Remaining Life Assessment

STI Technologies has 23 years of experience in investigation, analysis and software development of remaining life. This assessment covers a broad range of applications including machine tool, office equipment, automotive, transportation, industrial equipment, aerospace and the power/utility industries. We determine the remaining life of critical components through rigorous analysis of thermal/ mechanical stresses, natural frequencies and mode shapes, crack initiation, crack propagation and creep. In addition, we supplement this with a full line of stress and vibration testing. STI provides a range of life assessment services with expertise in:

Stress Corrosion Cracking (SCC)

Using advanced fracture mechanics techniques and SCC crack propagation data, STI has worked successfully with utilities in assessing the remaining life of low pressure disks and axial and radial entry blade attachments subjected to stress corrosion cracking.

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Solid Particle Erosion (SPE)

SPE is often seen in the control stage blade rows for high pressure rotors. STI provides analysis of the dynamic stresses, crack propogation and 2D and 3D fracture mechanics evaluations to obtain remaining life estimates.

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Crack Propagation

The science of fracture mechanics, crack infiltration and growth are well understood at STI Technologies. Extensive experience and a broad range of data has gone into the development of comprehensive STI software codes for 2D and 3D crack propagation applications

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Low and High Cycle Fatigue (LCF and HCF)

In fatigue life design, useful life is defined by the cumulative damage resulting from a combination of infrequent large amplitude cycles and frequent small amplitude cycles. STI has extensive experience in measuring and calculating the values for the unsteady load component and applying these loads to a specific application list specific applications.

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Lifecycle Fatigue Crack Analysis Services

Spinning Blade Hazard, or the chance of throwing a blade, is a major concern for both plant operators and plant insurers. To better address this problem STI has recently developed an advanced state-of-art fatigue life prediction computer code called LifeCycle. This software can be applied to accurately predict the remaining life of turbine blades under known operating conditions. STI has developed this proprietary code to solve fatigue problems involving components subject to complex load sequencing. For additional information on LifeCycle refer to STI's Your Chance of "Throwing a Blade"

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What happens over the life of a product that would increase the probability of failure over time? Life assessment requires an understanding of the probability of failure at design, and the ability to track those changes over time that effect the probability of failure. STI-Technologies has extensive experience in determining the remaining life of critical turbine components - rotors, through rigorous analysis (and testing) of thermal/mechanical stresses, blade natural frequencies and mode shapes, crack initiation, crack propagation and creep for elevated temperature applications. This expertise is emphasized by a 20 year, successful working relationship with the U.S. Air Force. For additional information on probabilistic applications refer to STI's Published Papers on this Website. For additional probabilistic services provided by STI refer to " Design Optimization and Analysis- Probabilistics" on this Website.

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Nuclear Steam Generator Tube Wear and Life Assessment Services

In nuclear Pressurized Water Reactor (PWR) industry, assessment of the steam generator tube degradation is an important part of the maintenance decision-making process. Utility engineers must conduct a periodic assessment of these tubes based on current inspection data and projected estimates of wear depth at the end of the next operating cycle. This assessment allows the utility engineer to decide a course of action (repair, reinforce, plug or leave alone) and to determine an efficient schedule of future preventive maintenance events. STI Technologies Inc. is able to assist the utility engineer in making informed maintenance decisions based on analytical predictions of wear progression and fatigue damamge accummulation using a new software program developed by the Electric Power Research Institute (EPRI). For additional information on STI's nuclear steam genertor tube wear and life assessment services refer to the STI publication "Nuclear Steam Generator Services"

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Customized System Health Management

STI develops and supports customized system health management (health monitoring, diagnostics and prognostics, quality control) to meet the needs of your critical machines, where off the shelf CBM systems often prove inadequate. STI employs a multiple levels of diagnostic/prognostic information including standard tools (performance models, trends, alarms, rule bases, etc.), advanced technologies (fuzzy logic, neural networks, hybrid AI techniques, probabilistic analysis), and decision-level data fusion methodologies (heuristic and probabilistic). We will work with your in-house experts to develop and support customized CBM systems that apply the best techniques for information extraction from sensor signals worldwide. An example of a customized gas turbine monitoring and diagnostic system is shown.

STI provides initial systems installation consulting and application specific custom development for the ICHM®20/20, a wireless data acquisition and processing module produced by Oceana Sensor. The ICHM® 20/20 is a revolutionary data acquisition and processing module built on Bluetooth™ wireless technology and is designed to serve any type of monitoring and diagnostic application.

The ICHM® 20/20 provides:

  • A compact, reliable wireless data acquisition and processing node suitable for high and low bandwidth input signals.
  • Industry leading 24 bit ADC at up to 48 kHz sampling frequency for dynamic measurements (including 12 bit ADC for static measurements).
  • The ideal platform for remote monitoring and processing of a variety of sensor measurements.
For more information on the ICHM® 20/20 visit the Oceana Sensor home page at

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