Impact and Energy Absorption of Straight and Tapered Rectangular Tubes
Nagel, Gregory (2005) Impact and Energy Absorption of Straight and Tapered Rectangular Tubes. PhD thesis, Queensland University of Technology.
Over the past several decades increasing focus has been paid to the impact of
structures where energy, during the impact event, needs to be absorbed in a
controlled manner. This has led to considerable research being carried out on energy
absorbers, devices designed to dissipate energy during an impact event and hence
protect the structure under consideration. Energy absorbers have found common
usage in applications such as vehicles, aircraft, highway barriers and at the base of
lift shafts. A type of energy absorber which has received relatively limited attention
in the open literature is the tapered rectangular tube. Such a structure is essentially a
tube with a rectangular cross-section in which one or more of the sides are inclined to
the tube's longitudinal axis.
The aim of this thesis was to analyse the impact and energy absorption response of
tapered and non-tapered (straight) rectangular tubes. The energy absorption response
was quantified for both axial and oblique loading, representative of the loading
conditions typically encountered in impact applications. Since energy absorbers are
commonly used as components in energy absorbing systems, the response of such a
system was analysed which contained either straight or tapered rectangular tubes as
the energy absorbing components. This system could typically be used as the front
bumper system of a vehicle.
Detailed finite element models, validated using experiments and existing theoretical
and numerical models, were used to assess the energy absorption response and
deformation modes of straight and tapered tubes under the various loading
conditions. The manner in which a thin-walled tube deforms is important since it
governs its energy absorption response.
The results show that the energy absorption response of straight and tapered
rectangular tubes can be controlled using their various geometry parameters. In
particular, the wall thickness, taper angle and the number of tapered sides can be
effectively used as parameters to control the amount of absorbed energy. Tapered
rectangular tubes display less sensitivity to inertia effects compared with straight rectangular tubes under impact loading. This is beneficial when the higher crush
loads associated with inertia effects need to be reduced. Furthermore, though the
energy absorption capacity of thin-walled rectangular tubes diminishes under oblique
impact loading, the capacity is more maintained for tapered rectangular tubes
compared with non-tapered rectangular tubes.
Overall, the results highlight the advantages of using tapered rectangular tubes for
absorbing impact energy under axial and oblique loading conditions. Understanding
is gained as to how the geometry parameters of such structures can be used to control
the absorbed energy. The thesis uses this knowledge to develop design guidelines for
the use of straight and tapered rectangular tubes in energy absorbing systems such as
for crashworthiness applications. Furthermore, the results highlight the importance of
analysing thin-walled energy absorbers as part of an energy absorbing system, since
the response of the absorbers may be different to when they are treated on their own.
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|Item Type:||QUT Thesis (PhD)|
|Keywords:||Tapered Tubes, Energy Absorption, Axial, Oblique Impact, Finite Element Analysis, Computer Simulation, Crashworthiness|
|Divisions:||Past > QUT Faculties & Divisions > Faculty of Built Environment and Engineering|
Past > Schools > School of Design
|Department:||Built Environment & Engineering|
|Institution:||Queensland University of Technology|
|Copyright Owner:||Copyright Gregory Nagel|
|Deposited On:||03 Dec 2008 13:54|
|Last Modified:||29 Oct 2011 05:41|
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