Aerospace Fatigue & Fractography — Crack Origin & Growth Evidence
Fatigue and fractographic work on aerospace hardware establishes where a crack started, how it grew and which mechanism was involved. The component's service history and the untouched fracture surface are the primary evidence; cleaning or mating the surfaces destroys it.
Protect the fracture surfaces
Do not fit broken pieces together, clean them or apply coatings before the examination is planned. Record the loading history, cycles or hours, maintenance actions and the discovery circumstances. Ask the laboratory how the component should be sectioned for transport and what remote examination is possible before any cutting.
Read the fracture with the loading history
Beach marks, striations and other features are interpreted against the actual load spectrum, environment and material condition. SEM examination, hardness and chemistry each test specific hypotheses. A striation count is not automatically a life statement; ask what the spacing and morphology can and cannot establish for this alloy and loading.
Connect findings to the fleet or design decision
The report should distinguish the initiation site and mechanism from speculation about cause, and state what further work — residual strength, teardown sampling, fleet inspection — the evidence supports. For airworthiness or legal contexts, agree witness, chain-of-custody and data-retention requirements at the outset.
Sample considerations
- Provide the fractured component untouched, plus mating parts, service history and maintenance records.
- Identify material, heat treatment and loading environment; supply drawings where shareable.
- Agree sectioning authorization, witness requirements and evidence retention.
Questions to ask a laboratory
- What can the fracture morphology establish about origin and growth for this alloy?
- How are environmental versus mechanical contributions discriminated?
- What chain-of-custody and witness provisions apply to the examination?
Laboratories with relevant capabilities
- Westmoreland Mechanical Testing & Research Ltd (Banbury, Oxfordshire) — Fatigue Testing
- Composite Test & Evaluation Ltd (Honiton, Devon) — Fatigue Testing
- Touchstone Research Laboratory (WV) — Fatigue Testing
Frequently asked questions
- Can fractography determine the cause of a fatigue failure?
- Fractography identifies the crack origin and propagation mechanism; establishing root cause usually also requires loading history, material verification and design review.
Sources and scope references
Related testing briefs
Aerospace & Defense Materials Testing
Confirm standard edition, jurisdiction and actual laboratory scope. Service references are not partnerships or endorsements.