Documents disponibles écrits par cet auteur

Effects of couple stress on elastohydrodynamic lubrication at impact loading / Hsiao-Ming Chu in Transactions of the ASME . Journal of tribology, Vol. 130 N°1 (Janvier 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of tribology > Vol. 130 N°1 (Janvier 2008) . - 8 p. Titre : Effects of couple stress on elastohydrodynamic lubrication at impact loading Type de document : texte imprimé Auteurs : Hsiao-Ming Chu, Auteur ; Wang-Long Li, Auteur ; Yuh-Ping Chang, Auteur Année de publication : 2008 Article en page(s) : 8 p. Note générale : Tribology Langues : Anglais (eng) Mots-clés : Pressure  Viscosity  Lubricants  Stress  Elastohydrodynamic  lubrication  Fluids  Film  thickness  Force  Motion  Deformation Résumé : In this paper, pure squeeze elastohydrodynamic lubrication motion of circular contacts with couple stress lubricant is explored at impact loading. On the basis of microcontinuum theory, the transient modified Reynolds equation is derived. Then it is solved simultaneously with the elasticity deformation equation and ball motion equation, thus obtaining the transient pressure profiles, film shapes, normal squeeze velocities, and accelerations. The simulation results reveal that the effect of the couple stress is equivalent to enhancing the lubricant viscosity, which would also enlarge the damper effect. Therefore, as the characteristic length of the couple stress fluid increases, the pressure spike and the dimple form earlier, the maximum pressure and the film thickness increase, and the diameter of the dimple, the rebounding velocity, the maximum value of the relative impact force, and the acceleration decrease. Furthermore, the fact that the contact central pressure for a ball impacting and rebounding from a lubricated surface reached two peaks during the total impact period is proved numerically in this analysis. As the effect of couple stress increases, the first and second peaks form earlier; as the total impact time decreases, the pressure of the first peak increases and that of the second peak decreases. Moreover, the phase shift between the time of the peak value of the squeeze acceleration and the zero value of the squeeze velocity increases with increasing the characteristic length of the couple stress fluid. En ligne : http://tribology.asmedigitalcollection.asme.org/article.aspx?articleid=1467973 [article] Effects of couple stress on elastohydrodynamic lubrication at impact loading [texte imprimé] / Hsiao-Ming Chu, Auteur ; Wang-Long Li, Auteur ; Yuh-Ping Chang, Auteur . - 2008 . - 8 p. Tribology Langues : Anglais (eng) in Transactions of the ASME . Journal of tribology > Vol. 130 N°1 (Janvier 2008) . - 8 p. Mots-clés : Pressure  Viscosity  Lubricants  Stress  Elastohydrodynamic  lubrication  Fluids  Film  thickness  Force  Motion  Deformation Résumé : In this paper, pure squeeze elastohydrodynamic lubrication motion of circular contacts with couple stress lubricant is explored at impact loading. On the basis of microcontinuum theory, the transient modified Reynolds equation is derived. Then it is solved simultaneously with the elasticity deformation equation and ball motion equation, thus obtaining the transient pressure profiles, film shapes, normal squeeze velocities, and accelerations. The simulation results reveal that the effect of the couple stress is equivalent to enhancing the lubricant viscosity, which would also enlarge the damper effect. Therefore, as the characteristic length of the couple stress fluid increases, the pressure spike and the dimple form earlier, the maximum pressure and the film thickness increase, and the diameter of the dimple, the rebounding velocity, the maximum value of the relative impact force, and the acceleration decrease. Furthermore, the fact that the contact central pressure for a ball impacting and rebounding from a lubricated surface reached two peaks during the total impact period is proved numerically in this analysis. As the effect of couple stress increases, the first and second peaks form earlier; as the total impact time decreases, the pressure of the first peak increases and that of the second peak decreases. Moreover, the phase shift between the time of the peak value of the squeeze acceleration and the zero value of the squeeze velocity increases with increasing the characteristic length of the couple stress fluid. En ligne : http://tribology.asmedigitalcollection.asme.org/article.aspx?articleid=1467973

A model for line-contact EHL problems / Li-Ming Chu in Transactions of the ASME . Journal of tribology, Vol. 134 N° 3 (Juillet 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of tribology > Vol. 134 N° 3 (Juillet 2012) . - 08 p. Titre : A model for line-contact EHL problems : consideration of affects of Navier-slip and lubricant rheology Type de document : texte imprimé Auteurs : Li-Ming Chu, Auteur ; Jaw-Ren Lin, Auteur ; Wang-Long Li, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : tribology Langues : Anglais (eng) Mots-clés : EHL;  power-law  lubricants;  Navier  slip Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The coupled extended Reynolds (which includes the effects of Navier-slip and flow rheology), elasticity deformation, and the load equilibrium (under a constant load condition) equations are solved simultaneously for the EHL problems. Results show that as the slip length increases or the flow index decreases, the film thickness decreases, the central pressure increases, the pressure spike decreases, the maximum pressure switches from the pressure spike to the central pressure, and the film shape and pressure profiles moves gradually toward the outlet. A proper combination of flow rheology and slip length could fulfill some preferred EHL conditions. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE9000134000003 [...] [article] A model for line-contact EHL problems : consideration of affects of Navier-slip and lubricant rheology [texte imprimé] / Li-Ming Chu, Auteur ; Jaw-Ren Lin, Auteur ; Wang-Long Li, Auteur . - 2012 . - 08 p. tribology Langues : Anglais (eng) in Transactions of the ASME . Journal of tribology > Vol. 134 N° 3 (Juillet 2012) . - 08 p. Mots-clés : EHL;  power-law  lubricants;  Navier  slip Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The coupled extended Reynolds (which includes the effects of Navier-slip and flow rheology), elasticity deformation, and the load equilibrium (under a constant load condition) equations are solved simultaneously for the EHL problems. Results show that as the slip length increases or the flow index decreases, the film thickness decreases, the central pressure increases, the pressure spike decreases, the maximum pressure switches from the pressure spike to the central pressure, and the film shape and pressure profiles moves gradually toward the outlet. A proper combination of flow rheology and slip length could fulfill some preferred EHL conditions. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE9000134000003 [...]

Pure squeeze motion in a magneto-elastohydrodynamic lubricated spherical conjunction / Li-Ming Chu in Transactions of the ASME . Journal of tribology, Vol. 132 N° 4 (Octobre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of tribology > Vol. 132 N° 4 (Octobre 2010) . - 06 p. Titre : Pure squeeze motion in a magneto-elastohydrodynamic lubricated spherical conjunction Type de document : texte imprimé Auteurs : Li-Ming Chu, Auteur ; Jaw-Ren Lin, Auteur ; Wang-Long Li, Auteur Année de publication : 2011 Article en page(s) : 06 p. Note générale : Tribology Langues : Anglais (eng) Mots-clés : Lubrication  Magnetic  fields  Magnetohydrodynamics  Viscosity Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The pure squeeze magneto-elastohydrodynamic lubrication (MEHL) motion of circular contacts with an electrically conducting fluid in the presence of a transverse magnetic field is explored under constant load condition. The differences between classical elastohydrodynamic lubrication and MEHL are discussed. The results reveal that the effect of an externally applied magnetic field is equivalent to enhancing effective lubricant viscosity. Therefore, as the Hartmann number increases, the enhancing effect becomes more obvious. Furthermore, the transient pressure profiles, film shapes, normal squeeze velocities, and effective viscosity during the pure squeeze process under various operating conditions are discussed. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE900013 [...] [article] Pure squeeze motion in a magneto-elastohydrodynamic lubricated spherical conjunction [texte imprimé] / Li-Ming Chu, Auteur ; Jaw-Ren Lin, Auteur ; Wang-Long Li, Auteur . - 2011 . - 06 p. Tribology Langues : Anglais (eng) in Transactions of the ASME . Journal of tribology > Vol. 132 N° 4 (Octobre 2010) . - 06 p. Mots-clés : Lubrication  Magnetic  fields  Magnetohydrodynamics  Viscosity Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The pure squeeze magneto-elastohydrodynamic lubrication (MEHL) motion of circular contacts with an electrically conducting fluid in the presence of a transverse magnetic field is explored under constant load condition. The differences between classical elastohydrodynamic lubrication and MEHL are discussed. The results reveal that the effect of an externally applied magnetic field is equivalent to enhancing effective lubricant viscosity. Therefore, as the Hartmann number increases, the enhancing effect becomes more obvious. Furthermore, the transient pressure profiles, film shapes, normal squeeze velocities, and effective viscosity during the pure squeeze process under various operating conditions are discussed. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE900013 [...]