Research On The Relationship Between Structure And Mechanical Properties Of Branching System Of The Family Palmae

In the process of evolution and co-evolution of life for billions of years, all living creatures have formed the structure, which has the excellent ability to adapt to the environment. There-fore, the formation of branching system is an optimization process, which has been consi-dered as a multi-function under the influence of the external environment. There should be certain relationship between the growing environment and the structure of branching system of the coastal palm plants. By theoretical, experimental and numerical simulation methods, the relationship, between the structure of branching system of the family palmae and its me-chanical properties, is explored.In order to simulate the branching growing trend of the family palmae, the incremental model of branching system was established, then the relationship between branching angle and total deformation energy under the external force was obtained, and the three typical force conditions were discussed. At last, the results show that different external environment results in different branching angle, which meets the minimum deformation energy. Giving that the palm plants had formed certain angle by their own genetic factors and outside environment, the simplified model of the roystonea regia was established, and the mechanical deformation of trunk was analyzed. The results show that when the wind load is small, the branching angle and wind angle have little influence on the mechanical performance of the trunk; and when the wind load is large, the branching angle of the lateral branches would change for unloading purpose. The characteristic of wind-resistance has large significance for the design of umbel-late wind turbine under typhoon working condition.Meanwhile, under the support of equivalent modulus theory of sandwich structure, the equivalent modulus of the roystonea regia trunk were obtained, and the parameters of the trunk compared with of the other two structures composed of single material is analyzed. The results show that the sandwich structure of trunk has higher specific strength and stiffness. The sandwich structure provides a new idea for bionic design of wind turbine towers and blades.Further more, it was found by examining the microscopic pictures of each part of the roystonea regia achieved by ESEM and considering the physiological function of each part, that the volume fraction and structure of vascular bundles had important effect on the me-chanical properties of each part. Then, a simplified structure of vascular bundle was extracted and its FEA model was established. Finally, the theoretical analysis and numerical simulation were made for the model. The results show that the middle part of the vascular bundle is the main part to bearing the load, and the relative density plays a decisive role on the cellular ma-terial property. This structure of vascular bundle can be used for material bionic design.