Papers by Author: Jian Zhang

Abstract: This paper describes a 3D-deform simulation of porthole die extrusion process for producing harmonica-shaped tubes used for a cooling system of automobiles. Designing the related structure of the porthole die and observing the simulation results, the study was designed to evaluate the welding effect when the length of bearing exit take different values.The mean pressure and exit velocity at the welding plane are analyzed at the same time. The welding effect is determined by the mean pressure at the welding plane .The behavior of metal flow in the container is analyzed in this paper. Through the above analysis, the best structure and size can be obtained in the process of deformation so as to obtain the better machanical properties.

Abstract: Taking the high-strength steel 22MnB5 as the research object, starting from the phase transformation and the performance of the sheet at high temperature, the impact of various process parameters on the part was studied, pressing the stringers with hot forming technology simultaneously. Using metallurgical microscope, hardness tester and universal tensile testing machine, the microstructure and mechanical properties of the parts were analysed. The result show that, under the selected process parameters, the microstructure of the workpiece is desired lath martensite, the hardness is above 450HV, the tensile strength is above 1450MPa, which meet the production requirements.

Abstract: Tensile properties of 6061 aluminum alloy sheet were investigated by means of electric universal test machine, scanning electron microscopy ( SEM) etc．and compared with those parameters of 6010 aluminum alloy; By using machine performance parameters of 6061 aluminum alloy ,finite element software eta/DYNAFORM of Sheet Forming made the numerical simulation of Erichsen tester process of 6061 aluminum alloy sheet ,and the result of numerical simulation compared with actual Erichsen tester. The press forming performance of 6061 alloy sheet have been analyzed．The results show that compared with 6010 aluminum alloy, proof strength σ_s and tensile strength σ_b of 6061 aluminum alloy sheet exhibits worse,but even percentage elongation δ of 6061 alloy sheet exhibits similar; The value IE of numerical simulation exhibits similar with actual value IE. So 6061 aluminum alloy sheet have formability in a certain extent and apply in some fields of automobile instead of 6010 aluminum alloy.

Abstract: 6xxx based alloy auto body sheet will be used widely in the future, but, in the recent, one of the difficulty in practice is its poor formability. In this paper properties parameters of 6061 aluminum alloy sheet are investigated by means of examination; By using machine performance parameters of 6061 aluminum alloy, finite element software eta/DYNAFORM of Sheet Forming make the numerical simulation of auto deck lid outer panel .Stress, plastic strain, thick variety are analyzed; and the wrinkling and cracking prone areas identified. Therefore, the effective reference can be provided for design of forming process of 6xxx Based Alloy auto panel.

Abstract: In allusion to the non-linear relation in key parameters (internal pressure, axial extrusion force, radial back force) of Three-way tube hydroforming process, forecast and optimization models are established based on genetic algorithms and back propagation algorithms. By using the capacity of non-linear mappings of Artifical Neural Network and the capacity of global optimization of Genetic Algorithms，and using dynaform Finite Element simulation software to get samples and check results, the models can forecast and optimize parameters of T tube hydroforming process. The original tube could be in any bore, length, and wall thickness of a certain range. The results show that by using these models, parameters’ matching test numbers could be reduced, and the quality of T tube is excellent.

Abstract: This study simulated Bell-type annealing technology under laboratory conditions, and researched the effect of annealing time on the mechanical properties of SPCC cold-rolled steel sheet. The results indicate that the yield strength decreased with the extending of time; the plastic strain increases with the elongation of annealing time till a given time, and then decreased with the time extending; the cold-rolled specimen brittle fractured in tension while the annealed specimen shear fractured. Key words: microstructure mechanical properties Bell-type annealing SPCC cold-rolled steel sheet

Abstract: In power station big caliber thick wall seamless tube typical steel P91for example, The hot deformation behavior and heat flow stress-strain curve of the heat resistant steel P91was investigated with a compression test on Gleeble3500 simulator at a temperature range of 1050°C～1200°C and strain rate range of 10-4～5s-1. The test curve shows that P91 materials have the dynamic recrystallization and recovery behavior in high temperature and deformation. With the rise of temperature and strain rate of decreased, flow stress is lower and the dynamic recrystallization phenomenon is easier to occur. By metalloscope observed, in the high temperature and low strain rate conditions, the dynamic recrystallization area and new nucleation grain size are larger, and microstructure is more uniformly distributed.

Abstract: Employed DEFORM software to simulate vertical extrusion of large diameter thick-walled pipe, by using the Finite Element Method in the three-dimensional modeling software Pro/E of the CAD platform. Analyze the law of blank flow in extrusion process, distribution of stress and strain, and the influence of different extrusion ratio on deformation of thick-walled tube comparatively.

Abstract: The software of finite element simulation DEFORM-3D was used to simulate the extrusion process of the large diameter thick wall seamless steel tube, and the effective stress and load curves were analyzed in the situation of different concave die mould cone Angles. The simulation results show that with the increase of deformation degree, the effective stress and load of the blank increased gradually first and then reached a plateau. With the increase of the concave die mould cone Angle, the load of top die decreased.

Abstract: Hydraulic press is important pressure processing equipment, which has a wide range of applications in production and manufacturing industry. The structure of hydraulic press frame has an extremely significant effect on safety and usability. Against the structure of frame-type hydraulic press in this paper, a solid model has been built with CAD program Pro/E and the hydraulic press frame under working conditions is simulated by finite element simulation program ANSYS. This paper analyses the variation of stress, strain and frame deformation under working conditions, and the dangerous sections of hydraulic press frame can be found under the maximum work load. The research results show: The maximum value of effective strain and effective stress can be found in the screw holes of cylinder port, the maximum value of stress and strain in the direction of hydrocylinder force can be found in the confluence of upright column and lower beam, the maximum value of effective displacement and the displacement in the direction of hydrocylinder force can be found in cylinder port and part of upper beam.