Papers by Author: Xu Dong Yang

Abstract: Coal mine rescue capsules, whose structural strength defines miners' safety directly, are becoming important equipments for miners' underground escaping. In order to improve the rescue capsule's strength, in this study the finite element model was established in ABAQUS environment, and the influence on rescue capsule made by the pressure of gas explosion was obtained by using explicit integration method. The maximum stress of rescue capsule appears at the corner where it has stress singularity and the central part of the stiffeners where the stress reached the yield strength. But the overall stress is within the allowable range.

Abstract: The finite element model of cross simulator including supporting structure, beam, etc. was set up in the environment of ABAQUS. After the static analysis which meets the requirements, the model’s dynamic characteristics when bearing impact load was obtained using explicit method according to modal analysis results. Comparing different analysis results with technical index, it indicates that larger impact load makes the dynamic characteristics worse significantly.

Abstract: Based on topology optimization techniques of structural mechanics, an effective method for solving the structural design problems of heat transfer is presented in this paper. The topology optimization model of heat conduction is then constructed and the corresponding Optimization Criteria based on density approach is inferred to solve the optimal heat conduction equation of temperature field. A Filtering technique is employed in density field to eliminate numerical instabilities in the process of topology optimization. Some numerical examples are presented to demonstrate the accuracy and the applicability of the present method, theory and algorithm. This research provides a new idea and an access to the structural topology optimization design of temperature field, and is of good engineering application value.

Abstract: A novel profilometer for three-dimensional (3D) surface topography measurement is presented. The profilometer has large measuring range, high precision and small measuring touch force. It is composed of a two-dimensional (2D) displacement sensor, a 3D platform based on vertical scanning, measuring and control circuits and an industrial control computer. When a workpiece is measured, the vertical undulation of the profile at a sampling point leads to a zero offset of the 2D displacement sensor. According to the zero offset, a piezoelectric actuator and a servo motor drive the vertical scanning platform to move vertically to ensure that the lever returns to its balance position. So the non-linear error caused by the rotation of the lever is very small even if the measuring range is large. When the stylus barges up against a steep wall, the horizontal resistance force results in another zero offset of the 2D displacement sensor. If the zero offset exceeds a quota, the vertical scanning platform descends to make the stylus climb the steep wall successfully. According to the theoretical and experimental analysis, the profilometer can measure roughness, profile of sphere, step, groove and other 3D surfaces with curvature precisely.

Abstract: The surface topography characterization of MEMS device is very important to bonding technology of MEMS device. Motif characterizing method is a characterizing method of surface topography by graph. Aiming at the diversity and regionality of surface topography of MEMS device, in this study we have sampled the surface of MEMS device by 3-dimentinal grids using the surface profiler developed by us and characterizes the surface topography of MEMS device by the extended Motif characterizing method. The surface of MEMS device is divided into several Motif regions; the surface topography of every divided region can be evaluated respectively; the details of every region can be zoomed and these regions as a whole or every region can be revolved and projected; one of these regions can be as the reference of other regions. So the height, gradient and other characteristics of others regions of the whole MEMS device surface can be analyzed relative to the reference region; the whole and local surface topography of whole MEMS device can be analyzed.

Abstract: Focus detection method is one of non-contact profile measurement methods. However, the measurement accuracy of current focus detection method is limited by voice coil motor adopted by it. In this paper, based on an improved Foucault focus detection method, a new non-contact displacement sensor with diffraction grating metrology system is presented. Driven by a piezoelectric actuator instead of a voice coil motor, and a diffraction grating metrology system being with it, the sensor has high measurement accuracy. During surface profile sampling, according to focusing deviation signal, the focusing lens was driven to move vertically by the piezoelectric actuator so that its focus was always located on the workpiece surface, synchronously the vertical displacement of the focusing lens was obtained by the diffraction grating metrology system as the profile height of sampling points. The displacements of all sampling points gave the whole profile of the measured surface, which can be processed by a characterization software to obtain the measurement result. The resolution of the non-contact displacement sensor was 10 nm.