Materials and Modelling: Shaping NMS measurement research 2014

Transcription

1 Materials and Modelling: Shaping NMS measurement research 2014

2 The Materials and Modelling Programme at the National Physical Laboratory supports UK industry by providing the measurement infrastructure for the characterisation and effective use of materials, mathematics and modelling. In order to maximise the value of the programme, comment and challenge on its future direction are invited from all sectors of industry and academia. Such input is key to ensuring the programme effectively addresses current and future needs. Your feedback is eagerly awaited.

3 Contents Part 1: Introduction The National Measurement System The Materials and Modelling Programme Have your say... 5 Part 2: The Materials and Modelling Programme Science Strategy Programme Science Strategy... 6 Part 3: Science areas and proposed themes for investment Advanced Engineered Materials Theme for Investment: Engineered Surfaces Theme for Investment: Mechanical and Structural Properties Electrochemistry Theme for Investment: Environment Induced Cracking Functional Materials Theme for Investment: Functional Materials for Sensor Applications Theme for Investment: Function Material Measurements and Applications for Harsh (real-life) Environments Materials Processing and Performance (MPP) Composites and Thermal Metrology Theme for Investment: Manufacture, Characterisation and Performance of Polymer Composite Structural Elements Theme for Investment: Metrology for Thermal Performance Data Analysis and Uncertainty Evaluation Theme for Investment: Mathematics and Modelling to Support Traceability and the SI Theme for Investment: Mathematics and Modelling to Address Societal Challenges Materials Modelling and Simulation Theme for Investment: Modelling to Bridge Length Scales Part 4: How to respond Who should respond? How to respond... 24

4 Part 1: Introduction 1.1 The National Measurement System The National Measurement System (NMS) is responsible for stimulating good measurement practice and enabling business to make accurate and traceable measurements, for the benefit of the nation. This responsibility is provided through maintaining and developing the measurement infrastructure, representing the UK position internationally, enabling fair and safe competition, and providing support for innovation. The NMS is delivered through the National Physical Laboratory (NPL), the Laboratory of the Government Chemist (LGC) and the National Engineering Laboratory (NEL). Good measurement practice results in a better quality of life, through improved trade and consumer protection, a healthier environment and more effective health and safety measures. It also improves the competitiveness of business both at home and in export. The NMS invests approximately 55m a year in maintaining and improving measurement in the UK. 1.2 The Materials and Modelling Programme The NMS knowledge base consists of five programmes that develop the extensive existing capability and facilities of the UK National Measurement Institutes. Around 40% of the NMS effort is focussed on the core function of maintaining and extending the capability of the measurement infrastructure and the provision of top-level standards and certified reference materials. The knowledge base programmes typically address a current well-defined public, legislative or industrial need. Materials technology is vital to industrial competitiveness and innovation across all sectors 1. The remit of the NMS Materials and Modelling Programme is to provide UK industry with the necessary technological infrastructure for the development of advanced test methods and related standards required to ensure cost effective, valid and traceable measurement in the UK. The programme addresses measurement issues related to whole life cycles of materials including characterisation, design, production and performance of materials and materials systems. The programme supports innovation in the development and use of conventional and novel materials providing reliable test methods and predictive models. The NMS Materials and Modelling Programme is delivered by the National Physical Laboratory by groups covering six science areas 2 : Advanced Engineered Materials Group Deploy a range of cutting edge techniques to understand material and product performance by characterising the relationship between structure and properties. Electrochemistry Undertakes research to measure and model electrochemical and charge transfer processes in corrosion, fuel cell degradation, organic electronics, photovoltaics and catalysis. 1 UK businesses that produce and process materials have an annual turnover of 170 billion, 15% of the nation s GDP. David Willetts, Eight Great Technologies, Policy Exchange, More details on the full range of science and technology at the NPL can be found at 4

5 Functional Materials Work to understand and characterise materials that support coupling of multiple variables such as, transforming mechanical energy into electrical energy in piezoelectric materials - providing validated techniques for the measurement of piezoelectric, thermoelectric, dielectric and magnetic material properties. Materials Processing and Performance Develop a broad range of methods to understand the processing and performance behaviour of polymer composite materials throughout their life cycle. Work on standardised measurement of thermal properties of complex and reactive materials in a range of environmental conditions. Data Analysis and Uncertainty Develops and applies good practice in mathematics, statistics and scientific computing to support measurement across academia and industry and to ensure that inferences and decision making are reliable and traceable. All measurement generates data and the analysis of this data is the basis for inferences and decision making. Materials Modelling Work to define key properties that need to be measured, to design experiments needed to measure these properties, and to simulate experiments that are challenging to carry out in practice. 1.3 Have your say Delivering the NMS strategic goal, focus on leadership in measurement as applied to policy and regulation, support for a national infrastructure of measurement standards and services to underpin growth and innovation, and responding to national challenges requires an understanding of and response to the measurement challenges and needs of the researchers, businesses, and policy makers developing the technologies, products, services, and policies that will fuel growth and address national challenges. NMS and the NPL invite you to challenge, comment and help shape the areas of work that are proposed for investment in this year s NMS Materials and Modelling Programme formulation 3 by submitting feedback via the Have Your Say pages of the NPL s website or directly to formulation2014@npl.co.uk (See Part 4 for information). Questions for consideration: Do you feel the Programme Strategy aligns with the developing needs for material measurement within UK industry? If not, why not? How well do you think the aims of science areas align to the wider needs of UK industry and societal challenges? Do the proposed areas for funding align with your own material measurement challenges and needs? Do you have specific material measurement challenges in any of the proposed areas for funding? What are these? What are the key measurement research needs that are not currently represented and why should these be an area of focus for the Programme? 3 The programme of work within the Materials and Modelling Programme comprises three separate formulations conducted over a three year period. The work that is proposed within this document will equate to one third of the total programme of work that will be undertaken at NPL over the next three years. Details of the current complete programme of work can be found at 5

6 Part 2: The Materials and Modelling Programme Science Strategy The Materials and Modelling Programme s Mission Statement In support of the Department for Business, Innovation and Skills (BIS) vision of acting as the department for growth, delivering the industrial strategies, and supporting the eight great technologies, the Materials and Modelling Programme s mission is: To provide world-leading materials measurement capability to support the UK's future prosperity and quality of life 2.1 Programme Science Strategy The UK government has identified key sectors that are central to economic growth and societal development through its Industrial Strategies 4. Eight Great Technologies 5 have also been identified, including advanced materials. These sectors and technologies are essential to growth and to addressing impending societal challenges facing the UK such as energy security, sustainability, reducing environmental impact, supporting an ageing population, growth through innovative manufacturing, and developing information technology/communications. Underpinning the future requirements of all these sectors and technologies is the need to develop novel materials with tailored properties, to make radical advances in materials processing, to optimise manufacturing and engineering through knowledge-based design, and to establish innovative tools for predicting and characterising performance. Key to supporting these developments is the understanding and characterisation of microstructurally related physical/chemical mechanisms at an increasingly localised scale. This would enable prediction and manipulation of microscopic and macroscopic behaviour. Characterisation will require advances, and in some cases step-changes, in modelling, and the development of measurement tools capable of achieving the, significantly higher, 3D spatial and temporal resolution required. Theoretical modelling is essential in providing the fundamental framework that links materials behaviour at different length scales, identifying critical parameters and enabling prediction of performance. A further aspect is the ability to support and synthesize on the computer complex measurement systems that by their nature are increasingly expensive. A complementary and vital component is the understanding and the evaluation of the source and magnitude of uncertainties, in models, data and measurements David Willetts, Eight Great Technologies, Policy Exchange,

7 In partnership with industry and academia, the Materials and Modelling team at the NPL is developing state-of-the-art measurement and modelling techniques to characterise the physical properties of materials and their interaction at different length scales and relate these to the behaviour of samples, components, structures and devices in increasingly complex environments. There are four different themes that encompass the maintenance and development of novel measurement and modelling capability: 3D-time characterisation Modelling On-line and in situ measurement Surface properties/processes The Materials and Modelling team will apply these four themes to two broad areas of application: Materials metrology to sustain lifetime: Materials Integrity Metrology describes the measurement and modelling required to ensure sustained fitness-for-purpose of products, components and structures during their lifetime. Materials metrology to enable emerging technologies: Metrology for Emerging Materials describes the measurement and modelling required to remove the technical barriers to the adoption of new materials offering step changes in performance. 7

8 Part 3: Science areas and proposed themes for investment 3.1 Advanced Engineered Materials For a full description of the group s capabilities and current activities visit: With accurate measurements of properties and microstructure, product performance can be improved by modifying composition, controlling internal stresses or adding coatings or texturing surfaces. Such improvements underpin the sustainable development of novel materials, systems and processes for application to a range of sectors, but with particular focus on energy and advanced manufacturing 6. Through optimisation of test methods and material characterisation, the group supports material selection, component design and process development across industry sectors. The group s research focuses on: Mechanical properties: from macroscale properties of bulk materials to miniaturised tests to study variations of properties within products, aiding the understanding of failure mechanisms; Residual stress and full field strain measurement at a number of length scales, from microstructural analysis to buildings; Long term performance of materials in service conditions, high temperature corrosion and exposure to harsh environments for structural alloys and coatings; Surface engineering and tribology: sliding wear, abrasion, erosion, scratch testing, micro-tribology; Nanomechanical testing for surface and coatings properties by nanoindentation, surface acoustic waves and Atomic Force Microscopy (AFM); Material properties such as density, thermal expansion, modulus, creep, alloy viscosity. This research is coupled with the development of techniques for the microstructural characterisation of materials including: 3D optical microscopy; High resolution Scanning Electron Microscopy (SEM); High resolution Electron Back Scatter Diffraction (EBSD); FIB (Focused Ion Beam) / SEM for 3D nanoscale microstructural characterisation including EBSD and Energy Dispersive Spectroscopy (EDS). This science area has the aim of quantitatively relating material performance to microstructure through measurement and prediction applied to metals, ceramics and their composites. There is an emphasis on surfaces and surface engineering. 6 Enabling Technologies Strategy , Technology Strategy Board,

9 3.1.1 Theme for Investment: Engineered Surfaces The properties of surfaces are crucial to the performance of structural and functional materials. Surfaces are therefore often engineered and manipulated to enhance one or more properties needed for service 7. Surface engineering may be achieved through coatings, thermo-mechanical treatment, mechanical stressing, compositional control of the surface, or elemental enrichment of the surface. For example, using a water droplet erosion rig unique to the UK, the NPL has measured the benefit of altering the surface properties of turbine blades by coating. It has shown that the life of blades exposed to water droplet erosion can be extended by up to an order of magnitude by addition of carefully designed coatings. The aim of this theme is to develop a greater understanding of physical and chemical interactions and the degradation of engineered surfaces under different operating conditions, including thermal, mechanical or chemical extremes and to work with industry to facilitate the application of this expertise to industrially relevant processes. To address these challenges, developments are required in several areas: New test procedures for high temperature nanomechanical testing that will facilitate an improved understanding of how the properties and performance of materials change as a function of mechanical stresses, time and temperature; New and improved methods to measure the long term performance of high temperature protective coatings, and how their degradation relates to their detailed microstructure and exposure to extremes of temperature, and mechanical and chemical exposure; Relating the microstructural mechanisms of degradation of engineered materials in tribological contact to their durability with a focus of developing a predictive capability. The knowledge developed will enhance NPL s capability for 3D-time characterisation and modelling of damage initiation and propagation. It will also provide industry with improved accuracies in performance and life prediction of engineered surfaces over a range of application areas from tribology and mechanical properties to thermal protection and chemical barriers Theme for Investment: Mechanical and Structural Properties The drive to extend the performance of materials and structures under increasingly demanding conditions has highlighted a lack of validated mechanical property data, test methods and in-situ monitoring techniques 8. These gaps in knowledge severely limit the development and uptake of new materials and techniques for critical applications. Recent work at the NPL for example has used non-contact strain measurement with the Electro Thermal Mechanical Testing (ETMT) miniaturised testing, Thermal Mechanical Fatigue (TMF) and creep tests to give full-field, spatially resolved constitutive material behaviour at elevated temperatures, directly supporting the development and characterisation of new MARtensitic 9Cr steel strengthened by Boron and Nitrides (MARBN)-based steel compositions for extending the operating temperature of future power generation plants. 7 Surface Engineering: An enabling technology for high value manufacturing. Materials Knowledge Transfer Network, Materials Roadmap Enabling Low Carbon Energy Technologies, European Commission,

10 For mechanical properties the aim is to extend the test methodologies to higher strain rates and temperatures relevant to materials processing and future target operating conditions in the power generation and aerospace sectors. For structural properties the focus is on the development and application of reliable full field, in-situ strain and displacement measurements. Common to both areas is the integration of full field optical imaging with modelling, and the challenge of making measurements under demanding operating conditions. To address these challenges, developments are required in several areas: New and improved test methods, Good Practice Guides and draft Standards for the measurement of mechanical properties at high temperatures and strain rates up to 1000 s -1 ; Defining the relationship between mechanical property data, microstructure and strain rate for a range of metals and composites; Novel testpiece geometries and optical methods to obtain multi-scale spatial and temporal property data from a single test; Measurement techniques to enable in-situ full-field measurements of large structures, power plant components, and satellite components, using state of the art image processing combined with application specific platforms to obtain high quality repeatable data and low cost inspection techniques. Knowledge developed will provide UK industry with a suite of validated test methods for measurement of mechanical and structural properties. It will enhance the capability for generating accurate data for structural design and dynamic modelling codes, the validation of microstructural-property relationships over a range of operating conditions and novel insitu inspection techniques for measuring the performance of large structures across a range of industry platforms. X 290 images Z Y Work with the FIB system at the NPL has focused on the metrology for obtaining and reconstructing 3D slice images, examination of wear and stress corrosion cracking. 10

11 The NPL s FIB-SEM system has been used to capture 3D images of pitting and sulphide stress cracking in a simulated oilfield environment. The technique will support the development of work in small crack initiation and crack-path development. 11

12 3.2 Electrochemistry For a full description of the group s capabilities and current activities visit: Electrochemistry research underpins the development of more efficient and environmentallyfriendly energy generation and conversion processes as well as intelligent lifetime management of materials in safety-critical applications. The electrochemistry science area embraces four distinct themes: corrosion and environment induced cracking; fuel cells; catalysis; organic electronics and Organic Photo Voltaics (OPVs) Corrosion research is focused primarily on environment induced cracking (EIC) for which the NPL has a world leading reputation with respect to the underpinning science, development of measurement techniques and testing standards, and advanced modelling. EIC is the primary cause of failure of metallic structures and components in a wide range of industries with potentially catastrophic consequences for safety, the environment and economics. The NPL is in the vanguard of development and application of innovative in-situ techniques to measure the key parameters that determine the performance and degradation of polymer electrolyte membrane fuel cells. Coupled with multi-physics multi-scale modelling these are providing a unique capability for optimising design, operational efficiency and fuel cell durability. In catalysis, high resolution electrochemical imaging and in-situ molecular spectroscopy are being developed and applied to improve understanding of the dynamics of catalytic processes at a highly localized level. Combined with advanced modelling these will provide a basis for intelligent design and development of novel catalysts with tailored properties. In PVs and organic electronics the challenges are to improve efficiency and, quality control and to extend the lifetime of devices, which are being achieved by a combination of sophisticated multi-parameter modelling and in-situ high-resolution mapping of activity from the nanoscale up to the cm scale. These advances are complemented by exposure tests using a unique testing chamber with precise environmental control that allows unprecedented insight into mechanisms of degradation Theme for Investment: Environment Induced Cracking Environment induced cracking occurs in a wide range of industries over a spectrum of operational conditions of temperature, environment, stress and material. Outages caused by cracking are significant from both an economic and societal perspective. For example, a steam turbine failure can cost 10m to remedy, but perhaps more critically it would also mean the loss of availability of a power station for months at a time, when our electricity supply network is stretched. Although engineering design will be optimised to minimise the probability of occurrence of cracking, or to provide an acceptable life using appropriate design codes, there are several reasons why cracking may still be of concern: Welding can introduce defects and affect the material characteristics; Fabrication stresses may exceed the design values; 12

13 The operating conditions may be changed; Transient variations in stress, temperature or environment chemistry may occur, either from scheduled excursions (e.g. shutdown) or from unintentional fluctuation in system control (e.g. contamination); The character of the metal surface may change with time of operation (e.g. precipitation of a scale or deposit) or the material may age (e.g. irradiation effects); Localised corrosion processes, such as pitting and crevice corrosion, may be initiated, e.g. during an excursion, and become precursors for EAC; The ideal engineering choice of material for the specified process conditions may not be economically viable; Laboratory testing and modelling assumptions may not be realistic. Whilst some challenges remain, the incidence of EIC failures has been progressively reducing through greater recognition of the potential failure mechanisms, improvements in materials selection, informed system management, advances in inspection methodologies, and establishment of international standards and codes of practice. There is now a shift in emphasis in industry-related research towards improved understanding and prediction of the early stages of damage development in acknowledgment of the key role that this regime can play in determining the overall life of components and structures and in material selection/system management to avoid cracking. In that context, characterising the impact of surface state (topography, nature of the oxide, near-surface microstructure, mechanical properties and residual stress) on the propensity for cracking and the growth rate of cracks for realistic exposure conditions is paramount. To address this challenge, developments are required in several areas: Continued characterisation of the electrochemistry in harsh environments to underpin EIC tests; Development of very high resolution crack detection and measurement technique combined with characterisation of the mechanical driving force for small crack growth; Quantification of small crack growth rates, particularly for realistic surface finishes; Establishment of loci for crack initiation and crack path development using 3D XCT and FIB-SEM imaging combined with 3D EBSD and TEM mapping to provide input on the link to near-surface microstructural and deformation characteristics; Finite element crystal plasticity (or cellular automata) modelling to predict the effect of near surface gradients in material characteristics and residual stress on damage development; Integration of data at different crack length scale for life prediction. The knowledge gained will support the development of measurement and modelling methods to characterise the earliest stages of damage development as the key to enhanced confidence in constructing structures/plants for very long lives. 13

14 3.3 Functional Materials For a full description of the group s capabilities and current activities visit: Functional materials are materials that exhibit coupling between multiple variables. For example, transforming mechanical energy to electrical energy, or providing electrical control of magnetic properties. Functional materials are increasingly finding application in technologies ranging from sensors, to miniaturised electronics and energy harvesters, and across a range of sectors from advanced manufacturing, aerospace and automotive to sustainability, smart cities and energy 9. The Functional Materials science area supports a comprehensive capability that uses a wide range of experimental and theoretical techniques to investigate functional material properties, device performance and new application concepts. Research is focused on materials with electrical and magnetic functionality, specifically supporting: Electromechanical coupling, ferroelectric, pyroelectric and piezoelectric measurements; Magnetoelectrical coupling measurements (and multiferroic coupling generally); Electrical measurements in harsh environments (e.g. temperature, humidity, stress, field) and bias fields (e.g. electrical, magnetic); Dielectric measurements; Magnetic materials metrology for real world conditions. The science area has developed ab initio models and in situ experimental tools to describe fundamental properties of ferroelectric, multiferroic materials and the multifunctional behaviour of modern sensor/actuator materials. The linkage between atomic scale physics and macroscopic performance (as well as behaviour from femtosecond to year-long timescales) and specifically the role of metrology in elucidating this is also an important focus of the science area Theme for Investment: Functional Materials for Sensor Applications Over 8000 UK electronics companies are involved in the design and manufacture of sensor devices and these companies generate around 29bn a year in revenues and contribute over 12bn to gross value added 10. In , the UK s electronics sector was the fifth largest in the world. Advances in sensors, actuators and MEMS focus on improved performance of parameters such as noise, sensitivity and thermal stability. Novel functional materials provide the enabling technology to overcome technological barriers across a diverse range of sectors, from deep space telemetry systems to real-time health monitoring through sensors embedded into garments and the characterisation of 3D printed materials. However, these advances require improvements in sensor calibration at operational temperatures, materials characterisation and, as is the case with smart fabric (SF) and additive manufacturing (AM), the creation of innovative standards and procedures to provide underpinning metrology. 9 Functional Materials Future Directions, Foresight Materials Panel, IoM3, Enabling Technologies Strategy , Technology Strategy Board,

15 To address these challenges, developments are required in several areas: Facilities for characterisation of sensors and functional materials including the capability for real-life temperature environments; Facilities for characterisation of novel functional inks for 2D and 3D printing (including roll-to-roll and screen printing) of electronics and sensor interfaces; Standardised characterisation of AM produced electromagnetic materials. The knowledge gained will enable UK industry to utilise the functional performance enhancements of emerging materials (such as higher sensitivity and selectivity of sensors and higher actuation efficiency of solid state transducers for example) and thus create a competitive advantage as early adopters of new materials technology Theme for Investment: Function Material Measurements and Applications for Harsh (real-life) Environments The real-life applications of functional materials can include environments that may be considered harsh due to extremes of temperature (-200 C to 1400 C), stress (± 800 MPa), ionising radiation etc. Traceable measurement techniques, and related modelling capability, that will allow industry to characterise functional materials and sensors under the conditions in which they are used (e.g. engines, power plants, steel mills etc.) are key enabling capabilities for the successful application of novel materials. Importantly, these techniques include in-situ systems that will provide industry with better process monitoring and control. For example, real-time measurements provide greater control during steel processing and manufacture to create higher yields with superior tolerances on quality and the ability to develop enhanced properties, reducing waste and offering potential weight savings in transport applications, leading to reductions in fuel consumption. To address these challenges, developments are required in several areas: Measurements of functional materials under real world/industry conditions; Facilities for the real-time monitoring of material condition using electromagnetic techniques; Improve performance of existing energy harvesting materials and technologies by increasing efficiency within the operating environment (i.e. lifetime, temperature and pressure); Underpinning modelling work and novel metrology to quantify the extent of coupling in piezocaloric materials in harsh environments for the development of innovative solid-state cooling or waste-heat energy recovery. The knowledge gained will enable industry to apply new and emerging materials in environments which otherwise are unserviced, such that actuation, sensing, and transduction generally can be retained and even applied reliably in these extreme in-service environments. 15

16 NPL s new piezo MEMS tool for exploration of microscale piezo actuators enabling their application in electronics and microscale printing. Nanoscale ferroelectricity: BaTiO3 lamella (FIBBED by collaboration partners Queens University, Belfast) showing the emergence of ferroelectric domains and their relationship to sample scale and importantly geometry enabling application in FE RAM and nanoscale sensing technologies. 16

17 3.4 Materials Processing and Performance (MPP) Composites and Thermal Metrology The Materials Processing and Performance Science area at NPL develops a broad range of methods to understand the processing and performance behaviour of materials through their full life cycle. Polymer composites play an increasingly important role in existing (aerospace) and new (tidal power, rail, auto) applications due to their light weight, long term performance and design freedom. Such attributes are attractive to industries needing to improve the performance and sustainability of their products and processes 11. The increasingly important role of composites is reflected in the investment by the UK in national initiatives, such as the UK Composites Leadership Forum (CLF), National Composites Centre and CIMComp. The NPL expertise supports, and integrates, with key developments in these centres of excellence, as demonstrated by NPL s chairing of the Regulations, Codes and Standards Working Group, under the CLF. Metrology is required to provide greater confidence in the linked aspects of design, quality control and performance of polymer composites. The measurement infrastructure will be developed by applying best practice during build and evaluation of structural elements, including stiffened panels, connections and joints. The thermal metrology capability underpins characterisation by developing thermophysical property measurement techniques with low uncertainties, traceable to the SI. NPL provides comprehensive, world class facilities (a number being unique within the UK) for measuring thermal properties including: thermal conductivity, thermal diffusivity, thermal transmittance, heat capacity and thermal expansion. These techniques are employed to assess every stage of the materials lifecycle; from optimising processing conditions and clarifying the relationship between composition, and microstructure, to lifetime performance assessment and recycling at product end of life. The expertise at the NPL in both thermal metrology and materials science enhances the overall capability of this science area Theme for Investment: Manufacture, Characterisation and Performance of Polymer Composite Structural Elements For a full description of the group s capabilities and current activities visit: Uniquely for composites, the material is only formed when the product is manufactured. Hence, the manufacturing aspects are critical to material quality and therefore product performance. Consequently, there is a pressing need for metrology supporting processing, design and non-destructive evaluation (NDE) throughout the composite production cycle. In recognition of this need, NPL is working with European collaborators to develop and validate methods for novel NDE techniques: microwaves, active thermography, laser shearography and phased array ultrasonics. The overall aim of the work is to provide traceable procedures for these techniques with contrasting development capabilities and known detection limits. The experimental work in each case is supported by modelling of the techniques and prediction of probability of detection (PoD) limits. 11 UK Composites 2013, Composites Leadership Forum, Department of Business Innovation and Skills,

18 It is proposed to work with partners to broaden the current work in the development of reference defect samples to cover more of the product life cycle from initial manufacture to end of life, a need highlighted in discussions with industry, users and university researchers. In addition to this work, the group will collaborate with external partners to support the uptake of novel materials by developing characterisation techniques to support the development of nano-composites and measurement and understanding of the properties of recyclable materials. To address this challenge, developments are required in several areas: Standardisation and control of production through measurements related to, for example, ply/fibre placement, cure monitoring, resin impregnation of fibre preforms etc., thermal control of tolerances, etc. to achieve embedded quality; Validation and standardisation of NDE measurements in challenging types of components (e.g. stiffener on panel, bulkhead junctions, bonded joints) and damage growth compared to prior work (c.f. thin, flat/low curvature panels.); Validated approaches to the performance assessment of structural elements (with and without defects), such as short term tests, long term environmental and fatigue testing, in order to give increased confidence in long-term durability; and solutions developed for outstanding coupon test issues regarding compression and in-plane shear. Other challenges to be addressed, including through co-funding projects, are: Methods for particle characterisation in nano-composites and measurement of final product properties, in particular dispersion of the particles; Measurements related to end of life (recycling) issues, such as identification of specific recyclable materials and characterisation of recyclate. The knowledge generated will enable the quality of composites manufacture and therefore, ultimate performance, to be measured and validated, which is critical for use in structural applications. This knowledge will be applied through the production of Measurement Notes, Good Practice Guides, international standards, reference materials/data and predictive modelling Theme for Investment: Metrology for Thermal Performance For a full description of the group s capabilities and current activities visit: Thermal performance data on materials and structures is required for design and heat management in most forms of advanced engineering and processing. Thermal analysis of materials contributes to improvements in processing and performance of advanced materials in manufacturing, development of more sustainable and efficient materials for energy generation and transport systems, and improved safety through the use of thermal protection materials. The current themes this Science Area is focused on are measurement of: 18

19 Thermal properties of reactive materials; Thermal properties at extremely high application temperatures; Thermal properties of complex materials structures (layered materials, liquids). Increasingly, high quality, low uncertainty data is required under extreme environmental conditions, such as extremely high and low temperatures (difficult to replicate in the laboratory) 12. It is critical to understand both the measurement methodology and the impact of other materials properties on the measurement values obtained. Such understanding can be achieved through modelling of both the instruments used and the materials to be investigated. To address these challenges developments are required in several areas: Validated measurement techniques for indirect high temperature thermal conductivity analysis (above 800 C) with support from Finite Element (FE) modelling to assess contributions to uncertainty from dynamic methods, and behaviour of samples under both solid and liquid measurement conditions; Facility for characterisation of composite materials used for transport applications, including transfer reference materials for both thermal and mechanical testing; Characterised reference materials for high temperature (temp) thermal properties measurements and methodologies to transfer calibrations to third parties and enable validation. The knowledge generated will enable direct traceability of measurements made in academia and industry to the SI system and provide greater confidence in the data provided for applications in cautious sectors such as energy generation and transport, where innovation is often stifled by the understandable focus on safety and security. New NPL designed facility for measuring the thermal conductivity of polymers and composite materials. 12 Robin Beckwith, Drilling In Extreme Environments: Space Drilling And The Oil And Gas Industry, Journal of Petroleum Technology, September

20 3.5 Data Analysis and Uncertainty Evaluation For a full description of the group s capabilities and current activities visit: The work of the Data Analysis and Uncertainty Evaluation and the Materials Modelling (page 21) science areas is closely aligned. Together they form NPL s Mathematics and Modelling Group and contribute to projects across both science areas. Unlike other science areas in the Materials Programme, these science areas provide mathematical modelling and uncertainty analysis support to staff working across all NMS programmes and develop methods that have wide applicability throughout all branches of metrology. There is a longstanding history of joint projects and strong cross-fertilisation between the two areas, including current work investigating uncertainty evaluation using complex materials models. Measurement underpins development and growth across all industry sectors, providing data that is used as the basis for making inferences, informing decisions and controlling systems. These activities depend on the reliability, traceability and mutual recognition of measurement results derived from the data, established through modelling, mathematical and statistical methods of data analysis implemented in software, and valid statements of measurement uncertainty 13. The mission of the Data Analysis and Uncertainty Evaluation science area is to develop, apply and promote good practice in mathematics, statistics and scientific computing to all areas and applications of measurement. The science area covers conventional measurements, such as might be undertaken at a National Measurement Institute or accredited laboratory, for which models are fully understood and model inputs are well characterised. The science area also covers measurements made to support societal challenges, such as in climate and the environment, energy and sustainability, smart infrastructure, health and well-being, and high-value manufacturing, for which a new metrology paradigm is needed in which models are complex, only partially understood, where data is of limited integrity, and data may be obtained using a network of distributed sensors. The science area seeks to (a) undertake research to build new capability in the areas of measurement data analysis and measurement uncertainty evaluation underpinned by mathematical and statistical theory, (b) influence standardisation and regulatory bodies through the maintenance and development of Standards and Guides, and (c) disseminate good practice to users of the NMS including UK industry Theme for Investment: Mathematics and Modelling to Support Traceability and the SI Harmonisation of methods for metrology data analysis and measurement uncertainty evaluation is essential to ensure the reliability, traceability and mutual recognition of measurement results and, consequently, to ensure that those results provide a valid basis for making decisions. 13 The Strategy for the National Measurement System: , The National Measurement Office 20

21 The major drivers for the theme are the Guide to the Expression of Uncertainty in Measurement (GUM), the primary document regarding measurement uncertainty evaluation, and the Mutual Recognition Arrangement (MRA) supported by key comparisons, which are used to establish comparability of measurements made by NMIs and underpin traceability at the highest level. The theme will exploit partnerships with other NMIs and establish research collaborations. To address these challenges developments are required in several areas: Measurement data analysis, uncertainty evaluation and scientific computing including Bayesian methods, knowledge elicitation, decision analysis and experimental design; Underpinning of international and national Standards and Guides, such as through the development of the GUM and supporting documents to the GUM; Harmonisation of statistical methods for key comparison data evaluation to underpin traceability at the international level; Implementing and disseminating the outputs of international and national Standards and Guides to users of the NMS, including UK industry Theme for Investment: Mathematics and Modelling to Address Societal Challenges In areas such as climate and the environment, energy and sustainability, smart infrastructure, health and well-being, and high-value manufacturing, decisions are increasingly made on the basis of measuring systems involving models that are only partially understood, data of unknown or limited integrity, and networks of distributed sensors. Conventional analysis, which assumes that a measurement is made using a single sensor and can be modelled to a degree determined by the required accuracy of the measurement result, cannot be applied to such systems. As such, new capabilities and approaches are required to support the development of standardised approaches to modelling and measurement uncertainty evaluation. To address these challenges developments are required in several areas: Mathematical and statistical analysis, encompassing supporting algorithms and software, to address the gap in available analysis approaches, and ensure the measurement results provided by such systems are fit for purpose; New, data-driven techniques involving data assimilation and statistical learning for specific areas of application. The knowledge developed will in the short term be applied to help to establish how the metrology concepts of uncertainty, calibration and traceability apply to sensor networks. In the medium-term, projects will be proposed to address the wider problems of model uncertainty and data integrity. In the longer-term, the theme will provide the basis of a new generation of measurement good practice in support of Metrology applications to be encoded in Standards and Guides. 14 Metrology for the 2020 s, The National Physical Laboratory,

22 3.6 Materials Modelling and Simulation For a full description of the group s capabilities and current activities visit: Materials modelling and simulation are critical to the development of innovative methods to design, produce and operate products across a very wide range of industrial application areas. Materials modelling is used at NPL to understand quantitatively the nature and processing of advanced materials, to define key properties that need to be measured, and to design experiments needed to measure these properties. It is also used at NPL to simulate experiments that are challenging to carry out in practice, whether due to conditions (high temperatures and pressures, harsh or dangerous environments) or the nature of the material (toxic or radioactive elements). Simulations based on materials models are used extensively by industry to design new products and processes, and to evaluate virtually their expected performance in practical applications ( Towards zero prototypes 15 ). The science area embraces modelling across a range of length and time scales, including continuum mechanics, mesoscale modelling including composites and nano-scaled multilayers, and atomistic modelling, with a strong emphasis on thermodynamics (both equilibrium and non-equilibrium) at all scales and on modelling multi-scale and multi-physics phenomena. Continuum modelling research at NPL is focused on two distinct types of activity: Developing governing field equations for the realistic modelling of equilibrium and non-equilibrium, multi-scale, multi-physics systems; Developing the mathematical techniques (often based on finite element analysis) to enable the solution of these field equations subject to physically appropriate initial conditions and boundary/interface conditions. Meso-scale modelling research bridges the gap between continuum and atomistic modelling. Bulk scale behaviour in all areas of materials research is governed by events at the atomistic level. The current computational expense of modelling all the atoms in a large object makes a purely atomistic approach to all problems impractical. Mesoscale modelling aims to incorporate the effects of the atomistic structure at coarse-grained resolution or within continuum models. Atomistic modelling research provides a fundamental link between molecular properties and macroscopic bulk properties of materials, underpinning thermodynamics, hydrodynamics, the theory of elasticity and other continuum-based branches of science. Atomistic calculations can provide values of material properties, such as heat capacity, entropy, enthalpy, elastic constants, transport coefficients (often difficult to obtain experimentally), and can explain phenomena that are key to understanding bulk behaviour. Current atomistic work is focused on developing a radical new strategy for quantum-classical atomistic materials simulation, which can generate a complete description of many-body polarisation and dispersion required for accurate modelling of advanced materials. The group includes world-leading expertise in modelling of equilibrium thermodynamics and phase equilibria. Recent collaborative work with IBM and the University of Edinburgh on the simulation of water has generated international interest. NPL is world-leading in its modelling of composites and associated damage processes

23 3.6.1 Theme for Investment: Modelling to Bridge Length Scales The rapid growth in understanding of and ability to manipulate materials at the nanoscale has led to the increased use of miniaturised devices and hence increased needs for characterisation of nanoscale behaviour. Much current research is revealing that a material s lattice structure and associated defects (vacancies, dislocations, domains, micro-cracks and voids) become increasingly important as devices are reduced to nanoscaled proportions. Lattice mismatch at interfaces and distortions near both free surfaces and interfaces lead to very localised complex stress fields that contribute to surface energy, surface stress, edge effects and functional response (e.g. piezo effects). As the scale of practically important geometries is too large for atomistic simulation alone, there is an urgent need to develop methods that use atomistic models to inform continuum models and thus account for the important nano-effects. To address these challenges developments are required in several areas: Extend existing fluid simulations to solids by introducing a lattice concept, an appropriate strain definition, and vacancy/interstitial distributions, including the definition of appropriate fluxes, driving forces, and transport coefficients; Extend/develop the Gibbs energy functions approach for application to multiphysics simulations of multi-component solids involving multi-axial stress/strain states, surface complexation, and the presence of vacancies; Develop libraries of critically assessed parameters to provide Gibbs energies as a function of composition, temperature and pressure/stress for real materials, building a bridge from atomistic calculations to bulk applications with industrial impact; Develop continuum-level solution techniques to deal with localised stresses and strains at the nanoscale, including inter-granular behaviour for crystalline materials; Define atomic layer interaction laws for use in continuum simulations by using quantum Drude models or similar techniques to characterise localised deformations and Gibbs energy functions; Investigate using non-equilibrium atomistic techniques and linear response theory-based methods to estimate heat and mass/vacancy transport coefficients with emphasis on binary, ternary and higher order systems; Investigate extending all aspects of the approach to include piezoelectric and magnetic effects. Proposed work will involve partnering and collaboration to ensure that NPL can develop and deliver expertise in cutting-edge techniques across length scales and make optimal use of resources. The development of this knowledge will facilitate the use of sophisticated materials modelling in simulations to speed up and reduce the needs for prototyping. The proposed work will enable step changes in simulation in a wide range of application areas, including piezoelectric materials in electronic devices, fuel cells, hydrogen induced cracking, thermal barrier coatings and oxide growth. In all cases, the modelling will support the development of measurement techniques to obtain properties that characterise the behaviour of such systems. 23