Imperial College London

Dr Rob Hewson

Faculty of EngineeringDepartment of Aeronautics

Senior Lecturer in Aircraft Design
 
 
 
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Contact

 

r.hewson

 
 
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Location

 

341City and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
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72 results found

Gao L, Hua Z, Hewson R, 2018, Can a "pre-worn" bearing surface geometry reduce the wear of metal-on-metal hip replacements? - A numerical wear simulation study, Publisher: ELSEVIER SCIENCE SA, Pages: 13-21, ISSN: 0043-1648

CONFERENCE PAPER

Gao L, Hua Z, Hewson RW, 2018, Can a “pre-worn” bearing surface geometry reduce the wear of metal-on-metal hip replacements? – A numerical wear simulation study, Wear, Vol: 406-407, Pages: 13-21, ISSN: 0043-1648

Total Hip Replacement (THR) is generally a highly successful treatment for late stage hip joint diseases and wear, however, wear continues to be one of the major causes of metal-on-metal THR's failure. Hip replacements typically experience a two-stage wear; a higher initial wear rate in the beginning followed by a lower steady-state one with the surface profile changed. This alludes to the potential use of a cup with a non-spherical interior cavity with an initial geometry similar to a worn surface which may benefit from lower wear rate. In this paper wear is numerically simulated with a cup having a non-spherical geometry inspired by the initial stage of wear.A wear model was recently developed by the authors for the THR, which considered the lubricated contact in both elastohydrodynamic lubrication (EHL) and mixed lubrication regime, rather than a dry contact used in most of other studies of wear modelling in the academic literature. In this study the wear model has been updated by introducing the ‘λ ratio’ (the ratio of film thickness to surface roughness) and addressing the non-Newtonian shear-thinning properties of the synovial fluid. This wear model was able to describe the non-linear wear evolution process due to the change of worn profiles. Firstly the wear of a spherical hip joint was simulated until a steady-state wear rate is achieved. Then a non-spherical joint was proposed in which the cup bearing geometry was generated by the previously predicted worn profile from the spherical joint. At last the wear of this “pre-worn” hip bearing was simulated and compared to the spherical one. Approximately 40% reduction in the steady-state wear rate and 50% in the total accumulated wear has been observed in the non-spherical hip joint. This study presented a full numerical analysis of the relationship between lubrication, wear reduction and the geometry change, and quantitatively suggested the optimal geometry to reduce running-in wea

JOURNAL ARTICLE

Navadeh N, Hewson RW, Fallah AS, 2018, Dynamics of transversally vibrating non-prismatic Timoshenko cantilever beams, Engineering Structures, Vol: 166, Pages: 511-525, ISSN: 0141-0296

© 2018 Elsevier Ltd The present study deals with evaluation of the dynamic response in a pulse loaded homogeneous non-prismatic Timoshenko cantilever beam. Subsequent to the derivation of the partial differential equations (PDE's) of motion using the Lagrange-d'Alembert principle (or extended Hamilton's principle) the eigenvalue problem has been set up and solved for eigenfrequencies and eigenfunctions. Galerkin's method of weighted residuals was then applied to obtain governing ordinary differential equations (ODE's) for the system. The dynamic response under arbitrary pulse loading is obtained using the method of eigenfunction expansion which attributes to displacement and rotation fields generalised coordinates when the exact modes are chosen as shape functions. It has been shown that inclusion of few terms (in this case 5) in the series expansion provides a good correlation between the displacement fields and the truncated series. Dimensionless response parameters are introduced and two methods of non-dimensionalisation are proposed which could be useful in dealing with generic problems of a specified formulation.

JOURNAL ARTICLE

Wang H, Kow J, Raske N, de Boer G, Ghajari M, Hewson R, Alazmani A, Culmer Pet al., 2018, Robust and high-performance soft inductive tactile sensors based on the Eddy-current effect, SENSORS AND ACTUATORS A-PHYSICAL, Vol: 271, Pages: 44-52, ISSN: 0924-4247

JOURNAL ARTICLE

Bach C, Jebari R, Viti A, Hewson Ret al., 2017, Composite stacking sequence optimization for aeroelastically tailored forward-swept wings, Structural and Multidisciplinary Optimization, Vol: 55, Pages: 105-119, ISSN: 1615-147X

© 2016, Springer-Verlag Berlin Heidelberg. A method for stacking sequence optimization and aeroelastic tailoring of forward-swept composite wings is presented. It exploits bend-twist coupling to mitigate aeroelastic divergence. The method proposed here is intended for estimating potential weight savings during the preliminary aircraft design stages. A structural beam model of the composite wingbox is derived from anisotropic shell theory and the governing aeroelastic equations are presented for a spanwise discretized forward swept wing. Optimization of the system to reduce wing mass is undertaken for sweep angles of −35° to 0° and Mach numbers from 0.7 to 0.9. A subset of lamination parameters (LPs) and the number of laminate plies in each pre-defined direction (restricted to {0°,±45°, 90°}) serve as design variables. A bi-level hybrid optimization approach is employed, making use of a genetic algorithm (GA) and a subsequent gradient-based optimizer. Constraints are implemented to match lift requirements and prevent aeroelastic divergence, excessive deformations, airfoil stalling and structural failure. A permutation GA is then used to match specific composite ply stacking sequences to the optimum design variables with a limited number of manufacturing constraints considered for demonstration purposes. The optimization results in positive bend-twist coupling and a reduced structural mass. Results are compared to an uncoupled reference wing with quasi-isotropic layups and with panel thickness alone the design variables. For a typical geometry and a forward sweep of −25° at Mach 0.7, a wingbox mass reduction of 13 % was achieved.

JOURNAL ARTICLE

Gao L, Dowson D, Hewson RW, 2017, Predictive wear modeling of the articulating metal-on-metal hip replacements, JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART B-APPLIED BIOMATERIALS, Vol: 105, Pages: 497-506, ISSN: 1552-4973

JOURNAL ARTICLE

Raske N, Hewson RW, Kapur N, de Boer GNet al., 2017, A predictive model for discrete cell gravure roll coating, PHYSICS OF FLUIDS, Vol: 29, ISSN: 1070-6631

JOURNAL ARTICLE

Taherkhani AR, Gilkeson C, Gaskell P, Hewson R, Toropov V, Rezaienia A, Thompson Het al., 2017, Aerodynamic CFD Based Optimization of Police Car Using Bezier Curves, SAE International Journal of Materials and Manufacturing, Vol: 10, ISSN: 1946-3979

Copyright © 2017 SAE International. This paper investigates the optimization of the aerodynamic design of a police car, BMW 5-series which is popular police force across the UK. A Bezier curve fitting approach is proposed as a tool to improve the existing design of the warning light cluster in order to reduce drag. A formal optimization technique based on Computational Fluid Dynamics (CFD) and moving least squares (MLS) is used to determine the control points for the approximated curve to cover the light-bar and streamline the shape of the roof. The results clearly show that improving the aerodynamic design of the roofs will offer an important opportunity for reducing the fuel consumption and emissions for police vehicles. The optimized police car has 30% less drag than the non-optimized counter-part.

JOURNAL ARTICLE

de Boer G, Hewson R, Bryant M, Dowson Det al., 2017, An investigation into the contact between soft elastic and poroelastic bodies rotating under load, Tribology - Materials, Surfaces & Interfaces, Pages: 1-9, ISSN: 1751-5831

JOURNAL ARTICLE

de Boer G, Raske N, Wang H, Kow J, Alazmani A, Ghajari M, Culmer P, Hewson Ret al., 2017, Design Optimisation of a Magnetic Field Based Soft Tactile Sensor, SENSORS, Vol: 17, ISSN: 1424-8220

JOURNAL ARTICLE

de Boer GN, Gao L, Hewson RW, Thompson HMet al., 2017, Heterogeneous Multiscale Methods for modelling surface topography in Elastohydrodynamic Lubrication line contacts, TRIBOLOGY INTERNATIONAL, Vol: 113, Pages: 262-278, ISSN: 0301-679X

JOURNAL ARTICLE

Gao L, Dowson D, Hewson RW, 2016, A numerical study of non-Newtonian transient elastohydrodynamic lubrication of metal-on-metal hip prostheses, TRIBOLOGY INTERNATIONAL, Vol: 93, Pages: 486-494, ISSN: 0301-679X

JOURNAL ARTICLE

Gao L, Hewson RW, 2016, Development of A Wear Model for LubricatedMetal-On-Metal Hip Joints, 5th International Conference on Biomedical Engineering and Biotechnology 2016

CONFERENCE PAPER

Wang H, de Boer G, Kow J, Alazmani A, Ghajari M, Hewson R, Culmer Pet al., 2016, Design Methodology for Magnetic Field-Based Soft Tri-Axis Tactile Sensors, SENSORS, Vol: 16, ISSN: 1424-8220

JOURNAL ARTICLE

Wang H, de Boer G, Kow J, Ghajari M, Alazmani A, Hewson R, Culmer Pet al., 2016, A Low-cost Soft Tactile Sensing Array using 3D Hall Sensors, PROCEEDINGS OF THE 30TH ANNIVERSARY EUROSENSORS CONFERENCE - EUROSENSORS 2016, Vol: 168, Pages: 650-653, ISSN: 1877-7058

JOURNAL ARTICLE

de Boer G, Wang H, Ghajari M, Alazmani A, Hewson R, Culmer Pet al., 2016, Force and Topography Reconstruction Using GP and MOR for the TACTIP Soft Sensor System, 17th Annual Conference on Towards Autonomous Robotic Systems (TAROS), Publisher: SPRINGER INT PUBLISHING AG, Pages: 65-74, ISSN: 0302-9743

CONFERENCE PAPER

de Boer GN, Gao L, Hewson RW, Thompson HM, Raske N, Toropov VVet al., 2016, A multiscale method for optimising surface topography in elastohydrodynamic lubrication (EHL) using metamodels, STRUCTURAL AND MULTIDISCIPLINARY OPTIMIZATION, Vol: 54, Pages: 483-497, ISSN: 1615-147X

JOURNAL ARTICLE

Gao L, de Boer G, Hewson R, 2015, The role of micro-cavitation on EHL: A study using a multiscale mass conserving approach, TRIBOLOGY INTERNATIONAL, Vol: 90, Pages: 324-331, ISSN: 0301-679X

JOURNAL ARTICLE

Liu J, Richardson R, Hewson R, Whitehead Set al., 2015, Mechanical Design of Long Reach Super Thin Discrete Manipulator for Inspections in Fragile Historical Environments, 16th Annual Conference on Towards Autonomous Robotic Systems (TAROS), Publisher: SPRINGER-VERLAG BERLIN, Pages: 155-160, ISSN: 0302-9743

CONFERENCE PAPER

Raske N, Hewson RW, Kapur N, Gaskell PHet al., 2015, A predictive model for discrete cell gravure roll coating, 11th European Coating Symposium 2015

CONFERENCE PAPER

Taherkhani AR, de Boer GN, Gaskell PH, Gilkeson CA, Hewson RW, Keech A, Thompson HM, Toropov VVet al., 2015, Aerodynamic drag reduction of emergency response vehicles, Advances in Automobile Engineering, Vol: 4, ISSN: 2167-7670

This paper presents the first experimental and computational investigation into the aerodynamics of emergency response vehicles and focuses on reducing the additional drag that results from the customary practice of adding light-bars onto the vehicles’ roofs. A series of wind tunnel experiments demonstrate the significant increase in drag that results from the light bars and show these can be minimized by reducing the flow separation caused by them. Simple potential improvements in the aerodynamic design of the light bars are investigated by combining Computational Fluid Dynamics (CFD) with Design of Experiments and metamodelling methods. An aerofoil-based roof design concept is shown to reduce the overall aerodynamic drag by up to 20% and an analysis of its effect on overall fuel consumption indicates that it offers a significant opportunity for improving the fuel economy and reducing emissions from emergency response vehicles. These benefits are now being realised by the UK’s ambulance services.

JOURNAL ARTICLE

Amigo RCR, Hewson RW, Silva ECN, 2014, On the optimization of adsorption systems, 11th World Congress on Computational Mechanics (WCCM XI)

CONFERENCE PAPER

Berci M, Toropov VV, Hewson RW, Gaskell PHet al., 2014, Multidisciplinary multifidelity optimisation of a flexible wing aerofoil with reference to a small UAV, STRUCTURAL AND MULTIDISCIPLINARY OPTIMIZATION, Vol: 50, Pages: 683-699, ISSN: 1615-147X

JOURNAL ARTICLE

Gao L, Dowson D, Hewson RW, 2014, A numerical study of non-newtonian transient elastohydrodynamic lubrication of metal-on-metal hip prostheses: the effect of lubricant shear-thinning properties, Leeds Lyon Symposium on Tribology

CONFERENCE PAPER

Gao L, Hewson RW, 2014, A mechanical wear model of metal-on-metal total hip replacements in mixed lubrication conditions., 7th China International Symposium on Tribology (CIST)

CONFERENCE PAPER

Johns AS, Hewson RW, Merson E, Summers JL, Thompson HMet al., 2014, Internal twist drill coolant channel modelling using Computational Fluid Dynamics, Pages: 1114-1122

Coolant technologies have become increasingly used within twist-drill machining. Internal helical coolant channels are a common means of delivering high-pressure coolant directly to the cutting edge to increase the transfer of heat away from the cutting edge and to aid with chip evacuation. However, the complex behaviour of Coriolis and centrifugal forces generated by large angular velocities and the curvature of the coiled channel govern the highly turbulent flow of coolant. This research uses Computational Fluid Dynamics (CFD) to study the design of internal coolant channels across the internal section of the drill bit.

CONFERENCE PAPER

de Boer GN, Hewson RW, Thompson HM, Gao L, Toropov VVet al., 2014, Two-scale EHL: Three-dimensional topography in tilted-pad bearings, TRIBOLOGY INTERNATIONAL, Vol: 79, Pages: 111-125, ISSN: 0301-679X

JOURNAL ARTICLE

Berci M, Gaskell PH, Hewson RW, Toropov VVet al., 2013, A semi-analytical model for the combined aeroelastic behaviour and gust response of a flexible aerofoil, JOURNAL OF FLUIDS AND STRUCTURES, Vol: 38, Pages: 3-21, ISSN: 0889-9746

JOURNAL ARTICLE

Charpentier TVJ, Neville A, Millner P, Hewson R, Morina Aet al., 2013, An Investigation of Freezing of Supercooled Water on Anti-Freeze Protein Modified Surfaces, JOURNAL OF BIONIC ENGINEERING, Vol: 10, Pages: 139-147, ISSN: 1672-6529

JOURNAL ARTICLE

Charpentier TVJ, Neville A, Millner P, Hewson RW, Morina Aet al., 2013, Development of anti-icing materials by chemical tailoring of hydrophobic textured metallic surfaces, JOURNAL OF COLLOID AND INTERFACE SCIENCE, Vol: 394, Pages: 539-544, ISSN: 0021-9797

JOURNAL ARTICLE

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