Dear all,

If you were waiting for my newsletter last week, I can only apologize for not sending one. Its the holiday season and its been difficult to find time to write with my kids being at home for the holidays. I wish you all a wonderful holiday, if you are enjoying some time off - here in UK - August is typically a holiday month for many people. Today, I will be reflecting on the following:

1. Technical Reflections: Porous media and Periodic boundary conditions
2. Behind the Scenes at CM Videos: Exploring Paid Newsletters
3. Quote of the week: How to do your best work!

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Technical Reflections

Porous media and Periodic Boundary Conditions

Porous media are a very common type of material where voids exist within homogeneous or heterogeneous bulk of a material. A sponge cake is basically a porous media. Syntactic foams are porous media. They are very useful where you are looking for crash absorption because the air-filled voids serve as energy-absorpting media.

Challenges of modelling Porous media: The Porous Media are quite challenging to work with due to the following:

1. Geometric design challenges: There is a need to randomly distribute the voids/pores/cells within the microstructure of the homogeneous material. This is not always easy to do as will require a numerical implementation of the Monte Carlo methods to make this possible.
2. Boundary conditions effects: Due to the randomness of the void distribution within the microstructure, the boundaries of the RVE domain is not always clear and replicated. This means that use of traditional Dirichlet and Neumann boundar conditions approaches might prove problematic leading to non-representative deformation profile for the deformed porous media. Use of Periodic boundary conditions are recommended as they provide a middle predictive range beyond the upper bound (Dirichlet BC method) and lower bound (Neumann BC type).
3. Periodic Boundary conditions are hard to implement: Of course, a third challenge, having established the necessity of PBCs, we have to find a way to implement the PBCs on such a domain. Existing FE solvers such as Ansys and ABAQUS do not have a direct way of implemnting and extracting properties for such systems. This means a resort to bespoke pluggins.

A video illustration of modelling of porous media: In the light of the above, this week, I recorded and published a video on the YouTube channel dealing with precisely these issues with regards to the micromechancal modelling of porous media where a Periodic Boundary Condition implementation is used. If you want to go ahead and watch this video, then do check it out below:

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Steps in modelling porous media: In order to overcome the challenges identified above, in the modelling shown in the YouTube video above, here is what I did:

1. Virtual domain created in MontCarlGen2D: I used a software that I developed called MontCarlGen2D which allows the user to create randomly distributed circular inclusions within a 2D RVE. It is software written in MATLAB which creates random microstrcuture on a 2D domain. The unique feature of this implementation is that the software creates/writes for the user Python files that represent the virtual domain generated in ABAQUS. The Python file is then ran within ABAQUS to recreate the random microstructure virtual domain. The same type of implementation operates for a 3D system but that has not been used here. If you are interested in getting hold of the MontCarlGen2D code, then click here.
2. Periodic boundary condition implemented with PBCGen2D: The challenge of imposing PBCs on virtual domains of a porous media was overcome by use of another bespoke software that I developed called PBCGen2D. It represents a periodic boundary condition generator which works with MATLAB and an ABAQUS-generated input file (*.inp) by updating the input file with a *EQUATION commands (kinematical constraints) which compells directly opposite faces/edges and lines to deform periodically. It works for 2D RVEs but there is ongoing developments on a 3D version of same code. If you want to again, get hold of PBCGen2D, then click here.

Following completion of the simulation, results were generated from the study which showed a devastating effect of 20% porosity on the constitutive behaviour of the parent homogeneous material. This sort of finding strengthens the resolve for researchers to continue exploring bespoke development of porous media.

If you are interested in watching more videos like the above focussing on porous media, then check out the CM Videos YouTube channel which you can access here.

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Behind the Scenes at CM videos

Exporing Paid Newsletters

It is getting to two years that I have been writing this CM Videos Insiders Newsletter and have thoroughly enjoyed it. In these nearly two years, I believe I have only missed a weekly write-up of only three times out of a possible 100 or so newsletters.

I have learned a lot about writing, sharing my self with my audience. I look forward to sending out the emails every friday and have been amazed at the number of people that read the newsletter.

I would want the newsletter to continue to take a central pride of place within my CM Videos Insiders whilst also offering more premium service to a selection of you who may like to support the work I am doing financially.

This led me to start mentally exploring the addition of a Paid Newsletter element to supplement these free CM Videos Insiders. I am not decided yet on whether to do it or not.

This is where you come in! I will like you to tell me if you would be interested in a Paid Newsletter which for a few dollars, per month, you will have access to the following:

• All the existing features of this newsletter in the format I currently use.
• More indepth sharing of technical insights on specific topics within the computational modelling space.
• Priority access to me with direct opportunities for you to reach out to me directly with your questions which I will attempt to answer.
• Priority access to existing and new CM Videos products
• More personal behind the scene stories from my research, work, and business - with behind the scene images and videos to help you get to know me more intimately.

If you are interested in the following, then please do fill the form below to let me know.

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Tell me what you think about the Newsletter

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Quote of the Week

How to do your best work

If you are reading this newsletter, you might be thinking that there is this golden advice that I can give you on how to make sure you always do your best work. In this super-engaged era of productivity, everyone is obsessing on how to make sure they always get their best work done. Yet, I do not actually have any ten-step process that will get you to do your best work but rather, I lean on the quote from the book, At Your Best, by Carey Nieuwhof, where he stated:

On the surface, it might sound counter intuitive that you just have to start working even when you might not be feeling the conditions are perfect for it. You will often thinking such work is bound to produce mistakes and so you stop. Yet, the converse is rather the truth. This is why I feel that starting when the conditions are not perfect will be bound to help you do your best work:

1. Conditions are never perfect: Do not sit around waiting for perfect conditions as there will always be something that will make whatever condition you are in to be imperfect. Even, if you are lucky and you stumble on a perfect condition, something is bound to come and spoil that perfectness. So, it is useless sitting around waiting for a condition which you do not control and which you are not guaranteed will come. You have to step out and control what you can, which is just start where you are.
2. The one who never starts never does a best work: It is idealistic to dream of what fantastic book you will write and how wonderful it will be to people but until you put pen to paper, you are only going to continuing carrying about the intangible books of your dreams. You might be running a company and have ideas about what wonderful products the compnay will make. But, until you actually design something, put it out there, get feedback and iterate and repeat the process, you will never have tht best product. So, the advice is just start where you are.
3. Mastery comes from the mistakes we make: This is a subtle truth but very true nonetheless. The multitude of mistakes you make reinforces in your subconscious how not to fail. As you keep chipping off the rough edges of your masterpiece through the experience of your mistakes, you are gradually arriving at the best possible masterpiece you can create. A story is told of a professor in a photography lecture, who divided the class into two groups. The first group were to submit to him, periodically (say weekly), images they have taken without care of the conditions being perfect. The second were to submit only one work, the one that they have produced under perfect conditions. At the end of the year, the former class who have mutliple opportunities to take photographs were the best performing group as they had opportunities to iterate on their craft and learn from their mistakes. This is why I believe you should just start where you are.
4. My personal experience, for whatever it is worth: I remember when I started writing my FEM textbook, I did not have any experience of writing and actually did not know what I was doing. I had a vision and that was: write a book that will be useful to students, teaching FEM in the way I will like to be taught. I made mistakes but today, 50,000 downloads of the book have been made and people continue to recommend it to many. If I was waiting until I have had 10 lessons on writing a best-selling post-graduate textbook, I guess I will never be here. Today, the CM Videos YouTube channel has seen over 200,000 views and posts 3870 subscribers. When I started, I had a 720p web-came, a computer with OBS which I used to record my initial videos. They were crappy, and audio was not great. My editting was atrocious but I stuck at it. My vision was to help even just one student out there struggling with computational modelling and the rest they say is history. I believe the future of the channel is great and it is possible that conditions are not perfect even today for the channel to keep doing well, but I will persist because I must just start where I am.

The above is my quote for the week, and I hope you have found my reflections helpful. Please let me know in a reply if you agree with the quote and what is it that you are putting off starting because you are waiting for the perfect conditions.

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That is it for this week's newsletter. I hope you have found most of it beneficial. I wish you a very wonderful weekend and i will catch up with you sometime next week. God bless you and ciao!