Papers by Author: Jie Sun

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Authors: Gui Yu Li, Jian Feng Li, Jie Sun, Wei Dong Li, Liang Yu Song
Abstract: In the present study, the finite element model of machining carbon fiber reinforced aluminum matrix composites with representative fiber orientation of 90 degree is established with the following developments: (i) a Johnson-Cook constitutive model of each component in the multi-phase composite materials; (ii) a failure model of the composite material based on physical separation criterion; (iii) the interface between fiber and matrix defined by a interaction. This simulating method can be developed to each kind of fiber reinforced composite materials.
Authors: Dong Lu, Jian Feng Li, Yi Ming Rong, Jie Sun, Jun Zhou, Zhong Qiu Wang
Abstract: A burr formation process in micro-cutting of Al7075-T7451 was analyzed. Three stages of burr formation including steady-state cutting stage, pivoting stage, and burr formation stage are investigated. And the effects of uncut chip thickness, cutting speed and tool edge radius on the burr formation are studied. The simulation results show that the generation of negative shear zone is one of the prime reasons for burr formation. Uncut chip thickness has a significant effect on burr height; however, the cutting speed effect is minor. Unlike in conventional cutting, in micro-cutting the effect of tool edge radius on the burr geometry can no longer be neglected.
Authors: Fu Lai Sun, Jie Sun, Jian Feng Li, Liang Yu Song, Yu Guo Luo
Abstract: Linear expansion coefficient (CTE) is one of the important thermal parameters for materials, which has a great influence on the thermal deformation analyzing. Thermal Mechanical Analysis (TMA) is adopted to measure the CTE of pre-stretched aluminum alloy sheet 7050-T7451 in three vertical directions. The mathematical functions of CTE of aluminum alloy 7050-T7451 are established, which is with three directions and reflect the influence of the temperature. A comparison between the accurate CTE data and the CTE from reference is carried out .The reason of the CTE variation of aluminum 7050-T7451 with temperature also been explained qualitatively.
Authors: Feng Jiang, Jian Feng Li, Jie Sun, Song Zhang, Lan Yan
Abstract: For the analysis of cooling effect, the cutting inserts were heated to 900°C and then exposed in the room-air and cold-air with different pressure respectively. The temperature variation were recorded by infra-red (IR) pyrometer. The temperature-dependent global heat transfer coefficients were estimated by the theoretical analysis and experimental data. The finite element analysis (FEA) was employed to simulate the cooling process and modify the estimated heat transfer coefficients. The heat transfer coefficients decreased from 55.1 W/m2•°C (800°C) to 9.32 W/m2•°C (350°C) in the natural cooling and approximately 300 W/m2•°C (600°C) to 60 W/m2•°C (300°C) in the cold-air cooling. Cold-air cooling greatly increased the heat transfer coefficients, but it seemed the air pressure had little pressure on the heat transfer coefficients.
Authors: Rong Hua Yuan, Jie Sun, Jian Feng Li, Liang Yu Song, Yong Wu Zhang
Abstract: 69111-stainless steel has wide applications in aerospace industry due to its comprehensive performance. However, its machining properties are not well studied due to the short using history in product components. In this study, a series of end milling experiments were conducted to characterize surface integrity at various milling conditions. The experimental results have shown that the milled surface roughness value increases with increased feed and cutting speed, while decrease with axial depth-of-cut (DoC) , and presents an inflexion with the radial DoC, with a rang of 0.7~1.7μm. Residual stress determined by the coupling effect of mechanical and thermal deformations varies differently with the increased cutting parameters.
Authors: Jun Zhou, Jian Feng Li, Jie Sun
Abstract: In this paper, the micro-scale machining characteristics of a non-ferrous structural alloy, aluminum 7050-T7451 is investigated through a series of cutting experiments. The effects of cutting speed and undeformed chip thickness on the chip geometry, cutting ratio, effective rake angle and shear angle in orthogonal micro-scale cutting of Al 7075-T7451 are presented. Explanations for the observed trends are also given.
Authors: Fu Zeng Wang, Jie Sun, Jun Zhou, Jian Feng Li
Abstract: The mechanism of micro-milling modeling for aluminum alloy 7050-T745 is to be investigated, and a finite element model for micro-milling that reflects the actual state of the three-dimensional micro-milling is built by adopting the software of ABAQUS/Explicit. Experiment is conducted to verify the validation of the model. Simulated chip morphology in different cutting parameters agrees to the experimental results very well. Based on the FE model, cutting stresses, equivalent plastic strains, temperatures distribution and cutting forces are obtained and analyzed. This provides a good method to investigate the micro milling principles.
Authors: Jun Zhou, Jian Feng Li, Jie Sun
Abstract: In this paper, a series of simulation works by finite element method for predicting the temperature and the plastic strain distributions in micro cutting process with the tool edge radius considered were conducted. The workpiece is Aluminum alloy 7050-T7451 and its flow stress is taken as a function of strain, strain rate and temperature in order to reflect realistic behavior in machining process. From the simulation works, a lot of information on the micro-machining process can be obtained, such as cutting force, cutting temperature, distributions of temperature and plastic strain, etc. In addition, explanations for the observed trends are also given.
Authors: Fu Zeng Wang, Jie Sun, Pei Qin Sun, Jun Zhou
Abstract: In this paper, a finite element model with respect to actual state of micro-cutting is established by adopting software of ABAQUS/Explicit. Based on the FE model, the cutting force and specific cutting force with various uncut depth of cut with different cutting edge radius are compared and then analyzed with regard to this simulation. In micro-cutting, the nonlinear scaling phenomenon is more evident with the decreasing of uncut chip thickness. The likely explanations for the size effect in small uncut chip thickness are discussed in this paper.
Authors: Zhong Qiu Wang, Jian Feng Li, Jie Sun, Feng Jiang, Jun Zhou
Abstract: In the present study, two-dimensional orthogonal slot milling experiments in conjunction with an analytical-based computer code are used to determine flow stress data as a function of the high strains, strain rates and temperatures encountered in metal cutting. By using this method, the flow stress of Al7050-T7451 is modeled. Through the comparison of cutting forces between FEM and experiment, the FEM model using predicted flow stress can give precise cutting forces. The work of this paper provides a useful method for material constitutive equation modeling without doing large number of cutting experiment or expensive SHPB tests.
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