Failure investigation of hydrogen induced cracking of stabilator skin in jet aircraft

Bokwon Lee, Ryan Karkkainen

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

In this study, a 1 m long crack found in the stabilator skin of a jet aircraft has been investigated. SEM observation revealed that the crack initiated from the free edge of the inboard side where fatigue striations and ratchet marks were observed, then propagated transversely through the skin in the manner of a brittle crack. Predominantly intergranular fracture with quasi-cleavage morphologies was observed on the entire fractured surface. Fractography with hydrogen measurement as well as hardness testing indicated that hydrogen induced cracking (HIC) was the dominant cracking mechanism. Visual observation identified undesirable loads induced by several improper maintenance activities. Finite element analysis was used to correlate the experimental observations with these identified abnormal load cases. The location of the stress concentration determined by finite element analysis showed good correlation with the actual cracking location. It was concluded that an undesired assembly force induced a high residual stress, and operational aerodynamic loads combined with these maintenance loads contributed to exceeding the HIC threshold stress in the degraded metal due to hydrogen embrittlement.

Original languageEnglish (US)
Pages (from-to)182-194
Number of pages13
JournalEngineering Failure Analysis
Volume92
DOIs
StatePublished - Oct 1 2018

Fingerprint

Jet aircraft
Hydrogen
Skin
Cracks
Loads (forces)
Hardness testing
Finite element method
Aerodynamic loads
Fractography
Hydrogen embrittlement
Stress concentration
Residual stresses
Metals
Fatigue of materials
Scanning electron microscopy

Keywords

  • Honeycomb sandwich
  • Hydrogen induced crack
  • Intergranular crack
  • Stabilator

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)

Cite this

Failure investigation of hydrogen induced cracking of stabilator skin in jet aircraft. / Lee, Bokwon; Karkkainen, Ryan.

In: Engineering Failure Analysis, Vol. 92, 01.10.2018, p. 182-194.

Research output: Contribution to journalArticle

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