BIOMECHANICAL RESEARCH ON THE RADIAL CORRUGATION STRUCTURE OF PROSTERNAL TYMPANAL MEMBRANES IN THE PARASITOID FLY ORMIA OCHRACEA

摘要

The purpose of this study is to analyze the contribution of radial corrugation structure of prosternal tympanal membranes in the parasitoid fly Ormia ochracea for sound sensing. This animal has a remarkable ability to detect the direction of an incident sound stimulus in spite of the small size of its auditory sensory organ. The two tympanal membranes of this fly are jointed by a cuticular structure, which couples their vibrations mechanically. Its tympanal membranes have radial corrugations which stretch from the tympanal pit to the margin of the membranes. The role of these corrugations in vibration transmission is still unsuspected and need to be analyzed attentively. In this paper, a detailed three-dimensional finite element modal of the tympanal membranes is developed to describe its actual geometrical feature, and moreover, an additional finite element modal is set up, which have no corrugations on the membranes. These two modals have same external physical dimensions. By comparing the natural frequencies, modes, stress and strain distributions under the constantly acting loads, and dynamic responses under the sound excitations of the two mechanical modals, the functions and contributions of the radial corrugation structure of prosternal tympanal membranes in the parasitoid fly Ormia ochracea can be given quantitatively, which may help us understand the mechanism of this fly's ears and benefit the design of bionic auditory sensing device.