Tag Archives: design

Reinforcement ensures long-term structural integrity

Last month when I was in Taiwan [see ‘Ancient Standards‘ on January 29th, 2020] , I visited Kuosheng Nuclear Power Plant which has a pair of boiling water reactors that each generate 986 MWe, or between them about 7% of Taiwan’s electricity.  The power station is approaching the end of its licensed life in around 2023 after being constructed in 1978 and delivering electricity commercially for about 40 years, since the early 1980’s.  There is an excellent exhibition centre at the power station that includes the life-size mock-up of the reinforcement rods in the concrete of the reactors shown in the photograph.  I am used to seeing reinforcing bar, or rebar as it is known, between 6 to 12mm in diameter on building site, but I had never seen any of this diameter (about 40 to 50mm diameter) or in such a dense grid.  On the other hand, we are not building any nuclear power stations in the UK at the moment so there aren’t many opportunities to see closeup the scale of structure required.

Ancient standards

I have been involved in the creation of a European pre-standard for the validation of computational models used to predict the structural performance of engineering systems [see ‘Setting Standards‘ on January 24th, 2014]; so, an example of a two thousand year old standard in the National Palace Museum in Taipei particularly attracted my interest during a recent visit to Taiwan.  A Jia-liang is a standard measure from the Xin Dynasty dated to between 9 and 24 CE.  It is an early form of standard weights and measure issued by the Chinese emperor.  The main cylinder contains a volume known as a ‘hu’; however, if you flip it over there is a small cylinder that contains a ‘dou’ which is one tenth of a ‘hu’.  The object that looks like a handle on the right in the photograph is third cylinder that holds a ‘sheng’ which is one tenth of a ‘dou’ or one hundredth of a ‘hu’; and the handle on the left contains a ‘ge’ when it is as shown in the photograph and a ‘yue’ when the other way up.  A ‘ge’ is tenth of ‘sheng’ and a ‘yeu’ is a twentieth.  The Jia-liang was made of bronze with all of the information engraved on it and was used to measure grain across the Xin empire.

Thought leadership in fusion engineering

The harnessing of fusion energy has become something of a holy grail – sought after by many without much apparent progress.  It is the energy process that ‘powers’ the stars and if we could reproduce it on earth in a controlled environment then it would offer almost unlimited energy with very low environmental costs.  However, understanding the science is an enormous challenge and the engineering task to design, build and operate a fusion-fuelled power station is even greater.  The engineering difficulties originate from the combination of two factors: the emergent behaviour present in the complex system and that it has never been done before.  Engineering has achieved lots of firsts but usually through incremental development; however, with fusion energy it would appear that it will only work when all of the required conditions are present.  In other words, incremental development is not viable and we need everything ready before flicking the switch.  Not surprisingly, engineers are cautious about flicking switches when they are not sure what will happen.  Yet, the potential benefits of getting it right are huge; so, we would really like to do it.  Hence, the holy grail status: much sought after and offering infinite abundance.

Last week I joined the search, or at least offered guidance to those searching, by publishing an article in Royal Society Open Science on ‘An integrated digital framework for the design, build and operation of fusion power plants‘.  Working with colleagues at the Culham Centre for Fusion Energy, Richard Taylor and I have taken our earlier work on an integrated nuclear digital environment for the nuclear energy using fission [see ‘Enabling or disruptive technology for nuclear engineering?‘ on january 28th, 2015] and combined it with the hierarchical pyramid of testing and simulation used in the aerospace industry [see ‘Hierarchical modelling in engineering and biology‘ on March 14th, 2018] to create a framework that can be used to guide the exploration of large design domains using computational models within a distributed and collaborative community of engineers and scientists.  We hope it will shorten development times, reduce design and build costs, and improve credibility, operability, reliability and safety.  It is a long list of potential benefits for a relatively simple idea in a relatively short paper (only 12 pages).  Follow the link to find out more – it is an open access paper, so it’s free.

References

Patterson EA, Taylor RJ & Bankhead M, A framework for an integrated nuclear digital environment, Progress in Nuclear Energy, 87:97-103, 2016.

Patterson EA, Purdie S, Taylor RJ & Waldon C, An integrated digital framework for the design, build and operation of fusion power plants, Royal Society Open Science, 6(10):181847, 2019.

Amazing innovation in metamaterials

Most manufactured things break when you subject them to 90% strain; however Professor Xiaoyu Rayne Zheng of the Department of Mechanical Engineering at Virginia Tech has developed additively-manufactured metamaterials that completely recover from being deformed to this level.  Strains are usually defined as the change in length divided by the original length and is limited in most engineering structures to less than 2%, which is the level at which steel experiences permanent deformation.  Professor Zheng has developed a microstructure with a recurring architecture over seven orders of magnitude that allows an extraordinary level of elastic recovery; and then his team manufactures the material using microstereolithography.  Stereolithography is a form of three-dimensional printing.  Professor Zheng presented some of his research at the USAF research review that I attended last month [see ‘When an upgrade is downgrading‘ on August 21st, 2019 and ‘Coverts inspire adaptive wing design’ on September 11th, 2019].  He explained that, when these metamaterials are made out of a piezoelectric nanocomposite, they can be deployed as tactile sensors with directional sensitivity, or smart energy-absorbing materials.

Rayne Zheng and Aimy Wissa [‘Coverts inspire adaptive wing design’ on September 11th, 2019] both made Compelling Presentations [see post on March 21st, 2018] that captured my attention and imagination; and kept my phone in my pocket!

The picture is from https://www.raynexzheng.com/

For details of the additively-manufactured metamaterials see: Zheng, Xiaoyu, William Smith, Julie Jackson, Bryan Moran, Huachen Cui, Da Chen, Jianchao Ye et al. “Multiscale metallic metamaterials.” Nature materials 15, no. 10 (2016): 1100

For details of the piezoelectric metamaterials see: Cui, Huachen, Ryan Hensleigh, Desheng Yao, Deepam Maurya, Prashant Kumar, Min Gyu Kang, Shashank Priya, and Xiaoyu Rayne Zheng. “Three-dimensional printing of piezoelectric materials with designed anisotropy and directional response.” Nature materials 18, no. 3 (2019): 234