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MMS 13 4 th IAG Update on AEA Tasks Culham Science Centre 15 th January 2004

Assessment and Criticality of Defects and Damage in Materials Systems. MMS 13 4 th IAG Update on AEA Tasks Culham Science Centre 15 th January 2004. Assessment and Criticality of Defects and Damage in Materials Systems. Task 1 Review Purpose

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MMS 13 4 th IAG Update on AEA Tasks Culham Science Centre 15 th January 2004

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  1. Assessment and Criticality of Defects and Damage in Materials Systems MMS 13 4th IAGUpdate on AEA TasksCulham Science Centre15th January 2004

  2. Assessment and Criticality of Defects and Damage in Materials Systems • Task 1 Review • Purpose • Review & assess current industrial guidelines & codes of practice from a range of industrial sectors • Procedure • Review existing guidelines for defect assessment (Dow, CEN, BSI, ISO, ASME, NORSOK, ESA, NASA, Boeing, MIL HDBK-17, etc.) • Examine defect types applicable to various materials systems • Review approaches for different industry sectors • Compare defect assessment codes with those for metals • Task 1 report issued to IAG for comment and subsequently revised

  3. Assessment and Criticality of Defects & Damage in Materials Systems Defect Types Inclusions Debonding Delamination Fibre breakage Improper splicing/ joining Fibre misalignment and wrinkling Incorrect stacking sequence Porosity Resin starved areas Damage from tooling removal Machining imperfections Matrix Cracking Heat damage Manufacturing defects In-service defects

  4. Assessment and Criticality of Defects & Damage in Materials Systems Task 3 NDE Assessment Visual inspection Ultrasonics (reflection & transmission) Radiography (X-ray and - ray) Laser shearography Thermography Tap/ vibration testing Acoustic emission

  5. EXISTING COMPOSITE RELATED DESIGN STANDARDS & GUIDELINES including manufacturing defect assessment BS 4994 :1987 ASME RTP-1:1995 ASME X: 2001 ISO 14692: 2002 DNV F-100: 2001 DNV OS-C501: 2003 EN 13706: 2001 NORSOK M-622: 1999 Dow Chemicals Specifications ESA Composite Design Handbook Guidelines Commercial aircraft industry guidelines (NASA/ Boeing & Airbus) MIL-HDBK-17: 2002

  6. MMS 13 Assessment and Criticality of Defects & Damage in Materials Systems DEFECT ASSESSMENT CODES FOR METALLIC STRUCTURES BS 7910: 1999 CODE R6 - NUCLEAR ELECTRIC: 1990 API 579: 2000 Contents – Minimum Requirement Definition of the defect types Definition of material properties needed to perform the assessment Guidance on defect characterisation - geometry Definition of loading to be considered Definition of the analysis procedures Guidance on acceptability criteria

  7. Inspection techniques • Practical assessments on the following inspection techniques have been made during the medium term pressure tests; • Acoustic emission • Ultrasonics • Eddy current • Thermography • Shearography • X-rays • For thermosetting polymers the time scale for crack initiation is much greater than for crack propagation. This is the fundamental inspection challenge

  8. Ultrasonic Testing • The simplest technique uses a hand-held pulse-echo probe - unable to detect 5 mm diameter hole in the steel pipe under the composite overwrap. More sophisticated versions of the ultrasonic technique (angled twin probes, Time of Flight TOFD) were then assessed • The Harwell trials were carried out using a multi-channel AEA digital ultrasonic imaging system. • The features of this equipment are: • Low inherent noise characteristics • Signal averaging noise suppression capability • Long range capability • Grey scale imaging capability with image enhancement • Ultrasonic velocity =  [Bulk Modulus (K)/ density ()] • Typical velocity ~ 5.9 mm/msec for steel ~ 2.4 - 2.8 mm/msec for composite

  9. Ultrasonic Testing – Principles of simple hand-held probe

  10. Laser shearography – HST 125 composite cabs

  11. Delamination around opening

  12. LIXI Profiler - summary of results • Rapid, hand held scanning. • Surprisingly effective! High POD in CRIS trial. • Information on which wall of pipe defect is in done by moving source. • Detected: • Severe corrosion in HOIS small bore connector specimen, moderate corrosion not clearly found • In UK demo, detected defects under insulation, under composite repair, and internal corrosion in bare straight-pipe • Limited information in 1-D profiles, compared with full radiograph

  13. Inspection - Recommendations • For composite overwrap repairs there are 3 prevalent defect types, namely the following inspection techniques are recommended; • General wall loss of the substrate (e.g. through internal corrosion) • – EM techniques (PEC) or X-rays • Pin hole leaks (e.g. through localised corrosion at a weld) • – US although further refinement of the most appropriate form is required • Delamination of the composite laminate (e.g. through debonding) – Laser shearography again further refinement is required • Potential for further work continuing on these latter 2 inspection techniques. Also X-ray techniques will be assessed for the detection of pin hole leaks

  14. Assessment and Criticality of Defects & Damage in Materials Systems The End Thank You for listening !

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