P.M. Johns-Rahnejat

P.M. Johns-Rahnejat
University of Central Lancashire | UCLAN · School of Engineering

BSc MSc DIC PhD

About

23
Publications
4,735
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
290
Citations
Introduction
My main area of research is tribology, particularly contact mechanics of semi-infinite solids, as well as layered bonded elastic and viscoelastic solids as in coatings. I am also involved in experimental monitoring of contacts (thin film solids) and numerical analysis of elastohydrodynamics.

Publications

Publications (23)
Article
Full-text available
This paper commemorates Ramsey Gohar by acknowledging his contributions to the fields of contact mechanics and elastohydrodynamic lubrication (EHL) within the context of the developments of these subjects. A historical discourse is provided on elastohydrodynamics, from its inception in the 1940s to present. We demonstrate that Ramsey Gohar was not...
Article
Full-text available
In applications requiring high load carrying capacity, conforming contacting pairs with a relatively large contact footprint are used. These include circular arc, Novikov, and Wildhaber gears found, for example, in helicopter rotors. Closely conforming contacts also occur in many natural endo-articular joints, such as hips, or their replacement art...
Article
Full-text available
It is with great sadness that we note the passing of Professor Duncan Dowson on 6th January 2020. Duncan was an esteemed member of the Editorial Board of this journal. He will be remembered as one of the founding fathers of tribology and as a true gentleman. He was the last living member of the Jost Committee, set up by the UK Government (1964–1966...
Article
Full-text available
A new finite element-based contact mechanics analysis of layered viscoelastic solids of low elastic modulus is presented. The methodology is based on the Maxwell viscoelastic element, with stress relaxation taken into account by the Prony series’ representation of the bulk and shear material moduli. Simultaneous solutions for deviatoric and volumet...
Article
Full-text available
Thermo-mixed-hydrodynamics of compression rings and big-end bearings are presented. Frictional losses under normal engine operating conditions for a gasoline engine and those with cylinder deactivation (CDA) are predicted. With CDA, the combustion chamber pressure increases in the active cylinders, whilst some residual pressure remains in the deact...
Chapter
Full-text available
Volume 18 addresses friction and wear from a systems perspective, while providing a detailed understanding of why it occurs and how to control it. It explains the basic theory of friction and wear, and offers valuable insight on the forces, mechanisms, and interactions that are involved. It examines common wear scenarios, including wear by particle...
Article
Full-text available
Noise and vibration refinement and energy efficiency are the key drivers in powertrain development. The final drive (the differential) is a source of vibration concern and also contributes to the powertrain inefficiency. To optimise differential characteristics for the key objectives of refinement and efficiency, detailed models of the gear interac...
Article
Full-text available
The paper describes a combined tribodynamics analysis (dynamics and contact tribology) of cylindrical roller bearings of a heavy duty truck transmission under high applied loads. The dynamic analysis provides the transient variations in contact load. It also determines the vibration spectrum of the bearing as well as that of contact dynamics. It is...
Article
Full-text available
The paper presents the solution of an elastohydrodynamic point contact condition using inlet and outlet lubricant entrainment with partial counter-flow. The inlet and outlet boundaries are determined using potential flow analysis for the pure rolling of contiguous surfaces. This shows that Swift–Stieber boundary conditions best conform to the obser...
Chapter
In the first part of this study, dynamic response and stability characteristics of gear-pair systems supported on bearings with rolling elements is investigated. The resulting mechanical models possess strongly nonlinear characteristics, accounting for gear backlash and bearing stiffness nonlinearities. The emphasis is first put on obtaining period...
Article
Full-text available
The paper provides some highlights in the developments of theories of lubrication and contact mechanics from early pioneering works of Reynolds and Hertz to the establishment of elastohydrodynamic phenomenon by Ertel and Grubin. Some historical discourse is made on the development of elastohydrodynamic theory in the past 6 decades, with particular...
Conference Paper
Full-text available
A tribo-multibody model for valve train kinematic analysis, quasi-statics of lubricated contact and assessment of structural integrity This item was
Article
Circular point contact EHD pressure distributions were investigated under various operating conditions using a thin film piezo-resistive pressure transducer. A series of controlled experiments, in which the active element of the transducer is positioned at various contact cross-sections, was carried out. The results are analysed and presented in th...
Article
Full-text available
This paper presents a sensory gripper, consisting of two tactile sensing matrices which acquire three dimensional images of objects of interest. The image processing algorithm uses elastostatic contact information to discriminate among a host of parts made of different materials. The algorithm also enables the assessment of orientation of parts wit...
Article
Full-text available
The influence of the roller axial profile on the contact pressure distributions is discussed for the cases of aligned and misaligned rollers. The results of numerical solutions show that careful profiling using radial arcs can result in a more even distribution of pressure. A design method employed by Harris for predicting pressures on misaligned r...
Article
Full-text available
This is a conference paper it is available online at http://www.mscsoftware.com/support/library/conf/adams/na/1997/uc970022.pdf Published

Network

Cited By

Projects

Projects (3)
Project
Developing a generic methodology for contact mechanics of highly loaded pairs with varying degree of conformity, applicable to gears, bearings, etc.
Project
1- Active tribotronic control 2- Condition monitoring 3- create thermal hydrodynamic predictive model