Wan X.-J.,Hubei University of Automotive Technology |
Zhang Y.,Wuhan University of Technology
International Journal of Machine Tools and Manufacture | Year: 2013
In the aerospace industry, the reasonable layout of fixture can efficiently suppresses machining vibration of thin-walled aerospace structure during machining. Based on the analysis of typical structural components encountered in the aerospace industry, a general frame-structure workpiece with fixture constraints can be equivalent as Mindlin plates with simultaneous elastic edges and internal supports. On basis of the equivalent models, the powerful pb-2 Ritz method defined by the product of a two-dimensional polynomial and basic functions can be introduced to be taken as trial functions. Substituting displacement functions into energy functional and minimizing total energy by differentiation leads to eigenfrequency equations of the workpiece-fixture system. Consequently, a novel nonlinear programming problem based on the frequency sensitivity can be built to optimize the layout of fixture supports to maximize the fundamental nature frequency of the workpiece-fixture system. The feasibility of the proposed approach is validated by a machining case. © 2013 Elsevier Ltd.
Wang H.K.,Hubei University of Automotive Technology
Applied Mechanics and Materials | Year: 2014
Studying the core component of the resonant machine by building the bench test system, utilizing the nonlinear analysis function of Abaqus/Explicit to solve the problem that the rigid-flexible coupling model can't take the material nonlinearity into adequate consideration. Simulating the nonlinearity of the vibrating beam by doing time integration over the kinematic equation to obtain an accurate and reliable result. Firstly, simplifying the bench testing system to simulating the low frequent vibration; And then, comparing the acceleration root value between the test data and the simulating result on the characteristically point to check the reliability and accuracy of the simulation; By studying the hammer vibrating amplitude curve and shear stress curve changing along the rubber spring thickness, providing a preference for the optimization. © (2014) Trans Tech Publications, Switzerland.
Liu C.-X.,Hubei University of Automotive Technology
Jisuanji Jicheng Zhizao Xitong/Computer Integrated Manufacturing Systems, CIMS | Year: 2012
Automobile pressing moulds had various types and complex structures, and the cost was hard to estimate, thus the quotation had great difficulty. By using fuzzy mathematics theory, the die cost prediction model was constructed combining fuzzy close-degree analysis with exponential smoothing prediction. To decrease subjective factors of die similarity judgment with fuzzy mathematics, a method to calculate fuzzy nearness combined with rough set was proposed. According to die cost information database, the knowledge was classified by this mothed, and die cost information decision table was created. Objective weight distribution was made for each element of die characteristic set by using rough set attribute importance. Based on subjective weight and objective weight of experts judgment, the comprehensive weights of each element in die characteristic set was determined, and perdiction accuracy was improved. Considering the different influence degree of each die characteristic on price, the empirical formula of adjusting coefficient λ in die cost prediction was improved. The reliability and rationality of proposed method were verified by a group of die samples.
Zhang Y.,Hubei University of Automotive Technology
International Journal of Digital Content Technology and its Applications | Year: 2012
In comprehensive assessment based on integral concept and designed for matters and phenomena affected by multiple factors, grey correlation analysis is a widely recognized method. Grey correlation analysis is a statistical analysis method involved with various factors. Firstly, it will figure out the sample data for processing. Secondly, an ideal correlation coefficient comprised by the sample data and the most optimal index will be worked out, so as to obtain the corresponding degree of association from this correlation coefficient. This paper has briefly stated the basic principle and computation method of grey system theory. On this basis, through investigation and interview, by drawing support from R-typed factor analysis method, the paper conducted quantitative analysis and research on physical quality of China's famous speed skating athlete - Yu Jing, so as to explore and discuss factors affecting the performance of speed skating, as well as to discover inherent laws. In the meanwhile, by making use of Equal Dimension Grey Recurrence GM Model, the paper has established a prediction model for speed skating performance and physical quality index of Yu Jing. With this mode, a short term training goal for 2001-2003 was set up. In addition, with grey correlation analysis method, the advantages of Yu Jing's special sports ability were also analyzed.
Han X.,Hubei University of Automotive Technology |
Hua L.,Hubei University of Automotive Technology
Journal of Tribology | Year: 2013
Cold rotary forging is an advanced but complicated metal forming technology with continuous local plastic deformation. Investigating the wear is significant for effectively predicting the life of the dies and improving the workpiece surface quality. This paper is aimed to use the FE method to predict the wear response over the surfaces of the dies and the workpiece in cold rotary forging. For this purpose, a 3D elastic-plastic dynamic explicit FE model of cold rotary forging of 20CrMnTi alloy is developed using the FE software ABAQUS/Explicit and its validity is verified theoretically and analytically. Based on this valid 3D FE model, a systematic study has first been conducted, modeling and explaining the contact pressure and slip distance response. Then, the wear response that occurs at the surfaces of the dies and the workpiece is achieved. Finally, the effect of the process parameters, rotational speed n of the upper die, feed rate v of the lower die, outer/inner diameter of the ring workpiece, on the wear response is revealed. The results of this research help us better understand the complicated wear mechanisms in cold rotary forging. Moreover, the modeling methods proposed in this paper have the general significance to study the wear problems in other complicated metal forming processes. © 2013 by ASME.