Topological design of electromechanical actuators with robustness toward over- and under-etching
Abstract In this paper, we combine the recent findings in robust topology optimization formulations and Helmholtz partial differential equation based density filtering to improve the topological design of electromechanical actuators. For the electromechanical analysis, we adopt a monolithic formulation to model the coupled electrostatic and mechanical equations. For filtering, we extend the Helmholtz-based projection filter with Dirichlet boundary conditions to ensure appropriate design boundary conditions. For the optimization, we use the method of moving asymptotes, where the sensitivity is obtained from the adjoint approach. Our study shows that the robust filter approach produces topology optimized actuators with minimal length control and crisp structural boundaries. In particular, the minimal length control of both structural features and gap widths avoids common modeling artifacts in topology optimization, i.e. one-element wide structural parts or gaps. It thus leads to physically realizable designs that are robust against manufacturing imprecision such as over- and under-etching.
A novel fully-decoupled dual-mass silicon micromachined gyroscope
A novel fully-decoupled dual-mass silicon micro-machined Gyroscope is presented in this paper to reduce the coupling between the drive mode and sense mode for high performance. The theoretical analysis was made based on the simplified kinematics model. Then, the configuration of the dual-mass double-linear vibratory gyroscope, a three-frame structure, was given. The numerical simulation was made, which shows the decoupling effect of the design. Finally, tests were done on the fabricated prototype. The bias instability is 3.02°/h and the nonlinearity of scale factor is less than 50ppm, which prove that this gyroscope has exhibited good mode-decoupling effect and good performance.
Modeling of chemical reactors—XXIX mixing-cell model for packed bed reactors. Steady state considerations. Problems of multiplicity
Abstract The axial heat and mass transfer in tubular catalytic reactors may be described by mixing-cell model and diffusion model as well. The diffusion description yields for a strong exothermic reaction and adiabatic conditions three steady state profiles, on the other hand the mixing-cell model gives rise to more than three steady states. A simple numerical and graphical analysis for mixing-cell model is presented.