# Tag Archives: Structure

## Dynamic Arches…

Tinkering about with SystemModeler a little further, I’ve managed to finally build a sprung arch, complete with dampers on the revolute joints.  I’m intending on using this principle in my research to create folded structures, so it’s interesting to see what effect the spring stiffness will have on the behaviour of the arch during the unpacking process – specifically looking at the accelerations on the masses at key points.

The thing that I was struggling with was creating a structure that had a set of equations that could be solved, the key concept I was initially missing was the closing of the structure with the special type of revolute joint to complete the chain.  Without this special revolute chain the equations are essentially unsolvable, so it’s important that one of these joints sits in the system somewhere.

Another concept is that the structure in the video has 3 straight segments, each 1m long; but the supports are only 2m apart…. forcing the arch to pop into a stable shape that balances the weights at each of the joints.  This is essentially what makes the arch wobble when solving the initial set of equations.  Next step is applying external forces and measurement points along the structure for displacement etc…

General

## Self improvement…

I’ve decided to take a few minutes to sit back and reflect on the past year, with the intention of creating a plan to make this coming year slightly more pleasurable and not as stressful.  To do this I’ve been reading up and running through a few blogs of other souls that are far more organised and driven than myself.  One blog article that I found particularly useful resides on the Personal Excellence website and in particular this article which I have taken the six questions from that I’ve used in the article below.  This is highly self indulgent as a read, but it’s intended more for my own benefit to try and construct my thoughts clearly about the year ahead.

## 1 What are your biggest accomplishments this year?

Last year I managed to pass my PGCAP course with an excellent grade and this entitled me to join the FHEA. I really enjoyed learning again, particularly in a creative manner which is something that I’ve never experienced before.

I began learning Mathematica and wrote a useful set of scripts looking at the behaviour of cable-chain arches towards my PhD. This has opened up a new found respect for maths and made me appreciate just how undervalued I’d allowed it to become in my life.

For the IStructE I co-ordinated what I feel is a varied and interesting programme of technical lectures for the regional branch and contributed to the new IStructE structural behaviour exam.

Through the course of the year we’d made massive progress on constructing our new house for our family to live in. I’m really looking forward to the building work to be completed, in part because I think it will open an exciting chapter in our family’s life and also because I’m hoping that the associated stress of building it will end.

This year I’ve managed to draft several journal articles for submission and created a video lecture for inclusion within a maths MOOC. This is an entirely new experience for me, I’m used to writing large design reports and can do this standing on my head, but structuring my thoughts and ideas in an academic writing style is a new challenge.

We finally seem to have found a medicine that is working for my son’s illness, whilst this comes with several risks including liver damage, the reduction of recurring MRSA infections that we’ve had the past 3 months cannot be underestimated or over valued.

## 2 What are the biggest lessons you’ve learned this year?

I’ve learned that I can be inspiring and terrifying in equal measure when I get a bee in my bonnet about something, I need to channel this passion more often, it’s infectious.

Adjusting to life as an academic is proving to be an ongoing challenge and one that I need to develop a strategy for if I’m to be half as productive as I know I can be. I’m still not convinced that I’m the sort of animal that responds well to the bureaucracy that life in the public sector seems to breed and I think this will be the year that determines how long I decide to stay in academia.

I am very unhealthy in what I eat and how I behave, combined with the stressful year I’ve had, this is having a very negative effect on my health and general demeanour.

I’ve lacked focus at times, this is probably because I take on too many responsibilities and don’t structure my time as smartly as I could.

I need to relax and make time to do more fun activities or I’m going to have a very short life.  I think I need to take a leaf out of my dog’s book, he’s a clever border collie, but only exerts just enough brain power to be devious… the rest of the time is spent plotting how to over throw the evil human dictators that limit how much time he can spend playing with his ball.

My wife appears to have endless patience, I wish I could be half the person she is… I’ve no idea how she keeps her cool at times.  She is a Jedi and I’m more of a Wookie… and I’m not used to losing at chess, you’re supposed to let the Wookie win.

When I’m tired and worn out, I’m a miserable, evil bastard.  I would quite happily pull someone’s arm out of the socket and beat them to death with the wet end at times.  It’s a good job I have a modicum of self-restraint, but I could learn to be more patient and not allow myself to get so fatigued which will help keep the inner Wookie in check.

I’ve learned that life is short and nobody looks back on their life and thinks “I’m really pleased I spent all of those late nights writing those reports and slowly killing myself for an extra £2k a year”. I’ve had a great career as a structural engineer and contributed to changing the skylines of several cities around the world, but I’ve also had a few colleagues die young and suddenly this year and it’s given me a change in perspective relating to work and what constitutes a rich and fulfilling life.

That said I’ve learned that I don’t have anywhere near as much disposable income as I had when I had a proper job and unfortunately my brain likes to buy things when it’s stressed out.

## 3 With a grade, how satisfied are you with how you spent the year? Why?

I’d give this year a B, it’s been a good year in many respects, I’ve been very busy and accomplished lots of things, but it has been at the personal cost of my health and happiness leaving me absolutely exhausted by the end of the year.

## 4 What do you want to accomplish next year, such that it’s your best year ever?

I really want to make significant progress on my PhD and develop a well-rounded approach to structural analysis that I can script into Mathematica which I think could be very useful for my students.

Further develop my ideas and thoughts on teaching into a series of lectures and trial them ‘in the wild’. When I’ve discussed my approach and demonstrated the prototypes to other academics and publishers the feedback has been overwhelmingly positive.

I really want to take time and make our new house into a home, as silly as it sounds I want to do a few little projects with the kids now we have a decent sized garden and a greenhouse. Even if this is something simple such as growing some tomatoes and cucumbers or using the produce to do more baking and cooking with them.

I would like to find an activity that we can do together as a family and do this regularly.

I need to improve my physical and mental well being over the course of this next year and I need to either improve my income back to the levels that I was used to or learn to rein in my spending over the coming year.

## 5 What new habits to cultivate that will help you to achieve your goals in Q4?

I need to be more structured about how I spend my time and energy. By being more structured I’m hopeful that I should be able to work less but remain as, if not more, productive. I also need to include times where I can just muck about and chill too if I’m to be anything close to approaching a human being again.

One piece of advice that I’ve come across is to walk… I love how on the 3MonthThesis site the first piece of advice given was every time that he felt he was becoming stressed or faced a problem he would put on his coat and walk. Previously he would fluff about on the internet, checking mails, twitter, etc… and this is what I find myself doing too, so this year I’m going to take his advice and just go for a walk every time I feel that I’ve gone off the rails a little bit.  I also think an activity such as Muay Thai that I used to love will help an awful lot, there’s a lot to be said for pummelling a punching bag within an inch of its life, much better to do it this way than growling and snarling every time someone asks you a stupid question.

Part of being structured this year will be finding a good place to work and write. I have a sneaky suspicion that this will be the key to me being productive over the coming year or two on my PhD and it’s become very apparent that my office at work isn’t the best place for this to happen as I am frequently interrupted.  That said I lacked quality mentoring when I first moved to Manchester and I think the students appreciate having a ‘proper’ engineer that’s actually designed quality buildings being their lecturer, I wouldn’t want to lose the connection with the students as I genuinely enjoy watching them have their Aha! moment, it’s all going to be about striking a balance.

To identify and deliver various activities to do as a family, this could be baking, growing stuff, walking, or any of a multitude of things that we all enjoy, but currently they happen a little too infrequently for my liking.  I think a good way to achieve this could be to let the kids pick an activity that we do together and no matter how silly it turns out to be, then that’s what we do for an afternoon.

## 6 What are your immediate next steps to achieve these goals?

I need to create a schedule that can help me structure my time more effectively, this needs to happen at two or three levels: daily, weekly, and monthly initially so as to build a plan. I need to stick to this program quite strictly at first and then continue to improve and refine it until it becomes habit.

I need to go and buy some packets of seeds ready to start planting with the kids ready for our new greenhouse.

I need to put my walking boots on more often…

## Cable-Chains…

Part of the work that I’ve been undertaking on Mathematica is to create a series of sheets that will calculate the geometry of a cable-chain arch with a set of given parameters.  In part I’m interested in how the cable-chain arch can behave as a deployable structure and looking to build on the work of (Li, Vu, & Richard, 2011) to see how practical a cable-chain structure can be made with regards economy, efficiency, and robustness.  Essentially a cable-chain structure is a curved arch that is sub-divided into straight sections, with cables spanning across the base of two struts as can be seen in the figure below.  Simple versions of these types of structures are widely used for the likes of temporary and deployable aircraft hangers to create large open spans.

Now that I’ve got the makings of a simple Mathematica sheet up and running and I’ve taught myself some rudimentary programming and graphics manipulation skills I’ve managed to start to knock together what I feel are some high quality illustrations for my thesis.

I’ve done this with a mixture of Mathematica to create the base diagram, which I save as a PDF.  I then import the PDF into OmniGraffle to annotate the diagram and then export to a PNG file to maintain the transparent background, this figure I can then host for linking into blogs etc.  Below is a sample figure which shows how the number of segments (nSeg) affects the internal area available for habitation within a typical parabolic arch.

Given that both of my brothers are colour blind and I’ve never done the test, I’m not convinced on my choice of colour schemes, but the good news is that it won’t take long to change if it turns out I’ve made my figures look like something off the set of Austin Powers.

So far I’m finding OmniGraffle quite limited compared to Visio that I’ve been using for my diagrams for perhaps 20 years or so.  I decided to use OmniGraffle though as most of my writing work is done on a Mac, although I also have a PC so I can always create the more complex diagrams on Visio if need be, especially as I’ve managed to get a legitimate copy from work for £12.

I’d love to hear how other engineers and academics approach creating technical figures and sketches on their Macs though, I’ve a feeling that I’m really missing out on something and there’s got to be a much slicker workflow out there.

References:

Li, Y., Vu, K. K., & Richard, J. Y. (2011). Deployable Cable-Chain Structures: Morphology, Structural Response And Robustness Study. Journal for the International Association for Shell and Spatial Structures, 52(168), 83-96.

General

## Keeping it real…

One of my colleagues has discovered an absolute gem of a piece of software called Physion that lets you mess about with various bits of structure, motors, gears, and other things all in a real time physics environment.  Now the tutorial videos themselves are pretty impressive, but with a little bit of JavaScript some of the things the Physion community has been creating are absolute works of genius.

This simple piece of software has been an endless source of entertainment for the past couple of weeks for the structural engineering lectuers and they’ve been busy creating models of shaker tables, backfilled arches with granular fill, disproportionate collapse simulations, and all sorts of other random stuff that simply looks cool when brought to life with real time physics.

I’ve to deliver a technical lecture in a few weeks for the Institution of Structural Engineers, but one of the things that I was struggling with was describing how some deployable structures and other lightweight structures can be susceptible to the effects of disproportionate collapse when the removal of a critical member occurs. I knew I wanted to do something along the lines of an animation to show this, but wasn’t sure what was the best way to go about it… until I discovered Physion.

I know the animation above is not the most exciting in the world, but it shows what happens when a critical member, either the restraint cable at the end of the pantograph beam, or any internal element is removed from the structure. The removal of just a single element brings about the complete collapse of the structure, this effect is known as disproportionate collapse and is an important concept for structural engineers to understand.  All buildings in the UK are designed to resist this effect to increase the safety of buildings in the event of accidental damage occurring.

The circular elements introduced at the beginning of the video are just there to create some weight on the structure to show that it’s stable and can support a sensible amount of load when the structure is undamaged.  Then using the delete tool, I’ve tried to show a couple of different failure mechanisms, there’s no sound on the animation as I intend to talk about this during the technical lecture I’m delivering.  We’ve already done some work on creating structurally stable pantographic beams with our MSc students here at the University, complete with additional safety mechanisms to prevent the failures above happening and it’s a research topic that is ongoing in our team. The original motivation was to see if we could use it to create a deployable bridge, perhaps in scenarios that have happened recently in Cumbria when the bridges were swept away by flood water… and it’s a concept that’s expanding.

At times I find life as an academic frustrating compared to being in industry, then I remember that they pay me to play with things like this for a living and I feel lucky…