Hello, What is the field variable that shows the nominal stress in the CZ material? I am trying to check if the CZ in my model follows Traction Separation law
As I said in the video, this is the simplest method that only needs stress-stress curve of the adhesive layer. However, if you need to obtain more accurate result you have to do some other tests like DCB or ENF to get fracture energies on modes I and II, respectively.
Nice video Dr. Khabaz. In the near future, I will try to make a clip which retraces you steps in the 3DEXPERIENCE platform with Simulia/Abaqus as the solver. Hopefully, it has all the needed features.
Thank you for the video it is so helpful. Please can you explain how to have travtion separation parameetrs in the case of belinear czm model. Thank's in advance
Nu is considered to be an elastic property. It's not an highly effective parameter. If you don't know the exact amount you can consider it among 0.3 to 0.4 for adhesive layer.
so we use the tensile test of the epoxy, specifically stress strain curve and compare with the lap shear test results: load disp? because my tensile test results do not look like in the video and when im comparing them with lap shear test load-disp results, they are too big
In this case, the adhesive shows a ductile behavior and this approach can predict final load very well. It should be useful in brittle adhesives as well. The main condition here is that you have got a cohesive failure in the bond line not an adhesive failure.
@@atakhabaz3607 i had 99% of damage, should i play around with G values? because im getting too big values for load and disp also can i contact you for more help?
Mr. Khabaz, I can't stress how thankfull I am for this tutorial, you basically saved my scientific initiation research on FEA! Have an excellent everything! =)
Good evening sir, thank for the video. When i trying to simulate slj test with cohesive element as interface layer, at the end of analysis cohesive elements distorted and haven't been deleted. Can you please tell me what is the possible reason of that?
In some cases element deletation doesn't work. However, you can check SDEG(the damage parameter) in your contour results and you can consider damage for elements with SDEG more than 0.98.
@@AlisherAshirbekov the thing that you mentioned is something else. It's the input value for your simulation that indicates the deletation should start when D is 0.98. However, sometimes Abaqus doesn't show the elements deletation. In those cases, you would better to check D parameter from you counter results. And consider If the damage parameter D exceeds 0.98 for specific elements, you can consider those elements to have failed. You can check the D parameter using SDEG.
great Job Sir, Can you please send me your paper "Creep behaviour of a graphene-reinforced epoxy adhesively bonded joint: experimental and numerical investigation" i am so interested on it.
Hello Dr. Ata, I followed your instruction, but my simulation does not run..... It is giving me "CRITICAL FRACTURE ENERGY IS SMALLER THAN THE ELASTIC ENERGY PRIOR TO DAMAGE INITIATION" My stress-strain curve is of triangular. So I multiplied the strain with thickness of the adhesive element to get stress-displacement curve. Now, when I take the area, it is coming about 2.0 N/mm. When I fed this in my simulation, it is not running. So I tried to decrease the energy (trial & error). So it runs. there must be wrong with my model. Please tell me what mistake I am doing? Than you for your help.
Hi MONO, Since I don't have detailed information about your simulation, I can only guess some probable mistakes. Please check the following: 1. You need to change either the initial stiffness or the Young's modulus in the normal and shear modes. 2. You are not allowed to mesh the bonded line with more than one element in the thickness direction. 3. You are not allowed to change the maximum traction because this parameter is more important than the G value. 4. Maybe you have experienced adhesive failure in your experiments. If so, the interface region is weaker than the adhesive layer itself, which introduces an error in your simulation.
@@atakhabaz3607 Thank you, Dr. Ata. I recalculated Young's modulus, my mesh is alos one element thick, Rest I have left all the default value. We simulate two conditions, one at room temperature and second at higer temperature. So now, my simulation runs, the cohesive elements starts to vanish, but then it stops with an error ..."THE SOLUTION APPEARS TO BE DIVERGING. CONVERGENCE IS JUDGED UNLIKELY." Thank you once again. Regards
"Hi, Dr. How are you doing? I wanted to thank you very much for your tutoring; it has provided me with great support for my research. If you don't mind, could you please give us a hint about shear stress and peel stress distribution?"
Thank you for your interest. I apologize if I didn't fully understand your question. From what I gather, you're asking about the relationship between stress, overlap length (X axis), and shear stress in a joint. In this context, we can consider the stress acting along the overlap length as shear stress, while the stress acting perpendicular to it (along the Y axis) can be considered as peel stress. It's important to note that this type of joint experiences both shear and peel stresses, with shear stress being the dominant factor. To further explore the effects of peel stress, you can simulate other joint geometries, such as a butt joint. This will allow you to observe and analyze the peeling effects more prominently and understand how they influence the joint behavior.
Thank you for the video it is so helpful. Please can you explain how to have travtion separation parameetrs in the case of belinear czm model. Thank's in advance
Thank you for your interest. Actually here we also used the triangular or bilinear CZM. this triangular damage model indicates using 3 individual parameters of 1. initial slop (or elastic Props), 2. the maximum amount of traction (Sy), and 3. the area under the triangle traction-separation diagram (Energy at failure).
@@atakhabaz3607 Hi I am working on DCB test , I made all steps but when I compare the RF at the reference point I find thant FEM force is so high compared with experimental force. I don't find the source of problem, Do you have any idea please.
@@imendebbabi8071 I think you have got the science border. But according to my experience it can be due to some reasons. 1. You maybe use a brittle adhesive in experiment. (If you use Araldite2011,then it was cured in room temperature maybe). 2. The domenant fracture area in DCB test is adhesive.
Okay, thanks, Doctor. To specifically note what I mean, how can we obtain the shear stress and peel stress distribution along the bond line over the overlap length? Which output tool in Abaqus is responsible for displaying the peel and shear stress? From what I've tried, 'S22' seems to represent peel stress, but I'm uncertain about the shear stress-whether it's represented by 'S11' or 'S12'. I know 'S33' is for mode 3 or out-of-plane stress. Again, I really want to thank you for your generous support.
Thank you for your insightful question. As you mentioned, in this case, S22 represents the peel stress. When it comes to shear stress, we cannot consider any Sii stress form as shear stress. Sii always represents the perpendicular stress in the ith axis. Shear stress always requires two individual axes to determine it properly. One axis indicates the applied plane, and the other indicates the stress direction. Therefore, in this 2D problem, S12 is the shear stress, not S11.
Thanks for the video. Can you please help to model the SLJ using explicit package since I need to understand the damage on the adhesive. Thank you
Hello, What is the field variable that shows the nominal stress in the CZ material?
I am trying to check if the CZ in my model follows Traction Separation law
Everything you said is true
As I said in the video, this is the simplest method that only needs stress-stress curve of the adhesive layer. However, if you need to obtain more accurate result you have to do some other tests like DCB or ENF to get fracture energies on modes I and II, respectively.
Nice video Dr. Khabaz. In the near future, I will try to make a clip which retraces you steps in the 3DEXPERIENCE platform with Simulia/Abaqus as the solver. Hopefully, it has all the needed features.
I really appreciate Dear Professor. I am waiting for it.
Thank you for making such a great content!
Thank you for the video it is so helpful. Please can you explain how to have travtion separation parameetrs in the case of belinear czm model. Thank's in advance
👍👍👍
thank you doctor
، excellent job
Many thanks!
nice video
Where did you get nu value from the G_t-s? or is it constant?
Nu is considered to be an elastic property. It's not an highly effective parameter. If you don't know the exact amount you can consider it among 0.3 to 0.4 for adhesive layer.
Congratulations and good luck, Dr. Ata
Thanks a bunch Dear doctor Asghar. Warm welcome to you.
Thank you 👍
Thanks for sharing
Thanks for your interest.
so we use the tensile test of the epoxy, specifically stress strain curve and compare with the lap shear test results: load disp? because my tensile test results do not look like in the video and when im comparing them with lap shear test load-disp results, they are too big
In this case, the adhesive shows a ductile behavior and this approach can predict final load very well. It should be useful in brittle adhesives as well. The main condition here is that you have got a cohesive failure in the bond line not an adhesive failure.
@@atakhabaz3607 i had 99% of damage, should i play around with G values? because im getting too big values for load and disp
also can i contact you for more help?
Wath is the solution of this problem plz
Dear Safa, sorry I couldn't get your point. Could you please ask your question more clear and/or with details.
Mr. Khabaz, I can't stress how thankfull I am for this tutorial, you basically saved my scientific initiation research on FEA!
Have an excellent everything! =)
@@luizgustavodelimapreviero4895 happy to hear that. Thanks for your interest.
I sincerely appreciate your generous support. Thank you, Dr.
Good evening sir, thank for the video. When i trying to simulate slj test with cohesive element as interface layer, at the end of analysis cohesive elements distorted and haven't been deleted. Can you please tell me what is the possible reason of that?
In some cases element deletation doesn't work. However, you can check SDEG(the damage parameter) in your contour results and you can consider damage for elements with SDEG more than 0.98.
@@atakhabaz3607 so if I specify the max degradation equal to 0.98 in my mesh control, so the distorted element could be deleted?
@@AlisherAshirbekov the thing that you mentioned is something else. It's the input value for your simulation that indicates the deletation should start when D is 0.98. However, sometimes Abaqus doesn't show the elements deletation. In those cases, you would better to check D parameter from you counter results.
And consider If the damage parameter D exceeds 0.98 for specific elements, you can consider those elements to have failed. You can check the D parameter using SDEG.
great Job Sir, Can you please send me your paper "Creep behaviour of a graphene-reinforced epoxy adhesively bonded joint: experimental and numerical investigation" i am so interested on it.
Thanks for your interest. Sure. Just send an email to: khabaz65@gmail.com
Hello Dr. Ata, I followed your instruction, but my simulation does not run..... It is giving me "CRITICAL FRACTURE ENERGY IS SMALLER THAN THE ELASTIC ENERGY PRIOR TO DAMAGE INITIATION" My stress-strain curve is of triangular. So I multiplied the strain with thickness of the adhesive element to get stress-displacement curve. Now, when I take the area, it is coming about 2.0 N/mm. When I fed this in my simulation, it is not running. So I tried to decrease the energy (trial & error). So it runs. there must be wrong with my model. Please tell me what mistake I am doing? Than you for your help.
Hi MONO,
Since I don't have detailed information about your simulation, I can only guess some probable mistakes.
Please check the following:
1. You need to change either the initial stiffness or the Young's modulus in the normal and shear modes.
2. You are not allowed to mesh the bonded line with more than one element in the thickness direction.
3. You are not allowed to change the maximum traction because this parameter is more important than the G value.
4. Maybe you have experienced adhesive failure in your experiments. If so, the interface region is weaker than the adhesive layer itself, which introduces an error in your simulation.
@@atakhabaz3607 Thank you, Dr. Ata. I recalculated Young's modulus, my mesh is alos one element thick, Rest I have left all the default value. We simulate two conditions, one at room temperature and second at higer temperature. So now, my simulation runs, the cohesive elements starts to vanish, but then it stops with an error ..."THE SOLUTION APPEARS TO BE DIVERGING. CONVERGENCE IS JUDGED UNLIKELY." Thank you once again. Regards
"Hi, Dr. How are you doing? I wanted to thank you very much for your tutoring; it has provided me with great support for my research. If you don't mind, could you please give us a hint about shear stress and peel stress distribution?"
Thank you for your interest. I apologize if I didn't fully understand your question. From what I gather, you're asking about the relationship between stress, overlap length (X axis), and shear stress in a joint.
In this context, we can consider the stress acting along the overlap length as shear stress, while the stress acting perpendicular to it (along the Y axis) can be considered as peel stress. It's important to note that this type of joint experiences both shear and peel stresses, with shear stress being the dominant factor.
To further explore the effects of peel stress, you can simulate other joint geometries, such as a butt joint. This will allow you to observe and analyze the peeling effects more prominently and understand how they influence the joint behavior.
Thanks for sharing
Thank you for the video it is so helpful. Please can you explain how to have travtion separation parameetrs in the case of belinear czm model. Thank's in advance
Thank you for your interest. Actually here we also used the triangular or bilinear CZM. this triangular damage model indicates using 3 individual parameters of 1. initial slop (or elastic Props), 2. the maximum amount of traction (Sy), and 3. the area under the triangle traction-separation diagram (Energy at failure).
@@atakhabaz3607 then I Can do thé same to get parameetrs. Thank you so much
@@atakhabaz3607 Hi I am working on DCB test , I made all steps but when I compare the RF at the reference point I find thant FEM force is so high compared with experimental force. I don't find the source of problem, Do you have any idea please.
@@imendebbabi8071 I think you have got the science border. But according to my experience it can be due to some reasons. 1. You maybe use a brittle adhesive in experiment. (If you use Araldite2011,then it was cured in room temperature maybe). 2. The domenant fracture area in DCB test is adhesive.
I mean Adhesive failure not cohesive.
Okay, thanks, Doctor. To specifically note what I mean, how can we obtain the shear stress and peel stress distribution along the bond line over the overlap length? Which output tool in Abaqus is responsible for displaying the peel and shear stress? From what I've tried, 'S22' seems to represent peel stress, but I'm uncertain about the shear stress-whether it's represented by 'S11' or 'S12'. I know 'S33' is for mode 3 or out-of-plane stress. Again, I really want to thank you for your generous support.
Thank you for your insightful question. As you mentioned, in this case, S22 represents the peel stress. When it comes to shear stress, we cannot consider any Sii stress form as shear stress. Sii always represents the perpendicular stress in the ith axis. Shear stress always requires two individual axes to determine it properly. One axis indicates the applied plane, and the other indicates the stress direction. Therefore, in this 2D problem, S12 is the shear stress, not S11.
I sincerely appreciate your generous support. Thank you, Dr.
Hi ata , Can you share such videos for other plotting options like shear and peel stress. thank you
Any individual model has its own condition but sure I will.
Wish u the best Dear Doc
great. thank you so much😍🥰
Thanks for your interest.
great content❤
Thanks a lot Dear Alaa