Research On Lightweight Structure Of A Spherical Robot Based On Two-Scale Simulation

Spherical robot has spherical or approximate spherical shell, which can effectively protect critical components of robot from external damage. Because of this, spherical robot has to endure harsh environment if it want to be applied to practical work. Thus, it is very important to do research on the shell of spherical robot.Taking the shell of the spherical robot as the research object, this paper have completed the following work:According to the structure of the spherical robot made by Beijing University of Posts and Telecommunications and design requirements, diversified shell structures such as split joint shell, hemispherical shell, hemispherical shell with the connection and skeleton shell are designed in this paper. Simulation loads are refined. Shell material is preliminarily concluded. The merits and drawbacks of different types of shells are also discussed in this paper.Two kinds of different shell structure are designed in this paper. Finite elements computational models for different types of spherical shell structure are created for static load simulations. The ten order modal frequency and vibration shape structure analysis of the spherical robot is done in this paper. Simulation results of different pressing angles and different shell thicknesses are compared in this paper to find the weakest pressing angle and suitable shell thickness. According to the results of spherical shell coarse computational model, weak areas are found and the geometry features of these weak areas are restored. Two-scale simulation method is used for precise analysis of weak areas. Boundary conditions of sub-model are calculated in the coarse computational model, and precise analysis of sub-model is done with the boundary conditions.A material model which can reflect carbon fiber reinforced epoxy resin matrix composite material failure process is created in this paper through ANSYS secondary development platform according to three-dimensional Hashin failure criterion as well as stiffness degradation rule. The validity of the created material model has been verified in this paper through comparison of self-defined compound material layer tensile test results in ANSYS and literature data. The failure load on weakest condition is predicted with the material model.Topology analysis on spherical shell inner structure is done so as to provide theoretical basis for inner structure lightweight.