NSMS Fundamentals

• Overview
• Externally Mounted Senors
• Various Measurement Capabilities
• Event Time Determination
• Arrival Times to Deflection Conversion
• Deflection to Stress Conversion
• Complete System Characterization
• Flexible Test Scheduling
• Synchronous Realtime Analysis
• Non-Synchronous Realtime Analysis
• High Cycle Fatigue

High Cycle Fatigue

High-Cycle Fatigue has been identified as a leading cause of turbine engine failures, excessive maintenance costs, and source of responsibility for numerous standdowns affecting operational readiness over the past decade. High-Cycle Fatigue (HCF) is fatigue that occurs at relatively large numbers of cycles and is caused by high frequency vibrations in both static and rotating hardware. The distinction between high-cycle fatigue and low-cycle fatigue is made by determining whether the dominant component of the strain imposed during cyclic loading is elastic (high cycle) or plastic (low cycle), which in turn depends on the properties of the material and on the magnitude of the stress. View Source

High-cycle fatigue (HCF), proved as the severest cause of turbine engine failures in aircraft, has resulted in the loss of aircraft and human life. Due to the high vibration frequencies, microcracks can initiate from defects, which are often associated with microstructural damage caused by fretting or foreign object impact, subsequently propagate to failure in short time periods, possibly within a single flight segment. Therefore, HCF-critical materials in engine components must be used below the fatigue-crack initiation or growth threshold such that crack propagation rate is lower than 109 m/cycle. There is an extensive database on the high-cycle fatigue threshold behavior of the materials used in turbine engines, however, the question as to whether microstructures of these materials can be optimized to promote HCF resistance has not been addressed. View Source

High Cycle Fatigue and Agilis

In the pursuit of reducing/eliminating high-cycle fatigue failures in turbine engines, many design and manufacturing paths have been explored. From Studying and understanding crack propagation and materials properties to designing blade aerodynamics uniquely suited to an application, a huge amount of time and effort has been spent to eliminate HCF-related failures from the Turbine industry. Vital to understanding and reducing cyclic stresses in a product is an accurate and complete analysis of the vibratory characteristics of the system.  Agilis Measurement Systems specializes in monitoring blade vibrations to the extremes of accuracy. Using NSMS hardware of the highest quality and software unparalleled in the industry, AMS is committed to helping our customers reduce, monitor, and ultimately eliminate High cycle fatigue stresses induced by synchronous and non-synchronous excitations in all turbine applications.