damage analysis in Abaqus based on Continuum Damage Mechanics

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Don’t hesitate to ask any questions you might have about the explanations presented in this video using the comments below. We try to answer all questions regarding the video details in the comments below.
In many engineering problems, material goes beyond its ultimate stress. So the material enters its damage region. At this case, damage must be introduced to the mechanical behavior of the material.
There are two different methods for damage analysis in FE models:
1) Fracture Mechanics(XFEM, CZM, VCCT)
2) Continuum Damage Mechanics(Ductile damage, Johnson-Cook damage, Shear damage, CDP)
In this video, damage analysis based on CDM is explained. explanations are related to tensile test. The Force-Displacement curve is discussed too.
damage analysis concepts including damage initiation point and damage propagation are explained in detail.
Table of content:
- Complete stress-strain curve including damage domain
- Several concepts of damage analysis
- Methods for damage analysis in FE models
- Damage simulation in tensile test
- Element deletion concept
- Force-displacement curve
- Types of damage propagation
- Comparison of progressive damage and instantaneous damage
- Element deletion settings
#tensile_test
#damage_analysis
#continuum_damage_mechanics
#damage
#ductile_damage
#Abaqus

[@imhusker]

The triaxiality is 0.333 not -0.333. Triaxiality is -p/q, p is pressure stress defined as -(s1 + s2 + s3). In simple tension p = -s/3 and -p is s/3.

[@FemexIran]

Hi. Yes. You are right. It was a mistake in the formula of calculating the pressure.

[@hosseinmohammadtaheri1688]

This field had been so weird for me before I watched this video. Thank you very much.

[@FemexIran]

Hi. You are welcome.

[@amrounesalah8706]

I greatly appreciate you sharing this fantastic video.

[@FemexIran]

Thank you so much. We have also These premium step-by-step tutorials for damage analysis: kzbin.info/www/bejne/eoDVipeCg65_kJo kzbin.info/www/bejne/ZnOnmKakeNiDrJo kzbin.info/www/bejne/jpisc5mjr8-BkMU

[@rasoolmokhtarihomami9169]

Thank you very much for your explanation. Keep it up. it is great.

[@abdillahibakari2449]

Hello Sir, Thank you so much for your explanation, it has been very helpful to me. I have a question for you.. In calculating the stress triaxiality values, I have seen some people using an array of values while others use only one value of stress triaxiality corresponding to one fracture strain and strain rate. Which one is the correct way of doing it. And why?

[@FemexIran]

hi. you are welcome. each value of stress triaxiality corresponds to a loading condition. loading conditions like: pure shear pure tension pure compression each of these loading modes has their own stress triaxiality. in your simulation, if the loading condition does not change during the simulation, you can use only one value of stress triaxiality.

[@pozaik1586]

Thank you for your video ! Very clear explanations I have a quick question. I found research papers using progressive damage modelling and others using continuum damage modelling. I don't get the difference between those two models, and after watching your video I have the feeling they are the same. Could please you tell me more about it ?

[@FemexIran]

Hi. You are welcome. I have not heard about progressive damage modeling but also I think they are the same because in the continuum damage modeling, we have two phases: 1) damage initiation 2) damage propagation or evolution and progressive damage modeling is referring to the second phase. So I think they are the same. Also we have a premium tutorial about ductile damage. This is its preview: kzbin.info/www/bejne/eoDVipeCg65_kJo

[@abdurrahimniazi7355]

thank you sir very helpful

[@FemexIran]

you are welcome.

[@寶兒-b9o]

Sir I have a question about how to define damage in hard & tough plastic (polymer), I use ductile damage model, but the stress strain curve after yield point goes with softening regime,steady flow regime then hardening regime. Right now i am following the damage evolution in abaqus to find the "fracture strain" in hard & tough plastic, but i am still confusing with Equivalent fracture strain at damage initiation, Is Equivalent fracture strain at damage initiation in hard & tough plastic equal the plastic stain after" yield point" ot after "steady flow". Thanks a lot, i appreciate it

[@FemexIran]

Hi. To have deep understanding about ductile damage definition, you can buy this premium tutorial: kzbin.info/www/bejne/eoDVipeCg65_kJo The prices are mentioned in the description below the tutorial. Or you can use our online consultancy service. For each of them you can contact me via email or WhatsApp. Email: [e-mail] WhatsApp number: ([phone]

[@GigaChad-hf4yo]

ty man really helped

[@FemexIran]

you are welcome

[@nctiii]

Thank you for the video! I have a question. Can you explain, how the strain at damage initiation can be obtained from experimental tensile test data? According to the literature, in general, the damage at fracture is calculated using ef=2ln(A0/Af). Is this value can be used in Abaqus as Fracture strain or there is a need for calculation of strain at damage initiation? Thank you!

[@FemexIran]

hi. you are welcome. I have answered your question in the complete version of this video : kzbin.info/www/bejne/eoDVipeCg65_kJo

[@CP-ig3rg]

Thank you for your video! It is very helpful to me. I have a question. Does continuum damage mechanics apply to polymer materials, for exammple PCL, PLA. Thank you.

[@FemexIran]

Hi. Yes of course.

[@CP-ig3rg]

@@FemexIran Thank you.

[@FemexIran]

@@CP-ig3rg You are welcome.

[@韩江龙-c1j]

Thank you for your video. Could you explain how to calculate the strain rate in detail?

[@FemexIran]

hi. your welcome. the strain rate is equal to the speed that element length changes divided by its initial length.

[@leonardopieracci324]

Hello, thanks for the video. I have a question. I have a model of a church and I entered the concrete damage plasticity parameter I have. I selected like output request DAMAGEC and DAMAGET but in the visualization module it is 0 everywhere, except in two or three meshes scattered throughout the model. All the units are ok, there isn't distorted element and I can see other output. Do you know what these display problems are caused by? Has a similar case ever happened to you? Thank you in advance

[@FemexIran]

Hi. You are welcome. this kind of output can have several causes: 1) the mesh is not dense enough. so the element size must be decreased in the regions which damage arise. 2) the load is not enough to cause large damaged areas. so by increasing the load, damage will propagate in the structure. 3) you must change the visualization settings: a) the contour type must be changed to quilt. b) the number of contour intervals must be changed to 24 from 12 (default) c) the interval type must be changed to log if you did according to the explanations and the result didn't change, your model must be checked to find the mistakes and be modified. to do this, you can use our online tutoring and consultancy service.

[@leonardopieracci324]

Thanks a lot for suggestions!

[@FemexIran]

@@leonardopieracci324 you are welcome.

[@lulusukkar1324]

Thank you for the video I have simulated a composite concrete slab connected with steel beam in abaqus how can i determine if the failure happened in beam or in slab ?

[@FemexIran]

Hi. You are welcome. To investigate failure in each of them, you must define failure model for them. you must define CDP model for the concrete with tensile and compressive damages and request DAMAGEC and DAMAGET parameters in field output request to check its damage and then check them in the visualization module. For the steel you can also check the damage without defining damage model for it. You can check the PEEQ in the visualization module for steel. It is the equivalent plastic strain which is one of the default outputs of Abaqus. If this parameters exceeds the value of ultimate plastic strain which you have defined in the property module for steel, it means that it has entered the damage region. Please watch these videos about steel plasticity to understand the PEEQ and ultimate plastic strain : kzbin.info/www/bejne/qprQqqSPgNppp9k kzbin.info/www/bejne/Z2nTc4tmh5msaJo

[@sianourani1042]

thank you for the video, did you use true graph or engineering graph?(stress-strain)

[@FemexIran]

hi. your welcome. I used true stress-strain curve for plastic and damage analysis.

[@manojkumarneesu2773]

sir can you explain when do we use linear damage evolution and when do we use exponential damage evolution

[@FemexIran]

hi. actually it depends on the material. you must test both of them and then check the results and check which of them leads to more accurate results. for some of the materials the linear form is better and for some of them the exponential form is better.

[@manojkumarneesu2773]

@@FemexIran thankyou sir

[@FemexIran]

@@manojkumarneesu2773 you are welcome.