Meeting Abstract

78.3  Sunday, Jan. 6  Ramming, biting and cracking: the strength of animal and plant shells HU, DL*; SIELERT, K; GORDON, M; Courant Institute, NYU; Courant Institute, NYU; Courant Institute, NYU dhu@cims.nyu.edu

The thin-shelled dome provides lightweight armor for eggs, skulls, turtles, nuts, gourds and other common structures in the animal and plant kingdoms. In our combined experimental and theoretical study, we here compare across species the strength-to-weight ratio of domes found in nature. Using shell geometries measured from museum collections, data is presented in the form of the shell�s characteristic thickness versus characteristic length. This data is analyzed using elastic membrane theory to compute scaling relations for the maximum force that these shells can support. Particular attention is given to presenting a structural classification of these shells, allowing us to rationalize their various thickness-length aspect ratios according to the bite, ramming, or static forces they are likely to encounter. Also considered are the mechanics dictating the limitations of shelled gigantism, as exhibited by ostrich eggs, giant sea turtles and one-ton pumpkins.