How to mesh effectively and efficiently in ABAQUS
Dear Reader,
Welcome: I hope you are doing well. I welcome you to this week's newsletter. Please do let me know if there is anything you'd like my help in. Thank you very much for reading these Michael Okereke's perspectives every week.
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Content: Here are the content of the newsletter this week:
- Effective and Efficient Meshing in ABAQUS
- The impact of fibres-on-edge of an RVE
- Behind the Scenes in CM Videos: Recent milestones
- Quote of the week: Cal Newport and Deep Work
Effective and Efficient Meshing in ABAQUS
I was thinking this week about meshing strategies available in ABAQUS. Mesh play a crucial role in the sort of results you generate from a simulation. Whilst most students understand the need to use the right mesh density for a simulation, often there is scant attention given to the optimal meshing technique that is used for a given simulation.
In this, I wanted to demonstrate this by exploring the stress concentration map resulting from an inplane shear testing simulation on a cruciform-shaped hole on a rectangular plate. The cruciform has multiple regions of stress concentrations and the intensity of the stress concentration will help determine what is the best mesh technique for a given simulation.
Three types of meshing techniques were used here and these are discussed below.
- Global Meshing: This sort of meshing involves using the global seeding approach available in ABAQUS where a uniform seed size is implemented on the domain. It is the default meshing type in ABAQUS with the smallest seed size often 10% of the longest edge of the domain. The result is shown in Figure A above. Key finding is that the stress concentration spreads over a wider region covering from the cruciform to the extremities of the plate. It predicts the largest stress-concentration map.
- Localized Meshing: This type of mesh requires that the user identifies specific regions in the model and mesh them intensively. This can be isolating regions where one expects a concentration of stress (usually corners, edges, notches, grooves) and finely meshing them. In Figure B above, it shows the stress concentration map shrinking to the regions where true stress intensity exist. It is an improvement on A. There is however still widespread regions of higher stress threshold across the plate.
- Adaptive Meshing: This is the third meshing technique that involves adaptive meshing. This feature is incorporated in ABAQUS and the user needs to specify a remeshing rule that informs which part of the structure is adaptively meshed in order to reduce the meshing error in such regions. It is the most optimal way of remeshing a model to capture true stress concentration maps in the model. Figure C above shows the contour plot with much localized stress concentration in the groves. This the truest representation of stress in the plate and should lead to better predictions.
Beyond the contour plots, some quantitative data such a stress-strain plots, numerically-determined stress concentration factors or even energy absorption need to determined to provide quantitative insight into the impact of any of these meshing techniques.
I will be making a video on the above over the next weeks so please watch out for that and do let me know your thoughts about the above, so I can incorportate those in the said forthcoming video.
The impact of Fibres-on-edge of an RVE
I published a video on the CM Videos YouTube channel this week where I considered the effect of having fibres on the edge or not of an RVE of a UD Composite. This is not something people often worry about but I was thinking about this and tried to justify to myself the importance of such knowledge to help design correct RVEs for FEA studies.
In designing the study, I used a case study of Steven, a first year PhD student who wanted to know if fibres on edge or not of an RVE do have effect on elastic properties, yield strength, damage evolution and energy absorption. In the end, the video concluded that fibres on the edge of an RVE (a feature described as periodicity of material) is critical in correctly predicting effective properties of a UD composite. This observation is true not only for a 120x120 micron-squared RVE but also for an even smaller RVE of size 45x45 micron-squared.
Below is the video for your review, in case you are yet to watch the video.
Behind the Scenes in CM Videos: Recent Milestones
On 18th September, 2022, I achieved two more important milestones in my YouTube Channel. I had reflected on achieving 100k views and 4000 watch hours in the past.
This week, I not only achieved125k total channel views but also achieved 8000 watch hours. It took me over a year to achieve 4000 hours so to double day in about 7-8 months is really satisfying.
I am particularly excited about the 8000 total watch hours for only 125k views. This suggests that anyone who watches my content is spending significantly a long time engaging with the content.
The area of computational modelling, where my niche is based, is not renowned for crazy viral views. I am therefore optimizing for longer watch times and extensive user engagement as those show me that my audience do like the content and want to keep watching for long. So, once again, I say thank you to everyone who continues to support the channel. It means a lot to me.
Quote of the Week: Cal Newport and Deep Work
I started reading this book titled Deep Work by Cal Newport. It is in deed an excellent book written by a Professor in Georgetown university, American. Cal has a background in computer science as well. As an academic who loves the Science, Technology and Engineering (STEM) subjects, I am drawn to Cal as he represents most of what I am.
The quote speaks to the concept of deep work, which refers to the intense work you do, without allowing for the ubiquitous distractions we see daily as we work.
If you are feeling distracted from doing your best possible work, it is time to read this book and see if you can learn how to work in a focussed way.
I am applying the same principles, especially with the start of a new academic year, I have a lot to focus on. I am writing my PBC book, developing codes for new software that I will be launching soon, and finally work on my research and teaching. These require deep and concerted attention, so implementing deep work is critical for me to be successful. This is why the above becomes my important quote for the week.
That is it for another week. I wish you a wonderful weekend. Mae sin laet (Bye bye in Scottish Gaelet)
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