Classic question about the use of a Cantilever beam for designing vehicle structures

Good afternoon everyone! I know it’s been a while since the last post but I’ve been (and still am) very busy with all kind of simulations, tests and writing papers and my doctoral thesis. Hopefully, I’ll manage to write some more articles during the summer! I recently had a conversation with some senior engineers from a F1 team regarding Cantilever beams and some erroneous assumptions which are commonly made, so I wanted to discuss it with you! Hope you enjoy this brief post!

A few weeks ago, I had the chance to speak with three top F1 designers and we had a chat about a certain question regarding the use of the Cantilever beam as a tool to design some vehicle structural components. First of all, let’s remind what this type of configuration is. A Cantilever beam is a structure which is fully constrained at one end, having a vertical load applied at the other end of the beam to study the effect of bending, as illustrated in Fig. 1.

Figure 1. Schematic of a Cantilever beam

This type of structure is very useful when designing certain components, since they can be simplified to this well-known beam, reducing the number of variables and being able to define simpler design targets. The thing is that usually, in reality, the components usually have some part of its length reinforced (e.g. thicker walls), so two questions arise: why is this non-homogeneous beam common and where should that reinforcement be placed?We agreed that a lot of people answer very quickly that it should be placed at the free end of the beam, i.e. where the load is applied. According to these people, the reason for this is pretty obvious, since that end will suffer the greatest deflection (I will write another post soon where I derive this and discuss some ways to calculate it by hand!). Hence, if that region was reinforced, the deflection would be smaller and the structure would be better in terms of bending performance. But, is this true? Let’s have a thought.

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About Tsai-Wu failure criterion

Predicting material failure is always a challenge, especially when it comes to composites and advanced materials. There are plenty of theories that try to provide a numerical approach to solve this complex problem, such as Maximum Stress/Strain Theories,  Hashin, Tsai-Hill or Tsai-Wu. Although all of them brought something valuable to the table, some of them don’t seem to be that precise when accurate results are needed. In these terms, Tsai-Wu is my least favourite criterion and I’ll explain the reasons for that.

First of all, Tsai-Wu is an interactive failure criterion for composite materials. This means that the theory takes into account the interaction of different stress components in order to predict failure. Basically, the criterion uses equation 1 (subjected to the condition given by equation 2) to calculate an index and, if its value is one, then it means the material is failing. Please note that i,j=1,2,…,6, where subindices 1 to 3 represent normal stress components and 4 to 6 are shear stress components. In the original publication, authors explain how the different coefficient can be determined through experimental tests (e.g. compression, tension, biaxial…). So far, so good.

Equation 1
Equation 2

Speed Read F1

Every year, with the start of the Formula 1 season, a lot of people ask about the rules, concepts, technology and history of the sport. For that reason, Stuart Codling recently wrote a new book called “Speed Read F1”, which tries to cover the keys to understand the basics of Formula 1. If you want to find out more about this book, keep reading this review!

Believe it or not, I first heard about this book on Twitter, where a considerable amount of motorsport journalists shared their excitement about the release of this book. I was curious so I decided to check who the author of this book was and I was shocked when I found out that it was written by Stuart Codling, who is a well known automotive and motorsport expert (you can find his articles in prestigious magazines such as “F1 Racing”). After that, there was no doubt I needed to get my hands on this book!

Let me start the review with the structure of the publication. The book is divided in seven sections based on different aspects of the sport: Technology; Drivers; Rivalries; Racing Circuits; Flag to Finish; Staying Alive; Taking Care of the Business. From my point of view, this division is very clever and helpful for new fans and people who just want to learn the basics of something in particular. Although the book is 159 pages long, it is written in a way that encourages the reader to finish it as quick as a Lewis Hamilton’s fast lap. In addition, another thing that I particularly enjoyed is that every subsection counts with three brief paragraphs on the left margin where the reader can find interesting information about something funny, history and a person of interest (always related to the main topic of the subsection).

Now, with regards to the content itself, I must admit that I got hooked from the beginning, which covers all the main technical aspects of the sport… but that may be because of my engineering background and my previous knowledge of F1. Besides, the chapter about rivalries provides amazing facts about old drivers that I never got the chance to see on the track, so I am sure almost everyone will learn at least one new thing while reading this section. Furthermore, another detail that I would like to highlight is that after each chapter, the author includes a glossary. This glossary is a very useful F1 dictionary that new fans will definitely take advantage of, mainly because it explains specific topics in a very simple way. Now you will be able to understand every word you hear during a Grand Prix on TV!

That being said, I must warn you that sometimes there is a bit too much of information in a very reduced amount of words. If you are not used to scientific papers or technical books you may struggle and will probably need to read certain paragraphs a few times. Also, as a non-native English speaker, I found it curious that in the book some words are written in British English whereas others are written in American English, such as “carbon fiber” (American) instead of “carbon fibre” (British). This is nothing bad, don’t get me wrong, but it made me pay more attention whenever I read something like that, especially about materials… And I found something that is not an accurate fact about composite materials. The author, in order to provide some background, gives a definition of carbon fibre that only applies to certain types of composites… I know this is a silly comment, but I am very picky when it comes to materials science!

Overall, I think it is a nice book to read if you are new to the sport or just a casual fan. However, I wouldn’t recommend it to people who have followed Formula 1 for a long time. From my point of view, this book should target an audience which is willing to get involved in this motorsport world. So, if you are one of these new fans, I definitely encourage you to get a copy of the book. After reading it (and it is very easy to read!), “rookies” will be able to speak about most things F1 related with people who have been enjoying the sport for ages. You won’t need to be asking all sort of basic questions anymore!

Coding subroutines in Abaqus

If you are an advanced Abaqus user, I am sure you have heard a word which some people try to avoid at all costs: subroutines. Today, I write about them as well as about my recent experience coding one for my research.

First of all, lets start with the main question: what is a subroutine? It is a script that, when run in parallel with the Finite Element (FE) model, allows users to request features which are not defined by default in the commercial software Abaqus. This FE package recognises a lot of different types of subroutines for both implicit and explicit simulations, depending on the information that we want to include, recalculate, modify, request… In other words, subroutines are useful when we want something that is not already available within the software and we need it in order to produce acceptable results.

Consider, for instance, that we were trying to simulate the response of a certain material, but the material model which was available in Abaqus did not quite reproduce the correct behaviour. What could we do then? The first option would be to contact Dassault Systemes to ask if they had any kind of expansion (with its corresponding extra cost, not too many things are given for free these days I’m afraid); sometimes, since a lot of users request the same thing, it is the company itself the one that creates the official subroutine. This option would save time and effort, but it would also affect our wallet. The second option would be to create a new material model from scratch. How could we do that? Well, we would need to code a UMAT (implicit) or a VUMAT (explicit) subroutine. In order to do so, we would need to learn how to code in Fortran, which is the only language supported by Abaqus (I know, this is a bit of a pain since Fortran is basically obsolete, but hey! It’s always good to learn something new!). We would also need to install two compilers and link them to the FE package, which once again is not straight forward (don’t worry, I’ll try to write another post to explain this). Some people might say that giving up would be the third option, but to me that attitude would be unacceptable, so don’t you dare! Continue reading

Spanish university to collaborate with the development of intelligent materials

The University of Alicante (Spain) is taking part in a project that will develop intelligent materials for aerospace, automotive and transportation industries. The main aim will be to improve the safety of occupants and the durability of the components.

Researchers from the Department of Civil Engineering from the University of Alicante and the tech company Applynano Solutions are carrying out this project known as MASTRO, which stands for Intelligent Bulk Materials for Smart Transport Industries. The project is part of the Horizon 2020 programme, which is the biggest investment system for R&D in Europe.

Their goal is to develop intelligent materials for the transportation sector. In particular, the aerospace and automotive industries will be the main targets. Amongst other innovations,  these materials will be able to monitor their own deformations and they will also be capable of heating and defrosting their surfaces. Besides, thanks to their capability to repair and protect themselves from damage, they will improve their efficiency, their durability and users’ safety. At the same time, manufacturing and maintenance costs will be reduced, as well as emissions.

In order to develop these materials, different matrices will be used, including polymers, concrete and carbon nanomaterials. Their functions will be based on three processes: the variation of electric resistivity when a material is subjected to a mechanical load, the relation between the heat that is generated and the electric flux, and electrostatic discharge.

One the one hand, the Spanish university will work on the development of the function related to perception of strain and damage on structures made of reinforced concrete. In addition, the previously mentioned institution will also focus on the heating of surfaces made of asphalt and concrete in order to avoid the formation of ice.

On the other hand, Applynano Solutions will work on the development of the carbon nanomaterials, the manufacturing of composites and the production of prototypes.

These are exciting news for the European research community, since not only Spain but also institutions from United Kingdom, Portugal, Italy, France, Germany and Sweden will collaborate with the MASTRO project. Hopefully, we’ll see encouraging results in the near future! I’ll keep you updated!

How to receive automatic notifications when your FE simulations are done

If you are a regular Abaqus user, I am sure that eventually you will need to run models for long periods of time. It can be quite annoying to go back to the office just to check if the simulation has finished to then find out that it is still running. For that reason, I’ve coded a simple python script that sends an automatic e-mail to the user once the simulation is completed or aborts due to errors.

While you run FE models that take a huge amount of computational time to finish, it is likely that you will be working on other things, such as experimental tests, reports, meetings and so on. Obviously, we want to check our results as soon as they are ready, but in order to do so we need to be checking our computer every now and then. This can be particularly annoying when you leave a simulation running for a few days and you are doing things out of the office. Hence you need to go and check if the model is done… and then you realise it’s still there, calculating more stresses and strains and that your trip to the office was a waste of time. To overcome this problem, I decided to create a python script to send a notification directly to my e-mail every time my analyses finish. I will try to explain you the basics so you can use this code on your computer. Continue reading

The Secret Science of Superheroes

Do you like science? Are you a comic geek? If your answer to both questions is “yes”, then “The Secret Science of Superheroes” is your book!

Last August I got myself an autographed copy of “The Secret Sicence of Superheroes”, thanks to Dr David Jesson and Dr Mark Whiting (University of Surrey) and I must say I don’t regret it at all! The book is distributed by the Royal Society of Chemistry and it was edited by Mark Lorch and Andy Miah. When I first heard about this book, Dr David Jesson told me that the whole thing was completed in just one weekend during an event in Manchester and that each chapter was written by a different author and it related a specific superheroe topic with the author’s field of expertise. Interesting, right?

I would review every single chapter, I really would, but… then you wouldn’t read the book! So, I’m just going to talk very briefly about the things I enjoyed the most. Basically, the text is written for a general audience, introducing the scientific concepts as the authors try to make their point. Continue reading

What is the aim of the front wing in a F1 car?

Have you ever wondered why Formula 1 cars have those extremely complex front wings? Some people may think that these structures are only there for producing downforce, but in reality their function goes beyond that. Do you want to find out more? Well, here’s your chance!

A few years ago I had the opportunity to meet Craig Scarborough during one of his pesentations about Formula 1 at Cranfield University (United Kingdom). For those who are not familiar with that name, Mr Scarborough is a well known expert in motorsport and, just so you know, he’s quite a celebrity on social media (Twitter, LinkedIn…), where he usually shares top quality information about racing and the engineering behind it.

Yesterday, I contacted him after watching his latest video for in which he discusses the function of a front wing with Willem Toet, one of the best aerdynamicist in the world. They use a 3D airflow animation in order to illustrate how the wing of the McLaren MCL-32 works. After asking for his approval, Mr Scarborough was kind enough to give me permission to share the video with the audience of Engineering Breakdown, so here it is! I hope you enjoy it!

(Please note that in order to watch the videos, you need to reproduce them on Youtube, following the instructions).

Introduction to Impact Dynamics: the ideal collision when playing pool

While I was playing pool the other day, I remembered a lesson that I learned during my time at the University of Seville as well as at Cranfield University. It is related to the quite complicated subject of Impact Dynamics… But don’t be afraid, today I’ll just cover a simple case as an introduction. In particular, I’m going to write about how the ideal collision between the white ball and the other ball that we are aiming to move.

First of all, we need to differentiate between different types of collisions, depending on the loss of translational kinetic energy or, in other words, the conversion of kinetic energy to rotations, vibrations or heat. For this case, let’s consider two bodies: one in motion (impactor) and another in stationary conditions. Hence, we can distinguish between the following categories:

  • Elastic collision: all the energy is transmitted from one body to another, i.e. the impactor stops and the stationary mass starts moving at the same speed as the initial one from the moving mass.
  • Completely inelastic collision: the moving mass stops after hitting the stationary body. The stationary mass remains as it was.
  • Inelastic collision: the impactor suffers a decrease in speed after the collision, whereas the stationary mass starts moving at a certain speed.
  • Superelastic collision: if additional energy is provided to the stationary body during the impact, then it will start moving at a higher speed than the one at which the impactor hit it.

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Formula 1 interview: Dr Nicholas Brown

Let me introduce you to Dr Nicholas Brown, one of the Composite Design Engineers at McLaren Racing and former EngD at the University of Surrey. It was a real pleasure having a conversation with him at the McLaren Technology Centre (MTC) in Woking, UK. We covered different topics about what is like to work at the top level of automotive engineering, including some tips for getting where he is now! Enjoy it!

First of all, I’d like to say how grateful I am to have you here, since I know you are extremely busy at the moment. Thank you for your time and your kindness. And now, let’s get started. Can you tell us a bit about your background?

So I did my masters first in engineering at Loughborough University; that was Aeronautical Engineering. I spent five years up there and did a placement year as well. So my placement year was with an aerospace electronic sort of warfare defense company, but I was doing more of the support work reliability team and things like that, writing general reports… Didn’t really do anything fancy, so I came out of there not wanting to do that and not really wanting to go on a graduate scheme. Then I had a year just between jobs and then the EngD came up, so I chose to do the EngD that as you know is a great opportunity. And then towards the end of it I was looking for more job roles and one came up at McLaren Racing as a Design Engineer, which implied using my composites knowledge for a more applied role. There are research aspects as well, but it’s mainly applying my knowledge. That was about a year and a half ago and now I’m still here! It’s quite fun! It’s good to apply all the things you know. As I said we do research up there but it is completely different to the research I did as an EngD.

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