Staff Profiles

Modules taught

U04513, U04514, U04515 and P04715

My research expertise is in predictive modelling for design of engineering components and mechanical behaviour of materials. I have had the privilege of working with automotive and aerospace companies. My research interests and publications are in the areas of  artificial neural networks applied to fatigue and non destructive evaluation (NDE), noise vibration and harshness, light weight vehicle structural analysis, springback during forming processes, functionally graded materials, metal ceramic joining, residual stresses, creep, finite element and boundary element numerical methods and analysis of adhesively bonded structures. i review articles for a number of journals in my field and I am consulted for review of grant applications. 

Research group membership

I am currently a member of the Mechanics, Materials and Design Group.

Research grants and awards

Visiting Fellow - Nanyang University of Technology 2015

EPSRC Funded NVH Project, £371k, total value £750,000 (2003 – 2007).

Finite Element Network, European Union, £4,000, 2001-04.  

DoITPOMs HEFCE Funded Dissemination of Information Technology for the Promotion of Materials Science, £7,500, Led by Department of Materials, University of Cambridge, 2001-03.

Quality Research Funding Grant, Oxford Brookes University, £32,000, 1997- 2000.

LIVEMAN, EPSRC Funded Adhesive Bonding for Lightweight Vehicle Structures, £181,000, 1997- 2000

(Held with Prof Beveers and Prof Hutchinson).

Consultant, Structural Materials Centre, Defence Research Agency, Farnborough, 1995.

Generic Research Funding Grant, £2500, Oxford Brookes University,1994/95.

Research projects

Visiting Fellow - Nanyang University of Technology 2015

EPSRC Funded NVH Project, £371k, total value £750,000 (2003 – 2007).

Finite Element Network, European Union, £4,000, 2001-04.  

DoITPOMs HEFCE Funded Dissemination of Information Technology for the Promotion of Materials Science, £7,500, Led by Department of Materials, University of Cambridge, 2001-03.

Quality Research Funding Grant, Oxford Brookes University, £32,000, 1997- 2000.

LIVEMAN, EPSRC Funded Adhesive Bonding for Lightweight Vehicle Structures, £181,000, 1997- 2000

(Held with Prof Beveers and Prof Hutchinson).

Consultant, Structural Materials Centre, Defence Research Agency, Farnborough, 1995.

Generic Research Funding Grant, £2500, Oxford Brookes University,1994/95. 

Research impact

My research has influenced work in the reas of functionally graded material, residual stresses, fatigue, creep, adhesive bonded joint analysis, noise vibration harshness, artificial neural network applied to materials.

Journal articles

• Priyadarshi A, Khavari M, Subroto T, Prentice P, Pericleous K, Eskin D, Durodola J, Tzanakis I, 'Mechanisms of ultrasonic de-agglomeration of oxides through in-situ high-speed observations and acoustic measurements'
  Ultrasonics Sonochemistry 79 (2021)
  ISSN: 1350-4177 eISSN: 1873-2828
  Abstract

  Ultrasonic de-agglomeration and dispersion of oxides is important for a range of applications. In particular, in liquid metal, this is one of the ways to produce metal-matrix composites reinforced with micron and nano sized particles. The associated mechanism through which the de-agglomeration occurs has, however, only been conceptualized theoretically and not yet been validated with experimental observations. In this paper, the influence of ultrasonic cavitation on SiO2 and MgO agglomerates (commonly found in lightweight alloys as reinforcements) with individual particle sizes ranging between 0.5 and 10 μm was observed for the first time in-situ using high-speed imaging. Owing to the opacity of liquid metals, a de-agglomeration imaging experiment was carried out in de-ionised water with sequences captured at frame rates up to 50 kfps. In-situ observations were further accompanied by synchronised acoustic measurements using an advanced calibrated cavitometer, to reveal the effect of pressure amplitude arising from oscillating microbubbles on oxide de-agglomeration. Results showed that ultrasound-induced microbubble clusters pulsating chaotically, were predominantly responsible for the breakage and dispersion of oxide agglomerates. Such oscillating cavitation clusters were seen to capture the floating agglomerates resulting in their immediate disintegration. De-agglomeration of oxides occurred from both the surface and within the bulk of the aggregate. Microbubble clusters oscillating with associated emission frequencies at the subharmonic, 1st harmonic and low order ultra-harmonics of the driving frequency were deemed responsible for the breakage of the agglomerates.
  

  Website 
• Durodola JF, 'Machine learning for design, phase transformation and mechanical properties of alloys '
  Progress in Materials Science 123 (2021)
  ISSN: 0079-6425
  Abstract

  Machine learning is now applied in virtually every sphere of life for data analysis and interpretation. The main strengths of the method lie in the relative ease of the construction of its structures and its ability to model complex non-linear relationships and behaviours. While application of existing materials have enabled significant technological advancement there are still needs for novel materials that will enable even greater achievement at lower cost and higher effectiveness. The physics underlining the phenomena involved in materials processing and behaviour however still pose considerable challenge and yet require solving. Machine learning can facilitate the achievement of these new aspirations and desires by learning from existing knowledge and data to fill in gaps that have so far been intractable for various reasons including cost and time. This paper reviews the applications of machine learning to various aspects of materials design, processing, characterisation, and some aspects of fabrication and environmental impact evaluation.
  

  Website 
• Priyadarshi A, Khavari M, Subroto T, Conte M, Prentice P, Pericleous K, Eskin D, Durodola J, Tzanakis I, 'On the governing fragmentation mechanism of primary intermetallics by induced cavitation'
  Ultrasonics Sonochemistry 70 (2020)
  ISSN: 1350-4177 eISSN: 1873-2828
  Abstract

  One of the main applications of ultrasonic melt treatment is the grain refinement of aluminium alloys. Among several suggested mechanisms, the fragmentation of primary intermetallics by acoustic cavitation is regarded as very efficient. However, the physical process causing this fragmentation has received little attention and is not yet well understood. In this study, we evaluate the mechanical properties of primary Al3Zr intermetallics by nano-indentation experiments and correlate those with in-situ high-speed imaging (of up to 1 Mfps) of their fragmentation process by laser-induced cavitation (single bubble) and by acoustic cavitation (cloud of bubbles) in water. Intermetallic crystals were chemically extracted from an Al-3 wt% Zr alloy matrix. Mechanical properties such as hardness, elastic modulus and fracture toughness of the extracted intermetallics were determined using a geometrically fixed Berkovich nano-diamond and cube corner indenter, under ambient temperature conditions. The studied crystals were then exposed to the two cavitation conditions mentioned. Results demonstrated for the first time that the governing fragmentation mechanism of the studied intermetallics was due to the emitted shock waves from the collapsing bubbles. The fragmentation caused by a single bubble collapse was found to be almost instantaneous. On the other hand, sono-fragmentation studies revealed that the intermetallic crystal initially underwent low cycle fatigue loading, followed by catastrophic brittle failure due to propagating shock waves. The observed fragmentation mechanism was supported by fracture mechanics and pressure measurements using a calibrated fibre optic hydrophone. Results showed that the acoustic pressures produced from shock wave emissions in the case of a single bubble collapse, and responsible for instantaneous fragmentation of the intermetallics, were in the range of 20–40 MPa. Whereas, the shock pressure generated from the acoustic cavitation cloud collapses surged up to 1.6 MPa inducing fatigue stresses within the crystal leading to eventual fragmentation.
  

  Website 
• Thomas Hogg,Stefan Stojanovic, Andrew Tebbs, Stephen Samuel and John Durodola, 'A Benchmark Study on the Flow Metering Systems for the Characterisation of Fuel Injectors for Future Heavy Duty Commercial Vehicles.'
  Measurement 153 (2019)
  ISSN: 0263-2241
  Abstract

  This study aims to determine the most suitable flow metering device for the characterisation of heavy duty diesel injector behaviour. The study focuses on three commercially available metering devices and the main principles they employ. An experiment was carried out to benchmark the performance of each device’s measurement repeatability in the characterisation of fuel injector behaviour. This study then compares the capabilities and suitability of each for use in a production environment. The comparison was carried out for Delphi Technologies using the new DFi21 heavy duty diesel injector which uses the miniaturised hydraulic three way control valve technology.

  Website 
• Durodola JF, 'Artificial neural network for Gaussian and non-Gaussian random fatigue loading analysis'
  Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 233 (23-24) (2019) pp.7525-7544
  ISSN: 0954-4062
  Abstract

  There has been a lot of work done on the analysis of Gaussian loading analysis perhaps because its occurrence is more common than non-Gaussian loading problems. It is nevertheless known that non-Gaussian load occurs in many instances especially in various forms of transport, land, sea and space. Part of the challenge with non-Gaussian loading analysis is the increased number of variables that are needed to model the loading adequately. Artificial neural network approach provides a versatile means to develop models that may require many input variables in order to achieve applicable predictive generalisation capabilities. Artificial neural network has been shown to perform much better than existing frequency domain methods for random fatigue loading under stationary Gaussian load forms especially when mean stress effects are included. This paper presents an artificial neural network model with greater predictive capability than existing frequency domain methods for both Gaussian and non-Gaussian loading analysis. Both platykurtic and leptokurtic non-Gaussian loading cases were considered to demonstrate the scope of application. The model was also validated with available SAE experimental data, even though the skewness and kurtosis of the signal in this case were mild.

  Website 
• Ramachandra S, Durodola JF, Fellows NA, Gerguri S, Thite A, 'Experimental validation of an ANN model for random loading fatigue analysis'
  International Journal of Fatigue 126 (2019) pp.112-121
  ISSN: 0142-1123 eISSN: 1879-3452
  Abstract

  The use of artificial intelligence especially based on artificial neural networks (ANN) is now prevalent in many fields of data analysis and interpretation. There have been a number of papers published in the literature on the use of ANN for fatigue characterisation. Most of these have however been developed for rather focussed application with limited capability for fatigue life prediction for a broad scope of material and loading conditions. The authors recently presented a uniquely generalised ANN model that is capable of making fatigue life prediction for a broad range of material fatigue properties and loading spectral forms. The model was developed using simulated data albeit subject to conceivable constraints between possible materials properties and load forms. This paper presents a validation of the ANN model using a Society of Automotive Engineers (SAE) random fatigue loading experimental test data. The capabilities and potentials of the model are demonstrated by comparison with the SAE random load fatigue test results and with results obtained from other predictive methods. The performance of the ANN is highly encouraging as a general tool for random loading fatigue analysis.
  

  Website 
• Adil H, Gerguri S, Durodola J, Fellows N, Bonatesta F, Audebert F, 'Comparative Study and Evaluation of Two Different Finite Element Models for Piston Design'
  International Journal of Engineering Research and Applications 9 (3) (2019) pp.23-37
  ISSN: 2248-9622
  Abstract

  The exposure of pistons to extreme mechanical and thermal loads in modern combustion engines has necessitated the use of efficient and detailed analysis methods to facilitate their design. The finite element analysis has become a standard design optimisation tool for this purpose. In literature two different approaches have been suggested for reducing the geometry of the cylinder and crank slider mechanism, to idealise piston finite element analysis load models,whilst trying to maintain realistic boundaries to obtain accurate results. The most widely used geometry is the combination of piston and gudgeon pin while the second geometry includes some portion of the connecting rod’s small end and cylinder in addition to the piston and gudgeon pin.No clear analyses have been made in literature about the relative effectiveness of the two approaches in terms of model accuracy. In this work both approaches have been carried out and analysed with respect to a racing piston. The results suggest that the latter approach is more representative of the load conditions that the piston is subjected to in reality.

  Website 
• Ahmed H, Durodola JF, Beale RG, 'DETERMINATION OF THE BUCKLING LOADS OF IRREGULARLY SHAPED PLATES USING A NEW DESIGN APPROACH'
  Advanced Steel Construction 15 (1) (2019) pp.66-72
  ISSN: 1816-112X
  Abstract Elastic buckling is one of a number of modes of failure that needs to be considered during the design of structures. Although elastic buckling has been researched for decades there is still a need to develop fast and comprehensive procedures that will reduce product design time especially during the pre-sizing stage. This paper presents a novel equation and parameters for the buckling analysis of plates that accounts for the interaction of geometry parameters, boundary conditions and different load distributions.  The method covers geometrical plate shapes such as triangular, evolutive, and slightly curved plates. In the place of classical methods the new procedure called the Parametric Buckling Analysis (PBA) combines a number of concepts in a novel heuristic manner to achieve a comprehensive solution. Among the concepts is an extension of the Euler column buckling boundary condition coefficients to various possible plate edge boundary condition combinations. Geometry parameters reflect the combined effect of plate aspect ratio and the number of buckle waves. A load parameter introduces a regularising factor that allows the effect of different load distributions to be included in the equation. The method is tested for flat plates of different rectangular, triangular, trapezoidal shapes and for slightly curved plates with cylindrical geometries. Eighteen different combinations of free, simple support and clamped edge boundary conditions are considered. Uniform and linearly varying edge stress loading conditions are also considered. The results obtained are compared with those obtained using analytical and finite element analysis.Website 
• Okeke CP, Thite AN, Durodola JF, Greenrod MT, 'A novel test rig for measuring bending fatigue using resonant behaviour'
  Procedia Structural Integrity 13 (2018) pp.1470-1475
  ISSN: 2452-3216
  Abstract

  A novel test rig for bending fatigue test that based on specimen resonant behaviour has been developed. Determining bending fatigue properties of polymer materials with the standard test systems is challenging, and in some cases results are unattainable. This is particularly true of polymers that exhibit a high level of non-linearity and large deflection. This novel test setup is similar to that of four point bending arrangement resulting in a simple support. The loading is achieved by inertial effect of small masses mounted on the test specimen. A vibration shaker is used to base excite the specimen at the first resonance frequency until it breaks. The proposed test setup reduces the time taken to obtain Stress v/s number of cycles (S/N) curves, typically 1/10th of the universal testing machine based approach. The effect of nonlinearities can be reduced by application of larger loads at higher frequencies using large acceleration and smaller deflection combination. The results based on the proposed approach are in good agreement with tensile fatigue results. It has been successfully used to determine the bending fatigue properties of Polycarbonate (PC) of which determining the tensile fatigue properties were difficult to obtain. The significance of this novel test rig is that it accelerates the fatigue testing and allows the determination of the fatigue properties of some materials that cannot be obtained with existing systems.

  Website 
• Okeke CP, Thite AN, Durodola JF, Fellows NA, Greenrod MT, 'Modelling of hyperelastic polymers for automotive lamps under random vibration loading with proportional damping for robust fatigue analysis'
  Procedia Structural Integrity 13 (2018) pp.1460-1469
  ISSN: 2452-3216
  Abstract

  The objective of this paper was to model random vibration response of components of an automotive lamp made of Polycarbonate/Acrylonitrile Butadiene Styrene (PC-ABS), Polymethyl methacrylate (PMMA) and Polypropylene 40% Talc filled (PPT40) materials using a nonlinear hyperelastic model. Traditionally, the Rayleigh damping matrix used in the dynamic response analysis is constructed considering linear elastic behaviour based on either initial stiffness or secant stiffness. The performance of linear stiffness matrices is compared in this work with that based on the nonlinear hyperelastic, Mooney-Rivlin model, specifically addressing Rayleigh damping matrix construction. The random vibration responses of 10 samples of each material are measured. The mean square error of acceleration response was used to assess the effectiveness. Considering three materials of study, the hyperelastic model resulted in the reduction of the least square error at best by 11.8 times and at worst by 2.6 times. The Mooney-Rivlin material model based Raleigh damping matrix was more accurate in modelling the dynamic behaviour of components of nonlinear materials and it also represented the manufacturing variabilities more reliably. 

  Website 
• Durodola JF, Ramachandra S, Gerguri S, Fellows NA, 'Artificial neural network for random fatigue loading analysis including the effect of mean stress'
  International Journal of Fatigue 111 (2018) pp.321-332
  ISSN: 0142-1123 eISSN: 1879-3452
  Abstract The effect of mean stress is a significant factor in design for fatigue, especially under high cycle service conditions. The incorporation of mean stress effect in random loading fatigue problems using the frequency domain method is still a challenge. The problem is due to the fact that all cycle by cycle mean stress effects are aggregated during the Fourier transform process into a single zero frequency content. Artificial neural network (ANN) has great scope for non-linear
  generalization. This paper presents artificial neural network methods for including the effect of mean stress in the frequency domain approach for predicting fatigue damage. The materials considered in this work are metallic alloys. The results obtained present the ANN method as a viable approach to make fatigue damage predictions including the effect of mean stress. Greater resolution was obtained with the ANN method than with other available methods. Website 
• Okeke C P, Thite A N, Durodola J F and Greenrod M T, 'Hyperelastic polymer material models for robust fatigue performance of automotive LED lamps'
  Procedia Structural Integrity 5 (2017) pp.600-607
  ISSN: 2452-3216
  Abstract The object of this paper is to determine the statistics of parameters of hyperelastic models specific to Polybutylene Terephthalate filled with 30% glass fibre (PBT GF30) and Polymethyl Methacrylate (PMMA) materials used in automotive lamps. The hyperelastic behaviour of both materials, a semi-crystalline and an amorphous, is modelled using appropriate hyperelastic models. The stress-strain curves of the materials were measured under uniaxial tension using a non-contact video gauge. Five samples each were tested to measure the effect of manufacturing variability. The model parameter statistics were determined, the mean value of the model parameters were used to construct average stress-strain behavior, which is then compared to the experimental stresses. Among all the models and their associated parameters studied, the 3-parameter Mooney-Rivlin model provided the most accurate prediction of the behaviour for both materials. The model showed excellent stability and is therefore the most appropriate model to represent variations due to the manufacturing process. The detailed study of the correlation of the model parameters provided a good understanding of how the parameters are related to each other, enabling construction of complete probability distribution functions for further analysis.Website 
• Aguilar Espinosa AA, Fellows NA, Durodola JF, Fellows LJ, 'Determination of crack growth for 6082-T6 Aluminium subjected to periodic single and block overloads and underloads using a two dimensional finite element model'
  International Journal of Fatigue 105 (2017) pp.244-261
  ISSN: 0142-1123 eISSN: 1879-3452
  Abstract The estimation of crack growth under variable amplitude loading is complex due to interaction effects such as plasticity, crack tip blunting, residual stresses, crack tip closure and crack tip branching. Crack closure has been identified to be one of the main interaction effects. In order to study the effect of crack closure the authors have previously carried out experimental testing to obtain more accurate measurements of crack opening and closure  ;  . They have also developed two dimensional plane stress Finite Element models utilising high mesh density whilst maintaining the ability to measure crack growth over long crack lengths [3]. This initial work has been extended in this paper to examine the effects of single and block overloads and random spectrum loading on crack growth. The crack length distance that is affected by overloads and underloads measured experimentally and predicted numerically are shown to be very close when using cyclic hardening material properties and kinematic hardening. In addition the comparison of experimental and numerical crack growth versus crack length graphs shows good correlation of the crack growth acceleration and retardation after the applied overload which has not been seen previously. These comparisons seem to be a very useful tool to validate numerical models.Website 
• Durodola JF, Li N, Ramachandra S, Thite AN, 'A pattern recognition artificial neural network method for random fatigue loading life prediction'
  International Journal of Fatigue 99 (Part 1) (2017) pp.55-67
  ISSN: 0142-1123 eISSN: 1879-3452
  Abstract Random vibration fatigue loading occurs in automotive, aerospace, offshore and indeed in
  many structural and machine components. The analysis of these types of problems is often
  carried out using either time domain or frequency domain methods. Time domain rainflow
  counting together with Miner’s linear damage accumulation assumption is widely accepted as
  a method of rationalising stress amplitude and mean stress from random fatigue loading and
  the damage caused to the component. Frequency domain methods provide a faster alternative
  for the analysis of the same problem but the results are generally conservative compared to
  those obtained using time domain methods. This paper presents an artificial neural network
  (ANN) machine learning approach for the prediction of damage caused by random fatigue
  loading. The results obtained for ergodic Gaussian stationary stochastic loading is very
  encouraging. The method embodies rapid analysis as well as better agreement with rainflow
  counting method than existing frequency domain methods.
   
  Website 
• Durodola JF, 'Functionally graded adhesive joints : a review and prospects'
  International Journal of Adhesion and Adhesives 76 (July 2017) (2017) pp.83-89
  ISSN: 0143-7496
  Abstract There is increasing demand for effective and efficient lightweight structures because of global environmental and resource sustainability concerns. Adhesive bonding has been adopted in many assembly arrangements because of its relative reduction of stress concentration in joints compared to mechanical fasteners. Functionally graded bonded joints presents even greater potentials for reduction of stress concentrations and the tailoring of stress distribution as may be desired in an adhesive layer. This capability provides opportunity for the design of high performance tailored structural assemblies. Although some encouraging analysis and experimental work have been carried out on the development of functionally graded joints, its wide application is still to be realised. This paper reviews the work that has been carried out so far on the method, in terms of analysis, fabrication, experimental testing and application. It also reflects on outstanding issues that need to be resolved in order for wider application to be feasible.Website 
• Aguilar Espinosa AA, Fellows NA, Durodola JF, Fellows LJ, 'Development of numerical model for the determination of crack opening and closure loads, for long cracks'
  Fatigue and Fracture of Engineering Materials and Structures 40 (4) (2016) pp.571-585
  ISSN: 8756-758X
  Abstract A two-dimensional Finite Element (FE) model has been developed for determining crack opening and closure stresses, with the eventual aim of investigating plasticity induced closure effects on crack growth under variable amplitude loading. An issue with model verification is obtaining accurate experimental values of crack opening and closure loads. Validation was therefore carried out using experimental data from constant amplitude loading tests, recently obtained by the authors1, 2 where there was good confidence in the accuracy of the opening and closing loads. Elastic-perfect plastic and work hardening material properties were investigated to determine the effect they had on crack growth. The modelling considered long cracks by dividing the crack into consecutive small lengths. For this purpose, the restart capability included in the ABAQUS code was employed. In addition, a mesh refinement strategy was optimised to reduce the memory requirements for the thousands of cycles analysed. This enabled both long crack lengths and small element sizes to be studied which has not been done in the literature before. The FE results were in good agreement with most of the experimental results and possible reasons are given for some of the minor discrepancies observed. Website 
• Stojanovic S, Tebbs A, Samuel S, Durodola J, Stephen S, 'Cepstrum Analysis of a Rate Tube Injection Measurement Device'
  SAE Technical Papers 2016 (2016)
  ISSN: 0148-7191 eISSN: 0096-5170
  Abstract With a push to continuously develop traditional engine technology efficiencies and meet stringent emissions requirements, there is a need to improve the precision of injection rate measurement used to characterise the performance of the fuel injectors. New challenges in precisely characterising injection rate present themselves to the Original Equipment Manufacturers (OEMs), with the additional requirements to measure multiple injection strategies, increased injection pressure and rate features. One commonly used method of measurement is the rate tube injection analyser; it measures the pressure wave caused by the injection within a column of stationary fluid. In a rate tube, one of the significant sources of signal distortion is a result of the injected fluid pressure waves reflected back from the tube termination.Cepstral analysis has shown to be a useful tool when evaluating formants in speech analysis, evaluating speaker harmonics and identifying sideband families in mechanical systems for fault identification. It is of particular usefulness in single input multiple output systems where the signal is distorted by echoes from its source. This study employs cepstrum analysis for evaluating fluid born frequencies present in a rate tube injection measurement device in order to identify sources of distortion in the injection rate signal.A rate tube was used to measure the rate of injection from a Delphi EURO 6 commercial vehicle common rail diesel injector. Injection rate signals were acquired under stable temperature conditions then digitally processed and its cepstrum evaluated. With knowledge of the system, this study shows that it is possible to identify the influence of components on the system and sources of signal distortion present in the rate measurement using quefrency and rahmonics. This paper presents a systematic methodology used for employing cepstrum for pulsating hydraulic systems to aid system optimization and fault detection.Website 
• Durodola J, Parikh T, Fellows N, Gungor S, 'An etching based axisymmetric solution for the determination of residual stresses in long fibre reinforced metal matrix composites'
  Journal of Composite Materials 48 (19) (2013) pp.2375-2386
  ISSN: 0021-9983 eISSN: 1530-793X
  Abstract Thermal residual stresses arise in long fibre reinforced composites such as metal matrix composites due to the mismatch of the thermal and mechanical properties of the constituents and the change in temperature during processing. This paper presents an inverse axisymmetric model that uses the fibre deformation obtained when the matrix is selectively etched away in order to back calculate the inherent residual stresses. The model is tested using finite element method simulation and also on published experimental data. Although, an approximate inverse solution exists in the literature, there is an ambiguity in the value of Poisson’s ratio to be used which can lead to large errors relative to the full solution presented in this paper. A sensitivity analysis is also carried out to quantify the effect of variability of material properties on the stress values obtained using the solution.Website 
• Ahmed H, Durodola J, Beale R, 'A new design approach for the determination of the buckling load of rectangular plates'
  Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 227 (7) (2013) pp.1417-1428
  ISSN: 0954-4062
  Abstract

  The objective of this article is to introduce and assess a new plate buckling analysis procedure which can be used for quick, approximate analysis of buckling loads in preliminary design. The method is applied to a range of plate edge support condition combinations including many where results are not readily available. The results obtained using the new procedure were compared against theoretical formulae available in the literature and by finite element analyses with good agreement

  Website 
• Aguilar-Espinosa A, Fellows N, Durodola J, 'Experimental measurement of crack opening and closure loads for 6082-t6 aluminium subjected to periodic single and block overloads and underloads'
  International Journal of Fatigue 47 (February) (2013) pp.71-82
  ISSN: 0142-1123
  Abstract Crack closure and opening stresses have been determined for 6082-T6aluminium, subjected to single and blockoverloads and single and blockoverloads and underloads, using an optical method. The distance between the overloads was varied in order to investigate the effect that crack growth distance between overloads has on crack growth rate. The optical method provided high magnification allowing crackclosure away from the crack tip to be determined and the crack advance to be monitored dynamically. The data obtained gives insight into the significance of periodic overloading and underloading as well as what effect interactions, such as crack branching, have on crack growth retardation. The results obtained also enable numerical and analytical codes to be evaluated.Website 
• Durodola J, Parikh T, Fellows N, Gungor S, 'An etching based method for the determination of residual stresses in metal matrix composites'
  Journal of Composite Materials online (-) (2013) pp.1-
  ISSN: 0021-9983
  Abstract Thermal residual stresses arise in long fibre reinforced composites such as metal matrix composites due to the mismatch of the thermal and mechanical properties of the constituents and the change in temperature during processing. This paper presents an inverse axisymmetric model that uses the fibre deformation obtained when the matrix is selectively etched away in order to back calculate the inherent residual stresses. The model is tested using finite element method simulation and also on published experimental data. Although, an approximate inverse solution exists in the literature, there is an ambiguity in the value of Poisson’s ratio to be used which can lead to large errors relative to the full solution presented in this paper. A sensitivity analysis is also carried out to quantify the effect of variability of material properties on the stress values obtained using the solution.Website 
• Farley SJ, Durodola JF, Fellows NA, Hernandez-Gomez LH, 'High resolution non-destructive evaluation of defects using artificial neural networks and wavelets'
  NDT & E INTERNATIONAL 52 (2012) pp.69-75
  ISSN: 0963-8695
  Abstract This paper presents artificial neural networks (ANN) and wavelet analysis as methods that can assist high resolution of multiple defects in close proximity in components. Without careful attention to analysis, multiple defects can be mis-interpreted as single defects and with the possibility of significantly underestimated sizes. The analysis in this work focussed on A-scan type ultrasonic signal. Amplitudes corresponding to the sizes of two defects as well as the phase shift parameter representing the distance between them were determined. The results obtained demonstrate very good correlation for sizes and distances respectively even in cases involving noisy signal data. (C) 2012 Elsevier Ltd. All rights reserved.Website 
• Farley S, Durodola J, Fellows N, Hernandez-Gomez L, 'High-resolution non-destructive evaluation of defects using artificial neural networks and wavelets'
  NDT and E International: Independent Nondestructive Testing and Evaluation 52 (November) (2012) pp.69-75
  ISSN: 0963-8695
  Abstract This paper presents artificialneuralnetworks (ANN) and wavelet analysis as methods that can assist highresolutionof multiple defects in close proximity in components. Without careful attention to analysis, multiple defects can be mis-interpreted as single defects and with the possibility of significantly underestimated sizes. The analysis in this work focussed on A-scan type ultrasonic signal. Amplitudes corresponding to the sizes of two defects as well as the phase shift parameter representing the distance between them were determined. The results obtained demonstrate very good correlation for sizes and distances respectively even in cases involving noisy signal dataWebsite 
• Rosales-Iriarte F, Fellows N, Durodola J, 'Failure prediction in carbon composites subjected to bearing versus bypass loading'
  Journal of Composite Materials 46 (15) (2012) pp.1859-1878
  ISSN: 0021-9983
  Abstract To lighten structures, many metallic components, such as aircraft wings, are being replaced by composite components. To join these components with the rest of the structure, various joining techniques are used. When using multiple bolted joints, bypass vs. bearing loading is developed around each joint. The ratio of bearing to bypass loading is known to affect the level of load at which failure occurs. There have been many models created to predict failure within composites but very little work has been carried out to investigate how well numerical models predict failure within bolted joints subjected to bearing and bypass loading. In addition, few models have been developed that account for the through thickness stresses that are developed underneath the bearing load. This paper compares a range of failure criteria and degradation models utilizing a three-dimensional model and compares how well they predict failure for bearing vs. bypass loading for a supported-pin-loaded joint.Website 
• Rosales-Iriarte F, Fellows N, Durodola J, 'Experimental evaluation of the effect of clamping force and hole clearance on carbon composites subjected to bearing versus bypass loading'
  Composite Structures 93 (3) (2011) pp.1096-1102
  ISSN: 0263-8223
  Abstract

  A series of carbon fibre laminate bearing versus bypass load tests were carried out investigating the effect of hole clearance, laminate lay-up, washer contact size and clamping force value. Explanations of the underlying effects that influence the results are discussed. The results compare well with literature but hole clearance was shown to increase joint strength when bypass loads are dominant, which seems counter intuitive, and has not been reported in literature

  Website 
• Puri RS, Morrey D, Bell AJ, Durodola JF, Rudnyi EB, Korvink JG, 'Reduced order fully coupled structural--acoustic analysis via implicit moment matching'
  Applied Mathematical Modelling 33 (11) (2009) pp.4097-4119
  ISSN: 0307-904X
  Abstract A reduced order model is developed for low frequency, undamped, fully coupled structural–acoustic analysis of interior cavities backed by flexible structural systems. The reduced order model is obtained by applying a projection of the coupled system matrices, from a higher dimensional to a lower dimensional subspace, whilst preserving essential properties of the coupled system. The basis vectors for projection are computed efficiently using the Arnoldi algorithm, which generates an orthogonal basis for the Krylov Subspace containing moments of the original system. The key idea of constructing a reduced order model via Krylov Subspaces is to remove the uncontrollable, unobservable and weakly controllable, observable parts without affecting the transfer function of the coupled system. Three computational test cases are analyzed, and the computational gains and the accuracy compared with the direct inversion method in ANSYS.
   
  It is shown that the reduced order model decreases the simulation time by at least one order of magnitude, while maintaining the desired accuracy of the state variables under investigation. The method could prove as a valuable tool to analyze complex coupled structural–acoustic systems, and their subsequent optimization or sensitivity analysis, where, in addition to fast analysis, a fine frequency resolution is often required.
  Website 
• Fessel G, Broughton J, Fellows N, Durodola J, Hutchinson A, 'Fatigue performance of metallic reverse-bent joints'
  Fatigue and Fracture of Engineering Materials and Structures 32 (9) (2009) pp.704-712
  ISSN: 8756-758X
  Abstract

  Adhesively bonded lap shear joints have been investigated widely and several ideas have been proposed for improving joint strength by reducing bondline stress concentrations. These include application of adhesive fillets at the overlap ends and use of adhesive with graded properties in the overlap area. Another, less common, approach is to deform the substrates in the overlap area in order to obtain a more desirable bondline stress distribution. Previous work carried out by the authors on a number of different substrate materials indicated that a reverse-bent joint geometry is useful for increasing joint strength. Results from static stress analysis and experimental testing demonstrated that significant improvements could be achieved. This paper presents results of further work carried out to assess the fatigue performance of reverse-bent joints. Substrates with different yield and plastic deformation characteristics were used and the effects of different overlap lengths on strength were examined. The results of this research show that the improvements obtained under static tests conditions translate to even higher benefits in fatigue. The paper also explains the failure mechanism of the joints under fatigue loading.

  Website 
• Lopez-Castro A, Durodola J, Fellows N, 'A closed form solution for predicting springback in bending of beams including hardening effect'
  Advanced Steel Construction 5 (2) (2009) pp.127-135
  ISSN: 1816-112X
  Website 
• Fellows N , Harris A, Durodola J, Beevers A, 'Effects of design and adhesive modulus on the torsional stiffness of automotive structures'
  Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 222 (8) (2008) pp.1421-1428
  ISSN: 0954-4070
  Abstract The torsional stiffness of automotive structures is one of the major factors that affect vehicle handling, safety, and passenger comfort. Several factors such as material property, geometry, and joining technique contribute to the stiffness of a structure. This paper investigates the effect of adhesive modulus on the torsional stiffness of idealized box beams and plenum chambers for a luxury car. The effect of the adhesive modulus was investigated by considering four different adhesives ranging in modulus from 6MPa to 3 GPa. To assess the influence of the apertures, some tests were carried out on box beams containing a single aperture on one side. Spot-welded plenum chambers and beams were also tested to provide a comparison of adhesive performance against conventional methods of joining. The effect of the adhesive modulus and the apertures in the plenum chambers on the results are discussed in the light of the results obtained, as well as the suitability of using adhesive bonding to reduce the vehicle weight.Website 
• Aviles L, Hernandez-Gomez L, Durodola J, Urriolagoitia-Calderon G, Urriolagoitia-Sosa G, 'Locating and classifying defects with artificial neural networks'
  Applied Mechanics and Materials 13-14 (-) (2008) pp.117-123
  ISSN: 1660-9336
  Abstract Locating defects and classifying them by their size was done with an Adaptive Neuro Fuzzy Procedure (ANFIS). Postulated void of three different sizes (1x1 mm, 2x2 mm and 2x1 mm) were introduced in a bar with and without a notch. The size of a defect and its localization in a bar change its natural frequencies. Accordingly, synthetic data was generated with the finite element method. A parametric analysis was carried out. Only one defect was taken into account and the first five natural frequencies were calculated. 495 cases were evaluated. All the input data was classified in three groups. Each one has 165 cases and corresponds to one of the three defects mentioned above. 395 cases were taken randomly and, with this information, the ANN was trained with the backpropagation algorithm. The accuracy of the results was tested with the 100 cases that were left. This procedure was followed in the cases of the plain bar and a bar with a notch. In the next stage of this work, the ANN output was optimized with ANFIS. The accuracy of the localization and classifications of the defects was improvedWebsite 
• Farley S, Durodola J, Fellows N, Hernandez-Gomez L, 'A neural network approach for locating multiple defects'
  Applied Mechanics and Materials 13-14 (-) (2008) pp.125-131
  ISSN: 1660-9336
  Abstract A method is presented to demonstrate the use of artificial neural networks (ANNs) in providing additional information regarding defects or flaws when used in conjunction with the ultrasonic A-scan method. ANNs were employed both as pattern classifiers and as function approximators to maximise the amount of data available from the temporal A-scan signal. A steel bar was modelled in 2D using ABAQUS finite element analysis (FEA) software. A single defect was introduced to the bar, modelled as a void, and parametric studies conducted to record data with the defect at various locations. An ultrasonic Lamb wave was introduced at the top of the bar. The longitudinal wave propagated along the length of the bar and was partially reflected by the defect. Multiple cases were simulated, modelling voids between 1mm and 6mm in width in various locations. Mean displacement of all the nodes at the top of the bar was recorded throughout the simulation, and features extracted from this waveform to create the data set for the ANNs. The ANNs were trained with a percentage of the data collected, selected at random, and assessed with the remaining data. The target data for the ANNs were the depth and size of the defect. The case of two separate defects was also investigated. The procedure was carried out in the same manner as for one defect, but in this case the target data for the ANNs were the depth of the first defect and the distance between the defects. A separate ANN was employed as a pattern classifier, to determine if the reflected A-scan signal represented one or two defects. The final system was tested using previously unseen data, and provided very good results both in determining the number of defects and the size and location of the defects, even with data to which noise had been added.Website 
• Urriolagoitia-Sosa G, Durodola J, Fellows N, 'Effect of strain hardening on residual stress distribution in beams determined using the crack compliance method'
  The Journal of Strain Analysis for Engineering Design 42 (2) (2007) pp.115-121
  ISSN: 0309-3247 eISSN: 2041-3130
  Website 
• Fessel G, Broughton J, Fellows N, Durodola J, Hutchinson A, 'Evaluation of different lap-shear joint geometries for automotive applications'
  International Journal of Adhesion and Adhesives 27 (7) (2007) pp.574-583
  ISSN: 0143-7496
  Abstract

  Adhesive bonding is used increasingly by the automotive industry to join structural components of metallic and composite materials. The most common joint configuration is the lap-shear joint, which has been investigated widely and several ideas have been proposed to improve its performance. For example, the introduction of fillets at the overlap ends or tapering of the substrates can reduce the peel stresses at the overlap end. Other approaches include the use of"reverse-bent" substrates and"wavy joints" to reduce peel stresses. This paper compares the stress distribution of the"reverse-bent" and the"wavy joint" , with the stresses of the traditional lap-shear joint, using finite element analysis (FEA). A parametric study was carried out showing trends influencing stresses in the adhesive layer. Experimental tests were conducted to evaluate the assumptions used in, and the findings of, the FEA. The joint strength of"reverse-bent" joints was found to be up to 40% higher compared to flat joints using various substrate materials, adhesives and overlap lengths.

  Website 
• Urriolagoitia-Sosa G, Durodola J, Lopez-Castro A, Fellows N, 'A method for the simultaneous derivation of tensile and compressive behaviour of materials under Bauschinger effect using bend tests'
  Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 220 (10) (2006) pp.1509-1518
  ISSN: 0954-4062
  Website 
• Harvey DA, Fellows NA, Durodola JF, Twin A, 'Influence of the heat-treatment process on the mechanical properties and dimensions of multi-filamentary composite Nb3Sn superconducting wires'
  Advances in Experimental Mechanics IV 3-4 (2005) pp.141-147
  ISSN: 1660-9336
  Abstract The levels of stress and strain experienced by the windings of a superconducting magnet during its manufacture and operation are dependent on the mechanical properties of the multifilamentary composite wire that the windings are comprised of It is also influenced by the change in dimensions of the wire during the reaction heat-treatment stage of the manufacturing process. Using specimens cut from a spool of 1.5mm diameter niobium tin type superconducting wire, the influence of the heat-treatment process on the mechanical properties and dimensions have been investigated. The heat-treatment was carried out in an inert atmosphere using apparatus specially developed for the purpose. For heat-treatment durations up to that required to complete the reaction of the niobium filaments into Nb3Sn, the volume and diameter of the wires increased with increasing heat-treatment duration. The maximum increase was 2% and 0.8% respectively. The length of the wires decreased slightly for the shorter heat-treatments, but increased up to 0.33% for the longer ones. The mechanical properties were significantly different for specimens that had no heat-treatment compared to those that had only a short heat-treatment, one that was insufficient to convert much of the niobium into Nb3Sn. Before heat-treatment the bronze within the wires is in a work-hardened state, but gets annealed during the heat-treatment and this is probably the major cause of the change in mechanical properties. Apart from becoming more brittle, the mechanical properties do not change much for different durations of heat-treatment. This is quite remarkable considering that the composition changes dramatically with the length of the heat-treatment.Website 
• Harvey D, Fellows N, Durodola J, Vázquez-Navarro M, Twin A, 'Tensile testing of superconducting wires'
  Revista mexicana de f{ísica 51 (SUPLEMENTO 1) (2005) pp.51-55
  Website 
• Zarco-Gonzalez J, Fellows N, Durodola J, 'A step-size independent method for finite element modeling of damage in composites'
  Composites science and technology 64 (10/11) (2004) pp.1679-1689
  ISSN: 0266-3538
  Website 
• Durodola J, Attia O, 'Property gradation for modification of response of rotating MMC discs'
  Materials science and technology 16 (7/8) (2000) pp.919-924
  ISSN: 0267-0836 eISSN: 1743-2847
  Abstract Aerospace and industrial gas turbine engine components such as discs, blades, and propeller shafts for which long fibre reinforced metal matrix composites are being made, operate under complex mechanical and thermal loading conditions. A major aim of functionally graded materials application is to optimise component response through appropriately tailored microstructures. This paper explores the influences of property gradation, centrifugal body force loading, and thermal loading on stresses in rotating discs. The discs were modelled as non-homogeneous orthotropic materials such as those obtained through non-uniform reinforcement of a metal matrix by long fibres. The results show how different temperature change distribution patterns and property gradation types correlate with hoop stresses developed in the disc.Website 
• Steidler SM, Durodola J, Beevers A, 'Modelling of Adhesive Bonded Joints in Vehicle Substructures'
  International Journal of Materials and Product Technology 14 (1999) pp.467-475
  ISSN: 0268-1900 eISSN: 1741-5209
  Website 
• Durodola J, Ruiz C, Derby B, 'Uniaxial creep of long fibre reinforced metal matrix composites'
  Composites Engineering 4 (12) (1994) pp.1241-1255
  ISSN: 0961-9526
  Abstract

  A generalisation of McLean's (Directionally Solidified Materials for High Temperature Service, 1983, The Metals Society, London) uniaxial creep model which accounts for the effects of inherent residual stresses, matrix primary creep and the treatment of the effect of possible instantaneous matrix yield upon loading is presented. The model and numerical micromechanics approach are used to analyse the uniaxial creep of Ti-6AI-4V/SiC metal matrix composites. Excellent agreement is obtained between the analytical and numerical models and predicted results are in reasonable agreement with published experimental results.
  

  Website 

Book chapters

• Durodola JF, Fellows N, Winfield P, Gerguri S, Maruyama B, 'Continuously Reinforced Metal Matrix Composites' in Hashmi S (ed.), Reference Module in Materials Science and Materials Engineering, Elsevier (2017)
  ISBN: 978-0-12-803581-8
  Abstract Continuous fiber reinforced metal matrix composites (MMCs) presents the architecture or arrangement of fiber in matrix materials that offer realization of the highest possible mechanical and thermal management properties from the combination. The highest forms of specific stiffness, strength, fatigue and creep resistance are realized in this form of composite compared to particulate and short fiber reinforced MMCs. This chapter presents the types of matrix and fiber materials that are commonly used for the fabrication of long fiber reinforced MMCS. It presents the factors that influence the choice of fiber and matrix for the fabrication and the type of reaction problems that can occur during the high temperature processing that is often required. The types of fabrication methods such as liquid, physical and chemical vapor deposition methods, matrix coated fiber, foil–fiber–foil, and more recently ultrasonic processes are highlighted. The initiatives that have been taken to mitigate deleterious interfacial reaction are discussed. The effects of fiber volume fraction and mismatch of the fiber and the matrix properties on residual stress generated during fabrication and its consequent effects on fatigue and creep are underscored. The potentials of the composite have not been fully realized due to high processing cost. This has reflected in the unstable interests and involvement of manufacturing companies in its production over the years. The chapter lists outstanding suppliers of fibers and long fiber MMCs. Demonstrator components mainly for aerospace and electric power distribution industries are highlighted. Electric power distribution Al/Alumina fiber MMC cables that has become a commercial success case in diverse parts of the world is also presented.Website 

Conference papers

• Priyadarshi A, Subroto T, Conte M, Prentice P, Pericleous K, Eskin D, Durodola J, Tzanakis I, 'Ultrasound induced fragmentation of primary Al3Zr crystals'
  (2020)
  Abstract

  Ultrasonic cavitation melt treatment (UST) of aluminium alloys has received considerable attention in the metal industry due to its simple and effective processing response. The refined primary intermetallic phases formed in the treated alloys during controlled solidification, govern alloy structural and mechanical properties for applications in the automotive and aerospace industries. Since the UST is performed close to the liquidus temperatures of the alloys, understanding the refinement mechanism of the primary intermetallic phases has been beset by difficulties in imaging and handling of liquid metals. In this paper, the sonofragmentation behaviour of primary intermetallic Al3Zr crystals extracted from the matrix of an Al-3 wt% Zr alloy and fixed on a solid substrate was investigated. The intermetallics were exposed to cavitation action in deionized water at 24 kHz of ultrasound frequency. The fragmentation mechanism from the nearby collapsing cavitation bubbles was studied with in-situ high speed imaging. Results revealed that the main fragmentation mechanism is associated with the propagation of shock wave emissions from the collapsing bubble clouds in the vicinity of the crystal. The mechanical properties of the Al3Zr phase determined previously were used for the fracture analysis. It was found that an Al3Zr intermetallic undergoes low cycle fatigue fracture due to the continuous interaction with the shock wave pressure. The magnitude of the resulting shear stress that leads to intermetallic fragmentation was found to be in the range of 0.6 – 1 MPa.
  

  Website 
• Ahmed H, Durodola J, Beale R, 'A geometry based method for the stability of plates.'
  (2010) pp.813-820
  Abstract The objective of this paper is to introduce and investigate a new plate buckling analysis procedure based on geometry. The method is applied to a range of plate edge support condition combinations including many where results are not readily available. The results obtained by using the new procedure were compared against theoretical formulae available in the literature and by finite element analyses with good agreement. Following the verification of the new procedures the technique was extended to consider buckling of non-rectangular plates and cylindrically curved plate structures where the results were conservative but easy to use.Website 
• Puri R, Morrey D, Durodola J, Morgans R, Howard C, 'A comparison of structural-acoustic coupled reduced order models (ROMS): Modal coupling and implicit moment matching via Arnoldi'
  International Congress on Sound and Vibration (14th: 2007: Cairns, Australia) (2007) pp.4318-4325
  ISBN: 978-1-62748-000-0
  Website 
• Puri RS, Morrey D, Bell A, Durodola JF, Rudnyi EB, Korvink JG, 'Two-way Coupled Structural Acoustic Optimization Via Model Order Reduction (mor)'
  (2007) pp.4409-4424
  Abstract A reduced order model is developed for low frequency, fully coupled, undamped and constantly damped structural acoustic analysis of interior cavities, backed by flexible structural systems. The reduced order model is obtained by applying a Galerkin projection of the coupled system matrices, from a higher dimensional subspace to a lower dimensional subspace, whilst preserving some essential properties of the coupled system. The basis vectors for projection are computed efficiently using the Arnoldi algorithm, which generates an orthogonal basis for the Krylov subspace containing moments of the original system. A computational test case is analyzed, and the computational gains and the accuracy compared with the direct method in ANSYS. Further, the reduced order modelling technique is applied to a two-way coupled vibro-acoustic optimization problem, with stacking sequences of the composite structure as design variables. The optimization is performed via a hybrid search strategy combining outputs from Latin Hypercube Sampling (LHS) and Mesh Adaptive Direct Search (MADS) algorithm. It is shown that reduced order modelling technique results in a very significant reduction in simulation time, while maintaining the desired accuracy of the optimization variables under investigationWebsite 
• Zarco-Gonzalez JC, Fellows NA, Durodola J, 'Characterisation of Damage in Bolted Composite Joints Under Bearing and By-pass Loading'
  Revista Mexicana de Fisica 51 (2007) pp.47-50
  ISSN: 0035-001X
  
• Puri RS, Morrey D, Bell A, Durodola JF, Rudnyi EB, Korvink JG, 'Compact structural-acoustic coupled models via model order reduction (MOR)'
  The Thirteenth International Congress on Sound and Vibration, Vienna, Austria (2006)
  ISBN: 3950155457
  
• Gerguri S, Fellows LJ, Durodola JF, Fellows NA, Hutchinson AR, Dickerson T, 'Prediction of Brittle Failure of Notched Graphite and Silicon Nitride Bars'
  1-2 (2005) pp.113-119
  
• Beevers A, Steidler SM, Durodola J, Coackley M, 'Analysis of Stiffness of Adhesive Joints in Car Bodies'
  Journal of Materials Processing Technology 118 (2002) pp.96-101
  ISSN: 0924-0136
  

Membership of professional bodies

Fellow - Institution of Mechanical Engineers (FIMechE)

Editorial Board – Journal of Mechanical Engineering Science (IMechE Proc C)

Editorial Board - ISRN Applied Mathematics