Ductile Damage Modelling in ABAQUS: Failure Simulation via Standard & Explicit Tech - Tutorial

[@Professor3MEC]

Models can be donwloaded free from www.professor3mec.com Please do support the channel at ko-fi.com/professor3mec All proceedings go towards new videos and keeping the webpage going.

[@adshah20]

Absolutely great tutorial, learned a lot!!!!!! can you make a tutorial for GTN model as well???

[@Professor3MEC]

Thanks for liking. If you could please send me more details on the model. I will be more than happy to make a video. [e-mail]

[@sahamsharifi5012]

@@Professor3MEC I also have the same request.

[@ajayjayswal]

Very helpful video. Please make a video on damage modeling for brittle materials.

[@Professor3MEC]

Glad you found it useful. Will try to make one as you requested. Any specific material you are after?

[@ajayjayswal]

@@Professor3MEC Thank you for your quick response. I really appreciate it. I am looking for polymers such as PLA.

[@aouiched9613]

Thanks, can you give a reference paper for ductile parameters used thanks

[@Professor3MEC]

sure i will have a look and try to find.

[@mrkhan3617]

Thank you for your tutorial. How can the size of increments in case of dynamic explicit can be increased or decreased?

[@Professor3MEC]

You may try mass scaling but keep an eye on energies.

[@paradise_nsh]

Hi Professor, thank you for your tutorial.Why plastic strain (0.6) is more than fracture strain (0.15)?

[@Professor3MEC]

Hi Thanks for liking this and hope you found it useful. Not sure what you mean? Which quantity is 0.6?

[@paradise_nsh]

@@Professor3MEC I have downloaded your input file and I see plastic strain is 0.6 in damage initiation but fracture stran is 0.15.Why plastic strain is more than fracture strain ,whereas it should be viseversa?

[@Professor3MEC]

@@paradise_nsh plastic strain and corresponding yield stress just defines the plastic part of the curve, i.e. slope or plastic/strain hardening, while fracture strain is the strain at failure. I would suggest to please have a look at ABAQUS documentation for more details.

[@SaurabhDixit-g3k]

Hello sir, i am trying to do a dynamic explicit damage analysis with GTN model for SAE 1010 steel using tensile sample but somehow i am not getting the correct Load Displacement curve also i am not sure of what amplitude values should i enter, can you please please help with this Thankyou

[@Professor3MEC]

Sure email me the details and if possible I can have a quick look

[@ismaelerroussi9704]

thanks, what's the difference between this example and the xfem crack growth for example ?

[@Professor3MEC]

Both may be trying to achieve same. One is based on the fact that element is removed from the simulation and hence careful meshing, etc is need. While other is more suitable for crack growth problems which were inherently a big problem in FE codes.

[@vikramroy7471]

Sir is there any way by which we can model that material fails only in tension and not in compression

[@Professor3MEC]

All depends on the model/process being simulated. You can specify very high material damage parameters.

[@رامینمجرد-ف5ز]

Can I use ductile damage for weld? My model is about progressive collapse. I apply the load on a column and I want to calculate the strength of the weld and can you suggest any reference or guide for doing that please?

[@Professor3MEC]

Yes you may. If I come across any relevant paper then I will update here. Thanks

[@henmay3738]

Thanks for your video. A question is given as, why the Mises stress is non-zero even after the failure occurs? I'm wondering if it is numerical errors or the exact situation in reality?

[@Professor3MEC]

Sorry for the delay in replying. Just numerical issue and as we may have not allowed enough time in simulation after failure for the material to relax fully.

[@cuongvucong7953]

can you explain, why you use 'Ductile Damage Model' and not 'Johnson-Cook damage model'???

[@Professor3MEC]

I have used both please check other videos where I compared both

[@vaibhav8009]

Great Video.......but Which is best for doing Impact or Dynamic analysis ? any difference between two which one is better for which type of analysis?

[@Professor3MEC]

do you mean implicit or dynamic? as explained in the video, it highly depends on the problem. If you have a highly dynamic problem to simulate with short time duration then explicit dynamic would be suitable, otherwse implicit might be better. I hope his is what you asked?

[@vaibhav8009]

@@Professor3MEC Thanks.....highly dynamic problem means medium and high strain rate problems?

[@Professor3MEC]

@@vaibhav8009 you can use both if there aren't rigid body motions involved. For example, high strain rate uniaxial tensile tests. For very dynamic problems, such as foam crushing, etc. explicit might be better. But this is just my opinion.

[@ahmedoqasha5057]

Thanks for your excellent effort . however, if the strain rate will be considered in the damage initiation as a field variable how is done ?

[@Professor3MEC]

Ahmed Oqasha Thanks for the compliments. For strain rate dependence, you may try Johnson and Cook model? Or if you may send data or more details then I can comment more?

[@Professor3MEC]

Also, in the video the place where I define the fracture strain, you may specify strain rate dependent table. at 2:46

[@muralikartheekss2932]

Sir, I am trying to model an RVE composite material. My aim is to obtain a compressive stress-strain diagram upto 70% strain. Can you give some inputs regarding the material model, and step size?

[@Professor3MEC]

Sure let me know what you are after and I’ll will try my best to guide

[@muralikartheekss2932]

@@Professor3MEC can i email you my requirements ?

[@amrabdullah1995]

hello sir thans for the great effort i have a question please. what is the difference between fracture strain and displacement at failure ? i know that the fracture strain corresponds to ultimate stress.. what about the displacement at failure ?

[@Professor3MEC]

Hi, Thanks for liking the channel and videos. Displacement at failure is used in a phenomenological way to capture softening part of the stress-strain curve. This can also be estimated using failure strain and characteristic dimensions of the elements. I hope it is clear?

[@amrabdullah1995]

@@Professor3MEC Thanks for your reply. I will tell you basically what i am trying to do. I am modelling a steel pipe subjected to internal pressure. I want the pipe to crack when it reaches a certain stress or a corresponding strain. My steel has 292 MPa yield strength (0.001 plastic strain), 480 Ultimate strength (0.16 strain at failure (total fracture strain). those tensile tests results are obtained from a steel specimen (dumbbell-shaped sheet) which has a 200mm length and 12.5 mm. how can i calculate the displacement at failure ? since the fracture strain is 0.16.

[@Professor3MEC]

@@amrabdullah1995 IF you have uniaxial tensile test data then you can fit the experimental stress strain curve with uniaxial simulation in ABAQUs, and then use those parameters directly in ABAQUS for pipe model. Having said that, in pipe your structure might be under bi and tri- axial stress states so one needs to be extra careful, but it should still work.

[@rezaa6745]

Dear Expert, I Want to identify ductile damage parameters for doing the spinning simulation.The material is AISI 304 (Stainless steel) How can I do that? How can I select the proper thickness of notched tensile test specimens?

[@Professor3MEC]

Hi, you can fit stress strain data to do so.

[@rezaa6745]

@@Professor3MEC How can I select the notched specimen? What thickness? The stress triaxiality and fracture strain should be characterized.

[@Professor3MEC]

If you have uniaxial, BI- / triaxial experimental data then you don’t need actual sample but you can start with one element test as shown in another video on the channel. If you only have ct-specimen result then you may have to go with the full model. Email me more details to have a look so that I may suggest something suitable.

[@rezaa6745]

@@Professor3MEC Thank you for sharing your knowledge.I sent my question as an Email.

[@outplayed4511]

Thank you for the video. I have a question tho, not about this simulation but about a classic bullet impact simulation. Whenever I try to penetrate a shell plate with a discrete rigid bullet in explicit analysis with all the damage properties and element deletion on, shell elements deform hugely but does not rupture or delete, they form a shape similar to a spear head, big triangle shapes and such but they do not rupture, they stick to the bullet like a blanket on it, any idea about this issue ?

[@Professor3MEC]

Thanks for liking the video and channel. It could be due to various reasons, such as damage evolution parameters, contact properties, element types. Is it possible to share more details or input fie to have a quick check?

[@hnrwagner]

sounds like you have not activated the STATUS variable in the History Output Manager

[@outplayed4511]

@@hnrwagner Yes Dr. Wagner, that was the problem for about 5 months ago I've learned about that, but still thanks for the answer. But I am wondering something else: can I still keep the failed elements in the animation/frame. I don't want them to get disappear or deleted rather just stay afloat in the space.

[@sianourani1042]

great video! btw, I think these entered ductile damage data are wrong. I mean you have a tensile test so triaxiality is not 0... and you need to enter more data.

[@Professor3MEC]

Great point! I would suggest to have a look at the abaqus documentation, in this case we were not considering effect of triaxiality so it became irrelevant but i agree for uniaxial triaxiality should be around 1/3. Thanks for liking the video.

[@sajjadalam383]

My section is not breaking like yours, why?

[@Professor3MEC]

If you are following the same steps and parameters then only issue could be that in the field output may be ask for status as output variable.