The following is an excerpt.

Associate Professor Vegard Aune´s research evolves around severe blast loading events. At the 13th International DYMAT conference recently, he shared new insight on the underlying physics of extreme blast-structure interaction. Read about it – and watch the video on coupled simulation.

The video shows the coupled simulation and how the pressure in front of the plate is influenced by FSI effects.

Dr Aune´s topic at the DYMAT conference was Blast Loaded Structures and the question of  «What is the actual loading during large deformations»? His presentation summarised a recently published article titled «Influence of fluid-structure interaction effects on the ductile fracture of blast-loaded steel plates».

You can read the full article here

CRUCIAL TO UNDERSTAND PHYSICS WHEN DESIGNING STRUCTURES 

Fluid-structure interaction, FSI, happens when some movable or deformable structure interacts with an internal or surrounding fluid flow. In this context, the fluid is air coming from the pressure waves generated by an explosion. To date, we do not know the importance of FSI effects during the dynamic response of blast-loaded structures. It is therefore necessary to develop a methodology identifying scenarios where FSI is of importance in the design of civil engineering structures. 
The figure to the left shows the comparison between the experiments and the simulations on the coupled (FSI) and the uncoupled approach. 

A DEEPER INSIGHT INTO THE PHYSICS

One of the open questions in Dr Aune´s field of research is how FSI affects the dynamic fracture of lightweight and ductile structures. During the last years, the team have established a methodology that seems to bring them a bit closer to their goal: Namely, to gain a deeper insight into the underlying physics during extreme blast-structure interaction. 
The methodology combines an experimental and numerical approach. The first step is to use experimental data as a backdrop for numerical simulations. Next, they use numerical simulations to study the SFI effects. This relatively novel approach allows for detailed studies on the dynamic response of the blast-loaded steel plates. 

COMPARING THE PREDICTIONS 

The study presented at DYMAT investigated the effects numerically by comparing the predictions from an uncoupled and a coupled FSI approach. They carried out blast tests in the SIMLab Shock Tube Facility. Then they used the experimental results to evaluate the reliability of the numerical simulations.  The team of researchers emphasize that this is ongoing research. They plan to continue the work and hope to do more detailed studies on the reliability of the coupled (FSI) simulations. Still, they conclude that the computational methodology is well suited to study the influence of FSI on the ductile crack growth in blast-loaded steel plates. The results also motivate them to do similar studies on even more complex geometries. The figure to the right above shows the comparison of the pressure distribution on the plates for the uncoupled (top row) and the coupled (bottom row) approach at the same characteristic times as in the figure to the left above.

INTERNATIONAL COLLABORATION

Vegard Aune´s fellow authors on the study presented at DYMAT and published by EDP Sciences are Professors Magnus Langseth and Tore Børvik (SIMLab and SFI CASA) and Georgios Valsamos and Folco Casadei (European Commission, Joint Research Centre (JRC), Ispra (VA), Italy).
DYMAT organized  13th International Conference on Mechanical and Physical behaviour of Materials under Dynamic Loading (DYMAT) in Madrid, Spain, 20-24 September.
The DYMAT organization aims to bring together engineers and scientists working on the dynamic behaviour of materials. This research field is relevant in multiple applications, such as: 

  • crashworthiness in transport, 
  • terminal ballistics related to defence, shielding of satellites, of turbine blades and discs, 
  • blast effects due to industrial explosions and terrorist attacks,
  • material processing such as high-speed shaping of metals.

Including Dr Aune, four of CASA’ researchers presented novel research at this year’s conference: 

Karoline Osnes: An Alternative Approach to Modelling Ballistic Impact on Laminated Glass
Martin Kristoffersen:
Experts on Ballistic Impact Shared News on Concrete at DYMAT 
Benjamin S. Elveli: About Blasting Steel Plates and Why Material Properties Matter