The 13th International Conference on Fracture Fatigue and Wear (FFW 2025)

Abstract: Over recent decades it has become clear that the pouring of liquid metals is damaging to the liquid. The surface oxide is folded in, making a double oxide film, which acts as a crack. Most of our cast metals (but with interesting exceptions) are full of bifilm cracks originating from the casting process. The bifilm population, as a pre-existing population of cracks, is not easily detected because they are generally closed cracks with nano scale thickness. They are shown to initiate simple tensile failure, and fatigue. The bifilms become open cracks by the mechanism of precipitation cleavage, in which precipitates grown during certain sensitizing heat treatments form on the bifilms to reduce their strain energy of formation, and thereby prize the bifilms open. In this way metals become vulnerable to invasive corrosion, leading to stress corrosion cracking and/or hydrogen embrittlement. The reduction or elimination of bifilm populations by improved casting technology appears to lead to an order of magnitude increase in toughness of Al alloys and stainless steels, and appears to be a low cost technique to eliminate invasive corrosion, stress corrosion cracking and hydrogen embrittlement.

Biography: Educated in England at the universities of Cambridge, Sheffield and Birmingham he first trained as a physicist, then became a metallurgical engineer, but finally has spent much of his life in industry.
In the 1980s he built the casting operation for Cosworth Engineering, developing the Cosworth Casting Process, then a novel process making Al alloy cylinder heads and blocks for the Formula One racing engines, using counter-gravity filling of moulds by electromagnetic pump. The process has been taken up by Ford, Nemak and General Motors for the production of automotive cylinder blocks in North America and Mexico. This process still has the world record for production rates of sound and strong V6 and V8 blocks.
His industrial experience and his academic background including two masters degrees and two doctorates fitted him for his 15 years as Professor of Casting Technology in the University of Birmingham, UK. Here, he was able for the first time to define the nature of turbulence and the mechanism for the generation of casting defects, introducing the concepts of entrainment and the concept of the bifilm and the crack population of liquid metals. He has subsequently devoted much effort to the development of casting techniques to control defect formation. His mantra is the phrase “Making metals we can trust.”
He is currently working on the building of an integrated melting and casting machine which takes in tonnage quantities of recycled aluminium at one end, which is treated, producing aerospace quality aluminium castings and other high purity products with high properties at the other end. The process is low cost, high productivity, low labour content, low energy, low floor space, with few moving parts for maximum reliability. His other current interest is his quest to warn the world of the dangers of using vacuum arc remelted metals. It is not widely known that this expensive material contains bifilm cracks which bring down aircraft, but could be improved by abandoning the vacuum induction melted and cast electrode, and substituting a carefully cast low-cost air-melted electrode using the newly established casting technology.
His book “Complete Casting Handbook” published in 2011 and revised in 2015 is not light bed-time reading, but is all there: a bargain for the determined and fearless reader with an open mind. The “Mini Casting Handbook” 2017 and expanded in 2018 and 2023 is a basic, slimmed text specifically written for casting personnel.
His latest book “The Mechanisms of Metallurgical Failure - The Origin of Fracture.” 2020 is regrettably revolutionary and will be burned in the streets. It describes the potential elimination of failure mechanisms such as cracking, creep, fatigue, stress corrosion cracking etc in most metals, especially steels and high temperature alloys, by eliminating bifilms – the failure initiation sites introduced by turbulent pouring of the liquid.
In 1991 he was invited to become a Fellow of the Royal Academy of Engineering, and in 1993, Her Majesty, Queen Elizabeth, awarded him the Civil Honour, the Order of the British Empire, for services to casting technology.

Abstract: Structures and machine components are nowadays manufactured by additive manufacturing processes. This process dominates the resultant microstructural properties of the manufactured part and hence influences its damage behaviour. An effort is required to incorporate this influence into the existing concept of theoretical and applied mechanics models. At Cranfield, the damage mechanics research group is currently working to explore the mentioned influence with a special focus on structures made by fused deposition-based additive printing. So far extensive empirical testing schemes and computations have been used to analyse the trade-off in the values of printing parameters and the damage resistance of printed structures. Both simple and composite structures are tested under pure dynamic, pure thermal and coupled thermo-mechanical loads. The trade-off is evaluated on simple geometries such as plates and beams and also on composite geometries such as battery pack enclosures and metal-polymer riveted panels. This keynote lecture will provide the highlights of the key results, the complexities in data visualisation and modelling and future work.

Biography: Muhammad of experience, hKhan is the Head of the Centre for Life-cycle Engineering and Management and Reader in Damage Mechanics at Cranfield University. With over 23 yearse specializes in damage mechanics, modelling for life extension of engineering assets, and non-invasive techniques for asset health diagnostics. Khan has led and worked on projects sponsored by reputed organizations, including General Dynamics, MoD, QinetiQ, Cummins, UTC Aerospace, ESPRC, Atkins, and PTDF. He has authored a book on machine health diagnostics and published over 150 research articles in international journals and conferences. Dr Khan received his doctorate in machine health diagnostics from the University of Manchester in 2008 and he completed his post-doctoral research in damage diagnosis in aero-transmissions in 2011. He is a Chartered Engineer, a Fellow of the Institute of Mechanical Engineers UK, and a Fellow of Higher Education Academy UK, He is an active member of Condition Monitoring and Structural Health Monitoring Committees of British Institute of Non- Destructive Testing.

Abstract: Numerical methods have been extensively applied to the fracture mechanics, while they cannot simulate the problems without the mechanical models or constitutive equations. Artificial neural networks (ANNs) can be utilized to predict the complex fracture problems, but these approaches require large amounts of data for the training. Therefore, in this paper, to combine the advantages of the numerical methods and the ANNs, an improved back propagation neural network (BPNN) is proposed through introducing the enrichment used in the numerical methods into the activation function utilized in the neural networks. The enrichment is able to represent the crack tip field which can accelerate the convergence. At the field near the crack tip, the improved BP solution can converge to the analytical solutions which validate the high accuracy of the proposed method. Without sufficient data, especially the data are missing in the near field of the crack tip, the improved BP method can also achieve high accuracy and convergence, while the conventional BP method may not converge to the predetermined error bound. Numerical simulations of the quasi-static and fatigue crack problems demonstrate that the improved BP method can accurately predict the crack propagation and its growth rate with relatively little data.
Subsea carbon sequestration technology plays a crucial role in addressing global climate change, but CO2 leakage can harm the subsea ecosystem. Therefore, long-term monitoring and prediction of subsea carbon storage are essential. In this paper, forward and inverse Data-Assisted Physics-Informed Neural Networks (DA-PINNs) are established for subsea CO2 leakage prediction and detection. Firstly, the forward DA-PINN model integrates numerical simulation data and physical constraints including initial conditions, boundary conditions, and governing equations. This model is utilized to predict the CO2 velocity and pressure fields under different leakage widths and initial velocities. The results show that the proposed algorithm outperforms conventional Artificial Neural Networks (ANNs) in accuracy and exceeds the efficiency of conventional numerical simulations. Subsequently, the inverse model incorporates known initial and boundary conditions of leakage as training data, while the governing equations and pressure boundary conditions serve as physical inputs. The inverse DA-PINN model is then used to detect leakage widths and initial velocities under different velocity and pressure fields, achieving a prediction accuracy of over 97%. Compared to conventional ANNs and numerical simulations, the proposed DA-PINNs not only predict CO2 leakage with high accuracy and efficiency but also solve inverse problem with the same high precision and effectiveness.

Biography: Dr. Lihua Wang is a professor at School of Aerospace Engineering and Applied Mechanics in Tongji University, Shanghai, China. She is currently a General Council Member of the International Association for Computational Mechanics (IACM) and the International Chinese Association for Computational Mechanics (ICACM). She is the recipient of several awards, including the APACM Award for Young Investigators in Computational Mechanics, the Qian Linxi Computational Mechanics Award (Young Investigators), the ICACM Young Investigator Award, and the Du Qing-Hua Medal & Young Researcher Award of Computational Methods in Engineering. She has authored more than 120 peer-reviewed journal articles, including CMAME, IJNME, JCP etc., and has been invited to deliver more than 10 plenary and invited lectures at international conferences. She served as associate editor of Chinese Quarterly of Mechanics and as an editorial board member for four international/Chinese journals. Her research interests include development of meshfree methods and machine learning, fluid-structure interactions, high-speed impact, fracture mechanics.

Abstract: Fretting fatigue occurs in many engineering systems where load must be transferred between adjacent components. The consequences for system performance, durability and safety can be very significant. In most cases the cause of the cyclic loading is vibrations in the system. These either result from external loads or are generated in the system itself (e.g. due to out of balance loading or reciprocating mass). Frequently the vibration problem is treated entirely separately from that of fretting at the interface. However this is a simplification which can lead to misleading results. Interface friction is an important source of damping in the system and will have a significant effect on the levels of vibration experienced. Hence, in order to fully characterise the system, the vibration and fretting problems need to be considered in a holistic framework. The input to any model should be the loading experienced by the system and the output is a durability assessment. Interface contact conditions should be treated as internal variables. If the system is treated in this way, there is a possibility to optimise fretting fatigue life by changing interface geometry or friction. The paper will detail the steps required to implement a holistic model and present some sample results for a simple partial slip contact.

Biography: Professor David Nowell is Professor of Machine Dynamics at Imperial College London. He has been involved in research in solid mechanics and tribology for over 35 years and he has developed a particular interest in fretting fatigue. His recent research has focused on the role of frictional interfaces in providing damping in complex engineering systems. Professor Nowell is a Fellow and a Trustee of the Institution of Mechanical Engineers (I.Mech.E.). He is also a Fellow of the Institute of Materials Minerals and Mining (IoM³).