Hill Engineering Blog

Fatigue Analysis

Fatigue is a material failure mechanism whereby repeated sub-critical loads nucleate and grow cracks that can ultimately lead to failure of a structure. Hill Engineering routinely performs fatigue analysis to quantify and predict fatigue performance of materials. State-of-the-art fatigue analysis is subdivided into categories, including durability (crack initiation) or damage tolerance (crack growth). The appropriate fatigue analysis for a given design depends on the application.

Fatigue analysis of durability performance is used to determine when cracks will initiate in a structure. During the fatigue analysis, the expected performance of the structure is defined as the cycles required to develop a crack. Durability fatigue analysis methods are typically ether based on the strain level (strain-life) or stress level (stress-life) observed in a part. A durability fatigue analysis based on strain-life is used when high loads are expected. A durability fatigue analysis based on a stress-life approach is performed when cyclic lives are longer. Hill Engineering is intimately familiar with both fatigue analysis approaches and knows how to tailor them for the specifics of your design.

Fatigue analysis of crack growth (i.e., damage tolerance analysis) is performed when cracks are permissible in the structure. Fatigue analysis based on crack growth is often coupled with a periodic inspection program to ensure that cracks are detected before reaching a critical size and failure occurs. This type of fatigue analysis and management plan typically results in a more efficient and lighter structure; however it is often more expensive to maintain.

Hill Engineering has experience in all aspects of fatigue analysis and other related topics. Please look through our website for more specific information and examples including: additional information on fatigue analysis, the use of compressive residual stress to enhance performance, and details about fatigue testing. Please contact us for additional information. We’re here to help.