Hello Dr. Michael Okereke! I always appreciate your high-quality lectures. I have a question regarding the process of determining shear properties, as the stress values are not coming out correctly. I have set PBCs conditions and applied pure shear on the boundaries. Currently, the geometry information is as follows: Unit: [micrometer] N_number -> (x_coord, y_coord) N1 -> (0,0) N2 -> (300,0) N3 -> (300,300) N4 -> (0,300) The reaction forces at each node are as follows: Unit: [mN] N_number -> (RF1, RF2) N1 -> (-3400,-3130) N2 -> (0,3130) N3 -> (0,0) N4 -> (3400,0) Using this information to calculate the stress values results in a value of '0'. Could you please advise on what needs to be corrected? Thank you always.

Thank you very much sir. I always wait for your new video.

@MichaelOkereke

2 жыл бұрын

Hello Aman, thanks for your interest. Glad you look forward to the videos.

Thanks a lot sir,i was exactly looking for such video on youtube

@MichaelOkereke

2 жыл бұрын

You are most welcome Subrat.

Dr Michael Okereke, Thank you very much for the useful video!. Is there any relevance in applying PBC in biaxial loading of rve

@MichaelOkereke

10 ай бұрын

Certainly... PBC-based simulations give better results than the other BC types. You have to handle it carefully though making sure the rightboundaryconstraints are properlyspecified. I plan to make a video to show this... especially for a heterogeneous media as a particulate composite in 2D. Watch this space!

Dear Dr Michael Okereke very thank you for such informative videos. If possible, please post subtitles.

@MichaelOkereke

2 жыл бұрын

Hello Valerii, thanks for your interest in the channel. Indeed, accurate subtitles are important and maybe in future videos, I can invest in that. For now, you can turn on subtitles on your KZread watch platform and it will give you the auto-generated subtitles. Is this what you mean or are you referring to something else?

@Valera197615

2 жыл бұрын

@@MichaelOkereke Thank you very much for your reply!!!!! Probably KZread does not automatically turn on subtitles right away. Because I started looking at yours as soon as it appeared. And then there were no subtitles. They probably appear after a while. Now they are already there.

@MichaelOkereke

2 жыл бұрын

Hello Valerii, I did not know that.. thanks for the information. I am glad it worked out well for you.

Thanks for the video. Have you ever tried modeling a void in a unit cell and verify the Rice and Tracey void growth model?

@MichaelOkereke

Жыл бұрын

Not really... I don't know what that is.

@arjhunjhunwala

Жыл бұрын

@@MichaelOkereke okay thanks. it is a closed form equation for symmetric void growth in an infinite rigid-plastic media. here's a link to the paper - esag.harvard.edu/rice/020_RiceTracey_DuctileVoid_JMPS69.pdf

Thank you very much Dr. Michael. What modifications I need to perform if I want to increase the strain data for the corresponding stress. I mean, if want to get the stress-strain date up to 0.4 or 0.5 strain values unlike what we are getting up to 0.03

@MichaelOkereke

2 жыл бұрын

Hello @Murali Kartheek s s, thanks for your interest in the channel. I am not sure I completely understand the query but if you mean, how to achieve larger strain deformation in the model, then this can be done by specifying a higher displacement load in the ABAQUS Boundary Conditions (BC) module. For example, if your RVE edge is 100 microns, then specifying a displacement value of 10 microns along that edge leads to a 10% strain or 0.10. If you want say an 80% strain in that direction, then you have to specify a displacement of 80 microns. I hope this answers your query.

Thanks for these great videos! I have a question. Is the result True or Engineering stress/strain? Thanks!

@MichaelOkereke

Жыл бұрын

Hello @David, it is an Engineering stress/strain. For it to become true strain, then we have to track the evolution of the area which during the deformation which is not what is being done here. Though the forces are time-dependent and change during the deformation, we have not tracked the changing surface area of the structure so we cannot report a True stress/strain value.

Thanks a lot Dr Michael Okereke for your beautiful videos, they are helping me a lot during my university studies. Is it possible to know which properties of the constituent materials have been defined?

@MichaelOkereke

2 жыл бұрын

Thanks Emidio for your interest in the channel. On your question, Yes, of course Emidio. What do you want to know?

@emidiociccone4201

2 жыл бұрын

@@MichaelOkereke To estimate the strength of the composite material (tensile or compressive), which properties of the constituent materials must I assign?

@MichaelOkereke

2 жыл бұрын

Hello Emidio, if you are using the RVE approach shown here, you need Youngs Modulus and Yield stress. You might want to incorporate a damage model if you want... that's all really.

@emidiociccone4201

2 жыл бұрын

Thank you@@MichaelOkereke

Hallo Dr. Okereke, could you please make a video to explain the 3D-PBC and how to do a 3D-PBC manuell in Abaqus? Thanks a lot

@MichaelOkereke

2 жыл бұрын

Hello Tony, this is something that I am thinking about and hopefully in future will make such a video.

@tonyyang8209

2 жыл бұрын

@@MichaelOkereke thanks for your replying! I'm writing my master thesis in numerical simulation of fiber composites. And I will cite your article and video with no doubt. Many many thanks!

Dr Michael Okereke, Thank you very much for useful video! I am wondering what type of modification we need in the Excel spreadsheet in case we are using plane strain elements without thickness instead of plane stress elements. Looking forward to hearing from you! Best - Mojtaba

@MichaelOkereke

Жыл бұрын

Hello @Mojtaba Abdolkhani, thanks for the comment. For the case where you use plane strain elements, I am not sure there is need to modify anything. What we extract here is a reaction force for x and y axis (RF1 and RF2), displacement (U1 and U2) and coordinate positions (COOR1 and COOR2). These values are all extracted at node level not element level. So, even if you use a plane strain element, it should not affect your ability to use the Excel sheet as it is. Having said that, I have not tried it out to say for sure but I think it is correct.

@miloooo1956

Жыл бұрын

@@MichaelOkereke Thank you very much for your reply. I just asked so, because I noticed there are cells in the top of the excel spreadsheet where you mentioned the length, width and height of the RVE. Do these values need to be updated for RVE with different size? In other words, do they affect the calculations and stress-strain curve? And if so, what should we enter for height in plane strain case as we assume the RVE long enough that the height doesn't affect the results.

@MichaelOkereke

Жыл бұрын

Hello @Mojtaba, certainly you are right, you need to update the RVE length and width according to the dimensions of your specific RVE. For height, for plain strain problems, it should be always a constant and 1 will be acceptable. So, enter 1 for the height for plain strain 2D problems.

Dear Michael thank you for such informative videos. I have a request from you. I'm working on a problem but I extracted some wired results, so, if it is possible for you please help me with that. Problem: A 3D RVE with random fibres (such you create), fibre is carbon T700s with epoxy matrix. We put RVE under tension along fibre direction, and the aim is to calculate the stress concentration factor for the nearest fibre to the centre fibre (actually in the RVE there is a centre fibre which considers being broken and other fibres are around it randomly). The RVE is cylindrical with the boundary conditions: 1) top under tension 2) bottom z-symmetry instead of centre fibre which represent fibre break and traction free for cylinder surface. Thank you. Also, this is the paper: Stress concentrations in an impregnated fibre bundle with random fibre packing.

@MichaelOkereke

2 жыл бұрын

Hello @Funny Moments, thanks for your interest in my channel. I do understand your question. If you want my help, then please book a one-on-one consultation with me via this link: cmvideos.ck.page/products/one-on-one-consultation

Sir, how to design excel sheet as you have soon in ur video..please share the link of video to develop excel sheet

@MichaelOkereke

2 жыл бұрын

Hello @Ali, I am not sure I understand the question. I have provided in the description section a link to the Excel sheet. Please consult that and hopefully that should answer your questions. You will see within the excel sheet the formula for determining stress and strain from the history outputs, which I think is what you are after. Let me know if this answers your query.