Papers by Author: Shi Ping Sun

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Authors: Guo Hua Qin, Dong Lu, Shi Ping Sun, Hai Chao Ye
Abstract: In order that the required manufacturing processes can be carried out, fixtures are developed to locate and hold a workpiece firmly in the accurate position. However, source errors of fixtures can change the accurate position and in turn, cause the locating error. It follows that the evaluation of locating error is important to fixture design. Therefore, a general approach to the locating error analysis is formulated for the first time. Firstly, a kinematic model and its algorithm of the locating error are proposed to analyzing the linear dimension based on the velocity composition law of particle movement. In addition, according to the relationship between the linear velocity and angular velocity, another kinematic model and its algorithm of the locating error are also formulated to verifying the angular dimension.
Authors: Guo Hua Qin, Shi Ping Sun, Zhi Xiong Chen, Tie Jun Wu, Zhi Qiang Ao
Abstract: Multiple clamps are frequently used to serve the purpose of workholding in a fixture. So multiple clamping forces including their magnitudes, placements and application sequences, greatly influence contact forces and workpiece machining accuracy. In this paper, the impact of multiple clamping forces on workpiece location error is formulated analytically for a workpiece-fixture system. The proposed model takes into account the varying contact forces and friction force during entire clamping operation. It reveals that the historical accumulation of clamping steps influences heavily the final distribution of contact forces in the workpiece-fixture system. In addition, based on effect of contact forces from one step to another on workpiece location, a novel design model is presented to optimize the multiple clamping forces in order to minimize the workpiece location errors. Some numerical tests are finally demonstrated to validate the proposed model and approach.
Authors: Shi Ping Sun, Zheng Hu
Abstract: In this paper, the working frequency band gap of ultrasonic motor (USM) was investigated under finite element model and experimental prototype. The findings indicate that the discrepancy between theoretical analysis and experimental test is mainly related to the fixation conditions of stator. This work proposes a new geometrical symmetrical stator for standing-wave-type linear USM to reduce the discrepancy. The first longitudinal and the second bending modes of stator are combined to drive the USM. Parameterized finite element model with actual boundary is developed to analyze and optimize the stator performance. The results show that the gap between working frequencies can be substantial reduced compared to the initial design.
Authors: Shi Ping Sun, Yu Dong Lai
Abstract: A computational model, which can reveal the out-plane size variation of sandwich panel unit cell, is proposed to study the out-plane size effects of honeycomb sandwich panels. In this model, the three dimensional unit cell of sandwich panel, consisting of the upper and the lower skins and the homogenized core, is constructed based on homogenization method. Three methods, i.e., homogenization method, the finite element method and the classical laminated plate theory, are used to study the influences of the out-plane size variation on the bending effect and vibration response of sandwich panel. Numerical results show that the solution of finite element method agrees with that of laminated plate theory when the number of out-plane unit cell is small. However, once the number of out-of-plane unit cell is large enough, the finite element solution is close to the homogenization results.
Authors: Guo Hua Qin, Dong Lu, Shi Ping Sun, Yi Ming Rong
Abstract: In machining process, the workpiece is subject to cutting forces and torques. To resist these external loads, a fixture can supply clamping forces to completely restrain the workpiece. However, insufficient clamping forces cannot prevent the workpiece from translation and rotations, whereas excessive clamping forces may cause strongly the improper workpiece-fixture system deformations. Therefore, how to effectively determine the optimum clamping forces is the main objective of this paper. Firstly, a mechanistic model is proposed to measure the stability of clamping forces against these external loads. Secondly, a relaxation method is further established to true obtain the optimum clamping forces by solving the proposed model. The presented approach is conceptually simple and computationally efficient. It is particularly useful in the early stages of fixture design and process planning.
Authors: Ke Peng Qiu, Wei Hong Zhang, Shi Ping Sun, Ji Hong Zhu
Abstract: Nowadays, the topology optimization method is extensively adopted for the design of material microstructures to achieve desired behaviors. The present work is concerned with the optimal design of the stiffness and thermal conductivity of 3D microstructure unit cells with the specific material volume fraction in conjunction with the homogenization method and the finite element method. Numerical examples are given to demonstrate that optimal material layouts are successfully achieved and the initial layout has a great effect on the optimal microstructure.
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