Papers by Author: Mei Hong Liu

Abstract: In this paper, based on the analysis of coupled action of temperature, phase transformation and stress, the phase transformation condition and equation related to the thermal physical properties are discussed, and the transient temperature distribution of a Cr12 steel cylinder workpiece during gas quenching was obtained by solving the governing equations with a nonlinear boundary. According to the theories of thermal non-elasticity, computational mechanics and phase transformation, a new constitutive equation considering effects of phase transformation with a nonlinear surface heat transfer coefficient is proposed and is solved by means of finite element method (FEM). The thermal stress field is obtained and a way of simulating the technology of the heat treatment by computer is explored.

Abstract: Regular micro-surface structure in the form of micro-pores produced on the face of mechanical seals by laser technology can be used to improve the friction performance of the seal mating rings. A test rig with variable axial load was used to test laser-textured seal rings with micro-pores of various pore depth and pore ratio to study the effect of the laser-textured seal face structure parameters on the friction performance of mechanical seals. It is found that there are optimum texturing face parameters at which the friction torque and the face temperature rise of seal rings are minimum. Results of these tests show that the micro-pores on one of the seal mating faces can generate substantial hydrodynamic effect. Heat generation due to frictional contact on seal-ring surfaces is a major factor that causes deterioration of face seals and shortens their service life[1,2]. Excessive temperature rise can be avoided by improving structure of a seal surface. By means of laser technology return-flow structure, oblique line groove and spherical micro-pores are engraved on the seal face[3-5]. The research shows that substantial hydrodynamic effect can be generated between the seal faces with micro-pores[6-8]. In this study experiments are performed on laser-textured micro-pores seal faces at various axial loads to investigate the effect of the face structure and operating parameters on friction torque and face temperature rise.

Abstract: In order to get rid of health hazard of asbestos fiber, a new kind of non-asbestos fiber reinforce composite by beater-addition process, which is used for sealing and gasket, has been developed to replace traditional asbestos gasket materials. The mechanical properties of the new composite were tested, and the performance between it and asbestos sheet paper were contrasted. Results show that the density, cross direction tensile strength, machine direction tensile strength and ignition loss at temperature of 300°C of the new composite are 1.19g/cm3, 2.62MPa, 3.15MPa and 15.61% respectively, while the performances of asbestos paper produced under the same condition are 1.26g/cm3, 2.87MPa, 3.24MPa and 12.03% respectively. Excellent performance, low cost and simple manufacture process of the new composite make it is possible to substitute traditional asbestos paper and apply widely.

Abstract: A new nonlinear constructive model for description of temperature field of carbon steel axisymmetric body during the magnetic field quenching has been established based on thermo-magnetic coupling analysis. Using the model and finite element method, a numerical calculation program is developed with Microsoft FORTRAN 5.0, and cooling curves of center in a carbon steel sample of 30mm in diameter and 60mm in length during magnetic field quenching and common quenching are calculated and tested. Results showed that calculated cooling curves is accordant with corresponded tested cooling curves very well, and the calculated accuracy of temperature field during magnetic field quenching based on the new model is satisfactory.