Solutions for Durability, Reliability and Fatigue

Transcription

1 Last Update: 14 November 2017 Solutions for Durability, Reliability and Fatigue Tuesday, 21st November :00 09:45 10:00 10:45 11:15 Registration and Coffee Welcome and Introduction A Unified Approach for Calculating the Whole Life of Components Subjected to Significant Crack Initiation and Growth, Dr. A. Halfpenny, HBM Prenscia Cyclic Strain Life Physical Test Correlation using CAE, Mr. A. Blows, Jaguar Land Rover Refreshments 11:30 12:00 Material Fatigue Testing Fatigue Characterisation and Testing of Materials, Dr. A. Halfpenny, HBM Prenscia Statistical reliability and confidence Validate replacement materials Compare different suppliers Best Practices in Material Fatigue Testing and Characterisation, Mr. P. Lavelle, HBM Prenscia Advanced Metals The Application of Laser Shock Peening to Increase the Fatigue Life of Safety Critical Components and Structures Dr. N. Smyth, Coventry University Laboratory Tour Advanced Materials Characterisation and Test (AMCT) Facility Laboratory Tour 12:30 Buffet Lunch 13:30 14:00 14:30 15:00 15:30 16:00 16:30 16:45 Laboratory Tour Advanced Materials Characterisation and Test (AMCT) Facility Laboratory Tour Fatigue in Short Fibre Composites Dr. P. Heyes, HBM Prenscia Analysis of Static Strength and Fatigue in Long Fibre Composites Dr. A. Halfpenny, HBM Prenscia Additive Manufactured Metals Comparison of Strain-Life Fatigue Curves for Ti-6AI-4V between Wrought and AM Material, Mr. R. Plaskitt, HBM Prenscia Guidance for Airworthiness of AM Components for Military Aviation with respect to UK DefStan R. Mangham, DSTL Durability and Damage Tolerance of AM Ti- 6Al-4V Alloy Professor X. Zhang, Coventry University Refreshments Reliability-improved Durability: Lesson Learnt from In-Service Early Failures Dr. M. Bonato, Valeo Reliability Validation Planning for Engines in Connected Cars, Mr. Andrew Brown, Jaguar Land Rover Summary, Questions and Close Additional AMCT Laboratory Tour (if required)

2 Biographies and s A Unified Approach for Calculating the Whole Life of Components Subjected to Significant Crack Initiation and Growth Dr. Andrew Halfpenny, Director of Technology, HBM-Prenscia Dr. Halfpenny has a PhD in Mechanical Engineering from University College London (UCL) and a Masters in Civil and Structural Engineering. With over 25 years of experience in structural dynamics, vibration, fatigue and fracture, he has introduced many new technologies to the industry including: FE-based vibration fatigue analysis, crack growth simulation and accelerated vibration testing. He holds a European patent for the Damage monitoring tag and developed the new vibration standard used for qualifying UK military helicopters. He has worked in consultancy with customers across the UK, Europe, Americas and the Far East, and has written publications on Fatigue, Digital Signal Processing and Structural Health Monitoring. He sits on the NAFEMS committee for Dynamic Testing and is a guest lecturer on structural dynamics with The University of Sheffield. Durability engineers would like the ability to assess the whole life of a component; from initial crack nucleation by accumulation of fatigue damage, followed by modelling the growth of this crack by crack growth methods. For practical reasons predictive analyses of these have tended to concentrate on the dominant life stage, fatigue or crack growth, dependent upon the structure, its operating environment, inspection capability and risk of unexpected failure. This presentation describes a unified approach for calculating the whole life of a structure subjected to significant crack nucleation and growth. It describes a universal weight function approach to modelling the stress intensity ahead of a potential crack. A new cyclic crack-tip plasticity model is introduced which accounts for R ratio effects, crack closure and crack retardation. This approach is ideally suited the analysis of thick weld sections as well as light-weight automotive and aerospace components such as riveted joints where failure modes often involve substantial crack nucleation and growth prior to failure. Page 2 of 10

3 Cyclic Strain Life Physical Test Correlation using CAE Mr. Andrew Blows, Technical Specialist Durability CAE, Body & Exterior CAE, Jaguar Land Rover Fatigue life predictions using the strain-life method are used in the design of modern light weight vehicle, for the complex loading that occur with the structural durability tests that these vehicles undergo. The accuracy of these predictions is dependent upon the many factors; geometry, loads & materials etc. This paper details a new procedure to ensure the quality and accuracy of the material parameters for the fatigue life prediction software. The material parameters for the solver are obtained by performing strain-controlled fatigue tests. The geometry of the coupons tested is determined by size and thickness of the material specimen that they are machined from and the loading regime in the test. Detailed data analyzed is conducted on these tests and the parameters that are used as input into the CAE strain-life fatigue prediction software are generated. The issues associated with incorrect fatigue life predictions due to the loading varying thought each test, due to the cyclic stress hardening/softening characteristic of metal are discussed. This new procedure should ensure that issues with the generation of the parameters from the test data, as well as issues with fatigue solver inputs are detected, as the predicted fatigue life s will not correspond to the physical tests life s if any issue are found. Page 3 of 10

4 Fatigue Characterisation and Testing of Materials Dr. Andrew Halfpenny, Director of Technology, HBM-Prenscia (see previous) Best Practices in Material Fatigue Testing and Characterisation Mr. Peter Lavelle Application Engineer, HBM Prenscia A presentation pair Peter Lavelle completed his Masters in Mechanical Engineering at The University of Sheffield, with a focus on design improvements for the local steel manufacturing industry. Joining HBM Prenscia (formerly ncode) soon after graduating, Peter now has 5 years of experience as an Application Engineer. In this time he has worked with digital signal processing for fatigue, durability and reliability within a variety of industries. More recently, he has been working in the Advanced Materials Characterisation & Testing (AMCT) facility; in charge of test specifications as well as the analysis and reporting of results for metallic materials. Fatigue is the progressive and localized structural damage that occurs when a material is subjected to cyclic loading. In many cases, fatigue failures occur suddenly with little warning and so it is important to design structures to resist fatigue failure. While it can be technically challenging to simulate fatigue failure, it is possible to get accurate fatigue life calculations by using specific and reliable material data. This consider how material fatigue properties used in fatigue simulation are determined from laboratory tests. We will review the very first rotating-bend test invented by August Wöhler through to the popular load-control and strain-control test procedures used today. Particular consideration is paid to characterizing the material to derive a design curve for use in component fatigue analysis. By the end of the presentation, attendees will have gained an understanding of the process of fatigue testing, material characterisation and the effect of statistical analysis on the results. This pair of presentations will concentrate on: An introduction to metal fatigue and fatigue testing Material characterisation accounting for statistical reliability and confidence How many specimens to test How to validate replacement materials How to compare the performance of materials from different suppliers Page 4 of 10

5 The Application of Laser Shock Peening to Increase the Fatigue Life of Safety Critical Components and Structures Dr. Niall Smyth, Coventry University Dr. Niall Smyth is a senior researcher at Coventry University. He has worked in the area laser shock peening since 2009 and his research interests are in the areas of fatigue and fracture mechanics, residual stress, finite element analysis, advanced materials and structural integrity. He is a member of the editorial board of the International Journal of Microstructure and Materials Properties and the International Journal of Peening Techniques. Laser shock peening is an emerging technology used for enhancement of the fatigue performance of safety critical components and structures. This is achieved through introduction of a beneficial compressive residual stress field in the near surface layer of the component which counteracts applied tensile stresses and so extends the fatigue life. In the aerospace industry laser shock peening has been applied to the root of engine turbine blades and wing attachment lugs. This presentation will provide a brief overview of the origin laser shock peening as a surface treatment technology. This presentation will focus on past and current research programs in laser shock peening at Coventry University, its current application in industry and the challenges for the future. Durability and Damage Tolerance of AM Ti-6Al-4V Alloy Professor Xiang Zhang, Research in Materials Engineering and Structural Integrity, Coventry University Professor Xiang Zhang has conducted research in aircraft structural integrity for over 30 years, on both metallic and composite material structures, with a focus on the fatigue and fatigue crack growth behaviours and predictive models. Her career started from the Chinese aerospace industry, followed by PhD study and research associateship at Imperial College London, and academic appointments at Cranfield University and Coventry University. This talk covers two aspects. First, a summary of the state-of-the-art will be given on the fatigue and fracture properties of additive manufactured Ti-6Al-4V titanium alloy, including both the powder and wire based processes. Second, her team s recent work on Ti-6Al-4V materials fabricated by the Wire + Arc Additive Manufacture (WAAM) process will be presented. Effects of build method, material orientation, property anisotropy, microstructure characteristics and residual stress on fatigue crack growth rate and fracture toughness will be discussed. Page 5 of 10

6 Comparison of Strain-Life Fatigue Curves for Ti-6Al-4V between Wrought and AM Material Mr. Rob Plaskitt, Engineering Consultant, HBM Prenscia Rob Plaskitt has a degree in Mechanical Engineering (Loughborough) and a masters in Structural Integrity (Sheffield). He has over 25 years of experience working as an engineer at Prenscia (formerly ncode) in areas of automotive, aerospace, defence and power generation. ncode software is used for fatigue and durability design, from CAE concept design through full-scale testing and fleet durability monitoring. Rob has applied ncode software and technology in many industries including flight qualification processes in helicopters and identification of severe transient events occurring during delivery of sensitive equipment. He has worked in consultancy with customers across the UK, Europe, Americas and the Far East, has written publications on Fatigue and Digital Signal Processing and represents Prenscia at the UK Forum for Engineering Structural Integrity (FESI). This presentation compares strain-life fatigue test results for the titanium alloy Ti-6Al-4V between wrought bar and sheet material and additive manufactured material. For example, the image below compares strainlife mean and design curves with a couple of samples manufactured using laser powder bed fusion more test results will be included during the presentation. Page 6 of 10

7 Guidance for Airworthiness of AM Components for Military Aviation with respect to UK DefStan Rebecca Mangham, MChem MRSC Scientist - Power Sources and Materials, Platform Systems Division Defence Science and Technology Laboratory (Dstl) Since joining Dstl on the graduate scheme in 2011, Rebecca Mangham has had the opportunity to work on a range of projects across the materials domain. She has been involved in additive manufacturing at Dstl for four years, initially working on qualification and certification of metal powders for AM. Her projects now cover structural and multifunctional applications of AM and Rebecca is work package lead for the AM task as part of the certification of novel technologies project. Through this task Dstl and a consortium of industry, academia and government are producing a guidance note on AM for military aviation. The Military Aircraft Structural Airworthiness Advisory Group has initiated the development of guidance material for the qualification and certification of additive manufactured parts in military aviation. The aim is to focus on Grade A parts. A working group has been formed to contribute knowledge and to peer review the final document. The group contains representation from MBDA, BAE Systems, Airbus, Rolls-Royce, GKN, Leonardo Helicopters, Lockheed Martin, SAFRAN Landing Systems, SME AM Businesses, Civil Aviation Authority, National Physical Laboratory, Health and Safety Laboratory, AM Bureaux, Academia, MOD (MAA, 1710 Naval Air Squadron), Dstl, TWI, High Value Manufacturing Catapult and QinetiQ. This includes highlighting parts of the Regulations and DefStan that are especially relevant to AM and interpreting them for AM. For example the important things to consider (e.g. powder management) and appropriate standards and guidance from recognised sources (e.g. ASTM). This is not a new standard or any original work as such, more a bringing together of the existing regulations and standards for airworthiness of AM. Much of the focus of the work is on understanding the sources of variation in performance of AM parts and their significance. When complete the document will be published on the UK Government Website, as MASAAG Paper 124. Page 7 of 10

8 Fatigue in Short Fibre Composites Dr. Peter Heyes, Principal Technologist - Fatigue Analysis Methods, HBM Prenscia Analysis of Static Strength and Fatigue in Long Fibre Composites Dr. Andrew Halfpenny, Director of Technology, HBM-Prenscia A presentation pair Dr. Heyes studied Natural Sciences at Cambridge and then taught Physics for 5 years before turning to the dark side and becoming an engineer, by way of a PhD at Sheffield University. His research work on short fatigue cracks led to a job in 1992 as a consulting engineer at ncode, and apart from a short stint in vehicle body CAE (for MSX) he has been working for ncode ever since. During most of that time he has been involved in method development, responsible for introducing new methods for fatigue life estimation from finite element analyses. Methods developed include new analysis techniques for multiaxial fatigue, fatigue of welds, of spot welds and adhesive joints. He is currently focusing on implementing methods for fatigue analysis of composite materials. Dr. Halfpenny (see previous biography) Composite materials offer many advantages to the product developer compared to traditional materials such as metals. Advantages can include better strength with reduced mass, corrosion resistance and the scope to reduce the number of parts. These advantages are leading to rapidly increasing usage in many industries such as aerospace, automotive, marine, energy and civil engineering. However it is not possible to take full advantage of the benefits of composite material without the ability to optimise their structural performance, which in turn requires the ability to evaluate their durability with respect to expected loads using CAE tools. These talk look at some of the criteria that may be used to evaluate the strength and durability of composite structures, based on finite element simulations, and subject to realistic loading histories or duty cycles. The first talk looks at some of the challenges (and solutions) in evaluating the fatigue durability of short fibre reinforced thermoplastics. The second talk looks at criteria for evaluating the strength of continuous fibre reinforced composites and considers how these criteria might be extended to include estimation of fatigue damage. Page 8 of 10

9 Reliability-improved Durability: Lesson Learnt from In-Service Early Failures Dr. Marco Bonato, Valeo Marco Bonato is a Reliability Expert, in Valeo since His responsibility includes the elaboration of new specifications, the design of reliability studies related to engine cooling components, and development and implementation of customer-based engineering and reliability issues. Marco holds a Ph.D. in Physical- Chemistry from the University of Bristol (UK). Prior to this, he obtained a Master degree in Inorganic Chemistry at the University of Padua (Italy). He is currently Associate Member of the Royal Society of Chemistry and member of the Association pour le Développement des Sciences et Techniques de l'environnement (ASTE), the French engineering association of environmental testing. Nowadays leading automotive suppliers need to face higher and higher customer expectations. OEMs require new components to be innovative, performing, robust and reliable. During the development phase, components and subcomponents undergo a thorough validation process. The goal is to validate the robustness of the design, the product performances, the quality of the serial production etc. Design validation is commonly performed via accelerated durability test. In the case of early field failure, tools such Weibull analysis permit to perform risk assessments and to estimate the reliability of all products still in the field. Indeed, when wear out failures occur, the results from the reliability analysis can be used to improve the durability of the existing component, as well as newer products under development. This presentation will discuss the risk assessment of a Valeo engine cooling component (a cooling fan system) during in-field failures. After a brief introduction of the problem, the method and tools used to investigate the failure root cause will be shown. Then, the corrective and preventive actions taken to ameliorate the motor durability, and to improve a new model of fan system, will be illustrated. Page 9 of 10

10 Reliability Validation Planning for Engines in Connected Cars Mr. Andrew Brown, Reliability & Validation Methodology - SME Group, Powertrain Engineering Jaguar Land Rover Andrew graduated from Sheffield University in 2006 with a degree in Aerospace Engineering. Since then, he has worked on Internal Combustion Engines, starting his career with larger diesel products such as the 61- litre generator sets at Perkins Engines in Stafford and more recently working on the new Ingenium product range at Jaguar Land Rover. He has worked in Validation & Verification roles for most of his career and more recently moved into a Reliability Engineering role at JLR, focusing on Reliability Validation Planning and Test Methodology. Durability & Robustness testing is well established in the Automotive Industry, but as technology and complexity of engine powertrains grow exponentially, there is a requirement to dig deeper into our understanding of these legacy core durability tests and derive, at component level, the total damage inflicted by each test. Reliability demonstration is calculated from mathematical accumulation of statistical confidence gained from each test and referenced back to component specific reliability targets and usage profiles. Knowing how our customers really interact with the powertrain is paramount to the success of this methodology and using big data analytics we aim to build large banks of customer usage data that can be mapped back to individual component damage accumulation. In turn, this information will help build, steer and optimise DV test plans to ensure that future powertrains will not only grow in complexity, but will conversely become more reliable. Page 10 of 10