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Steve J Bull

Newcastle University, Chemical Engineering and Advanced Material, Faculty Member

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Currently Cookson Group Chair of Materials Engineering at Newcastle University where I have been working for over twenty years on the mechanics of coatings and layered materials. Previously I ran coating facilities and undertook contract research in Surface Engineering at AEA Technology, Harwell Laboratory.
Phone: +44 191 208 7913
Address: Chemical Engineering and Advanced Materials
Newcastle University
Merz Court
Newcastle upon Tyne
NE1 7RU
UK

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Roger S O Tomlin

University of Oxford

Kazeem Kayode Adewole

University of Ibadan Nigeria

Mohammad Mehrajuddin

Trần Văn Đẳng

Universitas Islam Riau ( Uir)

Olayemi Ogunrinde

Sabino Ayvar-Soberanis

Ghanta Siva Rajesh

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Papers by Steve J Bull

Finite element failure analysis of wires for civil engineering applications with various crack-like laminations

Engineering Failure Analysis, 2016

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 Intern... more

Experimental Investigation of the Effects of Reverse Bending and Straightening Process on Carbon Steel Bars used for Civil Engineering Applications

Civil Engineering Dimension, 2014

This paper presents an experimental investigation of the effects of reverse bending and straighte... more This paper presents an experimental investigation of the effects of reverse bending and straightening process on the mechanical properties of a typical carbon steel bar used for civil engineering applications. Twenty four specimens each were used for the metallogarphy, microhardness and tensile tests. The investigation revealed that the reverse bending and straightening process has no significant effect on the bars' through-thickness microstructure and hardness. However, the reverse bending and straightening process reduces the yield load, ultimate load, and displacement at fracture of the bars by 4.27%, 2.58%, and 18.62% respectively. These results highlight the need to take into consideration the effects of the previous loading history of the bars/wires, particularly the reduction in the displacement at fracture and consequently, the ductility of the bars/wires in the design and fitness for purpose assessment of components made from them, since the bars/wires could experience high strain during installation and in service due to overloads.

Mechanical Characterisation of Polymeric Materials Using Nanoindentation

Biologically-Inspired Systems

PolyHIPEs for Water Treatment

Journal of Physics: Conference Series, 2019

PolyHIPEs (polymers synthesized within high internal phase emulsions) are porous materials with h... more PolyHIPEs (polymers synthesized within high internal phase emulsions) are porous materials with high specific surface area which suggests their use in ion exchange applications. We have successfully synthesized and functionalized such materials to make then hydrophilic by mixing an oil phase and an aqueous phase containing deionized water and sulphuric acid. The PolyHIPE samples were also subjected to a further microwave-assisted post-sulphonation process to increase hydrophilicity and water uptake. Post sulphonation results in a higher concentration of benzenesulphonic acid groups which are necessary for ion exchange. PolyHIPE beads processed in this manner were able to remove low concentrations (∼20mg/l) of nickel and copper ions from solution with high removal efficiency (80-95%) depending on the initial pH of the water. However, recovery of the metal through regeneration at different pH levels was less successful.

The effect of processing parameters on the mechanical characteristics of PLA produced by a 3D FFF printer

The International Journal of Advanced Manufacturing Technology

3D printing by fused filament fabrication (FFF) provides an innovative manufacturing method for c... more 3D printing by fused filament fabrication (FFF) provides an innovative manufacturing method for complex geometry components. Since FFF is a layered manufacturing process, effects of process parameters are of concern when plastic materials such as polylactic acid (PLA), polystyrene and nylon are used. This study explores how the process parameters, e.g. build orientation and infill pattern/density, affect the mechanical response of PLA samples produced using FFF. Digital image correlation (DIC) was employed to get full-field surface-strain measurements. The results show the influence of build orientation and infill density is significant. For on-edge orientation, the tensile strength and Young’s modulus were 55 MPa and 3.5 GPa respectively, which were about 91% and 40% less for the upright orientation, demonstrating a significant anisotropy. The tensile strength and Young’s modulus increased with increasing infill density. In contrast, different infill patterns have no significant ef...

Numerical Prediction of the Effect of Lamination Orientation on Fracture Behaviour of Wires for Civil Engineering Applications

This paper presents a numerical investigation of the effects of lamination orientation on the fra... more This paper presents a numerical investigation of the effects of lamination orientation on the fracture behaviour of rectangular steel wires for civil engineering applications using fi nite element (FE) analysis. The presence of mid-thickness across-the-width lamination changes the cup and cone fracture shape exhibited by the lamination-free wire to a V-shaped fracture with an opening at the bottom/pointed end of the V-shape at the mid-thickness across-the-width lamination location. The presence of mid-width across-the-thickness lamination changes the cup and cone fracture shape of the lamination-free wire without an opening to a cup and cone fracture shape with an opening at the lamination location. The FE fracture behaviour prediction approach adopted in this work provides an understanding of the effects of lamination orientation on the fracture behaviour of wires for civil engineering applications which cannot be understood through experimental investigations because it is impossi...

The effect of temperature on the abrasive wear of coatings and hybrid surface treatments for injection-moulding machines

Wear, 2005

Glass-filled polymers are known to produce considerable wear on the screws and barrels of injecti... more Glass-filled polymers are known to produce considerable wear on the screws and barrels of injection-moulding machines and several coatings and surface treatments have been used to combat this ranging from chromium plating to high velocity oxy fuel (HVOF) WC/Co. However, quantification of the benefits of such coatings and treatments has proceeded on an ad hoc basis and there is little data available on which to aid selection. In this study, a specially designed wear tester has been used to simulate the conditions of wear which occur in the barrel of an injection-moulding machine in order to assess coatings and surface treatments which are often used in this application as a function of test temperature. The tester concept is similar to that of the ASTM rubber wheel abrasion test except that the rubber wheel is replaced by a grooved steel wheel heated to a fixed temperature (up to 250 • C) by hot air and the sand is replaced by pelletised plastic. The plastic is captured by the wheel and dragged past the sample, which is also heated to the same temperature. The sample is pressed against the plastic coated wheel with a small load and a wear scar is produced at the contact point by a combination of abrasive wear from the glass filler and sliding wear from the plastic. A specially designed feeder system allows the controlled supply of polymer feedstock for operating times of a few hours. In the case of glass-filled nylon, the best surface treatment was a diamond-like carbon coating, but hybrid surface treatments involving the nitrogen ion implantation of nitrided steel also showed excellent wear performance.

A simple method for the assessment of the contact modulus for coated systems

Philosophical Magazine, 2014

This work is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License ePr... more

An explanation of the indentation size effect in ceramics

Philosophical Magazine Letters, 1989

Numerical Prediction of the Effects of Miniature Channel Shaped Scratches on the Fracture Behaviour of Wires for Civil Engineering Applications Using Finite Element Analysis

The effects of the miniature channel-shaped scratches not detectable by the present inline elec-t... more The effects of the miniature channel-shaped scratches not detectable by the present inline elec-tromagnetic defect detection system employed for wires ’ surface defect detection on the fracture behaviour of the wires for civil engineering applications were investigated numerically. Finite element analysis revealed that both miniature channel-shaped across-the-thickness and across-the-width scratches change the fracture behaviour of the wires in terms of the fracture initiation locations and fracture process sequence. However, miniature across-the-thickness scratches does not affect the fracture shape of the wire while miniature across-the-width scratches changed the wires ’ cup and cone fracture to a fracture shape with a predominantly fl at fracture. These results provide an understanding of the fracture behaviour of wires with miniature scratches and serve as an alternative or a complimentary tools to experimental or fractographic failure analysis of wires with miniatures scratche...

On the origins and mechanisms of the indentation size effect

Zeitschrift für Metallkunde, 2003

ABSTRACT

The effects of ion implantation on the friction behaviour of sapphire

The friction behaviour of ion-implanted sapphire in contact with diamond cones and spheres of a r... more The friction behaviour of ion-implanted sapphire in contact with diamond cones and spheres of a range of materials has been investigated as a function of implantation dose and implant species. Generally, an increase in friction is observed at low doses followed by a decrease once amorphization takes place. For the sharp diamond cones this can be correlated with changes in ploughing behaviour controlled by near-surface plasticity, whereas, for the spheres, the increase in friction for low-dose implants is due to changes in adhesion between the spheres and the implanted layer. The implications of these observations for the creation of lubricating surface layers by high-dose ion implantation are discussed.

Simulation of the wire reverse bending test

Steel wires are used for pre-stressing concrete structural units and for the construction of susp... more Steel wires are used for pre-stressing concrete structural units and for the construction of suspension bridges among other applications in civil engineering. The reverse bending and straightening of wires by rollers is employed as a routine quality check to detect laminations in wires. Experimental work on the reverse bending of wires and Finite Element (FE) simulation of bending of wires has been investigated previously but the simulation of the reverse bending and straightening of wire has not been studied in detail. Also, the FE simulation of the bending of wire round a mandrel reported in the literature was conducted by pinning the nodes on one end of the wire to the mandrel and applying a concentrated load to the free end of the wire to bend the wire, which does not replicate the bending process in practice. In this paper, three dimensional FE simulation of the reverse bending of steel wires conducted as a part of the research to investigate the effects of the combination of r...

The hardness and elastic modulus of TiN films as determined by ultra-low load indentation

Investigation of Chemomechanical Effects on Sapphire Surfaces Modified by Ion-Implantation-Induced Carbon Impurities

Journal of Bio- and Tribo-Corrosion, 2021

Modification of the chemomechanical behaviour of the surface of sapphire by ion implantation to i... more Modification of the chemomechanical behaviour of the surface of sapphire by ion implantation to improve its near-surface mechanical properties has been investigated. 300 keV Ti+ ions at various doses were implanted and the concentration and damage profiles characterised using Rutherford Backscattering (RBS). At high doses (≥ 3 × 1016 Ti+ cm−2), a surface amorphous layer is formed due to implantation-induced damage. Nanoindentation was used to determine the hardness behaviour of the ion-implanted layer. Hardness increases at low implantation doses, associated with implantation-induced damage, but it is also observed that chemomechanical softening of the surface is reduced due to the removal of adsorbed water. In situ Raman scattering measurements demonstrate this removal at low doses and the re-establishment of the adsorbed water layer at high doses. The adsorption process is changed due to the introduction of carbon into the sapphire surface during implantation. For the optimum-impl...

$Research paper thumbnail of Tunable High Refractive Index Polymer Hybrid and Polymer–Inorganic Nanocomposite Coatings$

Tunable High Refractive Index Polymer Hybrid and Polymer–Inorganic Nanocomposite Coatings

ACS Applied Materials & Interfaces, 2021

Atomized spray plasma deposition (ASPD) provides a single-step, low-temperature, and dry approach... more Atomized spray plasma deposition (ASPD) provides a single-step, low-temperature, and dry approach for the preparation of high refractive index hybrid polymer or polymer–inorganic nanocomposite coatings. Refractive indices as high as 1.936 at 635 nm wavelength have been obtained for ASPD 4-bromostyrene/toluene–TiO2 nanocomposite layers containing low titania loadings. Thin films with any desired refractive index up to 1.936 can be easily deposited onto a variety of substrates by varying the precursor mixture composition. ASPD overcomes disadvantages commonly associated with alternative fabrication methods for depositing high refractive index coatings (elevated temperatures, wet processes, UV curing steps, and much greater inorganic loadings).

Sustainable Hydrogen Production from Waste Wood and CO2

Industrial & Engineering Chemistry Research

Surface engineering for manufacturing applications : symposium held November 28-December 1, 2005, Boston, Massachusetts, U.S.A

Surface interactions and modifications have become increasingly critical for a broad range of man... more Surface interactions and modifications have become increasingly critical for a broad range of manufacturing technologies. Applications can be in traditional manufacturing sectors and in manufacturing processes for microelectronics, optics, and micro-/nanoelectromechanical systems (MEMS/NEMS). Many applications demand engineered surfaces at different length scales that will function under extreme conditions. The goal of this book is to advance understanding of these diverse applications. In the field of tribological coatings, the increasing sophistication of coating processes to provide control over materials and composition gradients is being exploited to tailor properties such as adhesion, stresses, thermal barrier and wear resistance. Understanding the influence of nanostructure in coatings has become pivotal in the development of hard and wear-resistant materials. Modeling and simulation continue to make contributions to the understanding and predication of surface properties and...

Investigation of the Effects of Environmental Fatigue on the Mechanical Properties of GFRP Composite Constituents Using Nanoindentation

Experimental Mechanics

Background Fatigue failure criteria for fibre reinforced polymer composites used in the design of... more Background Fatigue failure criteria for fibre reinforced polymer composites used in the design of marine structures are based on the micromechanical behaviour (e.g. stiffness properties) of their constituents. In the literature, there is a lack of information regarding the stiffness degradation of fibres, polymer matrix and fibre/matrix interface regions affected by environmental fatigue. Objective The aim of present study is to characterize the stiffness properties of composite constituents using the nanoindentation technique when fatigue failure of composites is due to the combined effect of sea water exposure and cyclic mechanical loads. Methods In the present study, the nanoindentation technique was used to characterize the stiffness properties of composite constituents where the effects of neighbouring phases, material pile up and viscoplasticity properties of the polymer matrix are corrected by finite element simulation. Results The use of finite element simulation in conjunct...

Fatigue damage analysis of GFRP composites using digital image correlation

Journal of Ocean Engineering and Marine Energy

Glass fibre reinforced polymer composites are frequently used in marine applications where the co... more Glass fibre reinforced polymer composites are frequently used in marine applications where the combined effects of cyclic loads and the seawater environment limit their fatigue life. This paper aims to demonstrate the degradation that seawater causes to the stiffness of the composites. Three-point bending fatigue properties of cross-ply woven glass fibre composites commonly used to manufacture tidal turbine blades are reported for both wet and dry conditions. Failure analysis based on the Digital Image Correlation method was performed to identify damaged zones on the test coupon surface and to follow failure progression during the fatigue tests. To characterize the damage in the composite, stiffness degradation has been monitored during the entire fatigue history. Scanning electron microscopy was used to identify multiple failure mechanisms on the specimen fracture surface. In addition, for further verification of microscopy results, X-Ray Micro-computed tomography, was used to char...

Finite element failure analysis of wires for civil engineering applications with various crack-like laminations

Engineering Failure Analysis, 2016

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 Intern... more

Experimental Investigation of the Effects of Reverse Bending and Straightening Process on Carbon Steel Bars used for Civil Engineering Applications

Civil Engineering Dimension, 2014

This paper presents an experimental investigation of the effects of reverse bending and straighte... more This paper presents an experimental investigation of the effects of reverse bending and straightening process on the mechanical properties of a typical carbon steel bar used for civil engineering applications. Twenty four specimens each were used for the metallogarphy, microhardness and tensile tests. The investigation revealed that the reverse bending and straightening process has no significant effect on the bars' through-thickness microstructure and hardness. However, the reverse bending and straightening process reduces the yield load, ultimate load, and displacement at fracture of the bars by 4.27%, 2.58%, and 18.62% respectively. These results highlight the need to take into consideration the effects of the previous loading history of the bars/wires, particularly the reduction in the displacement at fracture and consequently, the ductility of the bars/wires in the design and fitness for purpose assessment of components made from them, since the bars/wires could experience high strain during installation and in service due to overloads.

Mechanical Characterisation of Polymeric Materials Using Nanoindentation

Biologically-Inspired Systems

PolyHIPEs for Water Treatment

Journal of Physics: Conference Series, 2019

PolyHIPEs (polymers synthesized within high internal phase emulsions) are porous materials with h... more PolyHIPEs (polymers synthesized within high internal phase emulsions) are porous materials with high specific surface area which suggests their use in ion exchange applications. We have successfully synthesized and functionalized such materials to make then hydrophilic by mixing an oil phase and an aqueous phase containing deionized water and sulphuric acid. The PolyHIPE samples were also subjected to a further microwave-assisted post-sulphonation process to increase hydrophilicity and water uptake. Post sulphonation results in a higher concentration of benzenesulphonic acid groups which are necessary for ion exchange. PolyHIPE beads processed in this manner were able to remove low concentrations (∼20mg/l) of nickel and copper ions from solution with high removal efficiency (80-95%) depending on the initial pH of the water. However, recovery of the metal through regeneration at different pH levels was less successful.

The effect of processing parameters on the mechanical characteristics of PLA produced by a 3D FFF printer

The International Journal of Advanced Manufacturing Technology

3D printing by fused filament fabrication (FFF) provides an innovative manufacturing method for c... more 3D printing by fused filament fabrication (FFF) provides an innovative manufacturing method for complex geometry components. Since FFF is a layered manufacturing process, effects of process parameters are of concern when plastic materials such as polylactic acid (PLA), polystyrene and nylon are used. This study explores how the process parameters, e.g. build orientation and infill pattern/density, affect the mechanical response of PLA samples produced using FFF. Digital image correlation (DIC) was employed to get full-field surface-strain measurements. The results show the influence of build orientation and infill density is significant. For on-edge orientation, the tensile strength and Young’s modulus were 55 MPa and 3.5 GPa respectively, which were about 91% and 40% less for the upright orientation, demonstrating a significant anisotropy. The tensile strength and Young’s modulus increased with increasing infill density. In contrast, different infill patterns have no significant ef...

Numerical Prediction of the Effect of Lamination Orientation on Fracture Behaviour of Wires for Civil Engineering Applications

This paper presents a numerical investigation of the effects of lamination orientation on the fra... more This paper presents a numerical investigation of the effects of lamination orientation on the fracture behaviour of rectangular steel wires for civil engineering applications using fi nite element (FE) analysis. The presence of mid-thickness across-the-width lamination changes the cup and cone fracture shape exhibited by the lamination-free wire to a V-shaped fracture with an opening at the bottom/pointed end of the V-shape at the mid-thickness across-the-width lamination location. The presence of mid-width across-the-thickness lamination changes the cup and cone fracture shape of the lamination-free wire without an opening to a cup and cone fracture shape with an opening at the lamination location. The FE fracture behaviour prediction approach adopted in this work provides an understanding of the effects of lamination orientation on the fracture behaviour of wires for civil engineering applications which cannot be understood through experimental investigations because it is impossi...

The effect of temperature on the abrasive wear of coatings and hybrid surface treatments for injection-moulding machines

Wear, 2005

Glass-filled polymers are known to produce considerable wear on the screws and barrels of injecti... more Glass-filled polymers are known to produce considerable wear on the screws and barrels of injection-moulding machines and several coatings and surface treatments have been used to combat this ranging from chromium plating to high velocity oxy fuel (HVOF) WC/Co. However, quantification of the benefits of such coatings and treatments has proceeded on an ad hoc basis and there is little data available on which to aid selection. In this study, a specially designed wear tester has been used to simulate the conditions of wear which occur in the barrel of an injection-moulding machine in order to assess coatings and surface treatments which are often used in this application as a function of test temperature. The tester concept is similar to that of the ASTM rubber wheel abrasion test except that the rubber wheel is replaced by a grooved steel wheel heated to a fixed temperature (up to 250 • C) by hot air and the sand is replaced by pelletised plastic. The plastic is captured by the wheel and dragged past the sample, which is also heated to the same temperature. The sample is pressed against the plastic coated wheel with a small load and a wear scar is produced at the contact point by a combination of abrasive wear from the glass filler and sliding wear from the plastic. A specially designed feeder system allows the controlled supply of polymer feedstock for operating times of a few hours. In the case of glass-filled nylon, the best surface treatment was a diamond-like carbon coating, but hybrid surface treatments involving the nitrogen ion implantation of nitrided steel also showed excellent wear performance.

A simple method for the assessment of the contact modulus for coated systems

Philosophical Magazine, 2014

This work is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License ePr... more

An explanation of the indentation size effect in ceramics

Philosophical Magazine Letters, 1989

Numerical Prediction of the Effects of Miniature Channel Shaped Scratches on the Fracture Behaviour of Wires for Civil Engineering Applications Using Finite Element Analysis

The effects of the miniature channel-shaped scratches not detectable by the present inline elec-t... more The effects of the miniature channel-shaped scratches not detectable by the present inline elec-tromagnetic defect detection system employed for wires ’ surface defect detection on the fracture behaviour of the wires for civil engineering applications were investigated numerically. Finite element analysis revealed that both miniature channel-shaped across-the-thickness and across-the-width scratches change the fracture behaviour of the wires in terms of the fracture initiation locations and fracture process sequence. However, miniature across-the-thickness scratches does not affect the fracture shape of the wire while miniature across-the-width scratches changed the wires ’ cup and cone fracture to a fracture shape with a predominantly fl at fracture. These results provide an understanding of the fracture behaviour of wires with miniature scratches and serve as an alternative or a complimentary tools to experimental or fractographic failure analysis of wires with miniatures scratche...

On the origins and mechanisms of the indentation size effect

Zeitschrift für Metallkunde, 2003

ABSTRACT

The effects of ion implantation on the friction behaviour of sapphire

The friction behaviour of ion-implanted sapphire in contact with diamond cones and spheres of a r... more The friction behaviour of ion-implanted sapphire in contact with diamond cones and spheres of a range of materials has been investigated as a function of implantation dose and implant species. Generally, an increase in friction is observed at low doses followed by a decrease once amorphization takes place. For the sharp diamond cones this can be correlated with changes in ploughing behaviour controlled by near-surface plasticity, whereas, for the spheres, the increase in friction for low-dose implants is due to changes in adhesion between the spheres and the implanted layer. The implications of these observations for the creation of lubricating surface layers by high-dose ion implantation are discussed.

Simulation of the wire reverse bending test

Steel wires are used for pre-stressing concrete structural units and for the construction of susp... more Steel wires are used for pre-stressing concrete structural units and for the construction of suspension bridges among other applications in civil engineering. The reverse bending and straightening of wires by rollers is employed as a routine quality check to detect laminations in wires. Experimental work on the reverse bending of wires and Finite Element (FE) simulation of bending of wires has been investigated previously but the simulation of the reverse bending and straightening of wire has not been studied in detail. Also, the FE simulation of the bending of wire round a mandrel reported in the literature was conducted by pinning the nodes on one end of the wire to the mandrel and applying a concentrated load to the free end of the wire to bend the wire, which does not replicate the bending process in practice. In this paper, three dimensional FE simulation of the reverse bending of steel wires conducted as a part of the research to investigate the effects of the combination of r...

The hardness and elastic modulus of TiN films as determined by ultra-low load indentation

Investigation of Chemomechanical Effects on Sapphire Surfaces Modified by Ion-Implantation-Induced Carbon Impurities

Journal of Bio- and Tribo-Corrosion, 2021

Modification of the chemomechanical behaviour of the surface of sapphire by ion implantation to i... more Modification of the chemomechanical behaviour of the surface of sapphire by ion implantation to improve its near-surface mechanical properties has been investigated. 300 keV Ti+ ions at various doses were implanted and the concentration and damage profiles characterised using Rutherford Backscattering (RBS). At high doses (≥ 3 × 1016 Ti+ cm−2), a surface amorphous layer is formed due to implantation-induced damage. Nanoindentation was used to determine the hardness behaviour of the ion-implanted layer. Hardness increases at low implantation doses, associated with implantation-induced damage, but it is also observed that chemomechanical softening of the surface is reduced due to the removal of adsorbed water. In situ Raman scattering measurements demonstrate this removal at low doses and the re-establishment of the adsorbed water layer at high doses. The adsorption process is changed due to the introduction of carbon into the sapphire surface during implantation. For the optimum-impl...

$Research paper thumbnail of Tunable High Refractive Index Polymer Hybrid and Polymer–Inorganic Nanocomposite Coatings$

Tunable High Refractive Index Polymer Hybrid and Polymer–Inorganic Nanocomposite Coatings

ACS Applied Materials & Interfaces, 2021

Atomized spray plasma deposition (ASPD) provides a single-step, low-temperature, and dry approach... more Atomized spray plasma deposition (ASPD) provides a single-step, low-temperature, and dry approach for the preparation of high refractive index hybrid polymer or polymer–inorganic nanocomposite coatings. Refractive indices as high as 1.936 at 635 nm wavelength have been obtained for ASPD 4-bromostyrene/toluene–TiO2 nanocomposite layers containing low titania loadings. Thin films with any desired refractive index up to 1.936 can be easily deposited onto a variety of substrates by varying the precursor mixture composition. ASPD overcomes disadvantages commonly associated with alternative fabrication methods for depositing high refractive index coatings (elevated temperatures, wet processes, UV curing steps, and much greater inorganic loadings).

Sustainable Hydrogen Production from Waste Wood and CO2

Industrial & Engineering Chemistry Research

Surface engineering for manufacturing applications : symposium held November 28-December 1, 2005, Boston, Massachusetts, U.S.A

Surface interactions and modifications have become increasingly critical for a broad range of man... more Surface interactions and modifications have become increasingly critical for a broad range of manufacturing technologies. Applications can be in traditional manufacturing sectors and in manufacturing processes for microelectronics, optics, and micro-/nanoelectromechanical systems (MEMS/NEMS). Many applications demand engineered surfaces at different length scales that will function under extreme conditions. The goal of this book is to advance understanding of these diverse applications. In the field of tribological coatings, the increasing sophistication of coating processes to provide control over materials and composition gradients is being exploited to tailor properties such as adhesion, stresses, thermal barrier and wear resistance. Understanding the influence of nanostructure in coatings has become pivotal in the development of hard and wear-resistant materials. Modeling and simulation continue to make contributions to the understanding and predication of surface properties and...

Investigation of the Effects of Environmental Fatigue on the Mechanical Properties of GFRP Composite Constituents Using Nanoindentation

Experimental Mechanics

Background Fatigue failure criteria for fibre reinforced polymer composites used in the design of... more Background Fatigue failure criteria for fibre reinforced polymer composites used in the design of marine structures are based on the micromechanical behaviour (e.g. stiffness properties) of their constituents. In the literature, there is a lack of information regarding the stiffness degradation of fibres, polymer matrix and fibre/matrix interface regions affected by environmental fatigue. Objective The aim of present study is to characterize the stiffness properties of composite constituents using the nanoindentation technique when fatigue failure of composites is due to the combined effect of sea water exposure and cyclic mechanical loads. Methods In the present study, the nanoindentation technique was used to characterize the stiffness properties of composite constituents where the effects of neighbouring phases, material pile up and viscoplasticity properties of the polymer matrix are corrected by finite element simulation. Results The use of finite element simulation in conjunct...

Fatigue damage analysis of GFRP composites using digital image correlation

Journal of Ocean Engineering and Marine Energy

Glass fibre reinforced polymer composites are frequently used in marine applications where the co... more Glass fibre reinforced polymer composites are frequently used in marine applications where the combined effects of cyclic loads and the seawater environment limit their fatigue life. This paper aims to demonstrate the degradation that seawater causes to the stiffness of the composites. Three-point bending fatigue properties of cross-ply woven glass fibre composites commonly used to manufacture tidal turbine blades are reported for both wet and dry conditions. Failure analysis based on the Digital Image Correlation method was performed to identify damaged zones on the test coupon surface and to follow failure progression during the fatigue tests. To characterize the damage in the composite, stiffness degradation has been monitored during the entire fatigue history. Scanning electron microscopy was used to identify multiple failure mechanisms on the specimen fracture surface. In addition, for further verification of microscopy results, X-Ray Micro-computed tomography, was used to char...