SUMMARY
Silk cocoons, constructed by silkmoths (Lepidoptera), are protective structural composites. Some cocoons appear to have evolved towards structural and material optimisation in order to sustain impact strikes from predators and hinder parasite ingress. This study investigates the protective properties of silk cocoons with different morphologies by evaluating their impact resistance and damage tolerance. Finite element analysis was used to analyse empirical observations of the quasi-static impact response of the silk cocoons, and to evaluate the separate benefits of the structures and materials through the deformation and damage mechanism. We use design principles from composite engineering in order to understand the structure–property–function relationship of silkworm cocoons. Understanding the highly evolved survival strategies of the organisms building natural cocoons will hopefully lead to inspiration that in turn could lead to improved composite design.
FOOTNOTES
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AUTHOR CONTRIBUTIONS
F.C. conceived the study, executed the experiments and the data analysis, and wrote the main body of the text. T.H. constructed the cocoon model and performed the FEA simulations. D.P. developed the material models for simulations from experimental data. F.V. provided the biological background for the study and revised the text.
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COMPETING INTERESTS
No competing interests declared.
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FUNDING
This work was supported by The Air Force Office of Scientific Research (grant number F49620-03-1-0111 to F.C.), the Intra-European Marie Curie Fellowship for Career Development (project number 234818, to T.H.) and the European Research Council (grant number SP2-GA-2008-233409 to D.P. and F.V.).
- © 2013. Published by The Company of Biologists Ltd