fe-safe

Durability Analysis Software for Finite Element Models

fe-safe/TURBOlife

How does elevated temperature service reduce durability? What is the cause of failure - creep, fatigue, or creep-fatigue interaction? fe-safe/TURBOlife has the answers.

fe-safe/TURBOlife is a powerful, unique and comprehensive suite of creep-fatigue analysis software. The creep-fatigue algorithms in fe-safe/TURBOlife have been successfully applied to nuclear power plant components, power station boilers, gas turbine blades and steam turbine components. fe-safe/TURBOlife is used increasingly in the powertrain industry where creep and creep fatigue interaction is prevalent in automotive exhaust components and turbocharger impellers.

fe-safe/TURBOlife:

  • Considers complex and interacting damage mechanisms induced by creep and fatigue conditions
  • Identifies whether the damage is caused predominantly by fatigue, creep or creep-fatigue interaction
  • Allows for damage computations using ductility exhaustion with creep fatigue interaction or strain range partitioning
At a Glance

fe-safe/TURBOlife identifies whether fatigue and/or creep are the dominant damaging mechanisms, thus allowing re-design to focus on the relevant damage mechanisms and significantly reduce pre-service component testing.

fe-safe/TURBOlife works from elastic finite element analysis and widely available materials data to construct complex, stress-strain hysteresis loops including stress relaxation due to creep. In this way, component-specific operating histories and the order of cycling are comprehensively accounted for.

fe-safe/TURBOlife creep-fatigue methodologies are based on the Ductility Exhaustion concepts and Strain Range Partitioning which have been developed over the past 25 years in the United Kingdom and the United States. These methods are used extensively throughout the nuclear and fossil fuel power generation industries for new designs and for continuous monitoring of applications on power station boilers and gas turbines.

fe-safe/TURBOlife calculates:

  • Where fatigue cracks will occur
  • When fatigue cracks will occur
  • How creep mechanisms will influence fatigue life
  • Factors of safety on working stresses - for rapid optimization
  • The endurance of components in high temperature environments where fatigue damage mechanisms and creep damage mechanisms interact to significantly reduce component life
  • Whether fatigue damage is caused predominantly by fatigue, creep or creep-fatigue interactions

fe-safe/TURBOlife is an add-on module to fe-safe, enabling users to include the effects of complex loading histories, multiaxial fatigue, and other advanced capabilities in fe-safe.

Capabilities
  • Calculates the endurance of components in high temperature environments where fatigue damage mechanisms and creep damage mechanisms interact to significantly reduce component life
  • Considers the necessary temperature effects, identification of the levels of creep and fatigue damage, and the probability of cracking
  • Works from elastic finite element analysis and widely available materials data to construct complex, stress-strain hysteresis loops including stress relaxation due to creep. In this way, component specific operating histories and the order of cycling are comprehensively accounted for
  • Identifies whether fatigue and/or creep are the dominant damaging mechanisms, thus allowing re-design to focus on the relevant damage mechanisms and significantly reduce pre-service component testing
  • Provides comprehensive graphical output in terms of life contours and stress safety factors, enabling critical areas to be easily identified
  • Includes comprehensive on-line help and information on materials data preparation
  • Includes direct import and easy data manipulation with FEA software
Benefits
  • Enables accurate fatigue life predictions of complex analyses based on creep strain, creep fatigue damage and material property changes at high temperatures
  • Allows for damage computations using ductility exhaustion with creep fatigue interaction or strain range partitioning
  • Enables the user to easily identify whether the main cause of fatigue failure is fatigue, creep or creep-fatigue related
  • Easy to learn and easy to use
  • Uses widely available materials data
  • Enables designs to be optimized rapidly, development times to be shortened, material costs to be reduced and the final design verified on the computer, giving confidence that it will pass test schedules as right-first-time
  • Supported by highly experienced fatigue and assessment engineers and the extensive materials testing laboratories at AMEC Foster Wheeler
Applications
  • Gas Turbine Blade
    • Complex design including internal cooling channels to limit the maximum operating temperatures
    • Very conservative design rules are typically used to assess gas turbines blades leading to overdesign and excessive use of materials
    • Use of actual operating cycles and fe-safe/TURBOlife enabled the user to predict very realistic life, thereby allowing considerable design optimization and life extension
  • Compressor Wheel
    • Aluminium alloy compressor wheels often fail by casing rubbing due to creep dilation at elevated temperatures, or by cracking due to the accumulation of cyclic creep-fatigue damage
    • The ultimate failure mechanism was determined by destructive testing under variable load creep conditions
    • Analysis of the test condition using fe-safe/TURBOlife established that the probability of creep–fatigue failure was very low, and that the calculated creep dilation correlated well with measurements
    • Creep dilation rather than creep-fatigue cycling was confirmed as the cause of failure by fe-safe/TURBOlife, allowing the designers to focus on the most effective method of extending the life of the compressor wheel