Hydrogen is ubiquitous and has two faces. On the one hand, it is at the core of the most promising solutions to our energy crisis. Hydrogen isotopes fuel the nuclear fusion reaction, the most efficient potentially useable energy process. Moreover, hydrogen is widely seen as energy carrier of the future and the most versatile means of energy storage. It can be produced via electrolysis from renewable sources, such as wind or solar power, and stored to be used as a fuel or as a raw material in the chemical industry. On the other hand, hydrogen is widely known to cause catastrophic failures in metallic materials and structures, hampering these opportunities. Metals become brittle when exposed to hydrogen-containing environments, with the fracture resistance decreasing by up to 90%. This so-called hydrogen embrittlement phenomenon not only jeopardises the role of hydrogen as a potential solution to the global energy crisis but also constitutes one of the biggest threats to the integrity of the current energy infrastructure. The problem is particularly severe in aggressive environments, such as those experienced by the offshore industry, as corrosive mitigation strategies like cathodic protection exacerbate the production of hydrogen. Moreover, hydrogen embrittlement is becoming increasingly notorious due to the higher susceptibility of modern, high-strength steels. Decades of metallurgical research have led to the development of metals with high and ultra-high strengths. These modern alloys open new horizons in reducing weight, material use and costs while increasing performance and safety (fatigue resistance). For example, ultra-high strength steels are essential in meeting targets on CO2 emissions through vehicle weight reduction. However, the susceptibility to hydrogen embrittlement increases with material strength and the increasing uptake of these new high-performance materials has made hydrogen assisted fractures commonplace across a wide variety of sectors and applications in otherwise benign environments, from bolt cracking at the Leadenhall tower to rail failures in underground systems. There is an urgent need to understand the multiple physical mechanisms behind this hydrogen-induced degradation and develop models that can predict failures as a function of the environment, the loading conditions and the material properties. This EPSRC New Investigator Award aims at developing a new generation of models that can predict local hydrogen uptake and subsequent cracking by resolving the electrochemistry-diffusion interface and shedding light into critical uncertainties in surface behaviour and trapping. An accurate estimation of hydrogen ingress for a given bulk environment is the main bottleneck preventing the application of current chemo-mechanics models in engineering assessment. Occluded areas such as cracks, pits or other defects exhibit very different chemistry to the bulk environment, and local measurements are unfeasible apart from controlled laboratory experiments. NEXTGEM will merge mechanics with electrochemistry, combining experiments, multi-physics modelling and Bayesian inference to resolve the scientific challenges holding back the applicability of hydrogen embrittlement models. This new generation of electro-chemo-mechanics models for hydrogen embrittlement will be used to enable a safe use of high strength alloys, optimise material selection and inspection planning, and prevent catastrophic failures. The project involves world-renowned academic collaborators with expertise complementary to that of the PI and leading firms in the offshore energy sector, operating the oldest large-scale wind farm in the world (Horns Rev 1). The applicability of the models developed will be demonstrated by continuous monitoring of critical components, in a piece of proof-of-concept research that can have wider implications across the transport, defence, construction and energy sectors.

Hydrogen is ubiquitous and has two faces. On the one hand, it is at the core of the most promising solutions to our energy crisis. Hydrogen isotopes fuel the nuclear fusion reaction, the most efficient potentially useable energy process. Moreover, hydrogen is widely seen as energy carrier of the future and the most versatile means of energy storage. It can be produced via electrolysis from renewable sources, such as wind or solar power, and stored to be used as a fuel or as a raw material in the chemical industry. On the other hand, hydrogen is widely known to cause catastrophic failures in metallic materials and structures, hampering these opportunities. Metals become brittle when exposed to hydrogen-containing environments, with the fracture resistance decreasing by up to 90%. This so-called hydrogen embrittlement phenomenon not only jeopardises the role of hydrogen as a potential solution to the global energy crisis but also constitutes one of the biggest threats to the integrity of the current energy infrastructure. The problem is particularly severe in aggressive environments, such as those experienced by the offshore industry, as corrosive mitigation strategies like cathodic protection exacerbate the production of hydrogen. Moreover, hydrogen embrittlement is becoming increasingly notorious due to the higher susceptibility of modern, high-strength steels. Decades of metallurgical research have led to the development of metals with high and ultra-high strengths. These modern alloys open new horizons in reducing weight, material use and costs while increasing performance and safety (fatigue resistance). For example, ultra-high strength steels are essential in meeting targets on CO2 emissions through vehicle weight reduction. However, the susceptibility to hydrogen embrittlement increases with material strength and the increasing uptake of these new high-performance materials has made hydrogen assisted fractures commonplace across a wide variety of sectors and applications in otherwise benign environments, from bolt cracking at the Leadenhall tower to rail failures in underground systems. There is an urgent need to understand the multiple physical mechanisms behind this hydrogen-induced degradation and develop models that can predict failures as a function of the environment, the loading conditions and the material properties. This EPSRC New Investigator Award aims at developing a new generation of models that can predict local hydrogen uptake and subsequent cracking by resolving the electrochemistry-diffusion interface and shedding light into critical uncertainties in surface behaviour and trapping. An accurate estimation of hydrogen ingress for a given bulk environment is the main bottleneck preventing the application of current chemo-mechanics models in engineering assessment. Occluded areas such as cracks, pits or other defects exhibit very different chemistry to the bulk environment, and local measurements are unfeasible apart from controlled laboratory experiments. NEXTGEM will merge mechanics with electrochemistry, combining experiments, multi-physics modelling and Bayesian inference to resolve the scientific challenges holding back the applicability of hydrogen embrittlement models. This new generation of electro-chemo-mechanics models for hydrogen embrittlement will be used to enable a safe use of high strength alloys, optimise material selection and inspection planning, and prevent catastrophic failures. The project involves world-renowned academic collaborators with expertise complementary to that of the PI and leading firms in the offshore energy sector, operating the oldest large-scale wind farm in the world (Horns Rev 1). The applicability of the models developed will be demonstrated by continuous monitoring of critical components, in a piece of proof-of-concept research that can have wider implications across the transport, defence, construction and energy sectors.

Over the next decades, there will be a huge expansion of offshore renewable energy facilities to add electricity to the grid and reduce greenhouse gas emissions around the world. Globally, an estimated 17% annual growth from 22 GW to 154 GW in total installed offshore wind power capacity will be seen by 2030. The UK's Offshore Wind Sector Deal (2019) also sets out a goal for the offshore wind sector output being 30 GW by 2030. To meet the ambition of offshore wind energy exploration, it is of great importance to design cost-efficient foundations which, due to the complexity of subsea soil behaviour, remains a major challenge. Offshore foundation designs are well known to be conservative, which has led in part to the foundations accounting for 25-34% of the overall budget of offshore wind farms. The design of offshore foundations is particularly difficult for carbonate soils which cover roughly 35% of the ocean floor because (1) the complex mechanical behaviour of carbonate soils for which a reliable constitutive model is yet unavailable and (2) carbonate soils around foundations often experience large deformations, such as during foundation installation, leading to significant changes of their properties which are difficult to evaluate using traditional finite element techniques. The research proposed in this project aims to develop advanced computer models capable of predicting the mechanical response of carbonate sands at offshore foundations from the installation stage to the operational stage. This will be achieved by developing a novel numerical approach called the particle finite element method (PFEM), for analysing large-deformation soil-water-foundation interactions, and a self-learning simulation framework based on advanced deep-learning techniques for training data-driven constitutive models for carbonate sands. The developed PFEM with the trained data-driven constitutive model for modelling the responses of carbonate sands at offshore structure foundations will be validated under both standard laboratory conditions and high gravity centrifuge testing conditions. The success of the proposed research will not only improve our understanding of the behaviour of carbonate sands surrounding offshore foundations but also provide engineers with a robust open-source computer tool to analyse interactions between submerged carbonate sands and foundations with large deformations and help achieve cost-effective foundation solutions for offshore renewable energy developments.

The biggest scientific and engineering challenges often lie in between disciplines. Through the years, we have gained a good understanding of how materials behave when subjected to mechanical loads (solid mechanics). We also understand the nature of the chemical reactions occurring when materials are exposed to a given environment (electrochemistry). However, predicting material behaviour due to combined exposure to mechanical loads and a degrading environment continues to be an elusive goal. Not being able to understand and predict electro-chemo-mechanics phenomena comes at a great cost since materials are very sensitive to environmental and mechanical degradation in many applications. The value of the fundamental science conducted in this fellowship will be demonstrated on two of these applications: (1) corrosion damage, and (2) Li-Ion batteries. Their importance cannot be emphasised enough. Solely in the UK, failure of structures and industrial components due to corrosion entails a staggering cost of £46 billion per annum. Li-Ion batteries are key enablers in achieving universal access to reliable, clean, sustainable energy. Now, there is an opportunity to develop models that can prevent corrosion failures and significantly enhance progress in battery technology. Larger computer resources and new algorithms enable simulating concurrent (coupled) physical processes such as chemical reactions, diffusion of species and mechanical deformation; so-called multi-physics modelling. However, the opportunity of building upon the success of multi-physics simulations to predict material degradation is held back due to our inability to model how the boundary between two different phases develops over time. For example, corrosion is often non-uniform, leading to small defects (pits) that grow and act as crack initiators. Preventing the associated catastrophic failures, such as the Morandi Bridge collapse, requires capturing how these defects will nucleate at the electrolyte-material interface and grow. But the modelling of morphological changes in an evolving interface has been long considered a mathematical and computational challenge. I will overcome this longstanding obstacle by smearing the "sharp" interface over a small diffuse region using an auxiliary "phase field" variable - a paradigm change that will make tracking of evolving interfaces amenable to numerical computations. A new generation of models will be developed and validated with powerful 3D techniques such as X-ray Computed Tomography, which have timely experienced notable improvements in spatial resolution and image reconstruction times. By explicitly capturing the damage process, this fellowship will not only open new horizons in the understanding of multi-physics material degradation phenomena but also set the basis for the introduction of simulation-based assessment in engineering practice; model predictions can be compared with inspection data, introducing the "Digital Twins" and "Virtual Testing" paradigms into engineering applications involving demanding environments. The near-term societal impact will be demonstrated by addressing salient technological problems in offshore energy, batteries, water supply networks and nuclear fission. Efforts will be guided by the fellowship advisory board, which includes leading firms in each of these sectors: EDF Energy, Rolls-Royce, SUEZ, PA Consulting, Vattenfall and Subsea7. For example, the new generation of models developed will be used to assist in the life extension decision of the oldest large-scale wind farm in the world, Horns Rev 1. The lessons learned in this world-first engineering assessment will set an example for the entire sector and demonstrate the potential of computer simulations in enhancing the economic viability of the leading renewable energy source. The successful fellowship will lay scientific foundations for new engineering solutions that will improve UK's competitiveness and our quality of life.

Wireless sensor networks using radio technology are used to gather data in many applications for infrastructure monitoring, environment monitoring and security. However this technology cannot be directly applied under water since radio waves are absorbed by water. Technologies exist for underwater communication using acoustic waves (sound) to carry data but this is a complex and demanding task requiring sophisticated processing. Hence these devices are expensive (£5-20k), bulky and power hungry which has generally limited their use to relatively small numbers and short duration. This has prevented the large scale deployment of sensor networks underwater despite huge demand for monitoring of subsea assets and the marine environment. The aim of this project is to create a smart underwater sensing framework based on ultra-low-cost underwater communication and sensing devices ('smart dust'). Pilot studies at Newcastle University have demonstrated the feasibility of producing underwater acoustic communication devices known as "nanomodems" which use novel approaches to signal processing to vastly reduce hardware complexity, size and cost. These have manufacturing cost as low as £50, very low receiver power consumption, to enable long life from small batteries, and tiny dimensions. However they can achieve data transfer and positioning capabilities found in much more expensive devices, over distances up to 1km through water. The communication technology will be extended, to further increase data transfer speed and power efficiency, and low cost sensor modules will be developed, along with flexible interfaces for commercially available sensors, to create mass deployable wireless underwater sensor devices. Protocols will be developed to allow large numbers of units to share the same communication channel efficiently while intelligent sensor processing techniques will ensure that the sensor network reliably extracts the maximum information available from the limited resources available. Hence the system will allow users to fully exploit the power of mass deployment, the whole being far greater than the sum of the parts. This will transform underwater sensor networks to allow long term monitoring with high spatial resolution, frequent updates and near real-time data delivery in a way that has been previously been cost prohibitive and impractical. With highly flexible sensor payload, the technology created may be applied to a wide range of monitoring tasks. However, the project will focus on three main demonstrator scenarios in close collaboration with industry & end users: - subsea asset monitoring e.g. condition of subsea cables, risers, seabed installations - marine environment / biodiversity monitoring - chemical or biological parameters - sensor nets for underwater security - detecting sound emitted or magnetic disturbances from underwater threats The novel contributions of this project will be: - Disruptive, low-cost technology enabling mass deployment with battery life of several years. - Large scale underwater monitoring (>100 devices) with high spatial resolution. - Rapid deployment and online data delivery (as opposed to data logging and collecting later). - Intelligent, adaptive sensing to maximise resource utilisation and fully exploit large scale. To maximise the impact of the project, an open test-bed will be created near the Northumberland coast. Potential end-users from across the subsea sector will be invited to take part in a series of workshops to identify new opportunities in distributed underwater sensing, which will be prototyped and evaluated via trials using the test-bed. The ultimate measurable objective of the project will be to demonstrate a step change in the efficiency of subsea data gathering. This will be defined in terms of the data delivered (volume, quality, coverage) versus overall cost of operations (hardware cost, boat time, staff time, infrastructure cost).