the mechanical design of euplectella aspergillum skeleton · 2017-12-15 · the mechanical design...

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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

*[email protected]

2

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

3



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

4



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

5



Scan at 16.4 N Scan at 18.7 N Scan at 3.6 N

µCT In-situ Compression

Fractured Sample

6



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

7



202 N 201.5 N 143 N -2.7 N

Compression Test: Specimen 12 bottom part

7

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

8



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

9



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

10



Acknowledgements

Dr Julie Etches

Dr Christian Knipprath

Dr Greg McCombe

Stuart Alexander

Chris Lynas

Norman Wijker

Philip Bradshaw

the mechanical design of euplectella aspergillum skeleton · 2017-12-15 · the mechanical design...

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