Aerospace Fracture Analysis
Fracture mechanics and damage-tolerance analysis for aerospace structures
Fidelis Aerospace evaluates what an assumed or discovered flaw means for crack criticality, growth, residual strength, detectability, inspection, remaining life, and continued structural use.
Fracture analysis combines the local stress field, crack geometry, material fracture and crack-growth data, loading spectrum, structural configuration, and inspection assumptions. The objective is to determine what the available evidence supports—and which assumptions or data most strongly control the conclusion.
When to engage Fidelis for fracture analysis
- A crack, flaw, indication, defect, or service damage has been discovered.
- A program must assume an initial flaw and demonstrate damage tolerance or fracture control.
- The team needs crack-growth life, residual strength, critical flaw size, or detectability assessment.
- A manufacturing defect or nonconformance may behave as a crack-like flaw.
- Inspection thresholds or intervals need an engineering crack-growth basis.
- A test article cracked unexpectedly and the failure mechanism or remaining capability must be understood.
- The internal team needs specialized fracture mechanics methods, independent review, or additional capacity.
Fracture analysis capabilities
Crack and flaw characterization
Define plausible crack locations, orientations, shapes, dimensions, through-thickness conditions, interaction assumptions, and the relationship between observed indications and analysis flaws.
Stress-intensity and fracture parameters
Determine crack-driving force using applicable handbook solutions, weight functions, finite element methods, or industry-standard fracture tools.
Critical flaw and residual strength
Estimate the flaw size or loading condition associated with fracture and determine remaining static capability for the defined geometry, material, and assumptions.
Fatigue crack growth
Predict crack extension under cyclic loading using suitable material data, load spectra, retardation or closure models when justified, and tools such as AFGROW or NASGRO where appropriate to the scope.
Damage tolerance and inspection support
Evaluate assumed initial flaws, detectable flaw sizes, inspection thresholds, intervals, growth periods, and residual-strength constraints as inputs to a broader damage-tolerance or airworthiness program.
Manufacturing defects and service damage
Assess whether pores, lack of fusion, scratches, gouges, corrosion, impact damage, machining marks, or other discontinuities can be represented credibly as crack-like flaws and what additional evidence is needed.
Fracture test and failure support
Support test planning, expected crack path, critical load, instrumentation, post-test interpretation, and correlation between observed fracture behavior and analytical predictions.
Independent review
Review crack scenarios, stress solutions, geometry factors, material data, spectra, tool settings, detectability, residual-strength criteria, and conclusions produced by another organization.
Damage tolerance in practical terms
Damage tolerance asks whether a structure can sustain a credible flaw long enough for the flaw to be found, managed, or shown not to threaten the required safety or mission objective. The analysis is not only a crack-growth calculation. It also depends on residual strength, likely damage locations, load spectra, inspection capability, structural redundancy, material behavior, and the consequences of failure.
Information commonly needed
- Geometry, thickness, local detail, crack location, orientation, and structural configuration.
- Applied loads, local stress history, load spectrum, residual stress, and stress solution.
- Material fracture toughness and fatigue crack-growth data for the relevant condition and environment.
- Initial-flaw or observed-indication assumptions and nondestructive inspection capability.
- Residual-strength criteria, load factors, mission or service requirements, and acceptance basis.
- Existing fatigue analysis, FEA, test results, fractography, service history, or prior assessments.
Potential outputs
Depending on scope, outputs may include crack-scenario definition, stress-intensity solutions, critical-flaw calculations, crack-growth curves, residual-strength results, inspection-support inputs, sensitivity studies, AFGROW or NASGRO analysis files, test predictions, review findings, design recommendations, and a technical report.
Fracture analysis versus fatigue analysis
Fatigue analysis usually estimates life to initiation or damage accumulation before a crack is explicitly modeled. Fracture analysis begins with a flaw or crack and evaluates its driving force, growth, residual strength, and detectability. When a crack has been observed—or the program requires an assumed initial flaw—fracture mechanics is the appropriate analytical framework.
Need to understand what a flaw or crack means for your hardware?
Share a non-sensitive summary of the structure, crack or assumed flaw, loading, material, inspection information, and the decision the analysis must support.
Frequently Asked Questions
What is fracture mechanics?
Fracture mechanics evaluates the behavior of structures that contain flaws or cracks. It relates crack geometry, stress, material resistance, and loading to determine crack criticality, growth, residual strength, and the risk of unstable fracture.
What is damage-tolerance analysis?
Damage-tolerance analysis evaluates whether a structure can safely sustain credible fatigue, corrosion, manufacturing, or accidental damage until it is detected, repaired, retired, or otherwise managed. It commonly combines crack-growth, residual-strength, load-spectrum, inspection, and structural-redundancy considerations.
Can crack-growth analysis support an inspection interval?
Yes. Crack-growth analysis can help determine the time or usage for a crack to grow from an assumed or detectable size to a limiting size. A complete inspection basis also depends on inspection reliability, access, structural consequences, load uncertainty, material data, factors, and the governing approval framework.
What inputs are needed for a fracture assessment?
Typical inputs include crack geometry and location, local stress or loads, load spectrum, residual stress, fracture toughness, fatigue crack-growth data, material and environmental condition, initial or detectable flaw size, residual-strength criteria, and relevant test or service evidence.