Evaluating the blog-article experiment

Last week I tried out Rolf Hut’s idea of academic publishing in the form of a blog post, rather than an article. I did this by rewriting an existing article into a blog post.

Having let a couple of days pass, I thought now would be a good moment to collect my thoughts and evaluate my experience.

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An experiment: the blog-article

This week, the TU Delft scientist Rolf Hut published an intriguing idea: instead of publishing journal articles, scientists should use blogs to disseminate their findings. In (of course) a blog post, he explains why he thinks this would be a good idea. Blog posts, Hut argues, are more readable than traditional articles. Modern practices of archiving data and methods in collective repositories allow a blog post to be much more streamlined than an article. A blog post can present only the really interesting analysis, and just refer to various repositories for the raw data and methods.

Hut goes on to call on scientists to take up the challenge and publish their next article in the form of a blog. I think Hut has an intriguing idea, but I’m not entirely sure how big the benefits will be. As a scientist, that means there’s only one thing to do: perform an experiment!

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The DH. Comet crashes: How unknown-unknowns brought down Britain’s entry into the Jet Age

The 27th of July 1949 was a momentous day. After having made two 500-yard hops in the morning, the first de Havilland Comet took to the air for a 31 minute test flight. (You can see footage here). Britain had brought the world truly into the jet age.

No longer would airline passengers have to suffer the indignity of plodding along at a mere 500 km/h, flying at the same level as the turbulence. Instead, the jet set could look forward to zooming around at 740 km/h, and cruise high enough to go over the top of all but the largest thunderstorms. The USA might have been the first to break the sound barrier (at least in a way that allowed the pilot to talk about the experience afterwards); the Comet showed that Britain was still capable of world-class aeronautical engineering.

Development took another 3 years, but on 2 May 1952 the Comet carried its first paying passengers. All seemed to be going well for the Comet, but soon disaster struck.

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Applying the stress intensity factor to fatigue

Note for new readers, this is part of a series of posts on the history of fracture mechanics, you can find the first post in this series here.

Fatigue is the phenomenon that a structure gradually degrades due to repeated load cycles, eventually leading to structural failure at much lower loading than for an undamaged structure. The structural degradation usually takes the form of cracks, which initiate at some point during the lifetime of the structure and then grow by a small increment every time a load cycle is applied.

That fatigue is an issue that needs careful consideration has been known to structural engineers ever since the investigation into the 1842 Versailles rail disaster. In the wake of this disaster, which killed between 50 and 200 people, various engineers investigated the phenomenon of fatigue. Eventually this led to the discovery by the German railroad engineer August Wöhler that the lifetime of a certain part subjected to repeated loads is proportional to the amplitude of the load.

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Back to Stress: The Stress Intensity Factor

Note for new readers, this is part of a series of posts on the history of fracture mechanics, you can find the first post in this series here.

While Griffith, Irwin, Kies, and others were working on using the energy balance to predict when cracks would grow;, some researchers continued to work on calculating the stress around a crack tip. In particular, people wanted to know how the stress near a crack depends on the crack length and on the load being placed on a specimen as a whole.

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Some context regarding ‘self-healing aircraft wings’

Our bodies are capable of some amazing things. One of the most amazing, from the viewpoint of a materials scientist, is our body’s ability to heal itself. If for some reason you cut yourself, your body will leap into action, sealing the gap and generating replacement skin that is just as good as new. All without any conscious thought on your part.

Wouldn’t it be great if aircraft could do the same? Instead of having to regularly inspect and repair aircraft structures, both of which cost time and money, we could instead happily fly along, secure in the knowledge that any damage would be fixed, as if by magic.

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Zooming in on the energy balance

Note for new readers, this is part of a series of posts on the history of fracture mechanics. You can find the first post in this series here.

In my last post I talked about the energy balance during crack growth. I got some feedback that that part went a bit fast for some readers, so before continuing with the history of fracture mechanics I’ll discuss the energy balance in a bit more depth.

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