Compression after impact fatigue damage growth in CFRP – what does no-growth really mean?

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Abstract

Impacts on carbon fiber reinforced composites (CFRP) can produce a complex internal damage comprising multiple delaminations, which is hard to detect from visual inspection. This situation is known as barely visible impact damage (BVID). Considering that every airplane faces several impacts during its operational life, and that the majority of exposed surfaces in new generation aircraft is made of CFRP, there is a high chance that some aircraft will be flying with unnoticed impact damage. For this reason, BVID damage tolerance must be taken into account in design. The FAA and EASA dictate a no-growth design philosophy for BVID. Although multiple delaminations are present, BVID fatigue growth is usually assessed by measuring only the projected delaminated area with ultrasound inspections. This is done to simplify the damage description and because of the limitations in ultrasound inspection methodologies. In the present work, we show two cases of delamination propagation that are neglected following this procedure. Our experimental monitoring of delamination propagation with different ultrasound techniques shows a) growth inside the impact cone and b) faster growth of shorter delamination. The conclusion is that the projected area description is insufficient, since a no-growth in the projected area does not necessarily correspond to a no-growth in the actual damage.
Original languageEnglish
Title of host publicationProceedings of the 31st symposium of ICAF - the International Committee on Aeronautical Fatigue and Structural Integrity
Place of PublicationDelft
Number of pages9
Publication statusPublished - 2023
EventICAF 2023 – the 38th Conference and 31st Symposium of the International Committee on Aeronautical Fatigue and Structural Integrity: Structural Integrity In A World In Transition - Theater de Veste, Asvest 1, 2611 PK, Delft, Netherlands
Duration: 26 Jun 202329 Jun 2023
https://www.icaf2023.nl/

Conference

ConferenceICAF 2023 – the 38th Conference and 31st Symposium of the International Committee on Aeronautical Fatigue and Structural Integrity
Abbreviated titleICAF 2023
Country/TerritoryNetherlands
CityDelft
Period26/06/2329/06/23
Internet address

Keywords

  • BVID
  • Damage Tolerance
  • Delamination
  • Fatigue
  • Ultrasound-scan

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