The following is an excerpt.
The title of Guri Lillehaug and Marte Vestermo Nesje´s master´s thesis is «Combined impact and blast loading on concrete plates».
There are 15 students who will be working on master´s theses related to work at SIMLab and SFI CASA this semester. Guri Lillehaug and Marte Vestermo Nesje´s work will be a basic, generic project and the students started by moulding concrete plates with three different qualities.
Guri Lillehaug explains: «We will study the effect of a shockwave when the material is already damaged by the impact from the missile. Then, when the test is completed, we are going to make a numerical model in LS-Dyna».
Partners directly involved
A truckload of fluid concrete arrived on a freezing cold morning in early February. The SIMLab staff and students had to work fast and efficient to get the moulding done properly.
Senior engineer and researcher Oda Toreskås from the Norwegian Defence Estates Agency took her part of the work. She says that the student´s thesis will be useful. A numerical model that simulates impact from missiles on concrete will reduce the NDEAs need for physical tests.
«Besides, for me this is instructive too. I find that it is a good way to cooperate with SIMLab and CASA too», Toreskås states.
Before the plates are ready for bullets and blasts in the Gas Gun and Shock Tube at SIMLab they have to harden for about 30 days.
As the title of the student´s thesis indicates: Some plates will be subjected to impact from both missiles and blast loading. For comparison, some plates will only be subjected to missiles or blast loadings.
Brittle Materials – Challenging to Model
Anyone who has looked into this knows that it is challenging to model the behaviour of brittle materials as they tend to shatter when exposed to blasts or other types of impact.
Marte Vestermo Nesje is taking the master´s degree programme in Mechanical Engineering, while Guri Lillehaug is on the Civil and Environmental Engineering programme. They both specialize in applied mechanics and last autumn they joined forces and wrote their project paper together.
Crash-tests and Material Test in Project Paper
The paper “Behaviour and Modelling of an Aluminium Component Subjected to Impact Loading” was about aluminium and included a dynamic crash-test as well as a material test of an aluminium profile. The results were applied in Abaqus/Explicit simulations.
«I feel that what we did last autumn was very relevant for our master´s thesis. It was a very instructive semester for us», Marte says.
Guri Lillehaug is already employed by the consulting engineers Norconsult, where she is going to work on bridge structures when she has completed her master´s degree. She found her thesis topic without any difficulty as she wanted to do something that was relevant for her future work.
Relevant for CASA partners
The students point out that their work hopefully will be relevant for both the Norwegian Defence Estates Agency -Forsvarsbygg and the Norwegian Public Roads Administration project, the ferry-free coastal highway E39 from Kristiansand to Trondheim.
The E39 project can for instance realize the world´s first submerged tubular bridge. Irrespective of the choice of structure, the materials in use will have to withstand powerful explosions and fragment impact – such as those from tanker truck accidents.
For SFI CASA, master’s students are important in the value chain from research and testing to transferring and implementing technology in industry. The formal start-up for work with the master’s theses was 15 January. The date for handing in is 11 June 2019.