Imperial College London

ProfessorJianguoLin

Faculty of EngineeringDepartment of Mechanical Engineering

Head/Professor in Mechanics of Materials Division
 
 
 
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Contact

 

+44 (0)20 7594 7082jianguo.lin

 
 
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Assistant

 

Miss Valerie Crawford +44 (0)20 7594 7083

 
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Location

 

524City and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

285 results found

Chavoshi SZ, Jiang J, Wang Y, Fang S, Wang S, Shi Z, Lin Jet al., 2018, Density-based constitutive modelling of P/M FGH96 for powder forging, INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES, Vol: 138, Pages: 110-121, ISSN: 0020-7403

JOURNAL ARTICLE

Chung T-F, Yang Y-L, Huang B-M, Shi Z, Lin J, Ohmura T, Yang J-Ret al., 2018, Transmission electron microscopy investigation of separated nucleation and in-situ nucleation in AA7050 aluminium alloy, ACTA MATERIALIA, Vol: 149, Pages: 377-387, ISSN: 1359-6454

JOURNAL ARTICLE

Ganapathy M, Li N, Lin J, Abspoel M, Bhattacharjee Det al., 2018, A Novel Grip Design for High-Accuracy Thermo-Mechanical Tensile Testing of Boron Steel under Hot Stamping Conditions, EXPERIMENTAL MECHANICS, Vol: 58, Pages: 243-258, ISSN: 0014-4851

JOURNAL ARTICLE

Kopec M, Wang K, Politis DJ, Wang Y, Wang L, Lin Jet al., 2018, Formability and microstructure evolution mechanisms of Ti6Al4V alloy during a novel hot stamping process, MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, Vol: 719, Pages: 72-81, ISSN: 0921-5093

JOURNAL ARTICLE

Li Y, Shi Z, Lin J, Yang Y-L, Saillard P, Said Ret al., 2018, FE simulation of asymmetric creep-ageing behaviour of AA2050 and its application to creep age forming, INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES, Vol: 140, Pages: 228-240, ISSN: 0020-7403

JOURNAL ARTICLE

Li Y, Shi Z, Lin J, Yang YL, Saillard P, Said Ret al., 2018, Effect of machining-induced residual stress on springback of creep age formed AA2050 plates with asymmetric creep-ageing behaviour, International Journal of Machine Tools and Manufacture, Vol: 132, Pages: 113-122, ISSN: 0890-6955

© 2018 Elsevier Ltd Effect of machining-induced residual stresses on springback of creep age formed (CAFed) AA2050 plates with asymmetric creep-ageing behaviour has been investigated experimentally and numerically in this study. A finite element (FE) model integrating unified asymmetric creep-ageing constitutive model for CAF of AA2050 has been developed through a commercial FE software-PAM-STAMP and a simplified machining-induced residual stress field for aluminium alloy plates has been proposed and implemented into the FE model. Different levels of residual stresses have been considered in the FE model and numerical results have been compared with corresponding CAF experiments and surface residual stress measurements. Results show that the springback prediction of the FE models has been significantly improved when the residual stress effect was considered. The best prediction can be achieved with a certain residual stress level for each plate thickness and the level increases with decreasing thickness of the plates produced by machining, which agrees well with the surface residual stress measurement results. For CAF of AA2050 with asymmetric creep-ageing behaviour, different springback behaviour has been observed with different residual stress levels: introduction of residual stress fields can either decrease or increase formed deflections of CAFed AA2050 plates, depending on the relative levels of residual stresses and the stresses caused by applied external forces. When the residual stress is large, subsurface of the plate may exceed the elastic limit after applying external force, leading to a significant decrease of springback in the CAFed plates.

JOURNAL ARTICLE

Lin J, Axinte D, 2018, Professor Trevor A. Dean and his contribution to the Journal, International Journal of Machine Tools and Manufacture, Vol: 133, Pages: 1-3, ISSN: 0890-6955

JOURNAL ARTICLE

Pan R, Shi Z, Davies CM, Li C, Kaye M, Lin Jet al., 2018, An integrated model to predict residual stress reduction by multiple cold forging operations in extra-large AA7050 T-section panels, PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART B-JOURNAL OF ENGINEERING MANUFACTURE, Vol: 232, Pages: 1319-1330, ISSN: 0954-4054

JOURNAL ARTICLE

Politis DJ, Politis NJ, Lin J, Dean TAet al., 2018, A review of force reduction methods in precision forging axisymmetric shapes, INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY, Vol: 97, Pages: 2809-2833, ISSN: 0268-3768

JOURNAL ARTICLE

Politis DJ, Politis NJ, Lin J, Dean TA, Balint DSet al., 2018, An analysis of the tooth stress distribution of forged bi-metallic gears, PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE, Vol: 232, Pages: 124-139, ISSN: 0954-4062

JOURNAL ARTICLE

Shao Z, Bai Q, Li N, Lin J, Shi Z, Stanton M, Watson D, Dean Tet al., 2018, Experimental investigation of forming limit curves and deformation features in warm forming of an aluminium alloy, PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART B-JOURNAL OF ENGINEERING MANUFACTURE, Vol: 232, Pages: 465-474, ISSN: 0954-4054

JOURNAL ARTICLE

Shao Z, Li N, Lin J, Dean TAet al., 2018, Strain measurement and error analysis in thermo-mechanical tensile tests of sheet metals for hot stamping applications, PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE, Vol: 232, Pages: 1994-2008, ISSN: 0954-4062

JOURNAL ARTICLE

Xiao W, Wang B, Zheng K, Zhou J, Lin Jet al., 2018, A study of interfacial heat transfer and its effect on quenching when hot stamping AA7075, Archives of Civil and Mechanical Engineering, Vol: 18, Pages: 723-730, ISSN: 1644-9665

© 2017 The aim of this research was to investigate the effects of contact pressure and lubrication on the interfacial heat transfer coefficient (IHTC) between AA7075 sheet and H13 tool steel and the in-die quenching performance in hot stamping. Firstly, a series of designed in-die quenching experiments were performed using different contact pressures, 0.05–30 MPa and lubrication conditions to determine the IHTC values using an efficient methodology. Secondly, temperature evolution of the tools and blank during the in-die quenching was investigated. Mechanical properties of material in-die quenched under different process conditions, were measured to determine their relation to quench conditions. The results have shown that IHTC values increased with increasing contact pressure and use of lubricant. A strength level of T6 condition could be obtained using a contact pressure greater than 5 MPa in the lubricated condition.

JOURNAL ARTICLE

Zheng J-H, Lin J, Lee J, Pan R, Li C, Davies CMet al., 2018, A novel constitutive model for multi-step stress relaxation ageing of a pre-strained 7xxx series alloy, INTERNATIONAL JOURNAL OF PLASTICITY, Vol: 106, Pages: 31-47, ISSN: 0749-6419

JOURNAL ARTICLE

Zheng J-H, Pan R, Li C, Zhang W, Lin J, Davies CMet al., 2018, Experimental investigation of multi-step stress-relaxation-ageing of 7050 aluminium alloy for different pre-strained conditions, MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, Vol: 710, Pages: 111-120, ISSN: 0921-5093

JOURNAL ARTICLE

Zheng K, Lin J, Wu G, Hall RW, Dean TAet al., 2018, EXPERIMENTAL INVESTIGATION AND MODELLING OF HOT FORMING B4C/AA6O61 LOW VOLUME FRACTION REINFORCEMENT COMPOSITES, JOURNAL OF THEORETICAL AND APPLIED MECHANICS, Vol: 56, Pages: 457-469, ISSN: 1429-2955

JOURNAL ARTICLE

Zhou W, Lin J, Dean TA, Wang Let al., 2018, Feasibility studies of a novel extrusion process for curved profiles: Experimentation and modelling, International Journal of Machine Tools and Manufacture, Vol: 126, Pages: 27-43, ISSN: 0890-6955

© 2017 The work described in this paper concerns a novel method for directly forming curved profiles/sections from billets in one extrusion operation using two opposing punches. Its mechanics are based on internal differential material flow, and it has been given the acronym, differential velocity sideways extrusion (DVSE). A tool set enabling sideways extrusion to be performed using opposing punches moving with different velocities was used for a series of experiments in which punch velocity ratio and extrusion ratio were process parameters. Plasticine was used as a model work-piece material and a series of compression tests were undertaken, to determine its constitutive properties and gain an estimate of work-piece die friction for use in process simulation. Curvature of extrudate can be controlled and varied using a difference between the velocities of the two punches, defined by velocity ratio. Greater curvature is achieved with lower velocity ratio. Curvature is also dependent on extrusion ratio, an increase in which increases curvature, although curvature is less sensitive to it than to velocity ratio. The extent of work-piece flow velocity gradient across the die exit orifice, which causes curvature, has been identified. Severe plastic deformation of the extrudate occurs in a way similar to channel angular extrusion (CAE), thus a greatly promoted effective strain level is achieved, though it is not always uniform across a section. The inner bending region of an extrudate experiences maximum localised effective strain, which decreases with decrease in curvature. To the authors' knowledge this is the first publication in which extrudate curvature is deliberately induced using opposing punches with differential velocities. Although only fixed velocity ratio values have been used in the work described in this paper the ability to change during operation exists and the process has the potential for the production of a profile with different curvature along it

JOURNAL ARTICLE

Zhou W, Lin J, Dean TA, Wang Let al., 2018, Analysis and modelling of a novel process for extruding curved metal alloy profiles, INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES, Vol: 138, Pages: 524-536, ISSN: 0020-7403

JOURNAL ARTICLE

Zhou W, Shi Z, Lin J, 2018, Upper bound analysis of differential velocity sideways extrusion process for curved profiles using a fan-shaped flow line model, International Journal of Lightweight Materials and Manufacture, Vol: 1, Pages: 21-32, ISSN: 2588-8404

JOURNAL ARTICLE

Bai Q, Mohamed M, Shi Z, Lin J, Dean Tet al., 2017, Application of a continuum damage mechanics (CDM)-based model for predicting formability of warm formed aluminium alloy, INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY, Vol: 88, Pages: 3437-3446, ISSN: 0268-3768

JOURNAL ARTICLE

Dong Y, Zheng K, Fernandez J, Li X, Dong H, Lin Jet al., 2017, Experimental investigations on hot forming of AA6082 using advanced plasma nitrocarburised and CAPVD WC: C coated tools, JOURNAL OF MATERIALS PROCESSING TECHNOLOGY, Vol: 240, Pages: 190-199, ISSN: 0924-0136

JOURNAL ARTICLE

Ganapathy M, Li N, Lin J, Bhattacharjee Det al., 2017, Investigation of a new hot stamping process with improved formability and productivity, Pages: 771-776

In order to improve the drawability of boron steel and also to increase the productivity of hot stamping process, a new hot stamping process with pre-cooling has been proposed. Stress-strain behavior at various temperatures was investigated and compared with that in traditional hot stamping processes. Detailed studies were carried out on the strain hardening parameter, n, at different temperatures and deformation rates. To evaluate this concept, hot stamping experiments were performed with both conventional (without pre-cooling) and new process (with pre-cooling) for a scaled down B-Pillar automotive component. The new hot stamping process with pre-cooling was able to produce the B-Pillar at low temperature (500°C) with less thinning than the hot stamping carried out without precooling at high temperature (765°C). Also the in-die quenching time was reduced by about 60%, by adopting the new hot stamping process with pre-cooling, which would increase the productivity significantly for automotive mass production without compromising the part quality.

CONFERENCE PAPER

Ganapathy M, Li N, Lin JG, Abspoel M, Bhattacharjee Det al., 2017, Test-Piece and Test-Rig Designs to Obtain High Accuracy Experimental Data for Boron Steel at Hot Stamping Conditions, 3rd International Conference on Advanced High Strength Steel and Press Hardening (ICHSU), Publisher: WORLD SCIENTIFIC PUBL CO PTE LTD, Pages: 109-113

CONFERENCE PAPER

Huang X, Wang B, Lin J, Zhu Cet al., 2017, Effect of mandrel diameter on non-circularity of hollow shafts in cross wedge rolling, Pages: 2376-2381

© 2017 The Authors. Published by Elsevier Ltd. Because of the need for lightweight design, the application of hollow shaft parts rapidly increases. The mandrel plays an important role in the process of forming hollow shafts using cross wedge rolling (CWR). This paper presents the experimental and numerical analysis on the effect of the mandrel diameter on non-circularity in CWR for the hollow shafts with mandrel. A thermomechanical finite element (FE) model was developed to simulate the CWR process of hollow shaft. The experiments and numerical analysis suggest that the diameter of mandrel has a great effect on the non-circularity of hollow shafts. During the CWR process, because of the effect of the mandrel, the workpiece is compressed in radial direction and extended along the circumferential direction, which lead to the increase of the non-circularity. With increasing diameters, the workpieces show larger non-circularity. The non-circularity slowly increases when mandrel diameter is small. However, when the mandrel diameter exceeds a certain value, the non-circularity increases rapidly. Besides, the non-circularity of the inner hole is larger than that of the outer circle. According to the strain curves during the forming process, it can be found that circumferential compressive strain plays an important role in the rounding forming stage. Larger compressive strains decrease the non-circularity of the rolled pieces.

CONFERENCE PAPER

Huo Y, Lin J, Bai Q, Wang B, Tang X, Ji Het al., 2017, Prediction of microstructure and ductile damage of a high-speed railway axle steel during cross wedge rolling, JOURNAL OF MATERIALS PROCESSING TECHNOLOGY, Vol: 239, Pages: 359-369, ISSN: 0924-0136

JOURNAL ARTICLE

Huo Y, Wang B, Lin J, Bai Q, Ji H, Tang Xet al., 2017, Hot compression deformation behavior and microstructure evolution rule of a high-speed railway axle steel, Indian Journal of Engineering and Materials Sciences, Vol: 24, Pages: 447-454, ISSN: 0971-4588

© 2017, National Institute of Science Communication and Information Resources (NISCAIR). All rights reserved. The high performance of high-speed railway axle (HSRA) depends on the stress-strain state and microstructure formed in the hot processes, it is necessary to investigate the deformation behavior and microstructure evolution during hot uniaxial compression. Hot compression test was performed on specimen of a HSRA steel 25CrMo4 at a deformation temperature of 1040-1160oC at a strain rate of 1.0-10.0 /s using a Gleeble thermal mechanical simulator. During hot compression test, samples were compressed to different true strain: 0, 0.2, 0.4, 0.6 and 0.8. Hot compressive deformation behaviors and effects of processing parameters, including forming temperature, strain rate and deformation degree, on microstructure evolution of HSRA steel 25CrMo4 are investigated and studied by metallurgical analysis. Experiments results show that the peak value of flow stress increases about 30 MPa at a certain deformation temperature when the strain rate increases from 1.0 /s to 10.0 /s. At a certain strain rate, the peak value of flow stress increases about 20-30 MPa when the forming temperature decreases about 60oC. The average grain sizes increases with the increasing of forming temperature at a certain strain rate and a given strain. For a given forming temperature, grain size decreased before the critical strain of 0.4 and increased after strain of 0.4 due to grain growth, especially at lower strain rate. Therefore, grain size at lower strain rate is larger than that at higher strain rate when true strain reached 0.8.

JOURNAL ARTICLE

Ji H, Liu J, Wang B, Tang X, Lin J, Huo Yet al., 2017, Microstructure evolution and constitutive equations for the high-temperature deformation of 5Cr21Mn9Ni4N heat-resistant steel, JOURNAL OF ALLOYS AND COMPOUNDS, Vol: 693, Pages: 674-687, ISSN: 0925-8388

JOURNAL ARTICLE

Jiang J, Hooper P, Li N, Luan Q, Hopper C, Ganapathy M, Lin Jet al., 2017, An integrated method for net-shape manufacturing components combining 3D additive manufacturing and compressive forming processes, Pages: 1182-1187

© 2017 The Authors. Published by Elsevier Ltd. Additive manufactured (AM) or 3D printed metallic components suffer poor and inconsistent mechanical properties due to the presence of a large number of micro-voids, residual stress and microstructure inhomogeneity. To overcome these problems, a new forming process has been proposed, which effectively combines AM and compressive forming. The aim of this study is to prove the feasibility of this newly proposed method by providing preliminary results. Thus, we compared the tensile performance of hot-forged additive manufactured stainless steel 316L samples to none-hot-forged additive manufactured ones. Significant improvement in mechanical properties has been found in the tensile tests as well hardness test. In addition, our EBSD characterized grain orientation maps at each stage of the process revealed the corresponding microstructure revolution which provides insights into underlying mechanistic.

CONFERENCE PAPER

Kaye MC, Balint D, Lin J, Farrugia Det al., 2017, Test-piece design for experimental and numerical evaluation of damage in relation to spatial triaxial stress inversion, INTERNATIONAL JOURNAL OF DAMAGE MECHANICS, Vol: 26, Pages: 588-607, ISSN: 1056-7895

JOURNAL ARTICLE

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