Tag Archives: engines

Everything is flux but it’s not always been recognised

Decorative photograph or ruins of Fountains Abbey next to River SkellI am teaching thermodynamics to first year undergraduate students at the moment and in most previous years this experience has stimulated me to blog about thermodynamics [for example: ‘Isolated systems in nature?’ on February 12th, 2020].  However, this year I am more than half-way through the module and this is the first post on the topic.  Perhaps that is an impact of teaching on-line via live broadcasts rather than the performance involved in lecturing to hundreds of students in a lecture theatre.  Last week I introduced the second law of thermodynamics and explained its origins in efforts to improve the efficiency of steam engines by 19th century engineers and physicists, including Rudolf Clausius (1822 – 1888), William Thomson (1827 – 1907) and Ludwig Boltzmann (1844 – 1906).  The second law of thermodynamics states that the entropy of the universe increases during all real processes, where entropy can be described as the degree of disorder. The traditional narrative is that thermodynamics was developed by the Victorians; however, I think that the ancient Greeks had a pretty good understanding of it without calling it thermodynamics.  Heraclitus (c. 535 BCE – c. 475 BCE) understood that everything is in flux and nothing is at rest so that the world is one colossal process.  This concept comes close to the modern interpretation of the second of law of thermodynamics in which the entropy in the universe is constantly increasing leading to continuous change.  Heraclitus just did not state the direction of flux.  Unfortunately, Plato (c. 429 BCE – c. 347 BCE) did not agree with Heraclitus, but thought that some divine intervention had imposed order on pre-existing chaos to create an ordered universe, which precludes a constant flux and probably set back Western thought for a couple of millennia.  However, it seems likely that in the 17th century, Newton (1643 – 1727) and Leibniz (1646 – 1716), when they independently invented calculus, had more than an inkling about everything being in flux.  In the 18th century, the pioneering geologist James Hutton (1726 – 1797), while examining the tilted layers of the cliff at Siccar Point in Berwickshire, realised that the Earth was not simply created but instead is in a state of constant flux.  His ideas were spurned at the time and he was accused of atheism.  Boltzmann also had to vigorously defend his ideas to such an extent that his mental health deteriorated and he committed suicide while on vacation with his wife and daughter.  Today, it is widely accepted that the second law of thermodynamics governs all natural and synthetic processes, and many people have heard of entropy [see ‘Entropy on the brain’ on November 29th, 2017] but far fewer understand it [see ‘Two cultures’ on March 5th, 2013].  It is perhaps still controversial to talk about the theoretical long-term consequence of the second law, which is cosmic heat death corresponding to an equilibrium state of maximum entropy and uniform temperature across the universe such that nothing happens and life cannot exist [see ‘Will it all be over soon?’ on November 2nd, 2016].  This concept caused problems to 19th century thinkers, particular James Clerk Maxwell (1831 – 1979), and even perhaps to Plato who theorised two worlds in his theory of forms, one unchanging and the other in constant change, maybe in an effort to dodge the potential implications of degeneration of the universe into chaos.

Image: decaying ruins of Fountains Abbey beside the River Skell.  Heraclitus is reported to have said ‘no man ever steps twice into the same river; for it’s not the same river and he’s not the same man’.

Thinking out of the box leads to digital image correlation through space

This is the third in a short series of posts on recent engineering research published by my research group.  Actually, two have already been published: ‘Salt increases nanoparticle diffusion‘ on April 22nd, 2020; and ‘Spatio-temporal damage maps for composite materials‘ on May 6th, 2020 and then I got distracted.  This third one arose from the same project as the time-damage maps which was sponsored by the United States Air Force.  The time-damage maps allow us to explore the evolution of failure in complex materials; however, we already know that damage tends to initiate from imperfections or flaws in the microstructure in the material.  New continuous fibre reinforced composite (CFRC) materials based on ceramics are very sensitive to defects or anomalies in their microstructure, such as misalignment of fibres.  However, they are capable of withstanding temperatures in excess of 1500 degrees Centigrade, which offers the opportunity to use them in jet engines or nuclear power plants to help generate energy more efficiently.  Therefore, it is worthwhile investigating effective methods of inspecting their microstructure which we can do either destructively by repetitively polishing away the surface of a sample and viewing it in a microscope, or non-destructively using x-ray tomography.  In both cases, the result is hundreds of ‘images’ containing millions of data values from which it is challenging to extract useful information.  In our work, we have used a little lateral thinking, to show how digital image correlation, usually used to track deformation of structures using multiple images collected over time [see ‘256 shades of grey‘ on January 22nd, 2014] , can be used to track fibres through the multiple images of the layers of the microstructure.  The result is the sort of ‘stick’ diagram in the image showing the orientation of fibres through the sample.  We have demonstrated that our new algorithm was more reliable and 30 times faster than its nearest rival.

The image shows, at the top, a typical stack of images from the microscope of a ceramic matrix composite; and, at the bottom, a plot of 3d profiles of the fibres tracked using the DIC-based method with the fibres orientated nominally at ±45° from the sectioning (x-y) plane shown in red and green colours.

Source:

Amjad K, Christian WJR, Dvurecenska K, Chapman MG, Uchic MD, Przybyla CP & Patterson EA, Computationally efficient method of tracking fibres in composite materials using digital image correlation, Composites Part A, 129:105683, 2020.

 

Aircraft inspection

A few months I took this series of photographs while waiting to board a trans-Atlantic flight home.  First, a small ladder was placed in front of the engine.  Then a technician arrived, climbed onto the ladder and spread a blanket on the cowling before kneeling on it and spinning the fan blades slowly.  He must have spotted something that concerned him because he climbed in, lay on the blanket and made a closer inspection.  Then he climbed down, rolled up the blanket and left.  A few minutes later he returned with a colleague, laid out the blanket and they both had a careful look inside the engine, after which they climbed down, rolled up the blanket put it back in a special bag and left.  Five or ten minutes later, they were back with a third colleague.  The blanket was laid out again, the engine inspected by two of them at once and a three-way discussion ensued.  The result was that our flight was postponed while the airline produced a new plane for us.

Throughout this process it appeared that the most sophisticated inspection equipment used was the human eye and a mobile phone.  I suspect that the earlier inspections were reported by phone to the supervisor who came to look for himself before making the decision.  One of the goals of our current research is to develop easy-to-use instrumentation that could be used to provide more information about the structural integrity of components in this type of situation.  In the INSTRUCTIVE project we are investigating the use of low-cost infra-red cameras to identify incipient damage in aerospace structures.  Our vision is that the sort of inspection described above could be performed using an infra-red camera that would provide detailed data about the condition of the structure.  This data would update a digital twin that, in turn, would provide a prognosis for the structure.  The motivation is to improve safety and reduce operating costs by accurate identification of critical damage.

 

Engineering is all about ingenuity

Painting from Okemos High School Art Collection at MSU

Painting from Okemos High School Art Collection at MSU

Who was the first engineer?  It’s a tricky question to answer.  Some sources cite Ailnolth, who lived in the second half of the twelfth century and worked on the Tower of London, as one of the first to be called an ‘ingeniator’.  The word comes from the Latin and the Roman writer, Vitruvius, describes master builders as being ingenious or possessing ‘ingenium’.  Leonardo da Vinci (1452 – 1519) was perhaps the first person to be appointed as an engineer.  The Duke of Milan appointed him ‘Ingenarius Ducalis’ or Master of Ingenious Devices.

So it would appear that an engineer is ‘a skilful contriver or originator of something’,  which is the third definition in the on-line Oxford Dictionary after ‘a person who designs, builds, or maintains engines, machines or structures’ and ‘a person who controls an engine especially on an aircraft or ship’.  This type of engine, which uses heat to do work, is a relatively recent invention probably by Thomas Savery and Thomas Newcomen in the early eighteenth century.  Engineers have been contriving, designing and inventing ‘works of public utility’ [quote from my older hard copy Oxford English Dictionary] for many centuries before the heat engine hijacked the terminology.

Why does this matter?  Well, many people have a misconception that engineering is all about engines, the heat kind; and yes, some of us do design, build and maintain engines but very many more engineers contrive, design and invent works of public utility – in the broadest sense of the words, i.e. just about everything ‘invented’ in the world. In other words, engineering is using human ingenuity to produce something useful; preferably something that improves the quality of life – oh, but now we are moving into ethics and I will leave that for another day!

Sources:

Blockley D, Engineering: A Very Short Introduction, Oxford: Oxford University Press, 2012.

Auyang SY, Engineering – an endless frontier, Cambridge MA: Harvard University Press, 2004.

Little W, Fowler HW & Coulson J, The Shorter Oxford English Dictionary, C.T. Onions (editor), London: Guild Publishing, 1983.