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Abhishek Kumar

Regarding tensile test simulation

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Dear all,

I am want to simulate a tensile test experiment. Although I have simulated with the help of a video on youtube, but in my simulation I am getting some unusual results which generally not happened in my previous attempts.

I had attached the .hm and .h3d file. I am using HyperWorks v12.0 for my analysis.

 

Initially it shows good results because in actual experiments my specimen have fractured in same area where it shows in simulation.56df071841ee5_e8result.jpg.086ce5082bdbe

 

 

But after some time it show very unusual deformation.e8result1.jpg.228790a19ce91241ff66ded5d9

 

Please check my model and suggest me if I have done some thing wrong in this model.

e8_tensile1.hm

e8tensile.h3d

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Hi Abhishek,

 

Here is my result from HW 13.0. Change the shell element formulation to type 24 in PROP/SHELL and try again.

ToForum.gif

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Hii Prakash,

Thanks for your reply and your support.

  1. Can you explain the difference between the previous shell element formulation and the shell element formulation type 24?
  2. In this simulation it is not showing fracture after necking, it should fracture after necking. How I can get fracture in simulation?

Thanks and Regards,

Abhishek Kumar

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Abhishek,

 

Refer to th help regardinf different element formulations available. Here is some description about QEPH formulation.


You may have to introduce the failure model to simulate fracture. Refer to /FAIL in RADIOSS help.

Capture.JPG

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LAW 36 is piece wise non linear material model where you can give the stress strain values in the form of a curve.

 

Have you tried with /FAIL/XFEM_JOHNS

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Ok I just checked RADIOSS Manual. In this model we need to give values of D1,D2 and D3. But at present I don't have theses values for the material which I am simulating.This failure model is based on stress triaxiality and failure strain.For D1,D2 and D3 we need to plot a graph between failure strain and stress triaxiality.

But problem is that I am simulating tensile test simulation to get the value of stress triaxiality for different of specimen under different failure mode. So that I can get the values of stress triaxiality at failure strain.. Then only I can get the value of D1,D2 and D3.

Is there any other method to get the value of stress triaxiality at failure strain?

 

Thanks and regards,

Abhishek

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Hiii Prakash,

How I can evaluate my tensile test simulation results with experimental results? It means I want to compare the graph  (force vs. displacement or stress vs. strain) of simulation to actual experimental results.

 

Thanks and Regards,

Abhishek

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Abhishek,

 

here is a video which shows on how to plot for Stress Vs Strain in HyperGraph.

 

Similarly you can do the same for Force Vs Displacement. 

 

Before that, you need to create output blocks for elements to write stress and strain results to T01 file.

 

Please refer to TH/SHELL for more information.

CrossPlot.swf

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Thanks Prakash,

I will try your suggestions.

In actual tensile test experiment specimen breaks after 4-5 mm extension. So I wanted to know that can I simulate the experiment until this point only?Also how I can ensure that the displacement results in simulation are in mm and force results are in Newton. Please tell me about units of the material data which I should follow. Presently I am using following data for MATLAW 2-

 

Density of material- 2.7 kg/m^3

Elastic constant- 69000 MPa

a = 58.73 MPa

b = 83.81 MPa

n = 0.1382 

eps_max = 5.711

sigma_max 112.65 MPa

 

 

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Abhishek,

 

Check for nodal connectivity.

 

Go to Edges panel (Shift+F3)>> Select all elements>> Preview Equiv>> if there are any free nodes FIx them using>> Equivalence.

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20 hours ago, Abhishek Kumar said:

In actual tensile test experiment specimen breaks after 4-5 mm extension. So I wanted to know that can I simulate the experiment until this point only?

Abhishek,

 

You can use /SENSOR with type as DIST which works for nodal distance.

 

Please refer to help for more information.

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20 hours ago, Abhishek Kumar said:

Please tell me about units of the material data which I should follow. Presently I am using following data for MATLAW 2-

 

Type of units that have to be used is specified in help and this may vary for different material models. For LAW 2 here is the unit system:

Capture.JPG

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Dear Prakash,

Thanks for your continuous support.

 

I just checked the SENSOR/DIAS in RADIOSS manual. Can you suggest me how to edit the card image? I mean what values should I input to card image.

Should I use-

Tdelay- 0

node1- any node at fixed end.

node2- any node at velocity end.

Dmin- 0

Dmax- 0.006m (if I want to stop at 6mm displacement)

 

After that should I also edit engine file to stop the simulation at this prescribed displacement?

 

Thanks and regards,

Abhishek

 

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Abhishek

3 hours ago, Abhishek Kumar said:

After that should I also edit engine file to stop the simulation at this prescribed displacement?

 

Yes, you need to add the /STOP/LSENSOR to stop the analysis when the sensor activates. Please refer to STOP/LSENSOR.

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On 3/14/2016 at 10:12 AM, Prakash Pagadala said:

Abhishek,

 

here is a video which shows on how to plot for Stress Vs Strain in HyperGraph.

 

Similarly you can do the same for Force Vs Displacement. 

 

Before that, you need to create output blocks for elements to write stress and strain results to T01 file.

 

Please refer to TH/SHELL for more information.

CrossPlot.swf

 

Hii prakash,

Please find the attached pdf. In this example a comparison has been done between experimental results and simulated results. Same comparison I want to perform in my study.    

Example_11.pdf

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Hii,

I have simulated the tensile test experiment but the values of force which I am getting in simulation is very less compared to real time experiment. In simulated result I am getting max. force around 120 N but in experiment it is around 2660 N. Please check attached results and model. I have also attached the results of real time experiment.

 

Thanks and regards,

Abhishek 

 

e8_tensile.h3d

e8_tensile.hm

e8_tensileT01

Results.xlsx

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Dear Sir, 

I tried to plot the stress strain curve for tensile test simulation carried out by me. But, I was unable to do it, the .hm  is attached below.

 

 

 

Please plot the stress vs strain curve and also explain how to plot it.

 

Thanks and Regards

Pavan Kumar

 

First.hm

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Hi Pavan Kumar,
You can output Stress and strain creating Output Blocks in RADIOSS.

Go to Analaysis page>> Output Block>> elements. Card edit the created output block and change the variable to DEF for default outputs. Please go through /TH/SHEL in the Help Menu for more information about the output variables.

This video https://www.youtube.com/watch?v=1BnhOzRVkEQ&list=PLQ7KUGFuVz4u5y3SvIEIU07427-gATaG6&index=6 is a webinar showing creating output blocks in RADIOSS.

 

The other way is plot stress and plastic strain from HyperView.

Output Stress and strain through control cards and contour stress. Go to Plot curves and plot Stress Vs time. Similarly do the same for strain in the same existing window and do a cross plot in HyperGraph.

The attached document shows the steps to perform a cross plot in HyperGraph.

Cross_Plot.pdf

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