Development of Multi Layer Composite Energy Absorber Blocks for Aircraft Crashworthine
In this study, a novel concept of lightweight multi-layered composite energy-absorber blocks and beams have been developed that potentially can be retrofitted in aircraft and helicopter sub-floors in order to improve their crashworthiness performance. This novel structure encompassed of fibreglas...
Saved in:
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | English English |
| Published: |
2009
|
| Online Access: | http://psasir.upm.edu.my/id/eprint/7864/1/abstract__FK_2009_78.pdf http://psasir.upm.edu.my/id/eprint/7864/ |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | In this study, a novel concept of lightweight multi-layered composite energy-absorber
blocks and beams have been developed that potentially can be retrofitted in aircraft and
helicopter sub-floors in order to improve their crashworthiness performance. This novel
structure encompassed of fibreglass fabric wrapped around two or three foam layer
cores. This technique eventually prevented from core-to-facing debonding, especially
during axial crashing, whereby the debonding tendency is controlled by a hoop stresses
in fibreglass layers. Manufactured block can be used alone as an energy-absorber
element in structure or a series of blocks integrate in the form of beam. Inline assembly
of the fibre-reinforced blocks is covered with fabric glass fibre reinforcement in order to
integrate the blocks in a beam configuration. Two types of triggering modifications had
been applied to the developed composite structures and they are "bevel trigger" and "groove trigger". In the experimental work the composite blocks and beams were
subjected to a quasi-static crushing load. After obtaining the load-displacement curves
and determination of crashworthy parameters, a fmite element explicit dynamic analysis
code module, incorporeity ANSYS/LS-DYNA implemented to the simulation of the
quasi-static crash behaviour and energy absorption characteristics of the developed
crashworthy composite structure. The results from the fmite element analysis were
validated against the experimental results and good agreement between two approaches
was observed. A dynamic crash analysis was also conducted numerically in order to
simulate the dynamic crash event and estimating crash behaviour and energy absorption
characteristics of the multi-layered structures which are subjected to high velocity
impacts. It has been 0 bserved that by increasing the crushing speed load and energy
absorption of the structures will inherently magnify. From this research work, it has been
demonstrated that, the double-layered and triple-layered block and beam sandwich
design concept is a practical means of producing cost-effective sandwich structures, that
crush in a stable, progressive manner with high crush force efficiency.
Crush force efficiency (CFE) for all specimen types changed between 0.5 to 0.78 and
specific absorption energy (SAE) up to 12.78 kJ/ kg for blocks and 23.53 kJ/ kg for
beams were recorded. Moreover the obtained quasi-static numerical results of axial
compression model of composite blocks and beams are compared with actual
experimental data of crash energy absorption, load-displacement history and crush zone
characteristics, showing very good agreement with and without use of two types of the
collapse trigger mechanisms. On the other hand, dynamic simulations also showed a stable, progressive crushing with high crush force efficiency but less than quasi-static
condition. Increasing the crushing speed magnified the resistant load and consequently
energy absorption of the structures. For example, in a non-triggered beam with quasistatic
SAE equal to 14.37 kJI kg, a magnification factor equal to 5.46 achieved in 20
mis, i.e. SAE of structure was 78.5 kJI kg that is an excellent value in composite
sandwich structures. High CFE and SAE of new design is desired feature of composite
structures in crashworthiness applications. |
|---|