Studies On The Design Of New-style Spatial Cantilever Structures By Bionic Modeling Of Dragonfly Wings

The bionic design of architectural construction can be categorized into two types: One is a technique- push type, in which one kind or several kinds of biologic structure are studied firstly, and then the valuable ones are extended into architectures; the other is a demand-push type, in which engineers turn to biologic structures for inspiration and illumination when encountering difficulties in designing architectural construction(component). The optimized architectural construction can be designed from discrimination, analysis, combination and further simulation of some kinds of biological structures. This paper belongs to first type. The structure of dragonfly wings is studied in the round firstly, and the bionic design of spatial cantilever structure is done according to the structure character of dragonfly wings.Based on the model data which are get from experiment observation and correlated literatures, the numerical model of dragonfly's hind wings is established by the general finite element software of ANSYS ,and Beam189 and Shell 93 element are used respectively in modeling of the veins and the membrane so as to ensure their metabolism coordination. After analyzing the planar finite element model of the dragonfly's hind wings, the conclusion is drawn that: the primary veins undertake biggish axial force and bending moment, while the subordinate vein undertakes little or don't do at all. But the subordinate vein plays an important role in improving the integral rigidity and stability of the wing structure. It is discovered by analyzing the three-dimension finite element model of dragonfly wings that the corrugations of leading edge and the arch camber of wings improve the flexural rigidity of dragonfly wings greatly. The force transmission in the three-dimension model's structure is more direct and reasonable compared to the planar model's., its bending moment and axial force have less saltation .Furthermore; the existence of prestressing in the membrane is studied in this paper.The dragonfly wings can be regarded as a spatial cantilever structure composed of veins and membrane. According to the feature of dragonfly wings, seven different cantilever grid structure models are analyzed in this paper .Every grid structure has four types: with membrane and with corrugation, without membrane and with corrugation, with membrane and with camber, without membrane and with camber. The calculation reveals that the type of grid has a significant influence on the flexural rigidity of the cantilever grid structure under the same material consumption.In the fourth chapter, the bionic design of new -style spatial cantilever structure is discussed. Based on the structure character of dragonfly wings, four large-span spatial cantilever structures are designed in this paper. It turns out to be that all of the four types have favorable mechanic performance..The bionics structure also simulates dragonfly's wing naevus to carry a heavy block on the overhanging open-ends. It is found that the hanging heavy blocks on the overhanging open-ends by springs eliminate the vibration effectively.