Download Bengt Pipkorn

Development of a Finite Element model to predict rib fractures
- A study into modelling alternatives
Collaboration between Chalmers and Autoliv
The main restraint systems in cars are airbags and seatbelts. These restraint systems have
significantly reduced the number of occupants killed and injured in automobile crashes.
However, occupants are still injured in vehicle crashes. The chest is vulnerable and frequently
injured; frequent the ribs are fractured and can result in serious complications for those that
are elderly and can lead to soft tissue injuries, e.g. hemothorax and pneumothorax.
To design and evaluate occupant restraint
systems, a detailed knowledge about the
behavior of a human body when loaded in
crashes is needed. One of the tools used to
predict the behavior of an occupant in a
crash are crash test dummies. However,
these are crude representations of humans.
Other and more recent tools used to
predict the injury risk are mathematical
Human Body Models (HBM). With such
models detailed analysis of the behavior of
various structures of the body can be
evaluated.
In a recent project, a method to predict chest injuries using a particular HBM for pure frontal
load of the occupant was developed. In that project some deficiencies of the HBM was
identified. In addition there is a need for a method that predict the risk of injuries in more
complex loading; angled and lateral load of the chest.
The aim with this project is to evaluate the level of modelling detail that is necessary to
predict rib fracture and fracture locations. Such details can be mesh density, modelling
strategy, material data, geometry etc. To fulfill this aim a component evaluation and
validation on single ribs is to be conducted. Thereafter a parameter study to design the least
complex rib/thorax “to evaluate what level of modelling detail that is necessary to predict rib
fracture”. This latter part will be done in three steps:
1. Modelling the bending of single ribs
2. Predict the strain pattern of single ribs
3. Modelling the fracture behaviour of single ribs
The study will include a literature study and a detailed analysis of rib kinematics when the rib
is loaded from the front and the side. Single ribs will be modelled using a state-of-the-art
finite element tool, and the predicted kinematics will be compared to results from mechanical
tests with isolated ribs.
The project is suitable for two students studying mechanical engineering. Finite element
knowledge and experience is a pre-requisite.
Supervisor will be Johan Iraeus, Applied Mechanics and Bengt Pipkorn, Autoliv
Examiner will be Johan Davidsson, Applied Mechanics,
Email: [email protected]
Phone: +46 730 346 436