Defining a Multilinear Plasticity Hardening Model Using Ansys Mechanical - Lesson 1

Most metals undergo plastic deformation when subjected to loads beyond their elastic limit. During this deformation, they lose overall stiffness but undergo strain hardening, which increases their yield strength. In applications viz, metal forming and forging, it is important to include this behavior to accurately capture the mechanics. In Ansys Mechanical, this behavior is captured using several plasticity models, and multilinear hardening is one of the most used. It is easy to set it up, but one must understand how to extract the model parameters from experimental data. In this video, we will learn to define this material model from experimental data. For demonstration purposes, we used the data for the 316L stainless steel material published in this peer-reviewed article: doi.org/10.1016/j.ijpvp.2008....
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[@AnsysLearning]

Errata:
1:20 - In the true stress vs. true strain graph, the labels for “Elastic Strain” and “Plastic Strain” are reversed.
2:06 - In the true stress vs. true strain graph, the label for “Ultimate Strength” is labelled incorrectly.
This video is part of the free Ansys Innovation Course, "Topics in Metal Plasticity Using Ansys Mechanical". Access all the course contents, including additional lessons, handouts, simulation examples with starting files, homework problems, and quizzes here: courses.ansys.com/index.php/courses/topics-in-metal-plasticity/.

[@pandianshanthakumar4163]

Hi, it is really very important and great informative content for checking of plastic analysis in Ansys. Thanks a lot.

[@deepak8057173838]

Hello dear,
your presentation and explanation are marvelous. Thank you for your effort.

[@msdesf]

Great tutorial, thanks.

[@keyce123456]

Amazing video! Thank you so much!

[@leticiabarrerolopez1021]

Muy buen video, gracias

[@rajasekharsingam7574]

Great stuff sir , thanks

[@dr.ashwaniverma1661]

Thanks for the video.

[@robex2000w]

Thank you very much.

[@Mahmoud-fd2kn]

I really enjoyed your wonderful way of explaining the idea.
Could you please give your insight into defining steel material (for rebars) in cyclic loading?.
Many told me to use KINH or MISO+Chaboche; however, I still cannot effectively define their parameters to obtain realistic results.

[@koperaljali3253]

I thought the stress point before fracture is called "fracture strength", not "ultimate tensile strength" (UTS). UTS is the highest peak of stress-strain curve. Someone please correct me if I'm wrong

[@nathan.muller]

You're correct - ultimate tensile strength (UTS) is defines as the point of maximum load (force), making it independent of the changing cross sectional area during necking, and allowing it to be defined as such regardless whether using true or engineering values for stress and strain. Any authoritative source on this should confirm this - just pick up any mechanics of materials textbook for context!

[@hs-ri7xn]

Hello,
Thank you :)
Pleease we need Videos for Chaboche model ...

[@venubarathan8391]

hello sir,
Thank you for this wonderful video.
Does this multilinear isotropic hardening is applicable for composite materials? or any other model is available

[@cristobalsanchez9425]

Excelent thanks. Could you create a video of plasticity in a shape memory alloy?

[@JB-dc3bt]

Very good video thank you

[@AnsysLearning]

Glad you liked it! Interested in more learning content? Visit Ansys Innovation Courses for free courses that include videos, handouts, simulation examples with starting files, homework problems, and quizzes here: ansys.com/courses.

[@hasanrouf9834]

Thank you for this great video. Tensile test simulation was performed, it would be beneficial if you can show how to derive the tensile strength from the simulation results.

[@laodamasdimopoulos2655]

Hello and thanks for the great tutorial. What is the named selection that we are scoping to? What does it represent? Are we "looking" on a specific point or cross section? If we scope full geometry and plot max normal stress on Y, will it be different?

[@AnsysLearning]

Hello! Thanks for watching. For answers to your questions, please visit the Ansys Learning Forum at www.ansys.com/forum.

[@andyjonathan2486]

At 2:06, isn’t the UTS the PEAK stress value and NOT the stress value at failure?

[@melihagll]

How do I describe the negative slope part of the curve in ansys mechanical (for C30 concrete and s420 steel depending on the temperature)

[@AnsysLearning]

Thanks for watching! The Ansys Learning Forum is a great place to post and get answers to questions just like these.
Check it out here: www.ansys.com/forum

[@unurt9781]

Thanks Sir. Now can you explain about Chaboche Kinematic hardening material tutorial. How to determine these material parameters for Chaboche model?

[@AnsysLearning]

Thanks for watching! We’re currently working on several other topics in advanced plasticity. In the meantime, questions about this topic can be answered on the Ansys Learning Forum. Check it out here: www.ansys.com/forum

[@sanjeevkumar-zm5ok]

Ultimate Strenght is the point from where neacking is start forming. It's not where speciment fracture.

[@romansatosek395]

Hi, how can I get data needed to calculate lankford coefficient r value?

[@AnsysLearning]

Thanks for watching! You can get answers to questions just like these on the Ansys Learning Forum. Check it out here: www.ansys.com/forum.

[@TamonashJana]

But how to incorporate the experimental necking part (with the negative slope) in the multilinear data? Please someone help! I'm looking for it for a long time. 😢

[@lifeisbeautiful7144]

Sir what is the value of e total from which we subtract e elastic to get e plastic ( at point 7.09 of video) . Earlier you used terms e true and e engineering.

[@AnsysLearning]

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[@dilsoman]

Great presentation.. But can anyone please help how to model polycarbonate material which is NONLINEAR WITHIN THE ELASTIC LIMIT?

[@AnsysLearning]

Thanks for watching! Please post your query on the Ansys Learning Forum for a detailed answer from the wider Ansys Community: ansys.com/forum.

[@theamazingmiddleeast7824]

How can I model an orthotropic plasticity material behaviour in the LS Dyna workbench?
I used the APDL code for modelling of orthotopic bilinear material in static structural but apparently, I can't use the macro code in LS Dyna. Is there any method applicable to create this material model?

[@AnsysLearning]

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[@bettykuriakose2355]

Sir could you please do a video on this journal
Computational study of strengthening effects of stiffeners on regular and arbitrarily stiffened plates
October 2012Thin-Walled Structures 59(1):78-86
DOI:10.1016/j.tws.2012.05.001

[@aaaengineering8892]

How can we model softening behavior using the multilinear plastic model after a material has reached its ultimate strain limit? Thank you in advance for a response to my question

[@AnsysLearning]

Thanks for watching! Please post your query on the Ansys Learning Forum for a detailed answer from the wider Ansys Community: ansys.com/forum.

[@aaaengineering8892]

Can we use this model for compression behavior? compression model with elastic and perfect plastic parts.

[@AnsysLearning]

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[@mohmmadsaad1341]

how can i add FGM material and model at power law ?

[@AnsysLearning]

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[@shaghayeghnazar8336]

hello
If I want to model fatigue crack growth under elastic-plastic fracture mechanics, should I use Bilinear option?
I will be grateful if you help me

[@AnsysLearning]

Thanks for watching! Please post your query on the Ansys Learning Forum for a detailed answer from the wider Ansys Community: ansys.com/forum.

[@subodhchander]

Do we need to switch on long deformation for plastic analysis?

[@AnsysLearning]

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[@prathyusha186]

For total strain value we have to add all the values of true strain before the point ?😊

[@AnsysLearning]

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[@ilyagordievsky9530]

Hello. in 6:52 why the elastic strain is equal to approximately 0.14 mm/mm? As I understand the elastic strain should equal yield point value is about 0.04 mm/mm?

[@AnsysLearning]

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[@mojtabahassanvand3733]

can you guid me how to define an orthotropic bilinear material? it seems ansys has no option for this.

[@AnsysLearning]

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[@nafnaf0]

Would love to see something on the Johnson Cook model

[@AnsysLearning]

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[@idreeskhan-zp5ey]

How did you get so many stress strain data points? as shown in that excel file.
I have a stress-strain curve of AA 3003-0 but dont know how to get the data points,especially the stress data points.

[@AnsysLearning]

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[@RobertBaiko]

@@AnsysLearningThis is lazy. Answer the question.

[@fwilli6944]

Is there a possibility to use a Multilinear Plasticity Hardening Model with a 2-D-Model in Ansys ?

[@AnsysLearning]

Thanks for watching! Please visit the Ansys Learning Forum for an answer to your question. Visit at ansys.com/forum.

[@shaileshjoshi7912]

@ 7:14, shouldn't the arrow be pointing to elastic strain?

[@AnsysLearning]

Thanks for watching the video, Shailesh! The green line represents the plastic strain developed in the material up to that point and it is calculated by subtracting the elastic strain from total strain. Therefore, the arrow is pointing to the plastic strain. Hope this helps!

[@shaileshjoshi7912]

@@AnsysLearning The formulas are correct, what I meant was that the representation is incorrect. Suppose you unload the load at 0.2 total strain, then the unloading line will be parallel to the elastic region line. And the elastic strain then would lie to the right of this line, which in this case is shown to the left in blue. The proportion of the plastic and elastic strains should also be reversed, like at 7:14, for the pictured elasticity, plastic strain should be bigger than the elastic strain.
P.S - Not nitpicking, just pointing it out. The video is awesome as always, content wise as well as production wise.

[@kirillspec2574]

@@shaileshjoshi7912 Yeah, I also noticed this mistake

[@darshanpitroda5718]

Young's modulus of only 11111 MPa for 316L? I think data extracted is incorrect as young's modulus for 316L is generally around 190000 MPa value. 11111 MPa is way far from that value. Can you please confirm this?

[@AnsysLearning]

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[@prathyusha186]

Total strain is equivalent to true strain value

[@AnsysLearning]

Thanks for watching! Please post your query on the Ansys Learning Forum for a detailed answer from the wider Ansys Community: ansys.com/forum.

[@OM-of8vf]

Yield stress is the stress that corresponds to .2% strain. Please correct your definition of yield stress.

[@jakebilsborough9588]

He's not using the 0.2% strain offset method

[@simonprince123456789]

Amazing video! Thank you!