www.bris.ac.uk/composites
The Mechanical Design of Euplectella Aspergillum Skeleton
Desislava Bacheva1*
Richard S. Trask1 & Katharine Robson-Brown2
1Advanced Composite Centre for Innovation and Science (ACCIS), Department of Aerospace Engineering, University of Bristol, UK
2Imaging Laboratory, Department of Archaeology and Anthropology, University of Bristol, UK
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D.S. Bacheva, R.S. Trask & K. Robson-Brown
DTC conference, April 2012
Outline
The design principles of E. aspergillum skeleton
Aims and objectives
In-situ compression
Methodology
Results and analysis
Compression test of cylindrical specimens
Methodology
Results and analysis
Concluding remarks and future work
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D.S. Bacheva, R.S. Trask & K. Robson-Brown
DTC conference, April 2012
51 mm
The Design Principles of E. aspergillum Skeleton
Aims and Objectives
To measure the structural efficiency of E. aspergillum
Investigation of the structure-property relations
Extraction and utilisation of skeleton design principles for the development of novel composite aerospace structures
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D.S. Bacheva, R.S. Trask & K. Robson-Brown
DTC conference, April 2012
µCT In-situ Compression
Methodology:
Maximum sample size 9 x 17mm
Ends of the sample casted in epoxy resin EPON™ 828 with diethylenetriamine (DETA) as curing agent
Image pixel size of 4.9μm
Three loading cycles at rate 2μm/s
Sample configuration
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D.S. Bacheva, R.S. Trask & K. Robson-Brown
DTC conference, April 2012
Scan at 16.4 N Scan at 18.7 N Scan at 3.6 N
µCT In-situ Compression
Fractured Sample
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D.S. Bacheva, R.S. Trask & K. Robson-Brown
DTC conference, April 2012
Mechanical Testing - Compression
Methodology:
Sample length: 10 cells
Ends of the sample casted in epoxy resin EPON™ 828 with diethylenetriamine (DETA) as curing
agent
Imetrum Video Gauge Software to extract strain data from several zones of the skeleton
Load rate 0.175 and 0.250 mm/min
Casting of the samples
Experimental Set up
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D.S. Bacheva, R.S. Trask & K. Robson-Brown
DTC conference, April 2012
202 N 201.5 N 143 N -2.7 N
Compression Test: Specimen 12 bottom part
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Strain Data
Strain 1 T1-T2 Strain 2 T3-T4 Strain 3 T5-T6 Strain 10 T7-T8
Specimen before test -10
40
90
140
190
240
290
-1 1 3 5 7 9 11 13 15 17 19 21 23 25
Load
(N
)
Strain (%)
Strain 1
Strain 2
Strain 3
Strain 10
202 N 201.5 N
143 N
-2.7 N
2
1
7
8
3
4
6
5
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D.S. Bacheva, R.S. Trask & K. Robson-Brown
DTC conference, April 2012
Compression Test: Specimen 13 upper part
Strain Data
Strain 1 T1-T2 Strain 3 T5-T6 Strain 4 T8-T8
0
20
40
60
80
100
120
140
160
180
-10 0 10 20 30 40 50 60 70 80 90 100
Load
(N
)
Strain (%)
Strain 3
Strain 4
Strain 1
179 N
112 N
55 N 59 N
1
2
5
6
7
8
179 N 55 N
12 mm
Specimen before test
112 N 59 N
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D.S. Bacheva, R.S. Trask & K. Robson-Brown
DTC conference, April 2012
Concluding Remarks and Future Work
The effect of the loading rate on the compression behaviour of the sample during post-yield softening and densification will be further investigated.
Experimental investigations in regards to testing in torsion and bending of the cylindrical portions are in the process of planning.
Micro CT in-situ testing is a useful technique for detecting the onset of failure of the individual beams during compression on the investigated sample configuration.
Further work is concentrated on importing the generated 3D models into FE modelling packages
1.75 mm