Papers by Author: Yuan Wei Liu

Abstract: This paper mainly addressed the kinematics simulation of the Slider-Crank mechanism. After proposing a mathematical model for the forward displacement of the slider-crank mechanism, the mathematical models for the forward velocity and acceleration of the slider-crank mechanism are constructed, respectively and the simulation models for the forward kinematics of the slider-crank mechanism are constituted in the Matlab/Simulink simulation platform. Finally the forward kinematics simulation of the slider-crank mechanism was successfully accomplished based on Matlab/Simulink. Examples of the simulation for the forward kinematics of a slider-crank mechanism are given to demonstrate the above-mentioned theoretical results.

Abstract: In this paper, we investigated the knowledge modeling and proposed an ontology description logic theory based on fuzzy interval in order to support the management and reuse of design knowledge. We also established the methods to classify and represent the concept-design knowledge and developed an ontology-based model presenting the design knowledge as well as a model for modeling cycles. We further applied these methods and models to develop a specific ontology-based design knowledge model and validated them in the management system of design knowledge for the construction machinery.

Abstract: A micro grooved finger has smaller bending stiffness and can be used to improve the performance of some micro cantilever devices. The deflection and bending stiffness of a micro grooved finger are discussed in this paper. An analytical model of the deflection is built up to study the effect of the groove sizes on the bending stiffness and the deflection of the grooved finger. The calculation of the analytical model is consistent with the simulation and experiment results. When the grooves depth is 0.5 μm, the spring constant of grooved micro finger is 19.8% smaller than that of flat finger without groove patterns. The spring constant of the finger decreases with the increasing of the width and depth of the groove. A novel micro electric-thermal gripper is introduced based on the grooved finger. It consists of four sub-cantilever beams arranged at the diagonal lines of the square frame in the end of the main cantilever structure suspended from the silicon substrate, which guarantees an effective contact by the four-point contact area on the top surface to grab object of importance. The thermal expansion induced deflection makes the fingers moving vertically from an ‘open’ position to a working one. The grooved fingers help to decrease the bending stiffness of the finger and increase the deflection and the initial gap. The simple fabrication process has a feasibility of compatible and mass production.

Abstract: Formulae of stress re-distribution and distortion by stress releasing during milling process are deduced by elasticity theory. Theory prediction of milling deformation due to residual stress is finished, and some calculating equation is given for the deformation solution. By means of these researches, the mechanism of the milling deformation due to residual stress is analyzed, the machining distortion caused by residual stress are analyzed and summarized using the analytical method.

Abstract: A new concept of surface geometric microtexture design is put forward in this article. The conditions of surface geometric microtexture are closely associated with the working surface’s capabilities of machine parts. Therefore, the distinction of surface topography will make a great difference to functional characteristics. However, the link between surface topography and functional characteristics has been neglected for long. With the development of manufacturing technology, special surface geometric microtexture can be designed and processed to achieve some specific goals. Surface geometric mecrotexture design based on function has been one of the important design criterions in some fields along with principle design and structure design, on account of its engineering special pertinence plus its significance in engineering and theoretical study.

Abstract: In order to reduce the weight of airplane and increase its mechanical behaviors, more and larger integrated parts are applied in modern aviation industry. When machining multi-frame aeroplane parts, more than 90% of the materials would be removed, resulting in severe distortion of the parts due to the weakened rigidity and the release of residual stress. This might also lead to stress concentration and damage of the parts. The effect of material removal from residually stressed billet is simulated using FEA software ANSYS, and the causations of distortion is analyzed. To verify the finite element simulation, a high speed milling test on aluminum alloy 7050T7351 is carried out. The results show that the simulation result is consistent with the experimental one. It included that the original residual stress in the blocks of aero-aluminum component is one of key factors to cause machining distortion.

Abstract: The key problems in 2D FEM simulation such as the establishment of finite element model, the initial stress loading, the distortion appraisal are solved and 2D FEM simulation model is built to analyze the milling distortion caused by the residual stress. The FEM model is verified by the elasticity theory. Some machining cases are simulated by using of the FEM model. The machining distortion caused by residual stress are analyzed and summarized using the simulation results.

Abstract: In this paper, we investigated the definition of product design knowledge, design knowledge origin characteristics and design knowledge formalized representation method, etc. We also established the methods to classify and represent the concept-design knowledge and developed an ontology-based model presenting the design knowledge as well as a model for modeling cycles. From the design knowledge management’s angle, design knowledge modeling approach is studied to support the design knowledge development, transfer and reuse for the construction machinery the knowledge modeling.

Abstract: In this study, a method called “house-building frame modeling” based on the APDL language is introduced firstly, and the finite element model of the milling distortion analysis is established for a platform structure with 192 frames by the method, and the prediction analysis of the milling distortion under different milling conditions is carried out, by means of 3-D finite element simulation technology. Comparing the simulation results and the measurement ones of the milling distortion, the proposed model is modified; the modeling method and prediction method are proved to be effective.

Abstract: The machining accuracy and the surface roughness of workpieces machined by the PKM named BJ-04-02(A) are evaluated by machining experiments in this paper. The machining accuracy includes that of size, shape and position. Size includes the diameter and length. Shape accuracy includes straightness, roundness and cylindricity. Position accuracy includes perpendicularity, parallelism, inclination and concentricity. The experiment results show that the surface roughness and the straightness basically meet the demand of JB/T8771.7-1998, but other accuracy indexes are not consistent well with the mechanical standard. However, the machining accuracy becomes bad when machining tool is far away from the center of the workspace.