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Anybody knows how to change the density of materiel during a deformation process in a specific strain range, for example (when strain raise from 0.1 to 0.2) using VUMAT ABAQUS subroutine?
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Martin Veidt : Thank you for your comment, but there is no density dimension in the VUSDFLD subroutine nor Strain.
Based on what dimension density can be changed or assumed?
Can you please explain a bit specifically?
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Dear,
Please, how to use ABAQUS ''SWELLING'' option with Law as ''Input''. I have inserted a range of values for ''Strain rate'' and corresponding Field variable 1 - see attached screenshot file as pdf.
But when I run the job in ABAQUS it ONLY read the first value of the table (first row - as highlighted in the attached file) and ABAQUS doesn't read any other value for 'Strain rate' and 'Field 1'?
Please, can I use ONLY the tabular data (multiple values of Strain rate and corresponding Field 1) without using the subroutine USDFLD?
Many thanks for your support and time.
Best regards,
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I didn't work on this model, sorry.
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Hello everybody
Hope you’re doing great
Assume I have two material properties MATERIAL1 and MATERIAL2. I start my model with MATERIAL1 and calculate each element’s (von misses) stress and if any element’s stress exceeds N MPA I change its material to MATERIAL2 and continue till all the elements’ materials
are altered to MATERIAL2.
For this purpose:
Do you suggest Abaqus scripting by the following method:
1. Run the job
2. Write elements’ stresses to an .odb file
3. Check the elements’ stresses by reading the .odb file and change the desired elements’ material to MATERIAL2
4. Run the next job
5. Continue the above-mentioned loop by a script till all the elements’ materials change to MATERIAL2
Or
Do you suggest running a job and implementing Abaqus subroutines (USFLD etc)?
1. Which method is applicable?
2. What are the cons and pros of each one?
Thanks for your precious points.
Best regards,
Yunus.
PS: Let’s say the real model has 1000 elements or more and 5 different material properties to describe a small gap bone healing process.
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Hi Yunus Rezvanifar,
The best way to do this is to use a subroutine. If the ABAQUS has your material equations, it’s easier to use the USDFLD; otherwise, use the UMAT subroutine. Check the links below. They are articles that can help you write the UMAT subroutine.
Best wishes.
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Hello everyone
Hope you're doing great.
I'm trying to learn and implement Abaqus subroutines (particularly USFLD) and am struggling with the following Abaqus terms' meanings and applications:
1. field variables
2. material point (and material point quantities)
would please help me out here with the definitions and examples of the above-mentioned terms since I haven't found any useful website links online.
Best regards,
Yunus.
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Field variables in abaqus are quantities that are used to perform calculations when running user subroutines. They do not describe a specific
physical quantity but are often used to describe solution dependent material properties.
Integration points are referred as material points to distinguish between the
Langragian and Eulerian approach.
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Consider level 3 Fitness For Service of high pressure oil and gas equipment and thinning due to localized corrosion.
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Dear Mustapha,
Thank you for your answer.
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I wanted to add a stiffener to the rectangular plate by considering the maximum deflection node to the nearest minimum deflection node.
I can add the stiffener by considering the maximum deflection node (coordinates) to the minimum deflection node (coordinates), but it is not the nearest one.
Could anybody tell me how can I get the nearest minimum deflection nodes???
Odb Abaqus script for maximum and minimum deflection nodes but not nearest
stepframe = odb.steps['Step-1'].frames[-1]
displacement = stepframe.fieldOutputs['U']
field=displacement.getScalarField(componentLabel='U3')
maxp = max([(g.data,g.nodeLabel) for g in field.values ])
minp = min([(g.nodeLabel) for g in field.values])
nodel_label_01=minp
nodel_label = maxp[1]
coordinate = f.nodes[nodel_label].coordinates
coordinate_01 =f. nodes[nodel_label_01].coordinates
Maximum_deflection = maxp[0]
p_1 = coordinate[0]
t_1 = coordinate[1]
g_1= coordinate_01[0]
w_1= coordinate_01[1]
Min_2_x.append(g_1)
Min_2_y.append(w_1)
Max_2_x.append(p_1)
Max_2_y.append(t_1)
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Can you share your Abaqus model (.inp)?
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I simulated a pile embedded in sand soil. The pile was subjected to lateral and vertical forces. The model was aborted. I have printed the "Job Diagnostic" to present the causes of the aborted model. The problem occurred because of the nodes at the contact surfaces between the soil and pile. Some nodes were overclosure, and others separated, as presented in the figure below. How can I solve this problem?
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Good afternoon! If the model solution stops, it is desirable to check the boundary conditions, it is also possible to increase the size of the computational grid. The pile is usually monolithic and the moment of inertia is evenly distributed.
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I am running a model of concrete SOLID65 with LINK (bar) elements.
I have attached below my material properties and failure criteria.
The model has not converged yet.
Any tips on how to make the model converge?
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The answer to your question could be pages. I will suggest few things assuming the definitions of the material models and boundary conditions replicate the given specimens in the test (in case you are trying to validate your model with experimental results).
0- Apply displacement rather than forces.
1- Turn off the force convergence criteria and only keep the displacement.
2- Exclude the extra displacement shapes for SOLID65 (Keyopt 1).
3- Use finer mesh as SOLID65 is mesh dependent.
4- Use bond-slip relation by employing COMBIN39 element.
NOTE: check the value of uniaxial tensile strength as it seems too small for the given concrete strength. You may use ACI or any other code to find that value.
Let me know.
Good luck.
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Is their any FE modeling software to create porous structure in any solid model.
Basically I am designing acetabular cup in CREO on which i want to create trabecular porous structure on articulating surfaces. But I am unable to create porous structure in model.
I tried in ANSYS too but failed.
Any suggestion please..
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I have designed a python-based application regarding this purpose:
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Dear Researchers,
i am using a python script for a parametric study. This script generates .odb files automatically. The problem is, that i can't open the files with ABAQUS cause the Output database created by python is too recent. Error message: "... .odb is from a more recent release of ABAQUS."
The Version of python used by my ABAQUS Version is 2.7.3.
I would be glad about any tips on how to solve this problem. Unfortunatley upgrading ABAQUS is not an Option at the moment
Thanks in advance
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I have created 44 Video Lectures for ABAQUS Python Scripting:
suitable for beginners and experts.
The corresponding Code can be found at github:
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Dear researchers,
I am just trying to vibrate a plate with a horn (see attached figure) in one direction with ultrasonic vibrations in Abaqus. I am new to Abaqus, how can I apply an external vibration/vibrational load to surface of a plate? Harmonic analysis needs a force but can I manipulate it as a vibration? I am open to any suggestions.
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The cycle load module can completely solve this problem
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I have a streel structure and the welds need to be merged in share topology in SpaceClaim in order for the elements of both parts to match.
But the contact between beam must no be merged in shared topology so that I can make a contact frictionless in Mechanical.
I can only manage to either separate all bodies so that they all make contacts (but mesh does not match) or merge all bodies so that mesh matches (but no contact surfaces are created and I cannot make the beam-beam contact frictionless).
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I have found a solution for the above said problem. Bodies grouped under a single part in Design modeller can have selective shared topology using the option of 'Connect'. You may refer to this under the section of 'Selective Shared Topology: Using Connect after Share Topology' in Design Modeller User's Guide for further information.
Thanks.
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How to implement the crystal plasticity finite element model in Ansys?
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Hi,
Mfront can be used for the analysis. see attached a helpful document
Regards
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Hello, I have a static general simualtion, for which I hace created a specific Field Output request asking for those results (image).
However, when I check the results I don't have the option to choose these (image2)
Does anyone know why this is happening?
Thanks in advance
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Dear Ana,
Check that if your model fully supports these outputs. Make sure that the analysis type, material properties, and element type are defined in a way to produce these outputs.
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A pin on disc under lubricated sliding wear.
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Dear all
Please find attached the image T.jpg.
The image of the FE model attached is a hollow body with some prismatic textures on the interior surfaces. Here I need to select all the nodes at the interior surfaces of the FE model. I have tried to use:
NSEL, S, LOC, X, X1, X2
but as the body is having a certain curvature on one side, all the required nodes are not getting selected. And as the number of nodes is many i.e. above 100000, graphical picking seems to be a cumbersome task.
Please help.
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Dear all,
Probably it is too late to respond to this question. However, I wanted to put my two cents here.
Selecting interior nodes is always a challenge and simply selecting a surface and the nodes attached to a surface is not always going to work. The best way of selecting nodes is selection based on a coordinate system and a geometry referred to that coordinate system (as also suggested by
Claudio Pedrazzi
). In Mechanical (by default) you can select nodes based on a cube geometry which is related to a Cartesian coordinate system (in the background). You can developed algorithms that uses different shapes e.g. cylinder, sphere and etc. based on either Cartesian or Cylindrical coordinate systems.
I developed an ACT sometimes back that enables selecting nodes in ANSYS Mechanical based on different shapes and coordinate systems. This ACT is available in ANSYS app store right now. I put a pdf document here hat shows the ACT capabilities.
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Dear All
I need laboratory data to do a scientific research on cross laminated timber. I want to use artificial neural networks combined with meta-heuristic algorithms. Data can be suitable for my study work in any of the following cases:
Adhesive
Axial strength
Compressive strength
Bending
Connections
Damage
Finite Element
Panel
Fire
Multi stories
Shear
Shear walls
Are there websites, laboratories, or papers that can be used from them to collect or receive data?
Could you please kindly help me?
Best Regards
Mehdi Nikoo
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Thanks for sending valuable papers. Papers focused on various topics.
Do you have a dataset that focuses on a specific topic in Cross Laminated Timber?
Best regards
Mehdi
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I am simulating piled raft foundation subjected to seismic load (earthquake) in ABAQUS. I have modeled soil as solid elements and Mohr-Coulomb parameter. I want to know how can I apply geometric damping (silent boundary) to prevent the reflection of seismic waves?
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The simplest solution you can use in an Abaqus simulation is to place viscous dampers at the boundaries of your model as described by Lysmer and Kuhlemeyer (1969) and make sure your boundaries are not too close to the structure and foundation. This works well in the presence of a homogeneous soil profile and perpendicular/tangential waves with respect to the sides of your model. The next step would be to look at more advanced approaches such as: infinite elements, absorbing layers (e.g., CALM = Calm Absorbing Layer Method), PML (Perfectly Matched Layers) or even hybrid approaches mixing FEM and BEM formulations. However, I do not know if these methods are available in Abaqus software (perhaps using user-defined elements?) nor the particular problems that may arise when calibrating their parameters, numerical stability, etc.
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Hello everyone,
In some articles, some authors report the experimental values of Young modulus, yield strength and ultimate strength; but the ultimate strain values aren't reported (mostly for bolts). In that case, when using the data for an FE simulation in ABAQUS, what value of ultimate strain could be used?
Thanks for your time.
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Then its easy to input curve in that
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Hello everyone.
I am encountering some problems while chasing after the convergence of my model.
I am using Ansys APDL in order to model the creep in steel under high temperatures.
I already did all the code, but I cannot find the issue.
All the geometry is very simple, just a cantilever beam under tension stresses.
The material model is composed by the multilinear elastic model, multilinear isotropic hardening model, creep model (time hardening P+S) and thermal strains.
The solution is divided in three stages:
  • applying the uniform temperature;
  • applying the force;
  • enabling the creep effect by turing the rate on.
Even though, there is no convergence, and the log file keeps showing this:
"Material property EX of material 1 of element 2 is evaluated at a temperature of -14571.8048, which is below the supplied temperature range. Temperature range checking terminates."
Due to the excessive amount of errors and warnings, the program terminates. I've already looked in lots of discussions and could not find any situation similar to mine.
Here is what my solution steps looks like:
/SOLU
ANTYPE,0
NLGEOM,ON
OUTRES,ALL,ALL
NROPT,FULL
DK,1, , , ,0,UX,UY,UZ,ROTX,ROTY,ROTZ,
!-------------------------------------------------------------------------------
FK,3,FZ,1000
SBCTRAN
RATE,OFF
TIME,1e-8
AUTOTS,1
NSUBST,100,10000000,10
KBC,0
SOLVE
!-------------------------------------------------------------------------------
/SOLU
NLGEOM,ON
OUTRES,ALL,ALL
NROPT,FULL
BFL,ALL,TEMP,500
SBCTRAN
RATE,OFF
TIME,0.10
AUTOTS,1
NSUBST,100,10000000,10
KBC,0
SOLVE
!-------------------------------------------------------------------------------
/SOLU
NLGEOM,ON
OUTRES,ALL,ALL
NROPT,FULL
RATE,ON
TIME,1000
AUTOTS,1
NSUBST,100,10000000,10
AUTOTS,1
KBC,0
SOLVE
Anyhow, I've attached the .txt file (sorry for the portuguese comments, they help me to go through the problem).
If someone could give me a help, I'd be very grateful!
Kind Regards,
Arthur
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FEM has widely been used for large scale point specific slope stability analysis. I am looking for a program to perform FEM that is available for free and also stands up to research standard.
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I am now modelling shell and tube heat exchanger using COMSOL Multiphysics 5.3a.
I have several questions:
1. What is the benefit of modelling these equipments in finite element software, in terms of safety?
2. Does this FEM software really helpful on consultant engineer in designing the equipment. If yes, in what way? If not, why?
3. Do FEM software really credible and powerful? Many of the journal state that the error obtained ~15%, but ain't this software too good to be true?
4. One with skills using FEM software, is it in demand?
Thank you for answering!
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Simulation software is very helpful in a lot of ways. Firstly, it allows you to develop a better idea about the big picture of your project without having to run too many tests. Sometimes the simulation results can be more accurate compared to the experimental results, since there are more factors that can affect the uncertainty of the trials, operating errors, systematic errors and random errors, etc. I believe a lot of consulting engineers use the simulation software, such as fluent, starccm+, comsol in their research. The simulation result can serve as a strong indicator for the researchers when they scale up their reactors. In terms of the demanding situation for this type of skills, yes, as far as I know, people who are skillful in this area is highly competitive.
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Dear Abaqus users,
I perform a static analysis with a Standard module on a masonry wall macro model. Four surfaces interact with a reference point in the middle of the model as in the photo attached. Out-of-plane displacement defined on this reference point. Deformed shape and the damage profile matches perfectly with the test. But the curve of the upper point displacement and the reaction force at the base prone upwards (as seen in the attached photo).
Is that issue related with the material properties (concrete damaged plasticity material properties attached) or the constraint defined on the reference point ?
Thanks in advance !!
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I think you should consider again lateral and vertical contact properties, again consider to use penalty contact properties.
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Dear Researchers :
If someone is proficient in COMSOL and knows about the physics and applications of Electric Power Cables
Can help me on solving this model? What am I doing wrong ?
I need to compute the Temperature Distribution of this 2D model of a MV (35 kV) Power Cable.
The configuration is simple, and the application if for 25 kV AC.
I used a Study in two Steps
Step 1: a Frecuency Domain Analysis to solve first the Electric Currents (ec) and the Magnetic Fields (mf) physics. Followed from a
Step 2: a Stationary Study to solve the Heat Transfer phenomenon and its coupling with the (ec).
I'm attaching this image to shown how I can't get a Temperature Gradient, the Gradient I am getting is so tiny that practically the Temperature is uniform across all the Cable.
I'm doing something wrong
I'll appreciate the help,
Best Regards !
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Dear Franklin:
I agree with the opinions of my colleagues mentioned above, that it's difficult to find the problem since we can't see all the settings.
But you could benefit from this valuable article about your topic:
"Heat Transfer Modeling of Power Cables in Tunnels"
Electric power, in cities or for power plant outflow, is most often transmitted through underground cables. Due to increased electricity demands power suppliers make large investments to house these cables in deep or shallow tunnels.
The thermal environment is complex, with different kind of cables placed in different configurations, transmitting different powers. These are hard to take into account theorically, so thermal simulations using COMSOL Multiphysics® software were undertaken to measure the inaccuracy of the empirical models.
The Conjugate Heat Transfer interface is used, 2D and 3D models were developed and showed that several hypotheses lead to underestimation of the hottest cable temperature and two interesting possibility for improvement were found: the heat transfer correlations and cables proximity effects.
I have attached the pdf files ....
I hope it will be helpful...
With my best regards ...
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Hello, dear experts!
I need to create a mesh for Finite Element Method in 3D space around the junction of two hollow cylinders. This represents two intersecting oil wells.
I need hexahedral shape for cells (elements). I've found a way to generate a mesh around one cylinder using cylindrical coordinates to arrange the mesh nodes (https://i.stack.imgur.com/vjGiK.png), but can't find a way to adapt this approach to generate hexahedral cells in the area of cylinders junction.
The main question: is there any software or algorithm that can help me to generate the desired mesh? Either freeware, or not. I mean specifically mesh generator as a separate tool.
If I have to develop algorithm by myself, what approach could you recommend to do that? What literature could help?
Any advice and comment on the subject will be appreciated.
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Hi,
I am trying to model a wall with an opening in Opensees, when I use the "block2D" command, it doesn't allow me to draw multiple shapes to form the opening. I was wondering if anyone can guide me on how to draw a wall with openings in opensses.
this command only accepts nodes tag 1to4. How can I get around the problem?
block2D $nx $ny 1 1 $Plate 1 {
1 0 0 0
2 5 0 0
3 5 5 0
4 0 5 0
}
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Hi.
As far as I know, the OpenSees preprocessor is quite basic. You'll need to create some block2D commands around your hole.
Regards.
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Assuming a 2D or 3D thermal model representing a sample of different Z (thickness) layers, is there a way to calculate each layer's thermal resistance within ANSYS Mechanical APDL software?
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Correct! based on your geometry shown earlier, you need to use the heat flux extracted from Y direction. I used this method for calculating effective thermal conductivity of filler modified polymers before and worked out pretty good.
Thanks,
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Dear researchers :
Can one help me with the following mode? :
I'm trying to solve a simple Heat Conduction scenario of Heat Transfer between the core of a burried Electrical Insulated Cable, and the surrounding soil.
This Cable has several layers of components and is being heated by the Joule Heating Effect do to the current supplied .
I already set-up the geometry, assigned the materials, and I am using the Boundary Condition of "Thermal Insulation" and "Heat Source" in the central conductor (W=I^2 * R)
I'm traying to solve the model with a simple mesh, but I don't know what I am missing ,
This is the error I'm getting from the solver (image attached)
I will really appreciate someone's help
Best Regards !
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Hello, Franklin Uriel Parás Hernández, Whenever you design a cable model, try to design it step by step. First, disconnect the voltage source and try to simulate it first. Fill in the correct parameters according to the requirement. If you don't know the parameters then first try to find out by reading the literature and cable manual. I think this step-by-step simulation guidance will help you to play with the simulation.
After the simulation is ready then try to find the research gap and then focus on your task to find something novel.
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I have learned a few ways to improve the accuracy of the solution other than just increasing the mesh size. Here are they:
1. Decrease relative tolerance ~ usually in 10^-5.
2. Increase iterative refinements
3. Use different solver with 2 level solutions improves a lot
4. If u are using a time-dependent study ~ change the time taken by the solver ~ take time steps restricted to some min value or choose intermediate steps.
5. Don't use anything like andersan acceleration to get the convergence earlier.
6. Termination technique in solver ~ use solution + tolerance based ~ NOT the iterations based.
7. Play with scaled option ~ rather automatic use a defined value ~ normally its the max possible (usually if ur soln doesn't converge it is the best way to normalize the variables that are being solved).
If u know more please do share.
Cheers!
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Also, try using higher order discretization:
2nd order or higher order Lagrange instead of linear.
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Hi all, 
is it possible to solve time dependent ode in the boundary in COMSOL?
Please someone let me know.
With regards,
Vivekananda
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Hi guys,
i want to do a finite element model of hertzian contact between a sphere and a plate, i have defined contact between them as hard normal contact and frictionless tangential contact, also have defined main and secondary slave as shown in figure attached
but i ended having penetration instead of contact, why is that?
Note: the model is 2D
the model is attached
Please help, thank you
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"adjust just to remove overclosure" must be enough to solve your problem.
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I am a beginner in simulations. I want to simulate the current density in a fiber-reinforced polymer foam. However, I don't have access to COMSOL Multiphysics. Is there a free alternative to it that works well enough?
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Dear Researchers :
I need to stablish an AC Voltage of +/-35 kV (max. amplitud) to my model in COMSOL.
It is a 2-D Model, in which I'am trying to compute the Temperature Distribution across the whole cross section.
This is an application for an Underground Energy Cable of AC Medium Voltage.
What I am showing here is the geometry of the Cable with all its corresponding layers of insulation, and the bundle of conductors at the core.
My question is :
How I can set it up with the condition of an AC Voltage/Current rather than a DC Voltage.
Regards !:)
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Nice observations ,
Reagrding the color of the expression. The indication is "inconsistent unit on the argument"
but, the argument is [rad/s] + [rad] + [s] ? , or? I don't know
I will try to check it out,
I will se the option of selecting an "EM Heating"
Regards !
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Dear Researchers,
I hope you are all doing well,
I have a structure having inclined BEAM188 elements and I am using the element table to find axial stresses in members.
Element table -> By sequence number -> Ls
but I am not sure which value to put after LS,
is it LS, 1 LS, 2 LS, 3 LS, 4 ... LS, 30, LS, 31?
I noticed that LS, 3O gave the highest result
but what is the correct way to know which LS, to plot?
Thanks
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Claudio Pedrazzi
, thank you so much for your time and effort in explaining.
I think for axial forces I can plot SMISC, 1
and SMISC, 31 for axial stresses for inclined BEAM188 members without having to check for LS values.
Please correct me if I am wrong
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My SOLID65 element is reinforced concrete but what modulus of elasticity and material properties do I put? For nonlinear analysis
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I think this article will help you
Genikomsou, Aikaterini S. and Polak, Maria Anna (2015) Finite element analysis of punching shear of concrete slabs using damaged plasticity model in ABAQUS, Engineering Structures, Vol. 98
Regards
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I want my ABAQUS script to read values from excel (these values will be used to create the FE Model). After the analysis, I want to extract the results (for example, maximum displacement) and save it in another excel file.
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Excel is not a file format. The spreadsheet can simply be saved/exported as csv or tsv which can be used as any other normal file in any script.
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After meshing, I want to create a set comprising of all the nodes on a particular surface of a part (in my case, the top surface of a hollow cylinder). I successfully created the node set in the GUI but for a parametric study, I will be considering many different cylinders. So I want to generalize using a python script.
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Mesh size is not a parameter in my study.
Regards
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In the stress results, I get two stress values for the same node and the following error
" BEAM/PIPE elements are detected in the selected element set. They are ignored in the nodal averaging "
What could be the reason?
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In completion of what Prof. Mohammed Lamine Moussaoui described, as you know, the finite element method takes the inputs (like force or displacements) and obtains the unknown parameters by theoretical formulations. Based on the solution, FE calculates the stress values in the integration points and then interpolates them through the nodes. At this level, it can also show you the results on the elements. But the solution is the same. It’s just a matter of “displaying the results”. So perhaps you are seeing a list of stress shares of each node from the adjacent integration points as the neighboring elements are converging in that node. We know that we only get one displacement/force vector (not stress) per node (as an answer), but if you need only one stress for each node, you need to check the “mean stress” values on the nodes. As for elements, it is called “elemental mean”.
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I modeled a concrete deck slab on top of steel girders in ANSYS APDL
but my results for the bending stress (X component stress) from ANSYS do not match what I obtained from hand calculations Using Mc / I
using Mc / I i obtained 29 MPa
and from ANSYS i got 10 MPa
i attached below my calculation as well as my model and elements used.
i used MPC184 rigid link to connect between the concrete deck slab shell element and top flange steel girder.
the slab is simply supported (roller and pin)
any idea what might be wrong?
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Zeinah Mohamad Elnassar can you pls tell me which case of bending stresses u r evaluating ??there are many bending cases😊 if u r calculating Quazi-static then developed deflection & stresses will not change over time..! & also Pls check which step u have calculated. It looks your results can be acceptable if you do same condition by changing number of elements..that we called mesh independent study...in those case u will achieve ur hand calculated values hopefully!!
👍
Regards,
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Dear Researchers :
I need help,
I am trying to solve for the Temperature distribution of a 2D model of a Medium Voltage Power Cable, with all its components. This is a 2D model,
And I am considering the Cable is burrie underground.
So far, I was able to run the solution and get an arbitrary distribution of Temperatures, since I am writing an arbitrary value for the Heat Source.
But, How I can fix the value of the Heat Source correctly ? Does anyone know ?
I am attaching the image of my model where the information of the "Heat Source" has to be written
Do I have to use a "General Source", a "Linear Source" or a "Heat Rate" ?
I'll appreciate any help
Best Regards !
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Dear J. Anaya :
I see , got it,
well, let me explore this approach ...
I will report you back in one or two days,
Thank you bro,
Regards !
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When I define the beam cross section and give it b and h dimensions,
I notice that ANSYS switches the b and h after i mesh and assign the element
it switches the height with the width and vice versa,
Is it fine, do I complete and would the solution be correct?
Or, shall I switch my h and b (height and width) in the beam tool when I define the beam dimensions?
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switch my h and b in the defination
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Dear Researchers :
I will appreciate if someone can give me some help with this issue
I already have my 2D-model of a Power Energy Cable in COMSOL Multiphysics.
But so far I haven't been able to model the Heat Transfer and Temperature Distribution in the Cable due to the Joule Effect.
The Cable works under a DeltaV = 25 000 kV, has a Longitude of 1 m , its dimensions are given, as well as the material properties.
But I don't know how to stablish this condition in the model under the 'Heat Transfer in Solids' physics
I also selected the 'Joule Electromagnetic Heating' effect to include into my model, but I cannot solve the Temperature correctly.
How do I have to consider this condition? What Boundary Condition (or Domain Condition) do I have to use on the model ?
Thak you for any help !
Regards ! :)
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Hi,
You may get some useful information from the following paper:
Solution of a coupled inverse heat conduction–radiation problem for the study of radiation effects on the transient hot wire measurements
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Dear Researchers, I ask for help;
This is in COMSOL Muliphysics ver.5.6
I am tryring to solve a model of an Energy Power Cable which is burried in the soil, is a 2D model
I choose to couple the phenomena of: -Electrostatics, -Electric Currents and -Heat Transfer in Solids (this last one is coupled using the 'Electromagnetic Heating' sub-module within the AC/DC module).
I already could solve the Electric Potential and the Electric Field (both, E and D) distribution,
But as much as I tried, I cannot understand how to solve correctly the Heat Transfer part of the model
The coupled phenomenon of Heat Transfer is due to the Joule Effect, due to the Electric Current/Voltage passing across the conductor.
When I solve for the Temperature Distribution I get :
- All the model is at the same temperature
- The value of the Temperature is negative, and
- This value is x10^18 K
Defenitevely something is wrong, very likely with the boundary condition of the Heat Source I'am trying to stablish.
It could be an evident-to detect mistake, but I cannot understand it
I am attaching the pictures
The first one is of the view 100% zoomed out, to see the complete geometry (I am including the seccion of the soil in my model),
and the second image is the view zoomed in of the geometry of the Cable
Please, does any know, and can help me, Why I cannot solve this model correctly ?
I will really appreciate it,
Best Regards !
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I see, I did find the imput for the Volumetric loss density, electromagnetic (ec)
But, when I fix the Heat Source with this source, I got no Temperature (see attached image please)
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While performing the finite element modelling of FRP-hybrid steel and composite structures.
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While modeling an FRP-reinforced frame structure under seismic loading.
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You can read Chapter 11 : "The Finite Element Method" and Chapter 12 : "Multi-degrees-of-freedom systems: Free vibrations" in the book;
J.T. Katsikadelis, "Dynamic Analysis of Structures", Academic Press, Elsevier , 2020.
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Dear all,
I wanted to simulate flanges on a wind turbine tower. For this porpuse two different models were created.
1) Using tie constraints. Each segment (3 in total, so 2 connections) has a flange of the form of a shell ring of thickness 0.06 and width of 0.15. Flanges are glued together via tie constraints giving a total thickness of 0.12.(Figure 1)
2) Create a shell ring of thickness 0.12. Instead of using tie constraints and connect two different parts together a shell ring of width 0.15 and thickness 0.12 is created from the beginning.(FIgure 2)
The problem here is I am getting different Von mises stresses for each case. In case 1) max V.Mises is 1.341e6 and its location is at lower flange. In case 2) max V.Mises is 1.146e6 and its location is away from lower flange. I was expecting to get a similar response fro both cases since total thickness of the flange is the same and every other dimension is the same as well as BC. Any ideas will be great.
Ps 1. Please do not mention solids for flanges, I wanted to use shells
Ps 2. I also uploaded the .inp files for both models in case someone have time to take a look. gna_US-> no tie constraints are used , gna-> tie constraints are used
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Check out this article. I think this will help you
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Hello.
I modeled a complex ring in abaqus and with adding below command in keyword, extracted Stiffness matrix with Coordinate format. But output is a .mtx file that listed stiffness for each node (or element). What to do i to assemble this file to reaching to Global stiffness matrix (stiffness matrix for whole part, i mean m(d2x/dt2)+Kx=F)?
*STEP, name=exportmatrix
*MATRIX GENERATE, STIFFNESS
*MATRIX OUTPUT, STIFFNESS, FORMAT=MATRIX INPUT
*END STEP
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Nils Wagner so in your opinion for this work, it's better to extract this kind value using from K=F/dx? So that force is applied on part and then deformation is measured and stiffness is extracted used from K=F/dx.
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Hi,
I want to connect two nodes by using a multipoint constraint element MPC184 ( rigid beam / rigid link)
at first, i tried connecting both nodes by a line and then mesh the line and give it MPC184 element attributes but I cannot create a line from node to node on ANSYS. Only from keypoint to keypoint.
The attached image shows what i mean.
how to fix that?
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Hello,
As you work with a script in M-APDL environnement, I think it's quite easy to fix your problem :
* First, define an element type associated to the MPC184 element -> ET,10,MPC184 for example, in order to associated the MPC184 element to the element type n°10
* Then, adjust the key options in order to choose your MPC behaviour -> KEYOPT,10,1,3 for example to say that the keyopt n°1 for the element type n°10 is 3 / if the element type n°10 is associated to the MPC184 element, that means that you ask for a slider element behaviour (help MPC184 command line for help on MPC184 element and keyopts)
4/ as NODE1 and NODE2 exist, the sequence to define an element between NODE1 and NODE2 is ($ for new line character) : TYPE,10 $ E,NODE1,NODE2
(active the n°10 element type,which is already associated to the MPC184 element, with the appropriate keyopts, and then define an 2-nodes element between NODE1 and NODE2.
MPC184 is not associated to any geometric entity, that's why you can't mesh a line with a MPC184 element. You have to define it directly with the nodes.
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How I can proceed for finite element modelling of micro drilling on Additive manufacturing part. Please provide your valuable suggestions.
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Salah Uddin Thanks sir
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What is the shell orientation mean in ANSYS APDL?
Does it mean that if I have a shell on the XZ plane then I set the orientation as 0 degrees as shown in the pictorial view
and if I have a shell on the XY plane then I set the orientation as 90 degrees?
Or does it mean something else? Like the direction of the fibers in the material?
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Exactly, when using isotropic materials you can observe that the results won't change no matter the value of the orientation angle.
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I want to simulate a wind turbine's tower model. The cylindrical part constructed using shell elements (S4R) and the flanges using solid elements(C3D10).Internal stiffneres also included using shell elemnts. Shell and flanges are connected via shell-to-solid constraints.Only geometric non linear analysis is considered with RIKS method.
However Abaqus give me the following warning:Excessive distortion at a total of 4732 integration points in solid (continuum) elements. This warning appears when initial RIKS step is 0.02 and maximum step is also 0.02.However, when I increase the initial step at 0.05 and maximum step at 0.05 I get no warning.
What is this error about? Can affect my results and why initial step has an influence? And how to solve it?
PS: I also upload my .inp file
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Spyros Arvanitis This warning is due to unsuccessful attempt number1 on increment 38, when load proportionality factor increment was chosen too large (-1310.74). Correspondingly, distortional deformations took place. The attempt number 4 become successful. Of course, this was in vicinity of bifurcation point. The Riks method with larger initial increment (0.05) have passed this point more "smoothly". The choice of initial increment must not affect postbuckling results (at least if there are no neighboring postbuckling equilibrium states).
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Dear all,
I want to connect the surfaces of two shell structures (shell rings). For that purpose I was thinking tie constraints. However I am not sure how to do it properly. For example how should I assign thickness offset of each shell part (bottom surface, top surface , middle surface) in order to avoid any inconsistencies?
Best regards
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if you want to be spoon fed, good luck with that... already gave you ans n guidance
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I am modeling a bridge on ANSYS APDL using shell and beam elements. The beams and slab are connected using MPC184 (constrained element).
After I am done modeling and meshing I merge nodes with 0.001 tolerance yet I still get an error saying meshing will produce errors. even when i tried to merge all I still get a warning / error message
After Nummrg,all / Nummrg,NODE .... future commands which depend on the node to solid model connectivity (meshing, mesh, clearing, solid boundary condition transfer, etc.) may not operate properly.
My results are wrong. Is there a step that I messed?
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It is a “warning”, not an “error” message, so it only warns the user to pay attention because something is happening in the analysis. As far as understand, the message simply tells you that a node, which before merging belonged to only one CAD entity, after merging is shared by more than one geometrical entity – which is exactly the purpose of merge command. This was also explained very well by Naveen Bhatt.
I think that if areas are glued before meshing, nodes will be shared automatically at common boundaries. Anyway, besides this point, I have two comments:
- Why to connect shell/beams with MPC184 (constrained element)? Have you tried simply to connect them at a node? They should be compatible (i.e. same degrees of freedom);
- Why to use such small elements for the slabs? Normally, small elements should be only be used in regions where high stress variations are expected, otherwise they will increase the computational cost unnecessarily;
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Dear all,
I want to use ring stiffeners in order to increase bending resistance of a cylinder. The rings has outer diameter R1 = 2 and inner diammeter R2 = 1.85. Their thickness is 0.12 . They will be attached in the inner of the cylinder.For modelling them in abaqus, solids or shells should be used and why?
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I would choose solid, although the shell option works too.
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Dear all,
Is a good strategy to simulate thick structures using shell elements instead of solid ones. For example I have a cylinder consisting of 3 parts. The parts are connected with flanges with thickness 5cm on each part and mid--width 15 cm. For cylinder shell elements are used. Regarding the flanges I want to simulate them as rings. Is it good approach to use shell elements (S4R elements in abaqus) for the flange? Will the response getting with shell elements is comparable with solids?
Ps. The cylinder will be subjected to bending loads
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Here is an article I found useful when simulating bending of a tubular, perhaps you will find it helpful too: https://core.ac.uk/download/pdf/191701104.pdf
As ever with element selection, your choice will depend on the type of analysis, sought variables and level of accuracy you are interested in. A radius-to-thickness ratio of R/t=10 is generally regarded as a 'thick' structure, for which solid elements are recommended. I have surveyed many papers on pipe/tube modelling and typically those treated as 'thin' and modelled as a shell will have ratio significant larger than this (modelling a cylinder with ratio approaching 10 using shell elements may be challengeable).
The thick shell element formulation based on First Order Shear Deformation Theory available in Abaqus can give a reasonable solution for deflection/buckling type problems. However, such elements are not expected to yield a precise stress analysis (moreover through-thickness stresses cannot be obtained). If precise stresses are sought, in particular around your flange-to-cylinder region, solid elements may be appropriate. You can apply half-pipe symmetry to reduce your computational size.
Hope this helps.
JCH
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How to model delamination results from matrix cracking with XFEM?
Dear all,
I need to do 2D multicrack propagation in a composite laminate (GFRP) in tensile load. I have 3 parts namely (0-90-0 degrees plies). And I already have existing cracks which you can see below in attached pictures. Cracks propagate well, but when it comes to the boundary I couldn’t see correct delamination behavior. Is it possible to simulate delamination because of matrix cracking in Abaqus? I both tried cohesive surface and elements. With the elements it says I cant define XFEM crack zone for the cohesive element. With the surface, during loading I see some overclosures and clearances.
Here are my material properties.
Cohesive Surface:
Knn=Kss=Ktt= 1e6 N/mm3 (which I am not so sure)
Damage Initiation: Maxs damage initiation criteria Normal=Shear1=Shear2=3.4MPa.
Damage evolution criteria: Mixed mode behavior=BK(Power=2.2)
Fracture energy: Normal=Shear1=Shear 2= 0.27 N/mm2.
Also, frictionless tangential behavior, and hard contact.
For 0 degrees ply
Damage Initiation: Maxps=807MPa
Damage evolution criteria: Mixed mode behavior=BK(Power=2.2)
Fracture energy: 0.5, 0.5, 0.01 N/mm
Elastic, type=ENGINEERING CONSTANTS 35100.,9600.,9600.,  0.3,  0.3,  0.3, 4000.,4000.4000.,
For 90 degrees ply, I just swap E11 and E33 values, and maxps=15MPa
Can someone suggest me how I can model it and if my material properties are reasonable?
Regards
Berkay
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Here it is. Good luck
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I am working on experimental program comparing voided slab with hollow core and hollow block slabs and I want to simplify the finite element model
Can I model the voided slab in 2d rather thank 3d and how to take the effect of void distribution in both direction in such case?
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One of the most promising ways is still to run it as a 3D problem but separate into two scales. The first scale is 3D analysis of a representative volume, e.g., with one “sphere” to generate effective properties of such quasi-material. The second scale is also a 3D analysis where effective properties of such quasi-material are considered approximately as homogeneous. This approach may be less applicable for strength or toughness problems, but can be a reasonable simplification for deformation analysis, especially, linear one.
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Dear all,
I am looking for temperature-dependent material properties for aluminum alloys to compare different alloy grades. As for FEM modeling of welding, temperature-dependent properties are very useful. As JMatPro is excellent database software for steel, Nickel, and few other alloys. Is there any domain similar in the case of aluminum alloys? Please kindly suggest any valuable sources for database concern to aluminum alloys.
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Dear Anoop,
I have attached the "ATLAS OF STRESS STRAIN CURVE" for you. It is a useful resource.
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I have two materials, aluminum and steel, that I am simulating impact on. Both have the exact same material models:
  • J-C plasticity and damage
  • EOS
  • Specific heat and inelastic heat fraction
  • Damage Evolution via fracture energy, set to zero for both materials
  • Same velocity
  • Same contact parameters (Hard contact, frictionless, general contact)
  • Element deletion is on for both materials
I get a shear plug formation for aluminum (top image), which agrees with my experiments. But somehow for the steel material, the projectile penetrates through the target material (bottom image).
Even if the response isn't via shear plugging, why is the projectile mesh penetrating the target nodes? I would think the material immediately fractures to form a plug anyway if my fracture energy is set to zero.
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Zherui Martinez-Guo I see. I am not sure about the objective. however, If the impactor and the plate have similar Young's modulus, try to change the plug stiffness to a higher value. it may be conducive for the rigid-flexible body contact algorithm.
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Hi everyone,
to calculate the prying forces in the column base plate connections, we need to get the contact reaction between the plate and the concrete, but in my model, I have a part in compression and another one in tension. so how can I evaluate the surface of the plate in tension under the cyclic load ?
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Dear Aichouche
If I were you, I would forget the Castem and go for SolidWorks Simulation . it's more easier, faster, and efficient.
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