Fatigue Life Analysis Services
Fatigue Life Analysis for Reliability, Durability and Failure Prevention
Reliability Quality Solutions provides fatigue life analysis, prediction, assessment, and testing. RQS offers services to help clients understand how their products, components, and/or structures will behave under anticipated permitted service use and repeated or cyclic loads.
Failure due to fatigue can occur even with stresses below the materials’ ultimate strength. Damage caused by repeated loading, vibration, thermal cycling, cyclic variation in stresses, environmental changes, the characteristics of the material, the various stages of manufacturing, and stress concentrations can cause failure due to fatigue.
Reliability Quality Solutions’ engineering services include fatigue life analysis, fatigue life prediction, fatigue failure analysis, assessment of durability, fatigue testing, stress analysis, fracture mechanics, and failure analysis. These provide technical means to locate potential fatigue problems and to support practical design and reliability decisions.
RQS offers services to help determine fatigue failure risks and predict service life to a greater extent than before, and improve product service life, enhance reliability, and minimize customer complaints due to failure of products in service.
Contact UsOur Fatigue Life Analysis Approach
Reliability Quality Solutions employs a formal engineering approach to fatigue life analysis and prediction.
Determining Application and Service Scenarios
We examine the component, the function, and the intended use of the product, the performance environment, the anticipated service life, and the loading conditions.
Characterizing the Loading
Fatigue performance is highly dependent upon the specific loading on the component. When possible, field/test data can furnish a more realistic basis for a fatigue assessment.
Assessing the Stresses and Strains
Loading conditions, along with stress and strain, can help locate potential fatigue failure zones.
Selecting the Appropriate Fatigue Approach
The proper fatigue approach is a function of the material, the loading, and the type of behavior of the component, as well as the extent of the data available.
Predicting Fatigue Lives
The various engineering approaches and the available data on the material and loading are employed to perform a fatigue life analysis and identify potential critical fatigue conditions.
Evaluating the Design and Assessing the Risks
Design fatigue life is assessed relative to the required service life to determine the design/service life margin and identify areas requiring further assessment.
Validating Fatigue Life Assessment
Fatigue life assessment is conducted in the absence of appropriate testing. In the absence of analysis, fatigue life assessment is validated by fatigue life testing.
Fatigue Life Analysis Methods
Stress-Life (S-N) Analysis
Stress-Life analysis, commonly associated with S-N curves, is frequently used for high-cycle fatigue applications where elastic stresses dominate. The approach relates stress amplitude to the number of cycles to failure and can be useful for evaluating components subjected to repeated cyclic loading.
Strain-Life (ε-N) Analysis
Strain-Life analysis can be useful when significant plastic deformation occurs locally or when low-cycle fatigue is an important consideration. This method evaluates the relationship between strain and fatigue life.
Fracture Mechanics & Crack-Growth
When cracks or crack-like flaws are present, fracture mechanics and crack-growth analysis can be used to evaluate crack propagation and remaining life. These methods can be particularly relevant to in-service fatigue life assessment and remaining-life evaluations.
Cumulative Fatigue Damage
Components may experience different loading conditions throughout their service life. Cumulative fatigue damage methods can be used to evaluate the combined effect of multiple loading conditions and estimate accumulated fatigue damage.
Variable-Amplitude Fatigue
Real-world products rarely experience perfectly constant loading. Variable-amplitude fatigue analysis can consider changing load levels and service load spectra to provide a more realistic fatigue-life assessment.
Multiaxial Fatigue Analysis
Components subjected to loading in multiple directions may require multiaxial fatigue analysis to properly evaluate fatigue behaviour.
Uses of Fatigue Life Analysis
Fatigue Life Analysis for Product Design and Development
In the design and development of products, if fatigue analysis is incorporated early on, possible issues of durability may be uncovered prior to the product being manufactured. Early fatigue life prediction in design alternatives can help engineers determine possible solutions to address durability concerns and reduce manufacturing costs.
Fatigue Analysis for Existing and In-Service Components
Fatigue analysis is not limited to product development. For components already in use, fatigue analysis may be utilized to determine the possible future effects of operating loads that have already been accumulated on the performance of the component. Wherever enough data are available, analysis is able to estimate the remaining fatigue life and assist in making the decision of either extending the life of the component with a life extension or carrying out maintenance.
Factors That Affect Fatigue Life
Fatigue life is a multifaceted problem.
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Material: Materials may include factors such as strength, ductility, microstructure, heat treatments, inclusions, and defects.
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Geometry: The introduction of features such as notches, holes, abrupt changes in geometry, sharp edges, threads, welds, and other geometric discontinuities may create stress concentrations.
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Surface Condition: Factors such as surface roughness, machining, scratches, corrosion, and various surface treatments may affect a material’s fatigue performance.
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Loading: Most factors, such as stress amplitude, mean stress, frequency, load sequence, and whether loading is variable, affect fatigue life.
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Environment: Fatigue life may also depend on the temperature and humidity, as well as the degree of corrosion, chemicals, and other environmental conditions.
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Manufacturing: Manufacturing inevitably introduces residual stresses, defects, surface damage, and other problems related to fatigue performance.
Benefits of Fatigue Life Analysis
Professional fatigue analysis can help organizations:
- Improve Product Reliability: Previously unidentified weaknesses in product designs may cause failures. Anticipate product weaknesses before failures occur in the field.
- Increase Durability: Does the product stand up to expected loads in expected environments?
- Reduce Unexpected Failures: Determine where product failures are likely to occur in fatigue scenarios.
- Optimize Product Design: Perform fatigue analysis to evaluate trade-offs in various elements of design (geometry and material), and to improve the overall design significantly.
- Support Testing Decisions: Perform fatigue analysis to develop testing regimens that are efficient in terms of time and resources.
- Support Life Extension: Determine how long the remaining fatigue life of a component is.
- Reduce Cost of Quality: Reducing fatigue failures results in a reduction in warranty claims and unplanned product replacements.
Why Choose Reliability Quality Solutions?
Reliability Quality Solutions combines reliability engineering, fatigue analysis, failure analysis, testing, and practical product-development experience to help organizations address durability challenges. Our approach focuses on engineering decisions—not simply producing an analysis report.
Engineering-Focused Analysis & Recommendations
We focus on understanding the actual loading, failure mechanisms, material behaviour, and design conditions affecting fatigue life. Our objective is to translate analysis results into practical recommendations for improving product reliability and durability.
Lifecycle Support & Failure Prevention
We can support fatigue-related activities from product design and development through testing, manufacturing, field performance, and in-service assessment. We focus on identifying potential fatigue problems before they become costly failures.
Integrated Reliability Approach
Fatigue life analysis can be integrated with broader reliability engineering, risk management, failure analysis, design verification, validation, and product development activities.
Frequently Asked Questions About Fatigue Life Analysis
What is fatigue life analysis?
Fatigue life analysis determines the lifetime of a component, system, or product under loading or stress cycling conditions before failure caused by fatigue.
What is fatigue life prediction?
Fatigue life prediction entails estimating the lifetime of a component in cycles of loading or the duration of service before failure caused by fatigue in loading conditions, composition or properties of the material, design, environment, and a fatigue failure method.
What is fatigue life testing?
Fatigue life testing entails placing components or products under repeated loading conditions in order to test and determine the fatigue limits of the design along with the failure mechanisms.
What is the difference between fatigue life analysis and fatigue testing?
Fatigue life analysis relies on principles of engineering with supporting data and calculations or simulations. Fatigue testing relies on the actual performance of a fatigue test. For a design to be considered sufficiently durable in theory, analysis and testing should be utilized in tandem.
What is in-service fatigue life assessment?
In-service fatigue life assessment determines the fatigue condition and the potential remaining fatigue life of components that have been subjected to actual real-world fatigue loading.
Can you estimate the remaining fatigue life?
The remaining fatigue life can be estimated if the necessary information is available. Assessment of remaining fatigue life incorporates the loading conditions during service, the total number of cycles, the properties of the material, the current state of the component, results of inspections, and the behaviour of fatigue and cracks.
What methods are used for fatigue life prediction?
The methods used for fatigue life prediction include stress-life analysis, strain-life analysis, fracture mechanics, crack growth analysis, cumulative fatigue damage, variable-amplitude fatigue analysis, and multiaxial fatigue analysis, depending on the situation.
Can fatigue analysis be employed in product development?
Fatigue analysis is permissible, and in fact, beneficial in product development. Analyzing fatigue during the development of a product helps locate the risks of durability and the possible alternatives to design, set design margins, and, increasingly, the reliability of the product before it's produced.
Can fatigue analysis be done on a failure that has already occurred?
Yes, failure due to fatigue can help identify the mechanism of failure, the contributing factors, the location of the first crack, the loading conditions, the material, the design, and the manufacturing issues.
