J.Comparat.Physiol.A 195(9), 881-894, 2009

FINITE ELEMENT MODELING OF ARACHNID SLIT SENSILLA: II. ACTUAL LYRIFORM ORGANS AND THE FACE DEFORMATIONS OF THE INDIVIDUAL SLITS

B. Hößl¹², H.J. Böhm¹, C.F. Schaber², F.G. Rammerstorfer¹, F.G. Barth²

¹Institute of Lightweight Design and Structural Biomechanics,
TU Wien, Vienna, Austria
²Department of Neurobiology and Cognition Research,
Faculty of Sciences,
University of Vienna, Vienna, Austria


Abstract - Arachnid slit sensilla respond to minute strains in the exoskeleton. After having applied Finite Element (FE) analysis to simpliWed arrays of five straight slits (Höß et al. J Comp Physiol A 193:445–459, 2007) we now present a computational study of the eVects of more subtle natural variations in geometry, number and arrangement of slits on the slit face deformations. Our simulations show that even minor variations in these parameters can substantially influence a slit’s directional response. Using white-light interferometric measurements of the surface deformations of a lyriform organ, it is shown that planar FE models are capable of predicting the principal characteristics of the mechanical responses. The magnitudes of the measured and calculated slit face deformations are in good agreement. At threshold, they measure between 1.7 and 43 nm. In a lyriform organ and a closely positioned loose group of slits, the detectable range of loads increases to approximately 3.5 times the range of the lyriform organ alone. Stress concentration factors (up to ca. 29) found in the vicinity of the slits were evaluated from the models. They are mitigated due to local thickening of the exocuticle and the arrangement of the chitinous microWbers that prevents the formation of cracks under physiological loading conditions.


(hjb,091005)