Abstract
This paper examines and presents the internal energy assessment using both
numerical and physical tests and discusses the value of the internal energy as one of the
valuable index in the vehicle crash events.
In the usual vehicle crash event, initially the vehicle has only the kinetic energy. During the
crash event, this kinetic energy is gradually absorbed and converted to the deformation (strain
energy). Then after the crash event some of the kinetic energy is left with the vehicle
deformations. Therefore the distributions of the energy absorption in the vehicle and its
management as well as its time history are theoretically essential and important for designing
the body structures.
However in the previous studies regarding the vehicle structures, the loads and forces are used
as the main index for the evaluation and the studies are focused on the bumpers and front side
rails as they are thought to be the major role in the crash energy absorptions (1) (2) (3) .
In recent days thanks to the continuous development of the computers and its application
technologies, FEM models with more than one million elements / nodes are quite usual. In
these models, almost all the vehicle parts and components are equally modelled using the 5 or
10mm shells or solids. This enables us to assess the internal energies of all the body parts with
the equal precisions. As this result, parts such as panels and components which were thought
to be not important in the past can be objectively and equally evaluated using the internal
energy. This may give us the potential to reduce the vehicle weight.
In this paper, CAE internal energy is compared with the energy calculated from the physical
test measured by the load cells. And its consistency and equivalency are proved out. Then
several investigations using the internal energy are conducted and the benefits to adopt the
internal energy as one of the index to design the body structures are presented.
Keywords: Internal Energy, Drop Weight Test, Barrier Load, CAE, Energy Management