Hello Dr. Michael, Thanks for the great videos. Based on the following python code, we are trying to create a script in ABAQUS that automatically generates a kinking model according to the angle of the wavy fiber of a unit cell composite of length th according to the following conditions. 1. Creating a 2D mesh of the matrix and fiber cross-sections 2. extruding them along a sine wave trajectory, and setting up cohesive contact surfaces and periodic boundary conditions in ABAQUS However, it is difficult to write a python script according to the curve of the 2D mesh. Can you help me with this part?
Hello @KimsComposite, thanks for the comment. Unfortunately, this seem more of a project and not something I would help with. I tend to answer one-off specific questions and if there is a video worth making on such requests, then I will consider it. Good luck with this.
Hi Dr Michael thank you for sharing this video. I have one question, if I want to simulate the straight fiber with different fiber orientation (different stacking sequence like 90, -45, 45, 0), should I Use Default Orientation or custom it using a Discrete? When I tried to use the discrete, the error massage occurred. Looking forward to hearing from you. Thank you.
Hello, this is a good question. I will suggest ou use the Discrete option, as that will be more appropriate. Any of the fibres 90deg, 45deg, will have their discrete unique option. If you have too many orientations, then the user-defined option might be used. That will require a more careful and considered consideration.
@@MichaelOkereke thank you very much for your kind response Dr. Just wonder if you could help me with the different fiber orientation tutorial in your next video when you have a free time. Cheers!
Hello Dr. Michael, Thanks for the wonderful videos. I was wondering if you could show us (if you already did then please give the link) how to assign orthotropic viscoelastic material properties in Abaqus (I assume we probably have to write UMAT). TIA
Hello @fuandhassan, you are right, you would need some sort of UMAT to do this. There is no existing material modelfor this sort of orthotropic material within ABAQUS. If you have some experience with UMATs writing, then this will be the viable way to go. I unfortunately do not have a video like that. Thanks for the comment.
Hello Akash, please give me more information about the microstructure so I can better understand the query. You may suggest a relevant journal publication. Cheers.
@@MichaelOkereke i want to import SEM image of a two phase material into abaqus,, assign material properties to different phases and then study the plastic deformation by applying tensile or compressive loading.
Nice video Professor. Can we do this procedure for orphan mesh models in abaqus. There are no geometry present inside the model because of the orphan mesh. Then how to select the surface specifically?
Hello @Vishnu OS, this is a good question. It is always tricky working with orphan meshes as there geometry data is missing for such meshes. You may be able to convert the orphan mesh into a geometry. Dr Ronald Wagner, a TH-camr that I recommend, has done this. Check his video about this here: th-cam.com/video/y5U_Xa_yMlQ/w-d-xo.html&si=EnSIkaIECMiOmarE
Hi, Professor! I love your videos! I would like to know if is possible to make a video about random orientation of fibers. I would appreciate it a lot, because I tried to change the code in python however, during the assembling, most of the fibers stay outside of matrix. Do you have any suggestions about how to put them random but in a set limit? Thank you very much!
Hello @Willison, thanks for the comment and glad you love the videos. As regards random orientation of fibres, I am not sure what you mean. Is it random fibre positions i.e. centres of the fibres on a 2D plane or random angles of the fibres i.e. inclincation of the fibres along its longitudinal axis, as it relates to say short fibre composites? With the random centre of fibre positioning, I have a series of videos that deal with that an the MontCarlGen2D software (see link in description of this video) will help you automate that. However for the random inclination of fibres along the longitudinal axis, this is something I am yet to implement into a script. I have also not made any video about this. I see this can be best done using a python script and will consider this for a future video challenge. I am not sure why your script is not working, so do give me some more insight on get in touch with me via the CM Videos Insider Group (see link in description section of this video).
@@MichaelOkereke Thank you for your reply. Regarding my doubt, I am trying to put random fibers in a 3D matrix (3D-Plane). I wrote a code and it is working. However, since the fibers (in my case short-fibers) can assume any orientation, sometimes the fibers assume a position so they are outside of the matrix, so I need to adjust my code so the fibers get oriented but in a set limit according to volume fraction, otherwise the analysis will be incorrect since some of them are not inside the matrix. I watched your video about 2D random orientation and I think It can be extended to a 3D case, but I am still studying about that!
Great video, Thanks! Have you ever written a UMAT when a material orientation is specified? This adds some extra complication as the deformation gradient acts differently than in a global coordinate system. I did this before but always seem to get incorrect results when calculating the stress using the deformation gradient in the material coordinate system. This is a topic that is very hard to find information on.
@@khaledcine6542 You need to use state vaiarbles ('STATEV' in ABAQUS) to save the relevant quantities that you need at each step. You choose how many state variables you want when you are creating a material in the CAE. At the beginning of an increment, you define your relevant quantities as state variables. Then you use your equations to calculate the change in the relevant quantities. The properties are then updated for the next step using a numerical procedure such as Eulers explicit method (this works for basic models). Your updated quantities are saved as the relevant state variables which can then be used at the beginning of the next increment. Note also, that ABAQUS expects you to update the 'STRESS' (and possibly 'DDSDDE' depending on your problem) values at each increment of your UMAT also.
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Thank you Dr. Michael Okereke. This video helped me a lot.
Thanks
Excellent explanation Professor.
Many thanks!
Thank you Sir again for your uploading.
You are welcome
Very nice work, great videos!! Keep it up!
Thanks very much
Great tutorial as always!!!
Cheers Vukasin
Nice work!
Cheers
Hello Dr. Michael, Thanks for the great videos. Based on the following python code, we are trying to create a script in ABAQUS that automatically generates a kinking model according to the angle of the wavy fiber of a unit cell composite of length th according to the following conditions.
1. Creating a 2D mesh of the matrix and fiber cross-sections
2. extruding them along a sine wave trajectory, and setting up cohesive contact surfaces and periodic boundary conditions in ABAQUS
However, it is difficult to write a python script according to the curve of the 2D mesh. Can you help me with this part?
Hello @KimsComposite, thanks for the comment. Unfortunately, this seem more of a project and not something I would help with. I tend to answer one-off specific questions and if there is a video worth making on such requests, then I will consider it. Good luck with this.
Hi Dr Michael
thank you for sharing this video. I have one question, if I want to simulate the straight fiber with different fiber orientation (different stacking sequence like 90, -45, 45, 0), should I Use Default Orientation or custom it using a Discrete? When I tried to use the discrete, the error massage occurred. Looking forward to hearing from you. Thank you.
Hello, this is a good question. I will suggest ou use the Discrete option, as that will be more appropriate. Any of the fibres 90deg, 45deg, will have their discrete unique option. If you have too many orientations, then the user-defined option might be used. That will require a more careful and considered consideration.
@@MichaelOkereke thank you very much for your kind response Dr.
Just wonder if you could help me with the different fiber orientation tutorial in your next video when you have a free time. Cheers!
Hello Dr. Michael, Thanks for the wonderful videos. I was wondering if you could show us (if you already did then please give the link) how to assign orthotropic viscoelastic material properties in Abaqus (I assume we probably have to write UMAT). TIA
Hello @fuandhassan, you are right, you would need some sort of UMAT to do this. There is no existing material modelfor this sort of orthotropic material within ABAQUS. If you have some experience with UMATs writing, then this will be the viable way to go. I unfortunately do not have a video like that. Thanks for the comment.
Sir please make a video on plastic deformation of two phase microstructure using abaqus
Hello Akash, please give me more information about the microstructure so I can better understand the query. You may suggest a relevant journal publication. Cheers.
@@MichaelOkereke i want to import SEM image of a two phase material into abaqus,, assign material properties to different phases and then study the plastic deformation by applying tensile or compressive loading.
Nice video Professor. Can we do this procedure for orphan mesh models in abaqus. There are no geometry present inside the model because of the orphan mesh. Then how to select the surface specifically?
Hello @Vishnu OS, this is a good question. It is always tricky working with orphan meshes as there geometry data is missing for such meshes. You may be able to convert the orphan mesh into a geometry. Dr Ronald Wagner, a TH-camr that I recommend, has done this. Check his video about this here: th-cam.com/video/y5U_Xa_yMlQ/w-d-xo.html&si=EnSIkaIECMiOmarE
@@MichaelOkereke thanks for the reply professor. I will check this out.
Hi, Professor! I love your videos! I would like to know if is possible to make a video about random orientation of fibers. I would appreciate it a lot, because I tried to change the code in python however, during the assembling, most of the fibers stay outside of matrix. Do you have any suggestions about how to put them random but in a set limit? Thank you very much!
Hello @Willison, thanks for the comment and glad you love the videos. As regards random orientation of fibres, I am not sure what you mean. Is it random fibre positions i.e. centres of the fibres on a 2D plane or random angles of the fibres i.e. inclincation of the fibres along its longitudinal axis, as it relates to say short fibre composites?
With the random centre of fibre positioning, I have a series of videos that deal with that an the MontCarlGen2D software (see link in description of this video) will help you automate that. However for the random inclination of fibres along the longitudinal axis, this is something I am yet to implement into a script. I have also not made any video about this. I see this can be best done using a python script and will consider this for a future video challenge.
I am not sure why your script is not working, so do give me some more insight on get in touch with me via the CM Videos Insider Group (see link in description section of this video).
@@MichaelOkereke Thank you for your reply. Regarding my doubt, I am trying to put random fibers in a 3D matrix (3D-Plane). I wrote a code and it is working. However, since the fibers (in my case short-fibers) can assume any orientation, sometimes the fibers assume a position so they are outside of the matrix, so I need to adjust my code so the fibers get oriented but in a set limit according to volume fraction, otherwise the analysis will be incorrect since some of them are not inside the matrix. I watched your video about 2D random orientation and I think It can be extended to a 3D case, but I am still studying about that!
Great video, Thanks! Have you ever written a UMAT when a material orientation is specified? This adds some extra complication as the deformation gradient acts differently than in a global coordinate system. I did this before but always seem to get incorrect results when calculating the stress using the deformation gradient in the material coordinate system. This is a topic that is very hard to find information on.
Hi Dominic!: Are you familiar with using UMAT subroutine?
Somewhat but I'm far from an expert :)
@@dominicbrennan4823 Please Sir, do you know how to make properties of elements (Young's modulus) changes with each step based on an equation? Thanks.
@@khaledcine6542 You need to use state vaiarbles ('STATEV' in ABAQUS) to save the relevant quantities that you need at each step. You choose how many state variables you want when you are creating a material in the CAE. At the beginning of an increment, you define your relevant quantities as state variables. Then you use your equations to calculate the change in the relevant quantities. The properties are then updated for the next step using a numerical procedure such as Eulers explicit method (this works for basic models). Your updated quantities are saved as the relevant state variables which can then be used at the beginning of the next increment. Note also, that ABAQUS expects you to update the 'STRESS' (and possibly 'DDSDDE' depending on your problem) values at each increment of your UMAT also.
@@dominicbrennan4823 what about the steps, you create it manually in Abaqus as usual, or you write it in the script code of UMAT? Thanks