Karl D. Dearn

• PhD, MEng
• Lecturer at University of Birmingham

Tribological properties of laser sintered polyether-ether-ketone (EOS PEEK HP3) were investigated using a rolling-sliding test rig. This investigation aimed to study the wear and friction failure mechanism of EOS PEEK HP3. The main objectives included to conduct wear and friction tests under non-conformal contact, to monitor surface temperature, to...

Acoustic emissions have been used to interpret the frictional processes observed in a simulated metal-on-polymer joint replacement articulation during in vitro testing. The coefficient of friction profile is predicted from AE features using a nonlinear autoregressive neural network with an external input model, and the evolution of surface damage i...

The soot emissions can be decreased in diesel engine through an improved understanding of the soot formation processes and impact strategies of fuel injection using oxygenated cleaner fuel. The combined effect of the oxygenated fuel (B20) and strategies of fuel injection (FI) timings and pressures on characteristics of combustion and particulate ma...

Acoustic emission (AE) testing has been used in the detection of the onset and progression of mechanical flaws. It has also proven advantageous in the tribological assessment of mechanical systems and human joints as well as for implant condition monitoring. Current modes of diagnosing implant failures are becoming less effective and time consuming...

In this work, the influence of NbZr and ZrSi addition to TiCN coatings are studied, aiming for their use as protective layers for parts subjected to severe corrosion and wear. The coatings with C/N ratios ranging from 0.4 to 2.5 were deposited using the cathodic arc technique in a mixture of N 2 and CH 4 gases, on 316 stainless steel discs and Si (...

Partial hydrogenation of unsaturated fatty acid methyl esters, the so-called H-FAME, has been developed, particularly for application in warm climates, to improve the oxidation stability of biodiesel. During the H-FAME process, polyunsaturated ester molecules, which are a primary cause of biodiesel induced oxidation, can be reduced. In this paper,...

A novel green lubricating oil additive (carbon quantum dot (CQD) particle-doped nickel (Ni-CQD)) was synthesized from citric acid and nickel acetate. The effects of CQD and Ni-CQD nanoparticles on the tribological behaviors of polyethylene glycol (PEG200) were investigated under different loads and reciprocation speeds. The results indicate that CQ...

Recent developments in production methods for polymeric materials have meant that thermoplastics for high temperature mechanical performance can now be selectively laser sintered. This paper describes the performance and the potential applications of EOS PEEK HP3: a high temperature, laser sintered thermoplastic material. Thermal, tensile, flexural...

A novel carbon nanoparticle co-doped with sulfur and nitrogen (S, N–CN) was prepared from rice husk powder through a hydrothermal reaction. A series of modern analysis techniques was utilized to characterize the morphology, structure, and components of the S, N–CN nanoparticles. Their tribological properties as a lubricating additive to polyethylen...

In this study, the mechanical properties of a novel dual-core pedicle screw were compared with a commercially available cylindrical screw. In order to evaluate and compare their mechanical performance, a series of axial pullout, quasi-static and dynamic bend tests were conducted. In the pullout tests, three polyurethane (PU) foams (density: 0.16, 0...

2-Methylfuran (MF) and 2,5-dimethylfuran's (DMF) combustion characteristics have confirmed their validity as appropriate gasoline replacement and enhancement fuels. However, the performance of fuel injection equipment is dependant on the tribological performance of these fuels lubricity testing of MF, DMF and their blends with gasoline was undertak...

This paper describes the development of a dynamic implant designed to correct three dimensional spinal deformities in children with Early Onset Scoliosis (EOS). The device is a distraction-based implant that provides two innovative features: (1) a dynamic-viscoelastic system, which gives some flexibility to the implant, to avoid potential device fr...

An electroless deposition method was used to modify the surface properties of rice husk ceramic particles (RHC) by depositing nano-nickel on the surface of the RHC (Ni-RHC). The dry tribological performances of aluminum matrix composite adobes containing different contents of RHC and Ni-RHC particles have been investigated using a micro-tribometer....

Nano-additives have attracted lots of attentions in recent years due to their special performances. A traditional lubricating additive MoS2 with nano-scale and a novel additive graphene were reviewed in this chapter. The synthesis methods, properties, and tribological applications of these two kinds of nano-additives dispersed in media have been re...

For modern gasoline direct injection (GDI) engines, injector deposit is a concern because it can cause changes to the spray characteristics and lead to deterioration in fuel economy and exhaust emissions. In this study, in order to examine the link between spray variation and engine emissions deterioration due to injector deposit accumulation, 8 ne...

One major problem with ball and socket artificial discs is the migration of wear particles to the surrounding tissues. This debris can cause inflammation that can lead to implant loosening. Encapsulating the artificial disc with an elastomer sheath could prevent this problem by retaining the wear particles within the disc. The encapsulation sheath...

The modern approach of Virtual Engineering allows one to detect with some accuracy the residual life of components especially free of cracks. The life estimation becomes cumbersome when the components contain a crack. A straightforward formulation requires a parameter that considers geometrical constraints and materials properties. The magnitude of...

Lubrication properties and mechanisms of various oxygenated compounds, carboxylic acid, aldehyde, alcohol, ketone, ester, and ether, were investigated. The high-frequency reciprocating rig was used to measure the lubricity. The effects of functional group, humidity, and carbon-chain length on the lubricity of the oxygenated compounds were studied....

Laser surface texturing technology was employed for fabricating textured structures on cylinder liners. The tribological behavior of the cylinder liners with different texturing structures including line, dimple and line + dimple and texturing area ratio was investigated under the lubrication of esterified bio-oil with and without MoS2 microsheets...

The growth of energy demand generates an increase in the size of industrial structures. From 1910 to 2000, the diameter of the largest “transport” pipelines were multiplied by 4 and the transport pressure by a value of 60[1]. As a result, the various components relating to power plant, oil and gas facilities as well as petrochemical networks which...

As a kind of petroleum fuel alternatives, emulsified biomass fuel(EBF) can be used in a diesel engine. The problem of lubricating oil dilution by diesel engine fuel can't be prevented. Research on the effect of EBF on the oil film formation behavior of diesel engine lubricating oil was very important. The friction and wear behaviors of engine lubri...

To alleviate high friction and corrosive wear in piston ring and cylinder liner friction pairs lubricated with bio-oil, four kinds of coatings: Ni-P, Ni-P-MoS2, Ni-P-GO and Ni-P-MoS2-GO have been prepared via chemical nickel plating technology. A multi-functional engine piston ring-cylinder liner tribometer was employed to evaluate their tribologic...

Wear debris is a crucial factor in determining the lifespan of a total joint replacement. Not only do particulates between a bearing surfaces increase wear rates through third-body abrasion, but immune reactions can lead to inflammation and osteolysis. In this paper, the use of computer vision to analyse and classify scanning electron microscope im...

Zr, Nb and Si doped TiCN coatings, with (C+N)/(metal+Si) ratios of approximately 1, were deposited on stainless steel and Si wafer substrates using a cathodic arc technique in a mixture of N2 and CH4 gases. The coatings were comparatively analysed for elemental and phase composition, adhesion, anticorrosive properties and tribological performance a...

Fabricating high-quality graphene with simple methods has aroused considerable interests in recent years. In this paper, graphite was dispersed in esterified bio-oil as a lubricant for steel/gray cast iron friction pairs, and the shear-induced transformation from graphite to graphene was observed. The tribological behavior during this process, incl...

The effect of different chemistries on cleaning of hard surfaces has widely been investigated. However, a fundamental understanding of the physical aspects involved in grime removal is yet to be established. A series of surface experiments are presented in this paper to determine the mechanical properties of cleaning processes. Experimental results...

There are two major problems with ball and socket artificial joints; the migration of wear particles inducing an inflammatory response, causing toxicity, osteolysis and subsequent implant loosening; and the poor tribology between interstitial or synovial fluid and device's articulation surfaces. Experiments have been conducted to assess the potenti...

To expand the application of rice husk (RH) resource, this study developed carbon-based RH ceramic (RHC) particles using a common high-temperature carbonization method. The morphology, composition, and structure of the RHC particles were characterized with a series of modern analysis technologies and were then compared with those of the initial RH...

Graphene and MoS2 were dispersed in esterified bio-oil (EBO) and evaluated as lubricants for steel/steel contact. The tribological behaviors of steel/steel pairs were investigated under lubrication of graphene/MoS2 blends with different mass ratios, loads and rotating speeds. The micro-morphologies of the worn surfaces were observed by optical and...

A biomass oil/diesel blend was prepared using an emulsion method and combusted in a diesel engine. An injector was then removed and the morphology, composition, and structure of the carbonaceous deposits on the pintle-type nozzle were characterized using a combination of HRTEM, SEM/EDAX, Raman and XRD. Results showed that the carbon deposition of t...

Total disc arthroplasty is an alternative to spinal fusion, aimed at preserving flexibility; these devices typically involve a cobalt chrome molybdenum alloy socket articulating against an ultra-high molecular weight polyethylene (UHMWPE) ball. As with all artificial joints, wear debris is of particular concern due its effect on both implant life a...

The tribological behaviour of pyrolysis bio-oil with a synthesized nano-Lanthanum oxide (La2O3) additive was evaluated using a point contact four ball tribometer under different frictional conditions. Results were compared against a micro (μ)-La2O3 additive and an un-additised bio-oil as a control. The results show that nano-La2O3 impregnated bio-o...

There is an increasing recognition of injector deposit (ID) formation in fuel injection equipment as direct injection spark ignition (DISI) engine technologies advance to meet increasingly stringent emission legislation and fuel economy requirements. While it is known that the phenomena of ID in DISI engines can be influenced by changes in fuel com...

Due to the emission benefits of the oxygen in the fuel molecule, the interest for the use of ethanol as fuel blend components in compression ignition engines has been increased. However the use of fuel blends with high percentage of ethanol can lead to poor fuel blend quality (e.g. fuel miscibility, cetane number, viscosity and lubricity). An appro...

Biomethane and biogas produced from waste (i.e., from an anaerobic digester) have shown themselves to be promising fuels for internal combustion engines. They can improve fuel security and contribute in reducing emissions, including CO2, when used as a supplement to diesel fuel in dual-fueled diesel engines. In this work the influence of diesel fue...

The requirement for "maximum" product performance might occur when a robust knowledge transfer agreement is developed between host University and Industrial Company. A perspective of this agreement is related to the University of Birmingham and Truflo Marine Ltd., administered by the Technology Strategy Board Driving Innovation. The present paper d...

The tribological response of bio-oil derived from Spirulina algae has been assessed, according to the choice of catalyst during esterification. The bio-oil was upgraded over the selected catalysts of KF/HZSM-5 and KF/Al2O3 with ethanol. Physical and chemical properties were assessed throughout with the crystal structure of the catalysts was charact...

Glass manufacturing is a heat intensive process. There is a direct correlation between the batch distribution techniques and the furnace energy consumption, productivity, and quality of the glass manufactured. All four major segments (float, container, fibre, and specialty glasses) would benefit from using an optimised batch distribution technique...

The wear and friction in the pitch region of the centre of polymer gear teeth are not well understood. The transition around this point of the tooth between rolling and sliding has an important effect on the durability of polymer gear drives and can be simulated using a twin-disc configuration. This paper investigates the rolling-sliding wear behav...

This paper describes a study of the influence of soot contamination on the tribological behavior of engine lubricants. The candidate lubricants were a formulated engine lubricant, (CD SAE 15W-40) and a base oil (150SN). Soot particle contamination was simulated using carbon black with friction and wear measured using a four-ball tribometer. The res...

Export Date: 3 October 2013, Source: Scopus, CODEN: WEARA, doi: 10.1016/j.wear.2013.06.003, Language of Original Document: English, Correspondence Address: Hu, X.; Institute of Tribology, Hefei University of Technology, Hefei 230009, China; email: xghu@hfut.edu.cn, Funding Details: 51275143, NSFC, National Natural Science Foundation of China, Refer...

This paper presents an in-vitro tribological investigation of the PEEK (Poly-ether–ether–ketone) based self-mating articulation of the NuNec® cervical disc replacement. All tests were undertaken using Bose spine simulator. Discs were subjected to wear tests and this involved applying the load and motions given in ISO 18192-1. Wear was determined fr...

This paper describes the effects of hydroxylated biodiesel (castor oil methyl ester - COME) on the properties, combustion and emissions of butanol-diesel blends used within compression ignition engines. The study was conducted to investigate the influence of COME as a means of increasing the butanol concentration in a stable butanol-diesel blend. T...

Research suggests that there is a dramatic reduction in CO and particulate matter (PM) emissions when butanol is blended with biodiesel derived from rapeseed oil (RME), but a small increase in THC emissions. The addition of hydrogen as a combustion enhancer can be used to counteract the increase in THC emissions seen with the butanol fuel blends an...

Polymer gears can be run without lubrication, however, high running temperatures, driven by high contact friction, mean that the operating life of these gears, especially in medium to high power transmission applications, tends to be low and limited by wear. This paper describes an attempt to control friction and wear by reducing the running temper...

Little has been published on the behaviour of polymer gears operating under lubricated conditions. An experimental and analytical programme was undertaken to classify the regimes of EHL under which polymer spur gears operate. In doing so theoretical film thicknesses were calculated and then used to classify the regime according to Johnson's Map. Th...

2,5-Dimethylfuran (DMF) as a new synthesis alternative engine fuel has received much attention in terms of its production and combustion characteristics. However there is a distinct lack of information available on the tribological properties of DMF, and more specifically, its lubricity. In this paper the lubricity of DMF was studied using a four-b...

Wear processes are discussed for polymers used in a wide variety of implants in the human body, such as in joint replacement implants for the hip and knee. The articulation of metal or ceramic components against a polymer component can lead to the generation of wear debris and the effect this debris may have in the body is examined.

Biodiesel fuel is known to improve the properties of alcohol-diesel blends for use in compression ignition engines. In this work the effects on combustion characteristics and emissions of preselected methyl esters (i.e. biodiesel components) have been assessed. The most representative individual fatty acid methyl esters (FAMEs) were added to alcoho...

This paper presents a theoretical analysis of the maximum contact stress and the lubrication regimes for PEEK (Polyether-ether-ketone) based self-mating cervical total disc arthroplasty. The NuNec(®) cervical disc arthroplasty system was chosen as the study object, which was then analytically modelled as a ball on socket joint. A non-adhesion Hertz...

Spark ignition engines fuelled with alternative fuels are the topic of many studies. As alternatives for gasoline, ethanol and recently 2,5-dimethylfuran (DMF) have been investigated for their different properties. Lubricity analysis of fuels in fuel systems is vital because of the lubricating role of fuel. Lubricity of gasoline and its alternative...

The lubricating properties of two sustainable alternative diesels blended with ultra low sulphur diesel (ULSD) were investigated. The candidate fuels were a biodiesel consisting of fatty acid methyl esters derived from rapeseed (RME) and gas-to-liquid (GTL). Lubricity tests were conducted on a high frequency reciprocating rig (HFRR). The mating spe...

This article gives a condensed overview of Gas-to-Liquid (GTL), Biomass-to-Liquid (BTL) and Coal-to-Liquid (CTL) theory and technology by the use of Fischer–Tropsch (F–T) processes. Variations of the F–T process can be used to tailor the fuel properties to meet end user needs as well as aid vehicle manufacturers in achieving forthcoming emission re...

The lubricity of diesel fuel has a direct effect on the service life of the fuel injection equipment, and when alternative fuels are specified, is of vital importance. One such fuel is the Swedish diesel fuel, MK1 which contains low levels of sulphur and low lubricity. This paper investigated the use of ultra low sulphur diesel (ULSD) and fatty aci...

Polymeric gears are considered as being ‘low-noise’ components because their low modulus makes them resilient when the teeth come into contact. However, this does not account for the tribological noise generated as a result of the interacting tooth flanks. These are important considerations where high-precision motion control and low noise are requ...

The widespread reduction in teaching hours and increase in student numbers has resulted in pressure to reduce syllabuses. The increased number of students with varied cultural background and the need for multi-disciplinary teaching in order to reduce teaching duplication and costs, introduces the need for teaching innovation and teaching methods th...

This article describes an investigation into the contact behaviour of polymeric gear transmissions using numerical finite element (FE) and analytical techniques. A polymer gear pair was modelled and analysed using the ABAQUS software suite and the analytical results were calculated using the BS ISO 6336 rating standard. Before describing the result...

English: New renewable fuels have been developed for diesel engines, contributing to the reduction of carbon emissions and to fuel security. However, the combustion characteristics of these fuels and emissions still remain unclear. A study to investigate diesel engine performance integrated with biogas and hydrogen has been carried out. Biogas is p...

This paper presents a study of the role of materials in the generation of noise made by plastic gears. Sound levels were recorded for gears running in various running combinations. Frequency analyses were conducted on all the noise measurements and these showed that the harmonics for plastic gears mainly occur at multiples of the tooth meshing freq...

This chapter reviews the use of engineering polymers and short-fibre reinforced thermoplastics for machine elements such as gears, cams and pulleys where the polymers are in non-conformal contact. Both twin-disc testing and gear tests are examined for a variety of engineering polymers as well as the effects of temperature, fibre-reinforcement and g...

Transmission errors (TEs) are an important source of unwanted noise and vibration in gear drives. Errors can result from geometrical inaccuracies and from elastic deformations. Plastic drives are often loaded in a way that produces high deflections relative to steel gears, and the elastic component of TE is relatively more important. Furthermore, p...