Papers by Author: Jian Sheng Dai

Abstract: Pseudo-rigid-body model (PRBM) method, which simplifies the geometrical nonlinear analysis, has become an important tool for the analysis and synthesis of compliant mechanisms. In this paper, a simplified 2R PRBM with two rigid links and two torsion springs is proposed. The characteristic radius factor and stiffness coefficients are selected as the design variables; in order to be better to simulate the tip point and tip slope, a three-dimensional objective function is formulated to optimize the new pseudo-rigid-body model. It is revealed in this paper that the precision of the tip point simulation can be improved when the coefficient of the tip slope error in the objective function is reduced.

Abstract: Because of special structure and dynamic behavior, the dynamic equations of metamorphic mechanism are variable during the process of configuration change. In order to combine dynamics analysis and structure design of metamorphic mechanisms intimately, a new method of forming dynamic model of metamorphic mechanisms is proposed based on fully Cartesian coordinate’s method and the relation between origin mechanism and sub-configuration. A new concept named origin constraint equation is introduced which can be converted into constraint equations of each sub-configuration easily by adding corresponding constraint equations of configuration change. Constraint equations commonly used in configuration change and dynamic equations of each configuration are given in the form of natural coordinates. Finally, a four-bar spherical metamorphic mechanism is used as an example to validate this dynamic modeling method.

Abstract: Based on the nutation movement of a rotating coin on a table, the formulae for calculating the transmission ratio between two nutation gears is developed. The tooth profile with a double circular arc for helical bevel gears in nutation drives is proposed and then the meshing equation during the nutation process and the universal equation of the crown gear tooth surface with helical double circular arc profiles are obtained based on the gear meshing theory. Further, the modeling for nutation drives with the proposed profile is carried out in a virtual working process.

Abstract: The toroidal drive offers the advantages such as a high horsepower-to-weight ratio, coaxial configurations, compactness and high operating efficiencies. It combines most of the positive attributes of a circular worm-gear drive and epicycle gear drive without their negative aspects due to the introduction of a set of rollers in meshing contact with rolling movement between a sun-worm and planet worm-gears, and between a stationary internal toroidal gear and planet worm-gears. However difficulties were encountered in machining the toroidal surface of the stationary internal toroidal tooth profile. This paper investigates the toroidal meshing surface and develops a mathematical modelling of the meshing surface and the conjugate surface using motion analysis of the epicyclic gear train. Then the enveloping and NC machining methods are proposed and based on these machining methods the stationary internal toroidal gear is manufactured. This results the comparative study of the tooth profile of manufactured toroidal gears by the proposed methods.