Dear Reader,

Good day!

Welcome to this week's newsletter. I am going to reflect on the following:

1. Technical Reflection: How RVE Size affects the response of Particulate Composites
2. Behind the Scenes at CM Videos: I got a new microphone
3. Quote of the Week: Excellence in Life: What it takes!

Let us get into the reflections.

Technical Reflections

How RVE Size affects the response of Particulate Composites

When you work in the area of micromechanical study of material systems, one of the key questions you would always have to grapple with is:

The necessity of micromechanical studies

It is the pursuit of an answer to the above question that drives the reflection today. In particular, the focus is on particulate composite systems. These composite types will often consist of randomly distributed particles within a matrix medium. The common examples will be say a cubic volumetric representation of say Aluminium matrix housing spherical-shaped particles of Silica randomly distributed within the aluminium bulk. Such a domain becomes an AlSiC metallic particulate systems. Other examples can include a ceramic particulate system where the matrix is ceramics. There is yet another example of polymeric particulate with typically an epoxy resin as the matrix.

The objective of the micromechanical study is to use a representative volume element of the test composite to study a wide range of material behaviour for such a composite. This will be beneficial on computational time and also lead to excellent exploration of the different aspects of the mechanics, thermodynamics and even electromagnetic response of such a particulate system.

The Case for RVE size

So, the case has to be made for investigate the effect of RVE size on the expected material response. Without such studies, your RVE choice will certainly give you a result but how viable is that choice on the expected effective properties? Therefore, every objective micromechanical study MUST explore the effect of RVE size on the constitutive behaviour of the test material.

I did a similar investigation in a recent video on my YouTube channel where I investigated the effect of RVE size on an AlSiC particulate composite. Below is the video for your reference if you have not already seen it. The conclusions drawn below are discussed in the video below with suggestions on further work that can be done.

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Key findings on RVE size effects on particulate composite

1. Size of RVE does affect the mechanical properties of a particulate system and these can include elastic, strength and post-yield properties.
2. In particular, increasing RVE size seem to favour better convergence between predicted properties and real/analytically-derived properties of the composite. This is not surprising because the bigger the RVE, the more you are getting closer to the bulk properties. However, using a very big RVE is expensive on computational resources hence the need to isolate the right RVE that is small enough but gives you the most accurate predicted properties.
3. The greatest differences on predicted properties tend to be more in the yield and post-yield behaviour since with finite deformation, the size, positions and interactions of particulates within a defined bulk become significant.
4. To get improved elastic properties (Young's Modulus) a somewhat bigger RVE is needed.
5. For the study shown in the video above, we assumed a strong connection between the particulates and matrix without any interface component. This is potentially going to give a wrong result because properties of particulate systems are known to be affected when the interface region exists and the treatment of the surfaces of the particulates can lead to better bonding with matrix and hence improved properties.

Please let me know if you have any comments or thoughts on the above.

Behind the Scenes at CM Videos

New Microphone: Nicama Lavalier Microphone

I have been using the Rode USB mic for a while in recording my videos and they are quite good. Getting audio right when recording YouTube videos is much more important, in my experience, than the videos. So, right at the start of my YouTube journey, I invested in a Rode USB mic and it has served me quite well.

Recently, I noticed that the audio quality is going down. I am not really sure why. It could be a deterioration over time of the USB mic. It could be maybe the computer or as I have been experimenting recently, the position where the mic is when I am filming. I usually position it above my head (outside the field of view of the camera) but that mearnt I had a booming and echo-ey sound. In my last video, I brought it closer to my mouth, and within the view of the camera. I do not particularly like this but I had to as part of testing the system. It did not seem to make much difference.

As a last resort, I have seen people even on TV programmes using this clip-on lavalier mics, shown here. I invested in a really cheap one called Nicama Lavelier Microphone. I have used it to record my next video due to be published soon. I am not still happy with the quality of the output that I got. I will continue to iterate until I am able to get a good quality audio.

In my initial videos where I did not show my face, I used to wear a headset microphone which gave really good audio but would not want to go this direction. I might ultimately have to invest in a more expensive microphone like the Shure microphones or one that I recently saw called the DJI wireless microphones. Please watch this space and do let me know what I should do if you have any experience in this area.

Quote for the Week

Excellence in Life: What it takes!

My quote for the week is not a popular quote from anyone but something I used to tell myself a lot whilst I was a student studying for my Mechanical Engineering degree in Nigeria. Here is the quote (more like a philosophy for me):

One of the definitions of the word "philosophy" is "a particular system of beliefs, values, and principles" [Cambridge Dictionary]. So, the quote above is a driving belief system for me. It defines the values that shape how I relate with excellence and doing effective work. It is a pillar principle in my approach to work.

As a student, I worked with that philosophy a lot and there were real difficulties studying in Nigeria in her higher education sector. There, we did not have much access to laboratories to test out ideas. Our assessment was hugely tilted towards theory and the assessments were quite challenging. The quality of our professors was high but there seemed to be a propensity for assessments to be quite difficult. It was during this period that I started developing this value system that to excel in life, and especially in that engineering programme, was not simply due to the intellectual capacity (in fact there were many students who were extremely clever). I realized your capacity to adapt to the stressful situations we faced always as students had much to do with doing well.

In the end, I was able to make a first class grade and I think a lot of that was not simply because I worked harder than others but I believe my capacity to accept the stresses, creatively navigate them and then still do my best work was what got me there. I know above all these, God helped me marvellously.

So, you might be facing a lot of stresses in your academics or maybe career stage. I want you to accept that those are the challenges you have to overcome. Do not allow yourself to be overwhelmed. If you need to take a break, please do but do not accept giving up as an option. Coping in the face of challenges is what sets leaders and champions apart from those who one could describe as "also-ran". I wish you the best in your career.