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ReseaRch PRogRammes
Structures
Head of Programme: Tore Børvik
Design against accidental loads, such as explosions, impacts
and collisions, has become increasingly important for a number
of engineering and industrial applications. In order to meet
the challenges posed by such complex loading conditions,
product development and structural analysis are often carried
out in virtual environments using the finite element method
to achieve safer and more cost-effective designs. The long-
term goal of this research programme is to improve the
survivability of people and vital infrastructure to a given threat.
It is important to realize that the protective structure is the
last layer of defence against a threat when all other protective
measures have failed. It is thus of utmost importance that such
structures are designed and validated on a sound theoretical
and experimental basis. To do so, accurate, efficient and
robust constitutive models and solution techniques used in a
multiscale modelling context are required. Further, new designs
need to be validated through high-precision experiments
involving advanced instrumentation such as three-dimensional
digital image correlation for full-field displacement and strain
measurements. Although much information can be obtained
from laboratory tests, relying on such an approach would be
too costly and inefficient. Computer-aided design, together
with a strategy for material selection, optimization and well-
selected validation tests, can significantly lower the cost
and enhance the overall quality and efficiency of the required
protection.
The main objective of this research programme is to develop
and evaluate advanced computational tools and establish
validated modelling guidelines for computer-aided design of
safer and more cost-effective protective structures. Another
objective is to replace phenomenological models by physical
models in a top-down/bottom-up multiscale modelling
approach in order to reduce the number of mechanical tests
as much as possible in the design phase. This will be carried
out in close collaboration with the other research programmes
in CASA.
The main research activities in 2016 have been:
• Modelling and simulation of ballistic impact (PhD project,
Jens Kristian Holmen).
• Behaviour and modelling of flexible structures subjected to
blast loading (PhD project, Vegard Aune).
• Fragmentation of window glasses exposed to blast loading
(PhD project, Karoline Osnes).
• Impact against coated and uncoated offshore steel pipes
(PhD project, Ole Vestrum).
The two first PhD projects are activities from SFI SIMLab,
which are directly continued in SFI CASA. Jens Kristian Holmen
defended his PhD thesis in September 2016, while Vegard Aune
will defend his PhD thesis in May 2017. Jens Kristian Holmen
is employed as postdoc in CASA. Karoline Osnes’ PhD project
started in August 2015, while Ole Vestrum started his PhD
project in January 2016. In addition, a concurrent research
activity on blast-loaded concrete plates conducted by postdoc
Martin Kristoffersen (financed by the research project “Ferry-
free coastal route E39” hosted by the Norwegian Public Roads
Administration) has been linked to the research in Structures.
Examples from the PhD projects of Jens Kristian Holmen and
Vegard Aune are shown in Figure 9 and Figure 10, respectively.
Figure 10: Comparison between high-speed camera images (top) and simulations with
adaptive mesh refinement in EUROPLEXUS (bottom) from a blast-load experiment in
SIMLab’s shock-tube on a thin steel plate with pre-formed holes.
Figure 9: Numerical simulation of a hemispherical-nose projectile penetrating a sand
target at an impact velocity of 5 m/s applying the discrete particle method (DPM) in the
IMPETUS Afea solver.