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Details of Grant 

EPSRC Reference: EP/S012362/1
Title: NDE, DEsign and Engineering Critical Assessments (NDECA): Bridging the gaps
Principal Investigator: Larrosa, Dr N
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Henry Royce Institute John Wood Group plc NDE Research Association RCNDE
University of Cantabria Welding Institute
Department: Mechanical Engineering
Organisation: University of Bristol
Scheme: New Investigator Award
Starts: 01 October 2018 Ends: 31 March 2021 Value (£): 283,717
EPSRC Research Topic Classifications:
Eng. Dynamics & Tribology Instrumentation Eng. & Dev.
Materials testing & eng.
EPSRC Industrial Sector Classifications:
No relevance to Underpinning Sectors
Related Grants:
Panel History:
Panel DatePanel NameOutcome
07 Aug 2018 Engineering Prioritisation Panel Meeting 7 and 8 August 2018 Announced
Summary on Grant Application Form
The NDECA project aims to extend the applicability of fracture mechanics methods for predicting the behaviour of structures/components containing non-sharp flaws.

Many defects formed during manufacture or in service (e.g. porosity, dents or corrosion pits, weld defects, etc.) and certain design features (e.g. crevices in partial penetration welds) are not sharp i.e, have non-zero crack tip radius.

Common structural integrity assessment procedures- such as R6 [1] and BS7910 [2]- use fracture mechanics principles for the assessment of flaws that are assumed to be infinitely sharp. While this approach is appropriate for planar (2D) flaws, such as fatigue cracks, it can be excessively conservative for non-sharp defects, leading to erroneous decisions (replace/repair/re-inspect), thus reducing assets cost-effectiveness (through increasing operating costs and/or reducing service life).

Several assessment methods have been proposed in the literature to quantify the additional margins of safety of non-sharps defects compared to the margins that would be calculated if the defects were assumed to be sharp cracks. Unfortunately, the validation and application of these methods is currently limited by the lack of both credible non-destructive evaluation (NDE) techniques to distinguish between sharp and non-sharp flaws and; representative and reproducible effective fracture toughness testing procedures.

Therefore, this proposal will focus in the:

-Development and validation of novel NDE methodologies for accurate notch-tip acuity characterisation;

-Development of recommendations for future fracture mechanics-based test methods to account for the defect topology on the resistance to failure.

This multidisciplinary effort - it cuts across multiple academic fields, i.e. ultrasonics and NDT, mathematical modelling, engineering structural integrity, finite element analysis, and engineering design - will produce a step change improvement in damage tolerance methods for the next generation of design (by analysis) and structural integrity procedures of high integrity structures, allowing enhanced efficiency of assets. The project is supported by TWI, Wood, RCNDE, University of Cantabria and BP.

NDECA takes advantage of the UK's leadership and experience on the development of structural integrity assessment procedures (TWI, Wood, BP), the application of NDE methods for defect characterisation (University of Bristol Ultrasonics and NDT group, TWI and RCNDE members) and experience with FEA damage simulation and testing of non-sharp defects (Larrosa [PI], Wood, University of Cantabria).

The timeliness and critical needs for this project are reflected in requirement for more precise methods in life extension programmes for in-service nuclear power plants and Oil and Gas high integrity assets which are currently at (or close to) the end of the design life.

References

1. R6 - Revision 4, Assessment of the Integrity of Structures Containing Defects, Latest Updates: March 2015. EDF Energy, Gloucester, UK.

2. BS7910: 2013+A1:2015, incorporating Corrigenda Nos.1 and 2, 2016. Guide to Methods for Assessing the Acceptability of Flaws in MetalliMetallic Structures. British Standards Institution, London.

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Organisation Website: http://www.bris.ac.uk