FEM analysis of the options of using composite materials in flexsplines

Purpose: In the present study, as the structural material for toothed flexsplines of harmonic drivers, a composite material based on an epoxy resin matrix reinforced with glass or carbon fibres was used. A preliminary numerical analysis of the material and structural solutions for the harmonic driver flexsplines assumed to be applied was conducted. Design/methodology/approach: Under the studies performed, geometrical models of flexsplines being manufactured for the HFUC and HFUS type harmonic drivers were developed based on their actual structures and geometrical dimensions. In order to enhance the data preparation process, the model geometry was recorded in a parametrical form. By altering the individual properties of the models, it is possible to automatically generate finite element grids for flexsplines of various geometrical and structural properties. The calculations prepared for the sake of the study by application of the finite element method (FEM) were conducted using the MSC Patran/Nastran and Femap/NX Nastran software. Findings: Using composite materials in production of flexsplines enables increasing the values of their fundamental vibration frequencies. Using composite materials based on an epoxy resin matrix reinforced with glass fibres causes an increase of the fundamental frequency values by ca. 20%, and if the reinforcement is made with carbon fibres, the values increase by up to 35% compared to flexsplines made of steel. Research limitations/implications: The technological problem involved in production of flexsplines from composite materials comprises the difficulties related to manufacturing of their rim teeth. A solution to this problem may be fabrication of steel-composite flexsplines. Originality/value: The results discussed apply to application of new structural (composite) materials for harmonic driver flexsplines that are currently manufactured using alloy steels assumed to be quenched and tempered.