FE Analysis - Science topic

I have modeled a prestressed concrete beam in ABAQUS using following element type:

Concrete- C3D8R, Steel Strand- T3D2.

I have considered elastic and plastic behavior of both steel and concrete(CDP). While comparing load-deflection curve from both experiment and FEA, it has given me pretty much accurate value for ultimate load. However, the elastic response of the structure is much more stiffer from experiment data. I have already updated the FE model based on constructed specimen such as diameter of steel bar and prestress strand, concrete strength. What could be the problem?

Hi,

Despite the fact that commercial FE codes are the best candidates to model problems in mechanics and physics but most researchers and scientists around the globe cannot afford them, they are expensive and costly, but in exchange they represent a powerful tools, user friendly thanks to their advanced interfaces and incorporating most material models implemented in their roots.

The best alternatives to commercial FE codes are open source codes, most of them had been significantly improved over time, some of them had already been incorporated in Linux version "CAE Linux" (download: https://www.caelinux.com/CMS3/).

Warp3D is being given credit as the best open source FE code especially to solve problems in Fracture Mechanics, this code is used along with other open source tools (ex: Fortran compilers,….), meshing tools (ex: Cubit, ...) and data visualization tools (ex: Paraview,....), a complete tool box can be installed via Cygwin (download at: https://www.cygwin.com/). Warp3D can be downloaded along with manuals and tutorials (see: http://www.warp3d.net/).

If a researchers and students need to refer to an open source code, Warp3D can be the best choice, but running it successfully on your computing machine doesn't seem an easy task, like any other open source code, one have to afford a little bit efforts to master it, but first we need to gather all the other tools and learn step by step how to model a particular problem using it, since it is a FE code, one need to have a minimum knowledge about the FE analysis steps, then running it became a straight-forward task.

If there is any person interested in mastering these open source codes, especially Warp3D, it would be my pleasure to collaborate in order to make use of it in our research activities.

Keep me up to date

Thanks

Hi all,

Second question on the same or so topic.

I am working on subroutines (UMAT and others) for Abaqus to implement Tsai-Wu failure criteria for non-composite structures (I work on long bones such as the femur).

To my understanding, strains and stresses are calculated at each integration point and so is every other variable that I may use, such as state variables or my failure criteria.

To correctly define failure, I need to average the failure criteria values (that are at each integration point) over each whole element, and that is where I get stuck coding for. I would like to mimic an element deletion feature by setting Young modulus to a negligible value to avoid completely deleting an element.

I used an UEXTERNALDB subroutine to import the connectivity table hoping to use it to get element-scale values (averaged).

How should I implement that calculation ? Is there a way to calculate everything at the nodes ?

Thanks for your help.

Dear community, I need your support about my simulation.

I want to analyse the contact between a rolling wheel and rail as it is shown in the picture using ANSYS APDL but my results are not as was expected like specially the repartition of the stick and slip zones which is given in APDL by contact status. i don't know why there is no stick zone in the contact patch? the contact status indicates always that the wheel is in sliding status even when the wheel is not moving. Please let me know if you have any suggestions or corrections to my issue 🙏🏻🙏🏻🙏🏻.

To simulate the rolling motion of a loaded wheel, I defined three steps:

-step1: the bottom side of the rail is fixed

-step2: the contact is established by moving down the wheel by 0.006m

- step3: the load (FZ=-75000N) is applied to the pilot node

- step4 : translation velocity (Vx=50km/h) and angular velocity (Omgy)and are applied at the pilot node.

Here is the code corresponding to these load steps:

/SOLU

ANTYPE,4

nlgeom,on

TRNOPT,FULL,,,,,NMK

TINTP,HISP!GAMMA = 0.005

KBC,0

RESCONTROL,,NONE,None

autots,off

OUTRES,ALL,ALL

!First load step: Rim-mounting

Time,0.001

DELTIM,dt,dt,dt

TIMINT,off

! Constrain the rail base

asel,s,area,,42

da,all,all

Allsel,all

Solve

!Second load step: Establish the Contact Between the wheel and the Rail

Time,0.002

DELTIM,dt,dt,dt

TIMINT,off

!fix the pilot node in all directions

D,NODENUMBER+1,all

! Move the wheel toward the rail

D,NODENUMBER+1,uz,-0.006

Allsel

Solve

!Third load step: Applying a Vehicle Load to the 3D rail Model

Time,0.002+tfch

DELTIM,dt,dt,dt

TIMINT,off

!Delete the previously applied displacement loading

ddel,NODENUMBER+1 ,uz,,,on

!Apply the vehicle load on the pilot node

f,NODENUMBER+1 ,FZ,-Cn

Allsel

Solve

!step2 rolling

!inserting speed values

Time,0.002+tfacc

DELTIM,dt,dt,dt

TIMINT,on

D,NODENUMBER+1,omgy,Wr

D,NODENUMBER+1,velx,V

Allsel

SOLVE

!pick up solution stage d=115mm

Time,0.002+tfres

DELTIM,dt,dt,dt

TIMINT,on

Allsel

SOLVE

I've conducted FE analysis of composite structure as shown figure. However, the strain on the metal surface does not match the experimental values. I am new to FEM and I am having trouble understanding the cause of this. Interface1 is applied friction coefficient of 0.7, and Interface2 is applied friction coefficient of 0.3. I use Ansys mechanical.

Please accept my apologies for my poor English.

Greetings to all.

I am trying to make a composite ply sheet made up of 3 material, after assigning properties and visualizing ply stack layer it is NOT stacked along the thickness(which is needed) but in fact for some reason stacked along lateral direction.

I am attaching view-port image for reference , please guide me where I am going wrong.

Please assist me.

Dear community, I need your support about my simulation.

I'm trying to do the example shown in this picture using the ANSYS APDL and I need to know from your experience if i correctly defined the problem or not.

Please let me know if you have any suggestions or corrections 🙏🏻🙏🏻🙏🏻.

To simulate the rolling motion of a loaded wheel, I defined three steps:

- step1 : the load (FZ=-75000N) is applied to the pilot node (NODENUMBER+1) and the bottom face of the support is fixed in all directions.

- step2 : angular velocity (Omgy= 1729.9450336075deg/s)and translation velocity (Vx=50km/h) are applied at the pilot node.

I applied this procedure using the following Apdl commands:

!----------------------------

/SOLU

*Afun,deg

ANTYPE,4

TRNOPT,FULL

Lumpm,0

!step1 charging a static wheel

Nsubst,1,1,1

Outers,all,all

Time,.001

KBC,1

Asel,s,area,,160

Da,all,all

F,NODENUMBER+1,FZ,-75000

LSWRITE,1,

!step2 apply translation velocity and angular velocity to the wheel

Nsubst,4,4,4

Outers,all,all

Time,.002

KBC,1

D,NODENUMBER+1,,13.8,,,,VELX,,,,,

D,NODENUMBER+1,,1729.9450336075,,,,OMGY,,,,,

LSWRITE ,2,

!step3

Nsubst,4,4,4

Outers,all,all

Time,.019

KBC,1

LSWRITE,3,

Lssolve,1,3,1,

Finish

Thank you so much for your help🙏🏻🙏🏻,

Best regards,

In Abaqus, I want to create boundary conditions like the example in the attached image. But I'm having difficulty how to make it. Especially in creating continuous loads in the middle of the plate. I have tried many times but still haven't found a solution. I am using Abaqus version 2020.

I am currently working on a model which has steel beam whose one end is embedded in a concrete wall. The cantilevered end of steel beam is subjected to cyclic shear load. I am struggling to model the interaction between the portion of the steel beam embedded and the concrete. What will be the appropriate way to do it?

I tried by using 'hard' contact in normal direction and using coefficient of friction of 0.45 along tangential direction. The results obtained are different than experimentally observed.

Now, I am thinking of using surface based cohesive interaction, but I don't have necessary parameters which is needed for defining traction-separation and damage. Is there is a rational way to calculate these parameters without doing experiment?

Any suggestions and help will be appreciated.

can any one explain the procedure of nonlinear finite element analysis of concrete beam with reinforcement, using ansys drucker Prager model or any other way? How to find the ulimate load capacity of concrete beam.

I have a model that I am using to validate mechanical testing. I have validate three models up to 5% with a 1.5mm mesh. I have performed a mesh sensitivity study and found that smaller mesh sizes change my results. My model has the correct boundary conditions, correct material properties, etc.. I am trying to publish my paper and wondering if it's common that you can validate a model without mesh sensitivity? If it is not, what is the proper way of performing mesh sensitivity on a corrugated core? I don't want to go smaller in mesh because my models is no longer validated. Thank you.

Can anyone please tell me in detailed explanation what is the difference between the joint and the connection in steel joint?

given that :

joint rotation = total rotation of the beam-end - beam elastic deformation - column elastic deforamtion - block rotation

connection rotation = joint roation - column web in plane rotation + column elastic deformation + block rotation

Those equations are taken from the litterature

i am uploading this files, and I appreciate if anyone would accept to check it for me, I am trying to model a model of beam to column joint but the beam is bolted to the web column, I am facing a problem in the step of bolts pretensioning, it does not converge from the first increment, it indicates singularity warning along with zero pivot warning in the region of the bolts. I am confused because it's the same value of the force and the same bolts as another model i did in the past with the beam bolted to the flange, and it worked perfectly fine,only the materials are changed because of the experimental work. Waiting for any reponse.

Dear Researchers :

I will very much appreciate the help.

I have a 2D model in COMSOL. It's a plate, made of Polyethylene. An AC Voltage is applied on the upper electrode, the lower electrode is on V=0 (ground)

The sinusoidal function of the voltage is : Vo*Sin[wt + phi] where phi = 0 and V_o is equal to 2.4 kV

I am attaching an image of my 2D Geometry

I am solving the model in two steps

Step 1 : Using a Time Dependent Study (just to solve the physics of the electric currents module)

Step 2 : A stationary solver, to solve the Heat Transfer in Solids part.

I used the Multiphysics interphase of Electromagnetic Heating

I can correctly solve the Electric part of the model

But for the temperature, this is the graph that I get, which of course is not correct

Does someone might know where the mistake might be ?

Best Regards all :)

Dear amazing researchers,

I am working on a nonlinear FEM problem and using Python for coding.

To get the nodal values of the field variable, I have to solve a system of linear equation. In matrix notation, [A]{x}={b}, where [A] is a sparse-matrix (a lot of zeros away from main diagonal), {b} is the right hand side vector.

One trivial solution is {x}={b}/[A], but it is computationally heavy when needs to be done many times and [A] is large.

Lets take a simple example:

A = [[5, 2, -1, 0, 0],

[1, 4, 2, -1, 0],

[0, 1, 3, 2, -1],

[0, 0, 1, 2, 2],

[0, 0, 0, 1, 1]]

and b = [ [0],

[1],

[2],

[2],

[3]]

To store the complete sparse-matrix is waste of memory when a large number of element values are zero, so I wrote a code to store the matrix in a compact form, which stores the non-zero diagonals in every row.

[A_c]= [[ 0, 0, -1, -1, -1], [ 0, 2, 2, 2, 2], [ 5, 4, 3, 2, 1], [ 1, 1, 1, 1, 0]]

There is a function in "scipy" library. It is scipy.solve_banded(), which takes the "A_c", and "b" as arguments and return the solution {x}.

Could anyone help me to find out the algorithm behind scipy.solve_banded() function?

I will be very thankful for your help.

Hello everyone,

i have i very simple model, of beam to column steel joint, i have modelled it perfectly but the solution is diverging from the first attempt, i really could'nt understand where is the problem because i have zero warining except for some distorted element but not so much important.

Is is possible for someone to help me, if yes please write your email in the comments and i will send you the necessary files of abaqus ( i work with abaqus 6.14).

Hi,

I am modelling a beam reinforced with GFRP bars on ATENA 2D. The experimental and analytical load-deflection behaviours are in agreement with each other however, my FE model terminates 10 KN before the experimental load due to stress concentration near to loading plate. I tried to avoid it by increasing the plate's surface area but it didn't work. Please guide me on how to prevent stress concentration.

Dear everyone, now I have got the principle strain tensor (or increment) of a material point, as well as the reference hardening curve of the material (along the rolling direction) together with the anisotropic yield stress ratios. I failed to calculate the corresponding equivalent stress. I know that if the material is isotropic, the situation is very simple because I can get the equivalent strain first (igoring the elastic strain), and then find the corresponding yield stress from the hardening curve. But what can I do under the Hill anisotropic plasticity? Can anybody help me with that? Thanks so much. p.s., for simplification, the elastic strain can be ignored.

Hello

I have an FE model (linear elastic material, homogeneous) using shell181 elements. The structure is subject to constant acceleration and undergoes a static analysis (antype,static).

About shell,mid and keyopt(8), Ansys manual reports:

My midsurface results are not the average of top and bottom results, despite linear material and static analysis.

Just as an example for one element, I have for Von Mises (PRETAB):

ELEM STOP SMID SBOT

41848 0.20593E+008 0.60772E+007 0.26821E+008

where SMID, Von mises at shell,mid location, clearly is not the average between top and bottom.

So, why is this behavior happening given that I have linear material and no response spectrum analysis?

Thanks in advance.

Mathias

Hello good people

I am simulating multipass multilayer additive manufacturing with ANSYS transient-thermal module. The problem is that the Gaussian heat source (APDL code) works fine with the first layer, but when it comes to the second layer, it does not work. The heat flux does not even initiate for the second layer. I tried generating the code with a different coordinate system for the second layer, but that didn’t work either. I also tried incorporating the ‘z’ or the height of the second layer in the equation. Unfortunately, it didn’t work. But when I put the heat sources for both layers in the same time step, it works for both layers; they don’t work in different time steps.

How can I modify my code so that it works for the SECOND LAYER in the SECOND TIME STEP or any layer after the first layer?

The APDL code is mentioned below-

*DIM,HEAT_FLX1,TABLE,6,24,1,,,,0

!

! Begin of equation: 4e7*exp(-3*(({X}-0.05)^2+({Y}-0.01*{TIME})^2)/0.005^2)

*SET,HEAT_FLX1(0,0,1), 0.0, -999

*SET,HEAT_FLX1(2,0,1), 0.0

*SET,HEAT_FLX1(3,0,1), 0.0

*SET,HEAT_FLX1(4,0,1), 0.0

*SET,HEAT_FLX1(5,0,1), 0.0

*SET,HEAT_FLX1(6,0,1), 0.0

*SET,HEAT_FLX1(0,1,1), 1.0, -1, 0, 0, 0, 0, 0

*SET,HEAT_FLX1(0,2,1), 0.0, -2, 0, 1, 0, 0, -1

*SET,HEAT_FLX1(0,3,1),   0, -3, 0, 1, -1, 2, -2

*SET,HEAT_FLX1(0,4,1), 0.0, -1, 0, 3, 0, 0, -3

*SET,HEAT_FLX1(0,5,1), 0.0, -2, 0, 1, -3, 3, -1

*SET,HEAT_FLX1(0,6,1), 0.0, -1, 0, 0.05, 0, 0, 2

*SET,HEAT_FLX1(0,7,1), 0.0, -3, 0, 1, 2, 2, -1

*SET,HEAT_FLX1(0,8,1), 0.0, -1, 0, 2, 0, 0, -3

*SET,HEAT_FLX1(0,9,1), 0.0, -4, 0, 1, -3, 17, -1

*SET,HEAT_FLX1(0,10,1), 0.0, -1, 0, 0.01, 0, 0, 1

*SET,HEAT_FLX1(0,11,1), 0.0, -3, 0, 1, -1, 3, 1

*SET,HEAT_FLX1(0,12,1), 0.0, -1, 0, 1, 3, 2, -3

*SET,HEAT_FLX1(0,13,1), 0.0, -3, 0, 2, 0, 0, -1

*SET,HEAT_FLX1(0,14,1), 0.0, -5, 0, 1, -1, 17, -3

*SET,HEAT_FLX1(0,15,1), 0.0, -1, 0, 1, -4, 1, -5

*SET,HEAT_FLX1(0,16,1), 0.0, -3, 0, 1, -2, 3, -1

*SET,HEAT_FLX1(0,17,1), 0.0, -1, 0, 0.005, 0, 0, 0

*SET,HEAT_FLX1(0,18,1), 0.0, -2, 0, 2, 0, 0, -1

*SET,HEAT_FLX1(0,19,1), 0.0, -4, 0, 1, -1, 17, -2

*SET,HEAT_FLX1(0,20,1), 0.0, -1, 0, 1, -3, 4, -4

*SET,HEAT_FLX1(0,21,1), 0.0, -1, 7, 1, -1, 0, 0

*SET,HEAT_FLX1(0,22,1), 0.0, -2, 0, 4e7, 0, 0, -1

*SET,HEAT_FLX1(0,23,1), 0.0, -3, 0, 1, -2, 3, -1

*SET,HEAT_FLX1(0,24,1), 0.0, 99, 0, 1, -3, 0, 0

! End of equation: 4e7*exp(-3*(({X}-0.05)^2+({Y}-0.01*{TIME})^2)/0.005^2)

!-->

sf, s1, hflux, %HEAT_FLX1%

"Error in job messaging system: error in connection to analysis".

Sometimes I get this error while running multiprocessor dynamic explicit large analysis at random stages of the analysis. It might happen a couple of times. In case of running multiple jobs and one of them aborts for this reason then all the jobs get aborted at the same time. When resubmitting the job, the job might get completed without having edited the model at all. Any ideas? I have attached the status file.

Hello ResearchGate,

I'm simulating a blanking process in 2D using Abaqus Explicit with ALE. When the Johnson-Cook criterion is satisfied, elements start to be deleted, thus simulating the fracture at the end of the process. However, no matter how much I try to initially distort the mesh so that it gets more structured by the time fracture starts, the element deletion propagates "diagonally through the elements" (see attached screenshots), which leaves some of the not deleted elements connected by just one node (again, see attached screenshots). This stretches those elements to the point where my stable time increment gets pretty low, my burr is distorted and large, unrealistic stresses appear. I've tried to make the mesh finer, which hasn't really solved the problem. I've also tried to activate DELETE DISTORTED ELEMENTS, but this option doesn't seem to work, as the elements get stretched but their characteristic length remains large, as well as their area. I've tried applying the minimium dt option of this tool with no success (as the only parameter that seemed to be altered by these distorted elements was the stable dt).

This question: https://www.researchgate.net/post/How-can-I-solve-the-problem-of-excessive-element-distortion-in-2D-modelling-of-blanking-process-with-Abaqus-explicit deals with the same problem but none of the answers given seem to help.

I've attached a couple of screenshots that showcase the problem. If anyone knows a workaround or has any suggestion they will be very welcomed.

Have a nice day :)

Hi,

I have exported the mass and stiffness matrices for a 2D euler-bernoulli beam element (B23 in ABAQUS). These elements have three degrees of freedom for each node (two translation, one rotation), therefore, for a single element I would've expected a 6x6 matrix for both matrices, however, I have an 8x8 matrix for both.

Can anyone tell me where these extra DOF are coming from?

I have attached the input file I used to extract the matrices as well as the mass and stiffness matrices. The beam material properties are:

L = 1m

b = 0.01 m

h = 0.01

E = 70e9 Pa

rho = 2700 kg/m^3

v = 0.3

I am New to MDS simulation which software will be open source and free tutorial available for beginners?

Help i am getting the following error message in abaqus

**WARNING: Surf-1 is ambiguously connected at node ###. This surface cannot be used with *CONTACT PAIR. ***ERROR: 1 improperly defined surface(s). Please check your surface definitions. Make sure that all surface normals point outward.

Note:

The mesh is an orphan mesh and is generated outside ABAQUS.

The mesh is fine and has a huge number of elements.

Element typr for the mesh is C3D4

i have defined the surface using ABAQUS CAE and it was generated automatically using the following commands

*elset, elset=surf-1-S1-1

*elset, elset=surf-1-S2-1

*elset, elset=surf-1-S3-1

*elset, elset=surf-1-S4-1

....

*surface,type=element,name=surf-1

surf-1-S1-1,S1

surf-1-S2-1,S2

surf-1-S3-1,S3

surf-1-S4-1,S4

As you will see, i have followed section 2.3.2 Element-based surface definition in abaqus user's guide.

if you read "Creating surface facets by specifying solid, continuum shell, and cohesive element faces" you will see i have followed it.

So what is the issue here?

Hi. I am doing non linear FE analysis using a new material beam under flexural 2 point loading using ANSYS. I have defined a bilinear material model. The solution has converged. In results I am getting good stress strain curves (as expected, i.e slope decreasing post yield). However the load displacement curves show an increase in stiffness pattern. Please help me to correct the load displacement curves.

Greetings researchers!

I am using FEM to obtain the time response of the nonlinear forced vibration of plates. I am using plate elements based on Reddy's HSDT and Newmark time integration in conjunction with the Newton-Raphson iteration to obtain the time response.

It is well known that multiple steady-state solutions can exist in the case of nonlinear forced vibrations. Also, all steady-state solutions are not stable. In practice, unstable solutions are not realizable and the system assumes any one of the stable solutions depending on the initial conditions.

I was curious to know whether the FEM predicts only stable steady-state solutions. Or does it predict stable and unstable solutions and the stability of the predicted solutions needs to be determined through other means?

Thank you for your valuable time.

With best regards,

Jatin

Dear Researchers,

As you know, it is possible to generate the code of modeling in SpaceClaim and FE analysis in Ansys. However, I do not know how can I connect the codes of these sections.

I Ansys Apdl, it can be generated completely but I do not know how can I do it in Ansys workbench.

i've been trying to evaluate the strain energy consumed in the ring shown in image and i've marked the (energy) option at the F-output before submitting ......... however, there is no clear data shown in the results monitor

Any suggestions ????

I am trying to simulate the knee joint and I have a concentrated force applied on the femoral part of the model, the model also has a kinematic constraint that allows for the femur to flex and extend ie displacement boundary condition and the tibia part is fixed. the aim is to include the anterior-posterior motion of the tibia as well

The load is time based as well as the displacements. when I run the simulation, with the required load the stress generated is the same as when 4x the initial load is applied. How can I fix this?

Please find attached the cae file for this model

I have done a comparison by applying the hydrostatic pressure on the middle and top of the shell curve surface (Section Assignment: Shell offset = Middle or Top surface in Abaqus). In the case of the middle surface minimum deflection is 6.115 mm, but in the case of the top surface, the minimum deflection is 12.18 mm. The curve plate is simply supported from three sides.

I have attached images of the results.

Could anybody tell me, which one is correct and why?

Thank you very much

Dear members,

I am trying to predict temperature distribution in laser melting process using FEM. It is a 3D transient heat conduction problem.

I have modelled it without considering phase change at the melting temperature of metal, but I am not able to understand how to incorporate the phase change, particularly how to handle the nonlinearities associated with the phase change (the latent heat, enthalpy as well as heat conductivity might not be continuous at the point of phase transition)?

Please provide some resources or any kind of help will be helpful.

Sincerely,

Ravi Varma

Hello everyone,

I've written a rather simple linear elastic UMAT for orthotropic materials. I found that my output stresses are different from stresses should be.

For example:

In my model, I set a max load of 25 MPa and min load of 2.5 MPa (aka cyclic load ratio R=0.1). In my UMAT a wrote a line "write(*,*) "stress(2)=", stress(2) " to see how applied load matches outputs. I expect see alternation of 25 and 2.5 (when increment time=0.5), but I see the following:

stress(2)=0 - okay, initial step

...

stress(2)=-25 - okay

...

stress(2)=-49.99 ????

...

stress(2)=-2.5 - okay

...

stress(2)=-19.99 ????

then everything repeats

But in ABAQUS visualization stresses are as I set, 25 2.5 ...

Have you seen something similar? I'm bit confused, don't understand how it works.

If you have any ideas what can be wrong, let me know.

I have attached the UMAT subroutine file and inp file. Thank you.

Greetings to all.

I am new to UMAT in Abaqus and want to create UMAT for "shell" elements for an isotropic and anisotropic material, can anyone suggest any reference material, book, or website link which can help me.

Thank You

Dear ABAQUS users,

I want to make a three-dimensional model of the three-point bending simulation!

What do you think is the best element to use in ABAQUS for this problem? C3D8R - C3D8 - C3D20R - C3D20 - C3D8I

Can you please tell me about the advantages and disadvantages for each element or send me a reference for that!

I couldn't find any example or useful info online. Can anyone familiar with altair help me with it?

Basicly, I want to study the optimized parameters of a I-beam under given BC and max stress/strain.

I have created the beam using HyperBeam standard I-section and assign PROD properties to the component. Now, I am stuck here. I want to link the desvar in size optimziation to the dimensions of I-beam parameters. How do I do this?

Thank in advance for any help!

Hello everybody How can a three-dimensional FE analysis of a threaded screw (inserted into a material with an insertion torque) be substituted with an axisymmetric analysis of the same problem? Please kindly share good references' links if are available. Best regards, Yunus.

Dear Researchers:

I need help, please if someone knows how to, o can, help me, I'll really appreciate it

I am trying to solve a model of a Medium voltage Energy Cable. So I need to solve for the Temperature Distribution across the whole 2D cross section (my model is a 2-D Model).

I have two direct questions :

(first image) I am trying to use the coupled Joule Heating Multiphysics. This is the "Electromagnetic Heating (emh1)" section.

1. My first question is : Do I have to ad a domian of "Heat Source", or I don't need to add this Boundary Condition ?

And if so, on the "Heat Source" section is it correct to select "General Source" and then: "Volumetric loss density, electromagnetic (ec) for the "Qo" ? (as is shown in the first image attached).

2. And second. On the "Electric Current (ecs)" physics. Do I have to use the domain "Terminal" or the domain "External Current Density" ?? I have a fixed value dor the voltage in the problem, and I also know the electric resistance of my Cable

Does anyone know How to solve this ?

I am trying to analyse a large structure with multiple loading scenarios (independent - different loading directions), while considering geometric non-linearity. Using different steps is not sufficient, since each step starts off with the geometry shaped as it was at the end of the previous step.

I tried creating a dummy step just to deactivate all the loads from the previous step, but the non-linearity causes some distortion to remain even without any loads.

One obvious solution is to run each step in a separate analysis, but the model is quite large and the input file processing takes about about as much time as it takes the solver to solve a step, which would immediately double the time required to obtain the entire solution and there would also be redundant information in the result files (mesh data repeated in each result file). So creating a separate analysis for each step is something that I am trying to avoid for the moment.

Hello Researchers,

The FEM discretized (meshed) geometry/domain is considered stiffer than the actual geometry/domain due to the assumption of variation of the displacement within each element. This is analogous to the displacement being constrained to vary in a particular fashion within each of the elements. This results in the stiffness of the discretized domain being greater than the actual domain. As the element size decreases (or the number of elements increases), the constraint on the displacement loosens due to the smaller size of the element and hence, the smaller constraint zone. Thus, the stiffness of the meshed domain decreases and approaches that of the actual domain as the number of elements is increased.

Based on the above reasoning, the natural frequencies (on increasing the number of elements) must converge from above to the actual value (i.e. converge from higher values to the actual value).

Hello,

I am doing a harmonic analysis. I am dealing with force reaction, or simply speaking force output. ANSYS gives maximum amplitude but not RMS value.

Is there any way to get the RMS value directly from ANSYS?

Thanks for your attention :)

I want to do FEM analysis on cold extrusion.

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:

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.

Hello everyone,

I found in some papers that the bolt joint can be conveniently modeled using the thin layer element which has been integrated into many commercial FE packages.

In the tutorial Modeling the dynamics of mechanical joints (S. Bogradet al, 2011, MSSP), the authors have given a simple example (see Fig. 20 and Table 4 in section 3.5 of the attached PDF); however, it was completed in MSC. Nastran with which I am not familiar. I wonder if similar treatment can be done in COMSOL?

My final goal is to simulate how the pretension of the bolts affects the dampings of different vibration modes and I think the thin layer element based method can be a possible solution. If anyone has ever done or seen similar simulations before? COMSOL based tutorial will be of great help.

Thank you so much for reading and I appreciate your help.

Best regards,

Hao

Greetings,

We know that locking in the finite element method (FEM) is a numerical artifact due to the choice of the approximation functions. A couple of implications of locking in a static analysis can be mentioned as follows

I'd like to draw a simple model on Plaxis LE designer but I did not find any guideline video that could help me to design it.

The model sample I attached. Please I hope any one can help me as fast as you can

Thanks

Hello everyone

When I plot elements of a FE model with node numbering and multi plots ON, I am also able to see the nodes which are of elements that are opposite/adjacent/not relevant to a particular element of interest. Is there any option in ANSYS APDL to make sure that only the nodes of a particular element is only seen and not that of another element that is adjacent or opposite to that particular element of interest?

N.B: In the attached image, I don't want to see the red-marked nodes.

hello how to input materials parameter for the following

elastic - plastic material

I have the following parameters only

lame constants

yield stress

hardening parameter

young modulus and poisson's ratio

I know how to input everything except lame constants

Hello Researchers,

I am using Gauss Quadrature for numerical integration to obtain the stiffness and mass matrices for a plate element in my FEM code. We know that both these matrices are symmetric. However, I find that due to numerical integration the stiffness and mass matrix turns out to be asymmetric.

Kindly note that the asymmetry is not by any means large. The result of the subtraction of a symmetric matrix from its transpose is a null or zero matrix. If I subtract the stiffness and mass matrix from their respective transposes, the resulting matrix has all the non-diagonal terms of the order 10 to the power of -8 and all diagonal terms are zero (maybe for most cases it can be considered as a zero matrix).

At the point of writing this question, I am suspecting that this discrepancy (i.e asymmetry of the mass and stiffness matrices) is due to the finite precision arithmetic of floating-point numbers. (need your thoughts on whether my suspicions are true)

The end result of not having symmetric stiffness and mass matrices is that the 'eig' function in MATLAB gives incorrect eigenvectors although the eigenvalues are correct.

I would like to know if anyone has encountered such issues and how was it resolved.

I am also attaching a couple of links related to finite precision arithmetic errors below for your reference:

Thank you,

Jatin Poojary

I am using abaqus to model geosynthetic encased stone column (wished in-place). I am new to abaqus so how should I model geosynthetics in 3D and 2D (solid or shell or wire ) and can I get an idea about what type of interaction should I apply in between soil- geosynthetics and geosynthetic-stone column ( in 2D and 3D ).

is there sensor history output for energy ALLKE and ALLPD in abaqus 2020?

is there any one help me

Hello friends

Nowadays I am trying to use Code_Aster to simulate CABLE . I want to know how to add a force like this F=0.5*velocity^2 on selected nodes?

And how can people add a triangle distributed force on a moving cable whose coordinate is changing with time .

Thanks for your help in advance.

Hi,

I have an experimental tensile curve. This is the engineering stress strain curve right?

I have then converted it to a true plastic strain curve using Abaqus material conversion. Using these values, I have run a tensile simulation.

However, the results that I have obtained seem to replicate more of the true stress strain curve and not the experimental curve.

The load is displacement based where it is pulled by 32 mm which reflects accordingly to the experiment.

I have plotted misses stress vs LE11.(logarithmic strain along x direction ).

The peak stress in the experiment is 50 MPa while the peak stress for the true stress strain is 70 MPa.

I have attached my results below.

From the simulation, I am getting 70 MPa also which is not representative of the experiment.

Is this how its supposed to be or am I skipping something?

Thanks in advance for your help!!

Hi,

I am currently struggling to virtually ream an acetabulum from a segmented hemipelvis. This is required for an implantation of an uncemented cup. As my analysis involves FEA (ABAQUS), I am currently performing the virtual reaming using a sphere. I am currently applying a boolean subtraction operation in ABAQUS to remove the cortical bone (and expose the subchondral bone) by positioning the sphere on the Centre of Rotation of the Hip.

Nevertheless, I seem to get rid of more than desired trabecular bone. Thus, my uncemented cup doesn't seem to have contact with the reamed acetabulum unless the cup is deepened, which leads me to the next question of How to virtually implant an uncemented cup in an already reamed acetabulum?

I have reviewed some literature and some researchers seemed to have used a step in ABAQUS where they perform a displacement control until the uncemented cup is overhanged(certain level of contact is achieved). I haven't used this FEA technique before, so any comments about this is widely appreicated.

I hope I was able to explain myself and this questions aren't too technical to be answered.

Thanks!

I'm trying to reduce a 3d printer extruder vibration. When the extruder starts to move, vibrates that decrease printing quality. How can I reduce the vibration? I need a procedure to solve the problem using FEM methods like Abaqus. The procedure should contain an optimization method.

Hi,

When I open up Abaqus CAE, I am supposed to see the message area in the lower half of the window below the viewport. But in my system, I am not finding the "Message area" and "Kernal Command Line Interface". The screenshot is attached herewith.

Can anyone guide me where to find it?

Also, in the above link, it is given that the command line area is usually hidden, and we need to click the 3 arrows to get it. But in my case, I am not even finding the 3 arrows.

Please help.

Thanks in advance.

Hello everyone,

Hope you are doing great.

I am using coupled temperature-displacement step and coupled temperature-displacement elements as well. I need to use UMAT to model plasticity behavior and fracture. In every run I do, It takes 5-10 days to finish the simulation. I don't know if this is normal for my case study or something is missing?

Usually, I run my job by writing these lines:

---------------------------------------------------------------

abaqus job=xxx.inp user=yyy.for cpus=12 standard_parallel=solver int

OR

abaqus job=xxx.inp user=yyy.for cpus=12

---------------------------------------------------------------

Another thing I'm not sure about is my step setting, which is as follow:

---------------------------------------------------------------

*Step, name=Step-1, nlgeom=NO, extrapolation=NO, inc=1000000, unsymm=NO

*Coupled Temperature-displacement, creep=none, steady state

0.002, 1, 1e-10, 0.002

*Solution Technique, type=SEPARATED

*Controls, reset

*Controls, parameters=time incrementation

5000, 5000, 5000, 5000, 5000, 5000, , , , ,

--------------------------------------------------------------

I appreciate any help you can provide.

Mojtaba Ab

#Abaqus #fem #FE_Analysis #FEM_Simulation #Plasticity #Fracture #Elastic #Simulation

I have seen many research papers many people have worked on different software but I am unable to conclude that which is best for research purpose.

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.

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.

I wrote a subroutine VDLOAD for dynamic explicit analysis in ABAQUS. The load is spatially distributed as well as varying with time. The subroutine VDLOAD works fine. But the load has two horizontal and vertical components (component1 and component2).

Horizontal component of load = 1*value

Vertical component of load = 0.75*value

Value is defined in the VDLOAD subroutine.

I know that the magnitude data entered in the editor (Attached figure) are passed into the user subroutine in an Abaqus/Standard analysis but are ignored in an Abaqus/Explicit analysis (Abaqus/CAE User’s Guide(6.14) section 16.9.8).

How to model these two components of the load by VDLOAD?

I would be grateful if you guided me through this.

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 ! :)

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 !

Dear all,

Does anyone ever run site response analysis using Abaqus? Please upload some examples for reffrence.

I did but the results are very strange. I think I have problem with how to assign boudary conditions. I use tie constrain for lateral boudary and dashpot for base boudary.

Thank in advance all.

(my model is attached below)

No matter if I chose topology or shape optimization tasks (or whether they are condition-based or general) I can not see any thermally related variable to select as my design responses for heat transfer related optimization. All variables are all structural parameters (see the picture).

Does Abaqus Tosca work with heat transfer analysis at all? If it does how design responses can be defined as variables like temperature, conduction, etc.?

If you have experience performing thermal optimization using Abaqus optimization module your share of experience will be much appreciated.