications written in Tkinter into Ansys? Ansys has capability of written Tck/Tk applications. Tkinter is a library of python with Tcl/Tk GUI features, and easy to code (writing a GUI application in Tkinter is easy and fun). Any idea on the subject will be so much appreacited.
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Please check references below.. hope it will be helpful for you… Regards… http://support.ansys.com/staticassets/ANSYS/Conference/Boston/downloads/Customizing%20ANSYS%20WB%20-%20Sudharshan%20Renganathan.pdf http://support.esss.co/hc/en-us/articles/205250985-How-to-use-scripts-to-generate-a-plane-wing-using-ANSYS-Design-Modeler-15-0
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i am just completed my under grad and in post grad i want to know about the
book that will help me to make soft ware choosing elements i have completed
APPLIED FINITE ELEMENT ANALYSIS LARRY J.SEGERLIND...
Strain Hardening of material in ABAQUS
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Dear engineers, I am modeling some structures with ABAQUS and I want to know how can I introduce the strain hardening of steel materials with two main properties (yeild & Ultimate point). In some papers it is refered to "Plasticity" and "isotropic-kinematic hardening" which I did not pass these courses. I was wondering if you give me some information about this problem. Sincerely Azimi.Mohsen
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Hi dear Mohsen For define strain hardening of steel materials with two main properties you should use Modified Ramberg-Osgood model. good luck
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Abaquas is the best software which i have ever seen to analysis the displacement and deformation of different nodes.
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There is never one perfect software for everyone. I could recommend trying SimScale. It is based on open-source codes like OpenFOAM and Code-Aster etc. It is a cloud-based simulation tool and you can set up things using a browser. This reduces the hassle of licenses etc. They offer a free version that allows for 3000 simulation hours / year. However, in this case, the projects are available publicly through their public project database. They also have a professional version.
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Has anybody modeled a model with reinforced concrete pattern in ANSYS 13? I find it absolutely different from 12 Ansys...
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What is the "pressure" in field output stress component?
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Hi everybody, ABAQUS I do not know what is "pressure" in field output list exactly.(S11,...,Pressure,..) is it equal to "sqrt(2/3*I2)" where I2 is the second invariant? in this page: http://www.engin.umich.edu/class/bme456/ch2stress/bme456stress.htm i was wondering if somebody would tell me about it. Sincerely
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@Fatih: u shud not put trace(sigma_ii), bcoz sigma_ii itself is the trace of stress tensor (sigma).
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I am an undergraduate Mechanical Engineering student, and I want to learn FEM since it is not in our undergraduate curriculum and I wand to know how to learn it and which sciences I must have studied to start learning FEM and how to start it ?
Thank you :)
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There should be a good knowledge of mathematics, vibrations, structure, cfd, fdm and it actaully depends on what type of problem one is dealing with. The finite element analysis is the simulation of any given physical phenomenon using a numerical technique called finite element method (FEM). Engineers use this method to reduce the number of physical prototypes and experiments, and to optimize components in their design phase to develop better products, faster.
Modeling Concrete By ABAQUS.
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Hi, Is there someone who knows about modeling a concrete element in abaqus? I have been thinking about CFT(concrete filled tube columns) and I would need sb's advice. Sincerely
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Hello, I can send you some input file to ABAQUS concrete, reinforced concrete specifically, modeling.
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how to convert roller chain link in to fea model? which steps to follow? any idea
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Which package do you use? Do you want to carry a strength analysis of the roller chain mechanism itself? Can you more clearly describe what you intend to do?
thanks.
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Volumetric Locking is exhibited by incompressible materials such as rubber having poisson's ratio near or equal to 0.5 resulting in an overly stiff response. The overly stiff response is depicted in figure below.
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for finite elements it can be related to stiffness off deformation nodes.
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If some material is there then please forward to patel_am@yahoo.co.in
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Good question.. Please share me the best answer might you trust...
Regards…
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If some material is there then please forward to patel_am@yahoo.co.in
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what kind of material do you need of? do you mean material model? or specific mechanical properties of some certain material? please could you more clearly describe your need?
Thank you very much
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Hi
I am working in multiscale mechanics of fibre deformation.....
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Interest topic in computational mechanics. What software is currently active to implement the multiscale mechanics of fibre deformation?
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My thesis is about abaqus software.
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Will you code the boundary element in UEL? For what kind of problem solutions will that coupling be used?
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Is Ansys the best software for analysis of rubber materials..? Can anyone please comparison with software s such as Solid Works and Autodesk Algor.
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I think that Ansys, Abaqus and Comsol MultiPhysics are the best software for finite element analysis of nonlinear materials like elastomers.
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Abaqus contact
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you can also use node-to-surface contact between two elastic surfaces. it does not need to be a sharp corver, or rigid, or something like that.
the main difference is that the node2surface uses a master-slave approach. In that, the slave surface nodes slides over master-surface element faces. This means that master surface nodes can penetrate into the slave surface nodes. This is the reason why you need to select the fine-meshed surface slave, and the coarser one as master....
if you use surface2surface contact, with its more advanced contact algorithm, both surface element faces are considered, which in turn means no penetration of nodes on any of two faces, and a more realistic simulation. But this time it will be more expensive in names of speed and memory.
good luck
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There are certain advantages of FEM over BEM and vise versa, one can certainly take the positives out of both and merge them together. Is there any implementation of deriving Green's utilizing FEM? Is there any interest of such implementation in industry?
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Yes there is a real interest by industry in this approach. The reality is that the majority of industrial problems involve the growth of 3D cracks small naturally occurring (3D) initial defects that are typically less than a 1mm deep/long. Most components also have a standard uncracked FE model. To explicitly model the crack requires a major remeshing exercise and is time consuming. Furthermore as the crack grows and changes shape then you need to repeat the exercise (re-meshing) and resolve. In most cases at least 20-50 increments in the crack shape are required meaning that the problems will need to be re meshed and re-analysed at least 20-50 times. A typical real life subcomponent can be expected to have of the order of 600,000 degrees of freedom. On current computers this takes approximately 5 minutes elapse time. This means a total solution time of between 1-4 hrs plus all the time spent in assessing the meshes to ensure that they are OK. This is just not a practical way forward. For academic problems the meshing problems are much simpler and you do not need the same mesh density so this is not a problem for university academics who generally study simple geometries with simple load distributions.
The best way forward is to run the baseline fem or BEM model and determine the stresses in the uncracked structure. Extract the stresses on the plane of the crack then use Green Functions to determine the K solution for all possible combinations of a (depth) and c (length). Next fit a 3D surface to these solutions to determine the solution space for the problem. Then use this solution space to grow the crack and to determine the life of the component. Determining the solution space typically takes 2-3 minutes even for the most complex problems and the subsequent lifing takes less than 1 minute so that the total elapse time is less than 10 minutes. In other words the engineer can start the analysis walk away, make himself/herself a cup of coffee, bring it cack to his desk and by that time he will have his answer.
This is what we do routinely.
The problem is thus, how do you determine the 3D Green’s function for the problem of interest ? We have done this using the 3D Trefftz solution. However, you could do it using f.e. I would be most interested in that since there are classes of problems for which when using the Trefftz approach it is very difficult to obtain the Green function.
I should end by saying that it is irrelevant whether you use FEM or BEM to obtain the stresses in the uncracked body. Similarly both FEM and BEM take to long to solve real life fatigue life problems and are thus of little practical use. Of course this is not true if you only want to see if a given crack size will fail. In which case only a single static analysis is needed. Hope that this helps.
Rhys
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I have the boundary conditions in a fin but I don´t know how apply the neumann condition (k*dT/dx when x=L it´s 0)
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If the implementation is utilizing of Galerkin method you need to discretize the force and apply it to RHS of the system matrix.
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For example, if I attack a problem by Finite Difference Method, could I also do with the finite element method?
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You can use FEM to solve various dynamic problems. But in order to do that you first need to discretize the domain using Finite Elements. Then you will get semi-discrete system in time. After that you need to use popular implicit/explicit time-integration techniques to solve for the response, like displacement, velocity, acceleration etc.
You can't use FEM to solve a 'pure time dependent system' like mass-spring-damper system.
Hope this explanation helps.
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I need tutorials explaining how to perform a wrinkling simulation of thin membranes
I will be grateful for help
Best regards
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I dont know, that much depth .... Some of my friends are working on hyper-mesh and nastran and patran. I will ask them, if they know i will inform to you.....
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How can I calculate orthotropic properties for RCC in order to use it for composite structures in ANSYS?
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If you are using a recent release of ANSYS you have to go in Engineering Data and you have the option to define an orthotropic material (it depends by license). In addition in ANSYS there is ACP that is the module for composites but you need of the apposite license.
If is possible to define your model as shell it's possible define more layer on a single shell (probably also the angle) and it could be a good method, beacause a lot of users make in this way.
Calculate properties material it's very hard in ANSYS, usually is the producer of material that inform the FEM analyst.
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I'm surprised and a bit confused that I read somewhere that Young's Modulus doesn't affect the results in linear analysis. The writer of this statement said to try on two different beams, with all conditions the same except the material. I tried on two beams, one aluminium and the other steel, and noted no significant difference in stress intensities.
I've studied in FEA that we have a stiffness matrix which has Young's Modulus in its equation. I'm surprised about the effect of Young's Modulus in Linear analysis in ANSYS. If this is so, then how can we differentiate two linear analysis on two different materials?
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probably you put an high load on the bar and arise a buckling condition.
But to proceed in a better I suggest to you to make a modal analysis on the bar with the different materials and observe if arise some differences. For more accurate considerationds I need to observe the model if you want to send me it I will be able to help you, because I use ANSYS every day and I'm involved in ANSYS customer care.
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I would like to simulate a actuator made of silicon rubber in Ansys. How do I determine the constants that need to be feed? On what parameters does these constants depend on?
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Properties of rubber is very difficult, because it is time function, you can find some suggestion from this textbook, " An introduction to the mechanical properties of solid polymers". The authors are I. M. Ward and D. W. Hadley.
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Can someone suggest a basic book for finite element analysis relating to health?
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you suppose to to check the books of orthopedics bio-mechanics, FEA has vital role in Bio-mechanics.
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Anybody with good knowledge of Ansys classic interested in joining hands with a research scholar in Kochi for journal paper in Mechanical Engineering?
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I failed to understand your question...
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I am working on bolted joint in composite structures. The joint under consideration is a single bolted joint. The bolted joint is loaded in double shear i.e. there are 3 laminates, the center laminate is pulled along the length of the laminate and the other two laminates with an end tab is fixed betwen them just to avoid bending.
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Interesting..
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Can anyone recommend a resource for Topology Optimization module in ANSYS? I haven't found any book which contains "enough" info about using ANSYS in TopOpt.
Thanks!
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Hi.. It is good to see.. I am doing lot of projects on this topic. Doing topology optimization by using ansys workbench.. I know this topic very well. Let me know, what is your exact question, so I can resolve it..
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I have two options of software: ANSYS and Abaqus.
I want to learn FEM but I am not able to choose the software. Please help me with reason and your experience.
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It depends on your application. what do you want to do exactly?
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Diameter of shaft - 39.96mm
Diameter of bearing - 40.00mm
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Ansys is good
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Also I wand CFD analysis for the same and Matlab coding
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hmm...Sounds interesting, but I have no idea. Lets see, maybe some one is trying...
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I'm working on modelling of solar dryer (natural convection type) in ansys 8.0 ,but feeling difficult to apply boundry condition. Can anybody help me?
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Interesting..
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Is there any way to transfer the transient displacement function to forced periodic solutions?
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What do you mean?
If you have a transient system
[K]x(t) + [C]v(t) - [M]a(t) = F(t)
you can make a monochromatic expansion for a given frequency w
[K]x(w) + w[C]x(t) - w^2[M]x(t) = F(w).
So you solve for different frequencies w and with a convolution between the Fourier Transform of F(t) and the Transfer function you can have the solution in the time domain.
Regards,
Nicolás
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Hello, I need to apply finite element method to predict the heat and mass changes during grain storage in silos using CDF ansys. the problem is how I can make a prouse media like the grain bulk?
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3. Briassoulis D., 'Finite element analysis of a cylindrical silo shell under unsymmetrical pressure
distributions", Computers & Structures, 78, 1 – 3, 271-281, 2000
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Una herramienta que muestre cual es la actualidad o el estado del arte de este tipo de software en la actualidad muchas gracias.
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Thanks
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In many dental studies, the analysis of stress, strain, and displacement of tisues under applied forces shows the immidiate (momentary) effect of the force application, but they lack the ealuation of the time effect.
Usually forces fade by time, & also some biological responces occurs (compression leads to bone resorption, while tension leads to deposition). Also, sutures (lines between ones of the skull ) can be opened under forces applied for some duration.
Is there a way to simulate te effect of time in such cases?????
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The theory has been well established. You know even for metal such as tin, there is time-dependent deformation like creep and there are many mathematical description for that time-dependent behavior. You can find numerous papers on that subject if you search for example "visco-plastic" in the Web of Knowledge.
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Laser slab
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It is for a project on evaluating spring back in sheet metals and involves non-linear analysis
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If you have a 64-bit computer CAELinux if a free open source option. It comes with the open source codes bundled and pre-compiled. See http://www.caelinux.com/CMS/ for details. I'm not too strong on the solid mechanics side but my understanding is that the solvers (with Salome as the geometrt/meshing tool) like Code-Aster are for linear elasticity. For developing your own non-linear solvers you would ideally do it yourself using C++ libraries like deal.ii ( http://www.dealii.org/ ). The deal.ii library is very good and it won the Wilkonson prize for numerical software. I am thinking of seeing if I can write a non-linear FEM solid mechanics code later this year.
For fluid mechanics codes the underlying PDEs are coupled convective-diffusive by definition but the radial basis function approach is starting to look quite promising for straight non-linear analysis, and its nicer because unlike the FEM approach the dimensions of the underlying PDEs can be higher than three.
Regards,
Vishal
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thanks everybody actually i was a PG student doing my research work on 3D analysis of a laminated plate using FEM in the process got a doubt whether an analysis has to be carried out separately for fracture or not. And also is there any compulsion in going for fracture while analyzing a plate or else just finish at calculation of stresses.
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hello rama,as per your statement there is no need for fracture analysis.Explain in specific if you require more help.
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is it necessary to go for fracture for calculating stresses in a laminated plate or is there any other method available for calculating stresses without fracture using 3D Finite element analysis
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Nilanjan das chakladar said it depends what kind of analysis you are acrrying and what you are trying to obtain, besides if it is a linear elastic fracture mechanicas case, i think you could use finite element analysis for first approach, and compare the results with experimental data if you have such information, otherway if you are dealing with elasto plastic fracture mechanics the finite model may be a lot more complicated and still to assure the simulation results you need experimental data, and in this case acquire experimental data is a lot more expensive.
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FEM analysis of annular fins
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This seems to be a second order total diferential equation - having T (temperature?) as a function and r as a parameter. You can look for the general solution in a diferential equation handbook, but you won't like the expression of the solution. If you want to get closer to the result, you would have to find the expression of the T function. Further improuvement could be obtained from expressing the boundary conditions - and so you get your result - the variance of T with the parameter r. If you only want to find the derivative of T, you also need it's expression. Regards!
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I am modelling an extended end plate steel connection with ABAQUS. Here is my question; what should be the interaction type with end plate and and column? Surface to surface or node to surface? Also what should be the sliding formula, small sliding or finite sliding?
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Please provide more details, screenshots would be of great help here.