SimuTech Testing Services

Testing Services Overview

SimuTech Group 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.

Torsional Vibration Measurements

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Torsional vibration measurements are used to determine the natural frequencies and mode shapes of a rotor train as is twists about the axis of rotation. The shaft is instrumented with either strain gages or accelerometers at one or more locations. Signals from the rotating sensors are transmitted to a stationary data acquisition system by radio telemetry. This measurement technique may also be used to determine shaft torque, shaft bending strain and turbine blade vibration.

Modal Testing

Modal Testing 2Experimental 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. These modal parameters may be used for finite element model validation (correlation) and refinement, failure investigation, vibration troubleshooting and diagnostics, and quality assurance. Some applications for modal testing include aircraft components, turbine blades, impellers, automotive structures, buildings, optics, and piping. SimuTech performs modal tests both in its laboratory and on-site at customer facilities.

 

Vibration Diagnostics

Vibration DiagnosticsVibration diagnostics are used to identify the root cause of noise and vibration problems in machinery. Techniques such as operating deflection shape (ODS) analysis, spectral analysis, order tracking, and joint time frequency (waterfall) analysis are used to detect abnormal vibration characteristics. These techniques are applicable to a broad range of vibration related problems such as fatigue failures, excessive noise, resonance, manufacturing process quality issues, structural vibration, abnormal wear, and floor vibration.  Knowledge gained from these vibration diagnostic techniques leads to practical solutions such as specification of isolation systems, tuned mass dampers, surface damping treatments, shaft balance and alignment procedures, excitation source control, repair procedures, natural frequency detuning, and active vibration control. SimuTech performs machinery vibration diagnostics both in its laboratory and on-site at customer facilities.

Campbell Testing

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Campbell testing is a technique for measuring the natural frequencies and mode shapes of rotating turbine blade (bucket) rows. Strain gages and thermocouples are attached to the blades to measure dynamic strain and temperature as the blades rotate and vibrate. The gages are connected to a radio telemetry system that transmits signals from the rotating shaft to a stationary data acquisition system. A variety of excitation systems including air and steam jets, and electric magnets are used to stimulate vibration of the rotating blades. SimuTech performs Campbell tests both in high speed balance facilities and in operating power plants.

Strain Gage Measurements

Rotating TelemetryStrain measurements provide a means to determine the strain, stress, and load on machinery components. Strain gages may be used to measure static strain due to relatively constant loads such as pressure or thermal expansion. Strain gages may also be used to measure dynamic strain due to impact events or vibration. With adequate protection, strain gages may be used in harsh environments including elevated temperatures, high EMI, and immersion in sea water. Strain measurements are applicable to a wide variety of structures including electronics, aircraft, turbomachinery, piping, automotive components, and industrial equipment. Information from strain gage measurements is useful for validation of finite element models (FEM), establishing more accurate operating loads, and failure investigations. SimuTech performs strain measurements both in its laboratory and on-site at customer facilities.

 

Blade Frequency

Blade Frequency Testing

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.

 

 

 

Moment Weighing

Moment Weighing

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.

Failure Investigation

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Failure Investigation requires a comprehensive understanding of the nature of materials, environment and operating loads to aid in identifying the root cause of a failure.  Frequently there are several contributing factors that combine to produce such a failure. In some cases two structural components that are perfectly acceptable separately can fail when placed in close proximity to one another. For example an interaction between the operating equipment and the supporting structure might create a destructive resonant operating condition resulting in equipment failure. Frequently the steady and cyclic load components are not known, for these cases testing offers an excellent opportunity to define the actual magnitude and frequency of the operating loads. SimuTech Group has extensive experience integrating testing, analysis techniques (CFD and FEA), metallurgical results, potential failure modes, fracture mechanics and operating data to facilitate solving industrial failures of stationary and rotating equipment.