Every year, the Mechanics Department of the Royal Netherlands Society of Engineers (KIVI) awards two prizes for the best doctoral research within fluid and solid mechanics. This year’s Biezeno prize in the field of solid state mechanics has been awarded to UT researcher Björn Nijhuis. His research into the application of ‘directed energy deposition (DED)’ is scientifically outstanding and has applications in industry. Nijhuis’s work also has a high degree of sustainability. The award ceremony took place on 30 October during the symposium held by the Graduate School of Engineering Mechanics.
Large metal components measuring several metres can be manufactured using an additive manufacturing method known as Directed Energy Deposition (DED). Like other additive manufacturing methods, DED offers unprecedented freedom to create complex components with a high degree of functional integration. However, despite the promising advantages of DED, the components produced do not always meet the stated requirements. Excessive distortion and unwanted residual stresses can occur due to the way the component heats up and cools during the process.
To understand the origins of these undesirable effects and ultimately to reduce them, numerical models are often used to simulate the process. However, conventional DED process simulations are often slower than the real-life process, which means that simulating the production of large and complex components is not feasible. Nijhuis’s doctoral thesis aims to address this by proposing methods to speed up both the thermal and mechanical DED simulations.
Nijhuis proposes a simplified heat input model to speed up thermal simulations. This model uses the concept of ‘hot element addition’ in which new blocks of material at an elevated temperature are added into the existing geometry. This method results in the efficient combination of heat input and material deposition. Additionally, he developed a model-order reduction method which simplifies mechanical computations in a large part of the geometry. This significantly speeds up these computations.
This award for solid state mechanics is named after Professor C.B. Biezeno, who was one of the founders of solid state mechanics in the Netherlands. His most important work, a book entitled ‘Technische Dynamik’ written with Richard Grammel, was a standard reference work for others working in solid state mechanics in that period, and has been translated into several languages.
The Royal Netherlands Society of Engineers (KIVI) is the leading professional association for engineers in the Netherlands, and marks its 175th anniversary this year. The society is committed to supporting the professional practice of engineers, raising the profile of their work and forging connections between engineers and society.
Nijhuis’s research was carried out under the supervision of Professor Ton van den Boogaard and Dr. Bert Geijselaers, and co-supervisor Dr. Jos Havinga, the doctoral defence ceremony was held on 22 June 2023. A copy of Björn Nijhuis’s doctoral thesis is available on request.