Papers by Author: Ji Zhao

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Authors: Jun Zhao, Ji Zhao, Lei Zhang, Cheng Fan, Fei Fei Han
Abstract: Getting the real-time information of spatial data, height and length of weld bead is the key point during the process of grinding and polishing large-scale part. To tackle this problem, a robot visual system is completed by building the double CCD and the laser on the mobile robot. Combining the image search algorithm with the image preprocessing algorithm in time domain, the laser single pixel feature line is obtained. The positions of each point in feature line are optimized by curve fitting so that the right spatial data and dimension are obtained. The result shows the proposed method can provides the precise information of weld bead, and the accuracy of measurement is within 0.15mm, as steady as repeatability.
Authors: Shi Jun Ji, Ji Zhao, Lei Zhang, Hui Juan Yu, Xiao Long Liu, Xin Wang
Abstract: With the development of CAD/CAM, reverse engineering, geometric modeling, animation and computer graphics. In the past fifty years, many kinds of spline curve fitting methods have been produced. But, to authors knowledge, quality evaluation criterion about different spline curves are still not established and there is a lack of a comparing standard for analyzing different spline curves. Two spline curve fitting method comparing theorem is given and several various spline curves affecting factors are analyzed in this paper. Some comparable results are obtained by using the proposed quality evaluating theorem to different spline curves.
Authors: Wen Zheng Wu, Ji Zhao, Lei Zhang, Nan Feng, David W. Rosen
Abstract: Aiming to improve the defect mandible reconstruction operation success rate, the original mandible and fibular 3D model were modeling separately. According to the patient’s virtual reconstruction mandible 3D model, the mandible customized virtual ti-plate was designed and modeling. Through comparing the deformation simulation analysis of reconstructive mandible, the maximum deformation occurred near the mandible midline. There was little deformation at bilateral mandible ramus posterior. As the loading on the reconstructive mandible increasing, the maximum deformation near the mandible midline was increasing. According to the customized titanium plate virtual design and deformation simulation analysis of human lateral mandible defect before operation, the simulation could predict the mandible maximum deformation position after the surgery. The doctors could improve the operation precision of mandible reconstruction and probability of success significantly.
Authors: Zi Xuan Wang, Tian Biao Yu, Ji Zhao, Xue Zhi Wang, Xue Sun, Shi Xuan Liu
Abstract: To investigate the effect of Li2O, K2O and ZnO on SiO2-Al2O3-B2O3-Na2O vitrified bond for CBN grinding wheels, the refractoriness and fluidity of specimens with different additions were studied. The bending strength was measured by three-point bending tester and the microstructures were observed by super Depth-of-Field microscope. The results show that Li2O, K2O and ZnO can reduce the refractoriness and increase the high-temperature fluidity. Li2O and K2O make a contribution to improving the bending strength; however ZnO is harmful to specimens’ mechanical property. Additionally, the fluidity is important to control the number of gas bubbles in specimen according to the microstructure analysis.
Authors: Qing Zhou Sun, Ji Zhao, Shi Jun Ji, Lei Zhang, Shu Hong Zhou
Abstract: In this paper, a non-contact coordinate measuring machine with laser displacement sensor, which consists of three translational axes, is designed and built independently. In order to obtain the measuring precision, it needs to calibrate the coordinate measuring machine. Learning from the calibration method of contact coordinate measuring machine, a detection method is proposed for calibrating the precision of the non-contact coordinate measuring machine. Based on the homogeneous coordinate transformation theory, the error model of coordinate measuring machine is built under the condition that the positioning errors, angular errors, straightness errors and perpendicularity errors are taken into comprehensive consideration. The final error expressions of three axes can be calculated in the use of error model and homogeneous coordinate transformation theory. The final values of the errors are acquired through the analysis of the error curves, which can be obtained by using the laser interferometer system. The method proposed in this paper is using the two-dimensional ball plate to measure the errors. By locating three different positions of the ball plate in the space and using automatic centering procedure to measure the center position which is previously calibrated, the final errors of three axes can be detected directly. By comparing the two results, it testifies that the two-dimensional ball plate detection method is reasonable. Comparing with the laser interferometer method, the two-dimensional ball plate detection method reduces the workload of adjusting the optical path and the time of measuring errors, which has the vital significance in calibrating the precision of non-contact coordinate measuring machine.
Authors: Zhi Qing Hu, Ji Zhao, Zeng Ming Feng
Abstract: Micro-structured surfaces with drag reduction, desorption, and excellent optical performance are widely used in the field of automotive, aerospace, marine applications. Therefore, the manufacturing of the micro-structure on the metal surface is of high impotance. Although the processing methods for micro-patterning of surfaces have progressed in recent years, micro-structure processing is still not used on large metal surfaces. In this paper, a method of roll forming micro-structure on the plate surface is proposed. A simulation model for micro-structure roll forming (MRF) was presented by using three-dimensional finite element method (FEM). The strain and stress, and the displacements caused by micro-structure were analyzed. The results provide theoretical guidance for the design of different micro-structures and the sequence of their processing.
Authors: Shi Jun Ji, Lei Lei Liu, Ji Zhao, Jin Chao Li
Abstract: Silicon carbide, a high-strength material, has a ductile-brittle transition mechanism. In order to establish a reasonable silicon carbide abrasive belt grinding parameters to obtain high precision silicon carbide free-surface efficiently, a series of finite element simulations were conducted to comprehend the single point diamond grinding of silicon carbide using professional analysis software of nonlinear finite element in this paper. According to the differences of cutting parameter, such as cutting depth, cutting deformation of the chip and the maximum cutting force were studied. For the free-form surface with higher accuracy, the data showed that ductile machining of silicon carbide is more efficient along with the larger rake angle, the higher cutting speed and the smaller cutting depth.
Authors: De Xu Geng, Ji Zhao, Lei Zhang, Yun Wei Zhao
Abstract: This paper developed a novel elongation type of Pneumatic Artificial Muscle (PAM), which is mainly composed of the expandable internal rubber tube surrounded by the external cylindrical helical spring and the two ends are closed. The PAM is not only the actuator of the flexible joint but also the core components to make up of the flexible joint. Therefore, the mechanical properties of the PAM directly influence the performance of the flexible joint. A mathematical model on the axial deformation and bending stiffness of elongation type of PAM was built applying theoretical analysis and experimental research methods. The results show that the axial deformation of PAM and the air pressure supplying to the PAM are nonlinearly related due to the generic nonlinear of deformation of the rubber tube; the bending angle of the PAM is proportional to moment; Similarly, the bending angle of the PAM is also proportional to its length. Furthermore, it indicates that the air pressure indirectly affects the bending stiffness of PAM as the air pressure directly influences the elongation of PAM. Finally, this paper provides a powerful framework for the dynamic analysis and motion accuracy control of the flexible joint or the robot which is composed by the artificial muscles.
Authors: Cheng Fan, Ji Zhao, Lei Zhang, Jun Yuan
Abstract: In order to improve the ability to predict the manufacturability of the free-form surfaces, the complexity of geometries for free-form surfaces is defined and studied. The free-form surfaces are modeled, which is used to calculate the distribution feature values of the surfaces. According to the feature values, free-form surfaces are classified into several clusters based on the fuzzy clustering algorithm. Group patterns are established according to feature values of the samples in the clusters. Then, the method of fuzzy pattern recognition is used to evaluate the surface complexity. The surface samples in the same cluster have close geometry configuration, so they often have similar manufacturing processes. A case study shows that the method can quickly classify the surfaces, largely reflecting the complexity of the free-form surfaces, which can lay the foundation for manufacturability evaluation of the complex surfaces.
Authors: Zhi Qing Hu, Ji Zhao, Yu Shan Deng, Hao Han Zhang
Abstract: In this study, the principle of the stretch forming combined with roll forming(SRF) is proposed, to present the availability of this process, it is simulated by the Method of Finite Element Analysis(FEA) by comparing traditional stretch forming(SF) with stretch roll forming (SRF), the result is shown that the roller covered the rubber rolling sheet metal is benefit to formed part, such as Von mises stress, the thickness thinned and the coincidence curve of formed part are studied.
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