This 6-part series of 90-minute virtual seminars focuses on material and fatigue performance for structural durability – from material coupon testing to full structure testing.
The series begins with aerospace and automotive examples for physical structural and vibration tests, and how these can be complemented and enhanced using virtual sensors and structural simulations. These are followed by presentations on coupon and element mechanical testing, for material hardening parameters, baseline material and surface treatment enhancement and degradation, and characterization of joints.
The series concludes by showing how results from these durability tests and simulations become inputs to wider product reliability requirements. Application examples presented include full-scale aircraft structural tests, automotive electric vehicle battery and battery cooler tests and reliability.
Fatigue testing full scale airframe and large structural components require significant investment and resources for long durations. To reduce this duration, AIRBUS will describe the “Rapid EF” industry and university collaborative research programme. The Rapid EF objective is to shorten multi-year duration fatigue tests, to reduce overall aircraft development cycle time from a minimum of 8 years to less than 5 years. This is followed by the HBK contributions to Rapid EF, to reduce measurement setup time and reduce downtime in the DAQ measurement chain.
The session closes with University of Sheffield research to construct a structural dynamics digital twin of a Hawk T1A aircraft, to identify the outstanding questions and challenges to direct future efforts by academia and industry.
Rapid EF aims to reduce the fatigue test by reducing setup time (quicker instrumentation), cycle time (improved control algorithms) and downtime (anticipation of damage through digital twin). HBK contributions to Rapid EF are mainly responsible for reducing downtime. This presentation will address these challenges and their solutions including:
- to provide redundancy in the DAQ measurement chain to avoid or reduce single point failures
- to provide quick exchange in the DAQ measurement chain when required to avoid DAQ shutdown and reboot
- to provide an open DAQ architecture enable inclusion of tactile sensors, optical & thermal cameras, sound, etc.
- to automate and simplify sensor parameterisation, particularly for the 100’s or 1000’s of strain gauges required
- to quantify and minimize measurement uncertainty
- to provide virtual sensors to complement physical sensors for digital twin model correlation
- to provide measurement data streams for subsequent automated cleansing, analytics and data management
This presentation will look at recent work carried out at The University of Sheffield Laboratory for Verification and Validation ( https://lvv.ac.uk/) , in which the dynamics of a Hawk T1A aircraft were investigated with the aim of constructing a digital twin of this legacy asset. The understanding of this aircraft has been approached, in this project, from the viewpoint of structural dynamics. In the presentation the setup of these tests and subsequent analysis will be discussed. Rather than providing a blueprint for the construction of aerospace digital twins, this presentation will outline some of the outstanding questions and challenges with an aim to initiate discussion on where future efforts by academia and industry might be directed.
The qualification of many products, components and systems require shock and vibration testing to demonstrate their ability to meet performance requirements. National and International Standards define shock and vibration tests for many industries requiring a wide range of vibration test procedures. An electrodynamic shaker is at the centre of many vibration test systems. HBK will introduce vibration test systems and electrodynamic shakers, and then describe in more detail the high shock and high force shakers required to test EV (electric vehicle) battery packs and EV assemblies. AVL will extend this EV battery vibration testing application to a holistic test environment with all required subsystems integrated into a working vibration test system.
The session closes with HBK describing the complementarity of numerical simulation and physical testing and using fatigue equivalent methods to compare and tailor vibration tests, to decrease or increase test duration.
Vibration and specific mechanical shock testing are important for battery development. For us at AVL, it is important to not only understand the battery shaker, but also to focus on our customer’s application use cases to tailor our offerings accordingly. A holistic test environment with all required subsystems integrated into a working test system is essential. With our experience of existing labs and design studies, we support our customers from application to real test lab. We can even provide complete turnkey solutions to ensure a fast and efficient start-up. AVL's outstanding safety system underlines our extensive experience in battery testing and provides a safe and easy to use test environment. This presentation describes what is needed from a test system perspective and gives an overview of how we can support our customers on their successful journey.
This presentation will cover various topics around endurance vibration testing. In the first part of the presentation, we will look specifically at the vibration profile : how to create one from measurements, how to compare several profiles in terms of severity – especially if they are of different natures. We will understand how to scale up the profile to reduce the test duration or to scale it down to increase the test duration.
In the second part, we will discuss the complementarity of numerical simulation and physical testing, especially in cases where a component is responding dynamically to random excitations. We will insist on how CAE can enrich testing and vice versa. This will include the use of virtual sensors for test- CAE correlation and modal analysis for damping values and mode shapes.
Tim Gardiner, Product Manager - Vibration Test Systems, HBK
Tim Gardiner joined Hottinger Brüel & Kjær in 2021. Tim has nearly 20 years of experience in product management and commercial leadership both in the UK and Europe with a background in test and measurement. Tim has responsibility for all VTS products that serve in the aerospace, automotive and defence industries, He has a business degree from the Solent University in the UK.
Armin Karner, Senior Application Manager, AVL List GmbH
Armin Karner has graduated in the fields of Information Technology & Electrical Engineering. He joined AVL almost ten years ago and switched to electrified test systems in 2016. Since 2019, he has been working as Senior Application Manager for Battery and Electrified Test Systems in the Application Team Electrification. As an example, he is part of a standards working group to define test procedures for determining charging performance to provide reliable labelling in an understandable and reproducible way for end users. With his experience in these areas, Armin brings extensive technical and solution-oriented experience, especially in the field of battery environmental testing with electrodynamic shakers.
Dr. Frédéric Kihm, Product Manager – Analytics and Signal Processing, HBK
Frédéric Kihm is Product Manager at HBK, responsible for the signal processing related software products, which includes GlyphWorks, VibeSys and nCodeDS. Frédéric previously worked as an Engineering Consultant for nCode and then HBM, involved with signal processing, durability and vibration analyses in the automotive, aerospace, and defence industries. Frédéric holds a MS in Mechanical Engineering from IFMA University in France and a PhD from the Institute of Sound & Vibration Research (ISVR) in Southampton, UK.
Across all industries, it is becoming increasingly necessary to qualify components based on their reliability and risk of failure. Modern testing methods can improve fatigue prediction of engineered structures with new joining techniques, surface treatments, additively manufactured materials, and composites. The transportation industry is increasingly using novel hybrid joints in their desire for durable lightweight structures to reduce fuel consumption and emissions. The introduction of REACH regulations in Europe for protection of human health and the environment from the use of chemicals has led to the development of new surface treatment systems.
This introduces how materials strength and fatigue performance parameters can be determined and used to reduce the variability and uncertainty of fatigue life predictions. This session describes these materials testing and characterisation methods and introduces the following more detailed HBK Technology Day sessions for surface treatments, hybrid joints and use of failure mode and effect analysis to improve durability and reliability.
Any fatigue analysis is only as good as the materials data it is based on. For durable lightweight structures made with new construction techniques or material types, it can be a challenge to find high quality fatigue data. HBK's Advanced Materials Characterisation and Testing (AMCT) facility in the UK has extensive experience in standard and novel fatigue and durability testing. This presentation will illustrate how modern testing methods can improve fatigue prediction of engineered structures with new joining techniques, additively manufactured materials, and composites.
The structural design of mechanical systems is significantly enhanced by simulation. Fatigue simulation is conveniently divided into two stages:
This presentation addresses the characterisation of increasingly complex materials. It considers the simple strength and elastic modulus values, and extends this to include the non-linear, elastic-plastic behaviour. Parameters are shown for several mathematical models depending on the complexity of the stress analysis required.
The presentation continues by covering ULS and SLS failure models. These range from traditional static failures to SN and EN fatigue models, and on to complex thermo-mechanical fatigue and creep models.
For one or more materials connected as a “joint” (bolts, rivets, welds, adhesives, etc.), mechanical testing alone is insufficient in determining their fatigue properties. In this case the term 'stress' will depend on the FE modelling strategy. Different strategies may result in different stress values. It is therefore essential that the test coupons are modelled using the same FE modelling strategy as the final components. This analysis is described in the presentation.
Finally, it becomes necessary to consider the variability of material strength and how this affects the component design. The paper concludes by considering design parameters that are suitable for both traditional Deterministic designs (i.e. safe design curves), and parameters that are suitable for Stochastic design (i.e. simulating uncertainty).
Many structural components have surface treatments or coatings applied to the surface of the material to help protect against environmental or in service damage. Although these coatings are themselves not structural, it is important to understand the effect of these surface treatments on the fatigue life of a material. Select Engineering Services and HBK have worked together to provide the United States Air Force with more precise predictive models for the fatigue characteristics of landing gear subject to surface treatments and coatings during design, maintenance, and overhaul. This required conducting an extensive surface treatment fatigue testing programme for 300M steel, 4340 steel and 7075 aluminium, with a wide range of surface treatments and developing a Material Assessment and Predictive Analysis (MAPA) tool to manage these. The background and requirements of this work are presented in the 2021 HBK Technology Days. This session describes the results, including the novel combination of strain-life fatigue with surface treatment factors, the MAPA tool and the inclusion of fatigue properties for these baseline materials and their surface treatments in the nCode Premium Materials Database.
The strain-life fatigue method is generally preferred for military aircraft landing gear fatigue life predictions because at the higher strain levels they experience, the stress-life fatigue method breaks down. The strain-life fatigue method requires strain controlled fatigue testing over a range of strain amplitudes and wide range of fatigue cycles to failure, followed by characterisation to fit parameters for the Ramberg-Osgood-Neuber cyclic plasticity model and Coffin-Manson-Basquin strain-life model. A minimum of 25 fatigue tests are recommended to characterise baseline material fatigue performance for a full range (102 to 107 cycles) equally biased low to high cycle strain-life curve.
The Ksur method for surface treatment factors models the fatigue effect of a surface treatment with a single Ksur parameter to adjust the slope of a stress-life fatigue curve in the high cycle region. This method was originally derived for stress-life fatigue curves and assumes that surface effects are mostly confined to the high cycle fatigue region. It is reasoned that under high cycle fatigue loading, the applied loads are relatively low and localised fatigue initiation sites are dependent on the surface condition. Fatigue testing can be reduced to a minimum of 12 because there is only a single Ksur factor parameter to fit, and tests can be biased for results in the mid to high cycle fatigue region.
This presents how strain-life fatigue parameters can be combined with Ksur surface treatment factors, including sample results and fatigue methodology validation.
SES is developing the MAPA tool to provide the United States Air Force with more precise predictive models for the fatigue characteristics of landing gear subject to surface treatments and coatings during design, maintenance, and overhaul. The MAPA tool manages raw fatigue test data and generates curve fits, strain-life parameters, and plots for rapid data mining. The MAPA tool also exports material property files formatted for direct input to nCode DesignLife for fatigue analysis.
MAPA Data Management
· To manage all raw fatigue test data, and resultant strain-life and Ksur, fatigue parameters.
· To compare raw data and fitted curves.
MAPA Curve Fit Editing
· To curve fit raw fatigue test data into strain-life and Ksur, fatigue parameters.
· To control the curve fitting process, to include/exclude data points, and to set design curve reliability and confidence levels.
The nCode Premium Material Database (PMD) contains fatigue properties measured on materials tested at the ISO-9001 certified Advanced Materials Characterisation and Test Facility owned and operated by HBK nCode. This collection of fatigue properties contains over 150 materials, mostly commonly used types of steel and aluminium, plus some other non-ferrous materials, and includes recent additions for additively manufactured titanium and Inconel material.
From nCode 2024, the PMD will include fatigue properties for baseline materials and surface treatments resulting from work to characterise fatigue performance of aging aircraft landing gear through overhaul and maintenance cycles. The baseline materials are 300M steel, 4340 steel and 7075 aluminium, with a range of surface treatments including; electrolytic nickel, electroless nickel, cadmium and chrome coatings, and many of these with and without shot peen.
The use of adhesive and/or hybrid joints are increasingly popular in the transportation industry to achieve their desire for durable lightweight structures to reduce fuel consumption and emissions. To optimise the design of these joints and minimise the risk of in-service fatigue failures, requires robust and easy-to-use methods for their modelling and fatigue life estimation. This session describes how the methods developed for thin sheet welded joints, presented at the 2021 HBK Technology Days, have been extended to adhesive and/or hybrid joint. These methods include using cameras to monitor crack initiation and propagation and displacement transducers for calculating stiffness drops. These tests, coupled with finite element stress analysis to recover the needed stress, enables the transformation of high quality load-life data sets with low scatter into stress-life (SN) fatigue parameters.
The session closes with an introduction to fretting fatigue, and University of Brasilia and University of Leuven research for a new combined experimental and numerical approach to characterise and predict fretting fatigue damage accumulation under variable amplitude loading.
The need for more environmentally sustainable ways of transportation and for a reduction in emissions and fuel consumption make lightweight structures essential. The use of adhesive and/or hybrid joints represents one way to reduce the weight of components and it is becoming increasingly popular in the transportation industry. To optimise the design of adhesive and hybrid joints and minimise the risk of in-service fatigue failures, the transportation industry needs efficient, robust, and easy-to-use approaches for the modelling and fatigue life estimation of such joints.
This work presents a practical approach, easily adoptable by companies in the transportation industry, for estimating the fatigue life of adhesive and hybrid joints. The proposed approach includes Finite Element (FE) modelling guidelines to recover the needed stresses, that provide FE models computationally not too onerous, reasonably mesh insensitive and that do not require congruent meshes, with limited changes to the typical FE modelling strategies currently used. The fatigue life estimation is then carried out using standard SN-based nCode DesignLife analysis engines, with the stresses recovered from the FE model and bespoke SN curves obtained through testing used as inputs.
Fretting fatigue can occur in many structures, such as riveted lap-joint connections in aircraft fuselage and blade-disc connections in aircraft engines. Fretting fatigue is complex and multiaxial but is commonly simplified to constant amplitude loading, however, this condition is not the reality for many industrial applications. Recent research proposes a new experimental and numerical methodology for the life assessment of components subjected to fretting fatigue under variable amplitude loading. Experimental tests were conducted by applying H-L (High-Low) and L-H (Low-High) alternating amplitude loading blocks to the tangential load while maintaining a constant static contact normal load, and a constant alternating amplitude bulk fatigue load. The new numerical methodology proposed for fretting fatigue life assessment includes the effects of crack nucleation, wear, and crack propagation. Crack nucleation life estimation results are compared using a traditional Miners’ linear damage accumulation and a proposed new non-linear damage model from experimental observations of H-L and L-H loading sequences.
Reliability engineering uses the discipline and hierarchy of failure mode and effect analysis (FMEA) to identify and rank potential and actual failure modes from components to systems to full asset. During development and in-service operation, test and field data for failure and survival can populate a hierarchal FMEA with quantifiable failure distributions. Early in concept design failure modes can be ranked, and plans proposed for supplementary development testing where reliability requirements are high but confidence is low because minimal data are available. During in-service operation, analyses of warranty field data can give early identification of future unreliability enabling mitigating actions to be developed and deployed.
Valeo present their application of reliability methods and tools deployed to ensure reliability of their thermal systems for new automotive electrification challenges. Valeo have collaborated with University of Bradford research to develop a model-based system engineering (MBSE) approach to automate some FMEA generation, to alleviate the traditional time and resource intensive expert-centric FMEA approach. The session closes with HBK presenting how to prioritise the tests required to mitigate reliability risk exposure by prioritising supplementary development testing.
Continuous Improvement of asset reliability is made possible with a combination of test data and field data. Using Failure Mode and Effect Analysis (FMEA), we can ask the right questions when attempting to study test and field data to calculate failure distributions over time. Failure modes can then be ranked, and plans proposed for supplementary testing where the data are found to be weak, or the reliability is lowest. Changes to the asset with respect to reliability improvement is actioned and traced through FMEA revision control. In this presentation we demonstrate how FMEA may be used to improve component reliability by combining qualitative engineering judgement with quantitative evidence derived through statistical rigour.
While significant progress has been made with the development and adoption of computer modelling and simulation tools to assist with the systems design, many of the analysis methods, in particular those focussed on robustness and reliability for the design and process assurance, including the FMEA, remain expert-centred and time and resource intensive. This talk outlines the development of an MBSE-assisted automatic FMEA generation tool, that places the expert in-the-loop, tasked with providing inputs and systematically reviewing the outcomes as generated system models. The approach emphasizes integration and traceability of requirements and critical characteristics across the levels of decomposition and analysis of the system. A case study of a robotic manufacturing process design for an electric drive unit is used to illustrate the use of the tool in an industrial context. This illustrates the cascade of the critical characteristics across multiple levels of process and tooling design analysis, supporting the synthesis of robust process controls plans for an Industry 4.0 implementation. As well as discussing the effectiveness of the tool, a reflection on the interaction between the analyst / expert, the MBSE model and FMEA, facilitated by the tool is provided. The practical benefits are the robustness and integrity of the FMEA and other design assurance documentation, and their governance for future use.
This will bring together HBM, Brüel & Kjær, nCode, ReliaSoft, and Discom brands, helping you innovate faster for a cleaner, healthier, and more productive world.
This will bring together HBM, Brüel & Kjær, nCode, ReliaSoft, and Discom brands, helping you innovate faster for a cleaner, healthier, and more productive world.
This will bring together HBM, Brüel & Kjær, nCode, ReliaSoft, and Discom brands, helping you innovate faster for a cleaner, healthier, and more productive world.
This will bring together HBM, Brüel & Kjær, nCode, ReliaSoft, and Discom brands, helping you innovate faster for a cleaner, healthier, and more productive world.
This will bring together HBM, Brüel & Kjær, nCode, ReliaSoft, and Discom brands, helping you innovate faster for a cleaner, healthier, and more productive world.
This concept of “novelty” embraces many aspects related to durability: mission profiling, failure modes detections and preventions, determination of failure root causes, physical models to accelerated design validation tests, analyses of warranty field data, development and comparison of validation specifications, testing and simulations etc.
