Papers by Author: Zhong Qin Lin

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Authors: Zhong Qi Yu, Zhong Qin Lin, Yu Ying Yang
Abstract: Aluminum alloy sheet is becoming one of the main materials to take the place of steel components to reduce the vehicle mass due to the advantage of low special density, high strength and corrosion resistance. To predict the formability during the aluminium alloy sheet forming accurately, , a ductile fracture criterion developed by the authors, was for numerical simulation, in this paper. Fracture behavior in square-cup forming of the aluminium alloy LF21M was predicted by means of the criterion. Comparison of the predicted results with experimental values shows that the critical punch stroke and the fracture initiation position in square-cup forming of the aluminium alloy have been predicted successfully by the criterion.
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Authors: Shan Ling Han, Zhong Qin Lin, Xiao Yang Lu
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Authors: Hai Dong Yu, Zhong Qin Lin, Ke Shi Zhang, Yong Jin Guo
Abstract: The cell model with twenty-five random dispersion voids was employed to analyze the damage and fracture mechanism of the nodular cast iron. The results show that the growth velocity of the voids has obvious difference with each other due to the random dispersion of voids. In the early stage of the deformation, the growth of the voids is mainly determined by the distance of the voids since the triaxiality stress parameter of the matrix around the voids is approximately equal. With the increase of the triaxiality stress parameter of the matrix materials around the void, the evolution velocity of the voids increases quickly. At the same time, this will influence the neighboring voids to grow quickly. The chain reaction of the rapidly increase of voids lead to the final material failure. The results can explain the fracture appearance of the smooth bar specimens under uniaxial tensile load really.
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Authors: Ti Kun Shan, Wei Gang Zhang, Zhong Qin Lin, Shu Hui Li
Abstract: The dependence of the transformation rate on the multiaxial stress state corresponding to different loading paths is investigated. On the basis of the single shear, uniaxial tension, plane strain and equibiaxial stretching tests, the influence of stress state on stability of retained austenite is analyzed and an equation of transformation kinetics is developed. In sheet metal forming, the material undergoes complicated deformation, the prediction of the volume fraction of retained austenite during forming process is essential to estimate the contribution of the TRIP effect to improving formability. To this aim, the volume fraction of retained austenite in the part’s different regions has been calculated using finite element method. The calculated results were compared with the experimental data measured in deep drawing experiments.
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