Papers by Author: Wei Na Hao

Abstract: This paper presents a new cycloid permanent magnet gear(PM gear) based on Halbach array, which has the advantages such as extreme torque density and a very high gearing ratio. And the Halbach array can produce one-sided filed that will increase the magnetic filed intensity. The air-gap magnetic field of cycloid PM gear based on Halbach is got by adopting finite element method. At the same time, to research the torque characteristics, the factors which affect the magnetic torque of cycloid PM gear are studied respectively through the FEM, such as torque angle，offset，thickness of permanent magnets and yoke irons.

Abstract: A viscoplastic constitutive model with void damage is developed to analyze the macroscopic mechanical response and damage mechanism of lead-free solder alloy in CBGA packaging under cyclic thermal loading. The constitutive model is implemented into ABAQUS through its user defined material subroutine. Two-dimensional nonlinear finite element analysis of a ceramic ball grid array(CBGA) package is conducted to simulate the viscoplastic deformation and damage failure process of the lead-free solder joint under cyclic thermal loading. The damage model is helpful for optimization and reliability of electronic package.