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Crashworthiness of Axis Symmetric Composite Structures
for Automotive ApplicationsMaximillian D X Dixon
www.bris.ac.uk/composites
2/9Crumple Zone
Source: http://www.motortrader.com.my/news/euroncap-5-stars-for-2014-mazda3/mazda-skyactiv-structure/
Source: http://www.seriouswheels.com/pics-2008/nopq/2008-Porsche-911-GT2-Body-shell-1280x960.jpg
3/9Crush Response Metric
Displacement
Load
Progressive FailureCatastrophic Failure
DisplacementLo
ad
4/9
Progressive Folding1
Progressive Fragmentation1
• Global Buckling (Euler Buckling),• Progressive Folding,• Progressive Crushing,
– Progressive Splaying,– Progressive Fragmentation.
Progressive Failure Modes
Progressive Splaying1
1. Source: D Hull, 1990, “A Unified Approach to Progressive Crushing of Fibre-Reinforces Composite Tubes”.
5/9Fracture Toughness
Matrix Material
Interlaminar Fracture Toughness GIC (kJ/m2)
PEEK 1.6-2.4PEI 1.0-1.2PI 0.8-0.9Epoxy 0.2-0.3Source: G C Jacob, 2002, “Energy Absorption in Polymer Composites for Automotive Crashworthiness”.
Source: G C Jacob, 2002, “Energy Absorption in Polymer Composites for Automotive Crashworthiness”.
6/9Monolithic StructuresContributing factors include:Fibre Type, Matrix Type, Cross Section & Fibre Architecture
Material SEA (kJ/kg)Steel & Aluminium 15-30
Carbon/Epoxy 80Glass/Epoxy 60
Carbon/PEEK 194Carbon/PEI 155Carbon/PI 131Carbon/Epoxy 110
180
190
200
210
220
230
240
0 5 10 15 20 25S
EA (
kJ/
kg)
Fibre Angle (°)Source: G C Jacob, 2002, “Energy Absorption in Polymer Composites for Automotive Crashworthiness”. Source: S Ramakrishna, 1995, “Energy Absorption Behaviour
of Carbon Fiber Reinforced Thermoplastic Composite Tubes”.
7/9Off Axis Loading
0
5
10
15
20
25
30
35
0 5 10 15 20 25
Sp
ecif
ic E
ner
gy
Ab
sorp
tio
n
(kJ/
kg)
Loading Angle (°)
Carbon Glass HybridSource: V M Karbhari, 2003, “Energy absorbing characteristics of circular frustra”.
Source: F. Tarlochan, 2013, “Design of thin wall structures for energy absorption applications Enhancement of crashworthiness due to axial and oblique impact forces”.
8/9Sandwich Structures• Potential improved axial and off axis loading performance
• Monolithic SEA - 10.3 kJ/kg (no core)• Sandwich SEA - 30.3 kJ/kg (foam core)
• Further performance enhancement through use of “tied core” structures
Source: F. Tarlochan, 2012, “Advanced composite sandwich structure design for energy absorption applications: Blast protection and crashworthiness”.
Source: G. Pitarresi, 2005, “A comparative evaluation of crashworthy composite sandwich structures”.