SimuTech Group Canada provides advanced testing services to complement simulation-based analysis, diagnose machinery faults, and support failure investigations. For over 30 years, the SimuTech Group has combined experimental and simulation techniques to validate finite element models and update modeling parameters such as loads, material properties, damping, and boundary conditions with real data. SimuTech Engineers have used test and analysis results to successfully resolve thousands of machinery problems including high and low cycle fatigue, rotor dynamic faults, floor vibration, and acoustics in a wide variety of industries including power generation, aerospace, manufacturing, electronics, oil & gas, optics, and transportation.
Modal Testing & MAC
Experimental modal analysis is a vibration testing technique for determining the natural frequencies, mode shapes, and damping ratios of a structure. During a modal test a hammer or electromagnetic shaker is used to excite vibration of the test article. The vibration amplitude and phase (response) to the excitation is measured at multiple locations and frequency response functions are calculated. Curve fitting techniques are used to extract the natural frequencies, mode shapes, and damping ratios of a structure.
SimuTech’s test engineers has the knowledge, experience, and equipment to quickly resolve difficult vibration problems in a wide variety of applications. In over 30 years of service, SimuTech’s engineers have fixed a broad range of vibration related problems such as fatigue failures, excessive noise, resonance, manufacturing process quality issues, structural vibration, abnormal wear, foundation and floor vibration for industries including aerospace, automotive, military, electric power generation, research and development, tool and die, nuclear, petrochemical, air conditioning, and refrigeration.
Specific applications include steam turbines, gas turbines, pumps, blowers, compressors (Turbomachinery), bearings, foundations, buildings, optics, piping, and many more types of machinery and structures.
Gas Turbine Blade Engine Parts Manufacturer Approval
In Advisory Circular 33-X the Federal Aviation Administration (FAA) describes comparative test methods to be used in support of Parts Manufacturer Approval (PMA) applications for turbine engine and auxiliary power unit (APU) parts. The tests include experimental modal analysis, natural frequency measurements, and high cycle fatigue testing at operating temperature. These test methods are intended to show engine compliance with §33.83 (Vibration Test) and §33.87 (Endurance Test) of Title 14 of the Code of Federal Regulations (14CFR part 33), and APU compliance with paragraphs 5.10 (Vibration) and 6.3 (Endurance Test) of Appendix 1 of TSO-C77b, Gas Turbine Auxiliary Power Units, is still valid with the PMA part installed.
The vibration tests (modal analysis and natural frequency measurements) are designed to show that the natural frequencies of the PMA blade fall within the range of the original equipment manufacturer (OEM) blade. This is accomplished by performing an experimental modal analysis (Modal Testing) on sets of a few PMA blades and a few OEM blades. Modal Assurance Criterion (MAC) is used to correlate mode shapes and identify corresponding natural frequencies. The natural frequencies of 50 PMA blades and 50 OEM blades are then measured and compared to determine whether the range of PMA blade frequencies falls within the range of the OEM blades.
Strain Gage Measurements
Strain gage measurements provide a means to determine the strain, stress, and load on machinery components. SimuTech’s team of test engineers has extensive experience in strain gage and telemetry measurements on a wide variety of machinery components and structures. Strain gage measurements provide information for validation of finite element models (FEM), establishing safe operating loads, and failure investigations. Strain gages are suitable for high temperature and harsh environments.
Rotating Telemetry Measurements
Radio telemetry is a technique for collecting data from sensors on rotating machinery components. Signals from sensors such as accelerometers, strain gages, resistance temperature detectors (RTDs), and pressure sensors may be transmitted by radio telemetry from a rotating shaft to a stationary data acquisition system. Telemetry is often used to measure shaft torque, shaft bending strain, torsional vibration, and turbine blade vibration. SimuTech has experience using telemetry in hostile environments including the flow path of a steam turbine, submersed in sea water, and under centripetal acceleration up to 8000 g’s.
SimuTech provides a frequency testing service for new, refurbished, or reverse engineered turbine blades (buckets) to ensure that their natural frequencies are within specifications. This is especially critical for longer tuned steam turbine blades that are susceptible to high-cycle fatigue failure due to resonance during operation. Frequency testing also proves valuable for quality assurance of industrial gas turbine (combustion turbine) blades. SimuTech has extensive experience with vibration test fixture design and quality assurance frequency testing.
SimuTech provides a moment weighing service for finite element model validation and for quality assurance. Moment weighing is a technique for locating an object's center of gravity. A common application for moment weighing is optimization of turbine blade loading sequence (stacking order). Blade weight and the center of gravity location are measured and analyzed with a proprietary software package to determine the blade stacking position (loading chart) that minimizes unbalance. SimuTech has moment weighed turbine blades ranging in length from 1 to 60 inches.