Original Article Static and stability analysis of partial slip texture multi-lobe journal bearings TVVLN Rao 1 , Ahmad MA Rani 2 , Norani M Mohamed 3 , Hamdan H Ya 2 , Mokhtar Awang 2 and Fakhruldin M Hashim 2 Abstract This paper presents one-dimensional analysis of modified dynamic Reynolds equation derived for partial slip texture multi-lobe journal bearings. The novelty included in this study is the configuration of partial slip texture region on the bottom bearing lobe surface of a multi-lobe journal bearing under a constant vertical load. The nondimensional pressure and shear stress for steady-state and nondimensional pressure gradients for dynamic coefficients for each lobe with partial slip texture configuration are derived based on narrow groove theory. Linearized stability analysis is evaluated using infinitesimal perturbation method. Results of static and stability characteristics of partial slip texture multi-lobe (two-axial groove, elliptical, three-lobe and offset) journal bearings are presented. Partial slip texture configuration significantly enhances load capacity, coefficient of friction, and stability of two-lobe journal bearing. Keywords Partial slip texture, steady-state, dynamic coefficients, threshold speed, critical whirl frequency ratio Date received: 31 May 2018; accepted: 13 September 2019 Introduction The design of fluid film journal bearings is of primary importance in the determination of stability charac- teristics of rotating machinery operating at increas- ingly higher sliding speeds. Plain journal bearings are replaced with lobed journal bearings which exhibit superior stability of rotor bearing system. The dynamic stiffness and damping of fluid film bearings have a significant effect on unbalance response and system stability. Multi-lobe journal bearings are widely used in high speed rotor bearing systems as they offer required load capacity and wide range of stiffness and damping characteristics to suppress system instability. Lund and Thomsen 1 presented design data for stiff- ness and damping coefficients of two-axial groove, two-lobe, three-lobe, and offset bearing configur- ations. The calculation methods for multi-lobe bear- ing configurations are based on infinitesimal perturbation solution of the Reynolds equation. Li et al. 2 and Allaire et al. 3 studied stability charac- teristics and transient unbalance response of multi- lobe journal bearings based on variational solution of Reynolds equation. The results of dynamic performance of multi-lobe journal bearings using linear stability analysis were compared with transient analysis. Kumar et al., 4 Malik et al., 5,6 and Sinhasan et al. 7 presented comprehensive design data for static and dynamic characteristics of two-lobe and three-lobe journal bearings. A two-lobe bearing configuration can provide consistently good dynamic performance over a wide range of load conditions. The dynamic performance of three-lobe bearing improves in turbulent regime. Flack and Lanes 8 inves- tigated the stability of a rigid rotor mounted in three- lobe bearings considering variation in preload factor, offset factor, and load orientation. Three-lobe bear- ings with less offset factors and moderate preload fac- tors are often more stable than those with larger offset factors. Increasing the preload factor found to increase the rigid rotor stability. 8 Knight and Barrett 9 presented an approximate solution method to axial pressure distribution which allows one- dimensional solution of Reynolds equation. Temperatures within the multi-lobe journal bearing 1 Department of Mechanical Engineering, SRM Institute of Science and Technology, Kattankulathur, India 2 Department of Mechanical Engineering, Universiti Teknologi PETRONAS, Tronoh, Malaysia 3 Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS, Tronoh, Malaysia Corresponding author: TVVLN Rao, Department of Mechanical Engineering, SRM Institute of Science and Technology, Kattankulathur 603203, India. Email: tvvlnrao@gmail.com Proc IMechE Part J: J Engineering Tribology 0(0) 1–21 ! IMechE 2019 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/1350650119882834 journals.sagepub.com/home/pij