Aerospace Fatigue Analysis
Fatigue analysis and structural life assessment for aerospace hardware
Fidelis Aerospace evaluates how repeated loading accumulates structural damage, which locations and details limit life, and how changes in loads, geometry, material, manufacturing, finish, or usage affect durability.
Fatigue analysis supports decisions about design, test, qualification, service life, mission usage, maintenance, and additional evidence. The credibility of the result depends on the stress solution, load spectrum, material data, detail assumptions, and the intended use of the estimate.
When to engage Fidelis for fatigue analysis
- A component or installation has a cyclic-life or durability requirement.
- The program needs to identify fatigue-critical locations before test or release.
- A mission, duty cycle, or usage spectrum must be converted into an engineering life assessment.
- A design change affects local stress concentration, joint behavior, finish, load, or material condition.
- A test result or early crack suggests the predicted life does not match hardware behavior.
- The internal team needs specialized fatigue methods, an independent check, or additional capacity.
Fatigue analysis capabilities
Load spectra and cycle characterization
Organize mission, usage, qualification, test, or measured loading into cycles and ranges suitable for fatigue assessment. Evaluate sequence and spectrum assumptions where they materially affect the result.
Stress-life assessment
Use S-N methods to estimate high-cycle fatigue behavior where nominal or local elastic stress methods and appropriate material or detail data are applicable.
Strain-life assessment
Use E-N or local strain methods when significant local cyclic plasticity, low-cycle loading, or notch behavior requires a strain-based approach and adequate material data are available.
Mean-stress and notch effects
Account for mean stress, stress concentration, notch sensitivity, surface condition, size, finish, and other modifiers when supported by the method and data.
Cumulative damage
Estimate damage accumulation across variable-amplitude loading and identify the load ranges or mission events that dominate predicted life.
Joints and structural details
Evaluate fatigue-sensitive fastener holes, lugs, fittings, attachments, transitions, cutouts, joints, and other local details using appropriate stress and detail methods.
Sensitivity and design improvement
Determine how predicted life changes with load, geometry, material data, finish, residual stress, stress concentration, spectrum, or other assumptions; use the result to guide design or evidence priorities.
Test planning and correlation
Support test article selection, load definition, instrumentation, predicted critical locations, interpretation of failure, and comparison between observed and predicted life.
Fatigue analysis versus fracture analysis
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Fatigue analysis |
Typically estimates life to initiation or durability under repeated loading using stress-life, strain-life, or detail-based methods. |
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Fracture analysis |
Assumes a flaw or crack exists and evaluates criticality, crack growth, residual strength, detectability, or inspection requirements. |
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Use both when |
The program must address initiation, crack growth, damage tolerance, inspection, or a crack has already been observed or assumed. |
Information commonly needed
- Geometry and local detail definition at potential fatigue-critical locations.
- Nominal, local, or FEA-derived stress histories for relevant load cases.
- Mission, duty-cycle, qualification, test, or measured load spectrum.
- Material fatigue data, heat treatment, finish, process, environment, and temperature as applicable.
- Joint, fastener, interference, preload, residual stress, and manufacturing assumptions where relevant.
- Life requirement, reliability or scatter treatment, acceptance criteria, and intended use of the result.
- Existing test data, service evidence, cracks, failures, or prior life analyses.
Potential outputs
Depending on scope, outputs may include a fatigue-analysis plan, spectrum definition, cycle-count summary, stress extraction, critical-location screening, life calculations, damage tables, sensitivity studies, test predictions, correlation findings, design recommendations, and a technical report.
Interpreting a fatigue-life result
A calculated life is not a universal property of the part. It is the result of a defined model of geometry, load, material behavior, manufacturing state, environment, and failure criterion. Fidelis documents the assumptions, identifies the dominant drivers, and communicates how confidently the estimate can support the specific program decision.
Need to understand how long your hardware cn withstand repeated loading?
Share the hardware, life requirement, loading or mission information, available stress results, material condition, and the decision the life estimate must support.
Frequently Asked Questions
What is aerospace fatigue analysis?
Aerospace fatigue analysis estimates how repeated loading can initiate damage or failure in a structural component. It combines stress or strain response, load cycles or spectra, material or detail fatigue data, and damage models to estimate life and identify critical locations.
What data are needed for fatigue analysis?
Typical inputs include geometry, local stress or strain, a load spectrum or duty cycle, material fatigue data, surface and manufacturing condition, environment, mean stress, joint details, life requirements, and any relevant test or service evidence. The exact inputs depend on the method and decision.
Can fatigue life be predicted without testing?
An analytical fatigue-life estimate can be made without a dedicated component test when suitable loads, stress methods, material data, and assumptions are available. Confidence improves when the method is supported by representative coupon, element, component, or service data.
What causes low predicted fatigue life?
Common drivers include high local stress concentration, variable-amplitude loading, tensile mean stress, surface condition, manufacturing effects, joint behavior, material scatter, residual stress, environment, and assumptions that do not represent the actual hardware or usage.