Base plate mechanics of the barnacle Balanus amphitrite (=Amphibalanus amphitrite)

Abstract

The mechanical properties of barnacle base plates were measured using a punch test apparatus, with the purpose of examining the effect that the base plate flexural rigidity may have on adhesion mechanics. Base plate compliance was measured for 43 Balanus amphitrite (=Amphibalanus amphitrite) barnacles. Compliance measurements were used to determine flexural rigidity (assuming a fixed-edge circular plate approximation) and composite modulus of the base plates. The barnacles were categorized by age and cement type (hard or gummy) for statistical analyses. Barnacles that were ‘hard’ (≥70% of the base plate thin, rigid cement) and ‘gummy’ (>30% of the base plate covered in compliant, tacky cement) showed statistically different composite moduli but did not show a difference in base plate flexural rigidity. The average flexural rigidity for all barnacles was 0.0020 Nm (SEM ± 0.0003). Flexural rigidity and composite modulus did not differ significantly between 3-month and 14-month-old barnacles. The relatively low flexural rigidity measured for barnacles suggests that a rigid punch approximation is not sufficient to account for the contributions to adhesion mechanics due to flexing of real barnacles during release.

Keywords:

• mechanics of adhesion
• adhesion of plates
• fouling release
• barnacle
• release coatings
• Balanus amphitrite

Acknowledgements

The authors gratefully acknowledge Manoj Chaudhury of Lehigh University and Eric Holm of the Naval Surface Warfare Center, Carderock Division for helpful discussions. DBR and GHD were supported through the Naval Research Enterprise Internship Program at NRL. This research was funded by the US Office of Naval Research both at NRL and at Duke University (Grants N000140-510469, ‐710170 and ‐510580).