Institute of Fundamental Technological Research
Polish Academy of Sciences


X. Liu

Recent publications
1.  Liu X., Kopeć M., Fakir O., Qu H., Wang Y., Wang L., Li Z., Characterisation of the interfacial heat transfer coefficient in hot stamping of titanium alloys, International Communications in Heat and Mass Transfer, ISSN: 0735-1933, DOI: 10.1016/j.icheatmasstransfer.2020.104535, Vol.113, pp.104535-1-14, 2020

The interfacial heat transfer coefficient (IHTC) for titanium alloys is an important parameter in non-isothermal hot stamping processes to determine the temperature field as well as temperature-dependent material behaviours that consequently affect the post-form properties of the formed components. However, the IHTC for titanium alloys in hot stamping processes has seldom been studied before. In the present research, the effects of contact pressure, lubricant, surface roughness, tooling material and initial blank temperature on the IHTC for the titanium alloy Ti-6Al-4V were studied and modelled to characterise the IHTC values under various hot stamping conditions as well as identify the functional mechanisms affecting the IHTC. Furthermore, the results of hot stamping of Ti-6Al4V wing stiffener components were used to verify the simulation results of the temperature field of the formed component with an error of less than 5%.

interfacial heat transfer coefficient (IHTC), Ti-6Al-4V, hot stamping, experimental validation

Liu X. - other affiliation
Kopeć M. - IPPT PAN
Fakir O. - other affiliation
Qu H. - AVIC Manufacturing Technology Institute (CN)
Wang Y. - Beijing Aeronautical Manufacturing Technology Research Institute (CN)
Wang L. - Imperial College London (GB)
Li Z. - AVIC Manufacturing Technology Institute (CN)
2.  Wang Y., Melikhov Y., Meydan T., Yang Z., Wu D., Wu B., He C., Liu X., Stress-dependent magnetic flux leakage: finite element modelling simulations versus experiments, JOURNAL OF NONDESTRUCTIVE EVALUATION, ISSN: 0195-9298, DOI: 10.1007/s10921-019-0643-0, Vol.39, pp.1-1-9, 2020

Assessing the effect of defect induced stresses on magnetic flux leakage (MFL) signals is a complicated task due to nonlinear magnetomechanical coupling. To facilitate the analysis, a multi-physics finite elemental simulation model is proposed based on magnetomechanical theory. The model works by quasi-statically computing the stress distribution in the specimen, which is then inherited to solve the nonlinear magnetic problem dynamically. The converged solution allows identification and extraction of the MFL signal induced by the defect along the sensor scanning line. Experiments are conducted on an AISI 1045 steel specimen, i.e. a dog-bone shaped rod with a cylindrical square-notch defect. The experiments confirm the validity of the proposed model that predicted a linear dependency of the peak-to-peak amplitude of the normalized MFL signal on applied stress. Besides identifying the effect of stress on the induced MFL signal, the proposed model is also suitable for solving the inverse problem of sizing the defects when stress is involved.

magnetic flux leakage, magnetomechanics, Jiles–Atherton model, non-destructive testing, finite element method, multiphysics numerical simulation

Wang Y. - Beijing Aeronautical Manufacturing Technology Research Institute (CN)
Melikhov Y. - other affiliation
Meydan T. - Cardiff University (GB)
Yang Z. - other affiliation
Wu D. - other affiliation
Wu B. - other affiliation
He C. - other affiliation
Liu X. - other affiliation

Category A Plus


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