New CD available containining presentations and commentary on two recent EIS events:
“High Integrity with Minimum Testing” (2004) &
“A Business Case for Optimising Designs in Product Development” (2005)
Engineering Integrity Society
Introduction by Dr Frank Sherratt
The engineering development process has always comprised a combination of calculations and physical tests to ensure product integrity. Not surprisingly there has been a continuous drive towards the development of more efficient procedures, particularly as development can represent a large part of the final product cost, and many engineering organisations have seen significant benefits accruing from the integration of modelling and simulation into the design and development process. Reports of progress in this field have always been part of EIS activities and two recent events have concentrated on it:
• “High Integrity with Minimum Testing”, Nettle Hill Conference Centre, Coventry. 18 November 2004.
• “A Business Case for Optimising Designs in Product Development”, Ford Motor Company, Dunton Technical Centre. 18 May 2005.
The Society aims, through its journal and other media, to make as many presentations as possible available to the widest possible audience. Unfortunately, not all presenters have the time to produce formal, written papers. Therefore, we have looked at the slides for these two particular meetings and decided that, because they are all concerned with a similar topic, a selected series of items might convey valuable information, especially if some guidance about content is added. These presentations and commentary are now available on an EIS CD.
Classification of the presentations
Product development includes many activities, but it is convenient to describe the two main ones as (a) calculation, and (b) testing. The increasing use of computational tools such as Multi-Body Simulation (MBS) and Finite Element Analysis (FEA) has shifted the emphasis towards (a), and current discussions centre on how fast this shift will progress. Virtual Product Development (VPD) techniques envisage development based entirely on analysis or, possibly, on analysis plus simulated testing. As well as applying a particular analysis or test method correctly it is necessary to choose the correct blend of methods: this requires detailed knowledge of their individual strengths and weaknesses and strategic decision makers need authoritative guidance at this level.
The intention at both events was to give general guidance rather than specialist instruction. Grouping them by their main emphasis identifies those which:
A. Examine current practice and immediate future prospects.
B. Present Virtual Product Development
C. Describe ways of improving current techniques
If we regard B and C as alternative ways forward it is desirable to study A before comparing them. The presentations included on the CD are:
Category A
Blackmore, P. A., ”Product Development: Tools and Practice”
Hillmansen, S. and Smith, R. “Technology is Available”
Harty, D. “Theory is for Losers”
Carter, L. “The Future for Laboratory Simulation”.
Category B
Veltri, M., “Advancements in the Field of VPD.”
Dakin, J. and Zhu, H., “Fully Analytic Vehicle Loads and Virtual Durability Process”
Ensor, D., “Balance of Physical and Virtual World Development”
Category C
Johnson, R. “Guidelines and Best Practice for Reliable FE”
Cawte, R. “Using Test Feedback to Improve the accuracy of FE results for Fatigue Predictions”.
Halfpenny, A. “Methods of Synthesising and Accelerating Fatigue Tests”
These presentations have been chosen to give a reasonable survey of the current position.
Comments on the presentations
Dr Peter A Blackmore, Jaguar Cars Ltd. “Product Development: Tools and Practice”
After pointing out that integrity is affected by many aspects of the product development process, the presentation considers ‘assumptions and sources of uncertainty’, especially in the Computer Aided Engineering (CAE) process. The role of multi-body simulation (MBS) in providing data for early FE models is described, and sources of weakness in FE models are listed. The conventional view of fatigue life estimation, depending on loading, geometry and material properties, is used to examine the uncertainties introduced by each factor. The process of fatigue analysis by FE for an automotive component and customer usage simulation by test track and test rig is illustrated. The final conclusion that modelling and simulation are only valid if the assumptions are valid is adequately supported. The presentation is heavily text-based, and so is easy to study.
Stuart Hillmansen & Prof. Rod Smith, Imperial College London “Technology is Available”
Following a block diagram describing the traditional approach to estimating the probability of fatigue failure, the presentation turns to the long-standing problems of fatigue in railway axles and rails. The management of Non-Destructive Test (NDT) procedures is analysed and current data collection systems are described. The potential limitations of FE without proper control are emphasised. The slides are easy to follow without extensive commentary.
Liam Carter, Ford Motor Company “The Future of Lab Simulation”
This presentation starts with a clear statement that there will be a future role for physical testing, giving clear reasons. These are then supported by four case studies. The components studied are clearly important, the facts are clearly described, and the link with analysis is made clear. Full text content makes study easy.
Damian Harty, Prodrive “Theory is for Losers”
As the title suggests, this is a slightly tongue-in-cheek look at the relationship between analysis and test but the message is serious and includes many positive comments based on considerable experience. The slides are completely text-based, and need no commentary.
Marco Veltri & Fredrik Sjogren, MSC Software “Fatigue and Durability Advancements in the field of Virtual Product Development”
This goes into the detail of what VPD is and what it can do. It starts with block diagrams showing where VPD fits into the development process, initially in the general case and then in the fatigue and durability field. The characteristics of MBS and FEA analysis, when used in conjunction, are described. A detailed study of modal flexibility analysis follows. Two case studies are given, concerning an all-terrain vehicle and the fatigue of an automotive engine. The mathematical content is high, and would not be intelligible without substantial prior knowledge. The explanations of general principles are very clear, though, and contribute to an understanding of VPD without extra comments.
Dr Hong Zhu & Dr John Dakin, Ford Motor Company “Fully Analytic Vehicle Loads and a Virtual Durability Process”
Whilst this presentation is comprehensible to those with no prior knowledge of VPD and the drawbacks and advantages of FEA and MBS, a prior reading of the Blackmore and Veltri contributions could be helpful. The slides give very solid information about how one experienced group is using VPD methods. MSC/Adams provides the main software, Ford’s Lommel proving ground provides the test location, wheel force transducers provide in-vehicle measurement and laser profiling measures the external environment. Major vehicle sub-systems are the design target. The slides are fully supported by text, and the general message is clear.
David Ensor, MIRA “Balance of Physical and Virtual World Development”
Starting with an account of the histories of physical testing and VPD, the presentation goes on to examine a hybrid approach using relatively simple models to reduce the amount of testing. The effect of this hybrid approach is shown to benefit the design cycle. Wheel force transducers and (fairly elaborate) modelling of test track features are part of the technique. Extensive illustrations of test rigs and proving ground features at one of the most experienced development establishments are included.
Bob Johnson, DAMT. “Guidelines and Best Practice for Reliable Finite Element Analysis”
This is a step-by-step description of the process of FE analysis, from inserting CAD data to interpreting the output. The importance of constraints and boundary conditions is emphasised. Two case studies are presented: a pressure vessel and a torsion link. The latter is used particularly well to illustrate the principles of constraint. Detailed recommendations are made, including one to make hand calculations first. The subject requires a lot of line illustrations, which are given, but all are easy to read and fully explained.
Robert Cawte, nCode International Ltd. “Using Test Feedback to Improve the accuracy of FE results for Fatigue Predictions”.
Starting by examining the sources of uncertainties in FE modelling, the discussion is then taken on to uncertainties in strain gauge measurement and in testing. Simple tests, repeated, to verify previous models are recommended. The extensive text needs no additional commentary.
Dr Andrew Halfpenny, nCode International Ltd. “Methods of Synthesising and Accelerating Fatigue Tests”
The presentation considers in detail the steps needed to create a mission profile for a durability test. Both deterministic and stochastic loads are considered and ways of editing the data to reduce testing time are described. The included text needs no extra commentary.
A CD containing copies of these presentations and supporting commentary is available at a cost of £20+VAT from the EIS Secretariat: Tel: 0114 262 1155, E-mail: cpinder@e-i-s.org.uk
Frank Sherratt
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