Guang Jun Liu

Characterization of a MEMS Accelerometer Considering Environmental Temperature Fluctuations

This paper investigates the effects of environmental temperature fluctuations on the performance of a MEMS accelerometer. The model, vibration equation, and calculation of the output of detection capacitance for the accelerometer are presented. The fluctuations in temperature are considered when evaluating the actual performance of the device. The analysis results show that temperature fluctuations have a great influence on the output of the accelerometer although it has little influence on the resonant frequency of sensing mode and the sensitivity of detection capacitance. The performance deviations under the effects of temperature fluctuations are calculated accurately, which provides a reference for the design of temperature compensation method and robust design for the accelerometer.

Robust Optimization of an Accelerometer Considering Fabrication Errors

A robust optimization approach of an accelerometer is presented to minimize the effect of variations from micro fabrication. The sensitivity analysis technology is employed to reduce design space and to find the key parameters that have greatest influence on the accelerometer. And then, the constraint conditions and objective functions for robust optimization and the corresponding mathematical model are presented. The optimization problem is solved by the Multiple-island Genetic Algorithm and the results show that an accelerometer with better performance is obtained.

Cellular Automata Method for Reconstruction of Complex Groove of Milling Insert

This paper presents a self-organizing method for reconstruction of complex groove of milling insert. The local rule of Cellular Automata is proposed to design and optimize the groove of milling insert. The states of cells are modified according to the local rule applied. The state of the entire system is updated based on the state of the cell and its neighboring cell, and these cells’ states define the state of the entire domain, and the groove can be reconstructed. The reconstructed groove is tested by a FEM simulation. The simulation results show that the reconstructed groove has a satisfied performance on the stress field and temperature field.

Research on Maintenance Strategy of Large-Scale Grab Ship Unloader Based on Reliability

t is hard to acquire the failure data of ship unloader and the mean time to failure is not independent identically distributed, and there are many defects existed in the maintenance method such as high cost and bad effect. In this work, we propose a method based on Weibull Distribution model to deal with the failure data of a large-scale grab ship unloader, build up the model of MTBF (Mean Time Between Failure) and preventive maintenance time, and show the example with failure data, which provides references to maintenance of the ship unloader. Finally, we present the decision process of the reliability-centered maintenance strategy, maintenance type of the grab ship unloader and the maintenance of the key parts, which provides scientific decision support for the maintenance of the ship unloader equipments.

Experimental Study on Wear and Fracture of Ball-End Milling Cutter in High Speed Machining Stainless Steel 0Cr13Ni4Mo

An experimental study on wear and fracture of ball-end milling cutter in high speed machining martensitic stainless steel 0Cr13Ni4Mo is studied in this work. Through the SEM micrographs and energy spectrum analysis of the wear pattern of the rake face, severe coating spalling is found near the main cutting edge. Fracture is seen on the entire cutting edge, in which micro-chipping occurs on the both ends of the cutting edge, and chipping occurs in the middle of the cutting edge and is the conchoidal spalling on the rake face. Combined with the high-speed photography of the milling process, the fracture area is consistent with the chip-adhesion area.

Research on Solid Modeling and a Different Mode of Loading with Finite Element Analysis for Flat End Mill

This work aims to investigate parameterized modeling and a different mode of loading with finite element analysis for flat end mill. A loading mode is chosen according to the cutting force model of overall end mills. Normal and shear stresses which calculate from the cutting force experiments are loaded on the rack face of flat end mill. The stress distribution of end mill in high-speed cutting is obtained by finite element analysis. It is shown that the maximum stress is located at major flank face near the tool tip, rather than the nose of tool and the chisel edge. It shows the tool breakage mechanism in the local region. In the end, we compared the finite element analysis results with the experiment ones. It indicates that the analysis results agree well with the experimental data. Therefore, the proposed loading mode is available.

Three-dimensional Complex Groove Reconstruction of Cutting Tools using Multidisciplinary Design Optimization Method

In the design and optimization of cutting tool’s groove, it is necessary to comprehensively consider the multidisciplinary coupling effects of stress field, temperature field and working environment, and balance the coupling effects on the cutting performance. The multidisciplinary optimization method is employed to study the 3D complex groove reconstruction of cutting tools in this paper. The two-level reconstruction approach is proposed. The groove reconstruction of waved-edge insert is presented as a numerical example, and an optimal design of the groove is obtained. The optimization results show that the reconstructed tool has a satisfied performance on the stress field and temperature field.

MCA Model for Chip Breaking and Curling of Orthogonal Cutting

The Movable Cellular Automata (MCA) method is introduced into the analysis of cutting process, and is employed to build the discretised MCA tool-chip model of orthogonal cutting. The chip breaking and curling rule are proposed to determine the MCA local rule. The simple local rule and discretised method are presented to describe the continuous process of chip’s formation and breaking. The states’ rule of a cell and its neighbors can be used to predict and calculate the chips’ breaking and curling. The numerical calculation and a numerical example in the process of chip breaking and curling are proposed.

A Rapid Analysis Method for Microgyroscope Using System Vibration Modes

This paper proposes a rapid dynamic analysis method for microgyroscope using system vibration modes to solve the problems concerning to the computing time in the performance analysis of microgyroscope. The results of eigenvalue solution are employed to construct the state space model. The response of the microgyros cope can be reconstructed as a response superposition of the vibration modes, and then the system equation is decoupled into an uncoupled equation. The dynamic response of the microgyroscope can be calculated by a simple superposition.

Research on Temperature Field under Regular Gradient Heat Source of Milling Insert with Complex Groove Using Cellular Automata Algorithm

Lots of cutting heat is generated in milling process, and an unsteady temperature distribution is generated, which is the radical reason of impactive fracture and sticking-welding fracture of the tool. In this paper, the Cellular Automata model of regular gradient heat source on the rake face of milling insert is built using heat transfer theory and cutting principle to analyze the temperature field generated. The boundary condition of the insert is established and the unsteady temperature field of the insert is obtained using the Cellular Automata algorithm, which can be a basis for the direct reconstruction of the insert.