Machine analysis and diagnostics
Noise and vibration aren’t just annoying; they represent energy emissions that indicate inefficiency in machinery
Noise and vibration indicate issues that can affect a machine’s reliability, such as imbalanced parts, and can even cause machines to fail through their own damaging effects.
Machine vibration analysis
Rotating or reciprocating equipment such as compressors, power trains, engines, pumps and turbines, are constructed of many parts that each contributes to the sound and vibration pattern of the whole assembly. In these types of machinery, varying load conditions and imbalances caused by imperfections or uneven mass can result in vibration and associated noise. Achieving efficiency and minimizing vibration requires the detection of these faults and imbalances; however, they can never be entirely eliminated. Thus, when incorporating a machine into another structure – like an aircraft engine – it’s important to understand the machine’s vibration output to avoid consequences such as exciting structural resonances.
Understanding the vibration output of a machine requires analyses that can correlate vibration measurements with the machine’s processes. Order analysis relates vibration measurements to the revolutions of a rotating part, improving knowledge about machinery such as powertrains, pumps, compressors and electric motors. It’s important to be able to incorporate the machine’s own parameters, such as oil pressure and RPM, into the analysis via CAN Bus or auxiliary inputs.
Condition-based maintenance and condition monitoring
Changes in a machine’s vibration patterns can be indicative of machinery health. By diagnosing and addressing vibration problems in rotating and reciprocating machinery, performance can be optimized. Monitoring machine health ensures deterioration and fatigue failures can be prevented, maximizing productive uptime and allowing better scheduling of maintenance, repair, and overhaul (MRO) procedures, with more confidence between scheduled stops.
Imbalance results from an uneven distribution of mass in a rotor, causing vibrations that are transmitted to the bearings and other parts of the machine. Imperfect mass distribution can be due to material faults, design errors, manufacturing and assembly errors, and, especially, to faults occurring during operation.
Reducing these vibrations achieves better performance and more cost-effective operation and avoids deterioration and fatigue failure. This requires the rotor to be balanced by adding or removing mass at certain positions.
Important factors in modern machine design are dictated by increasing service speeds, higher performance-to-weight ratios and improved reliability. Balancing leads to better performance, cost-effective operation, longer service life and increased safety. Although errors and faults can be reduced, they can never be eliminated to the extent where balancing becomes unnecessary.
Our PULSE-based system determines balance quality for single- and two-plane balancing according to ISO 1940-1. Multi-plane Balancing Consultant Type 7790-B adds three- and four-plane balancing. An intuitive, task-oriented user interface leads you quickly through the tasks for set-up, measurement and reporting. The balancing process can be performed in situ, where the rotor is balanced on its own bearings and supporting structure, or by balancing the rotors in separate balancing machines. Trim balancing is also supported using rotor data stored from previous balancing sessions. The balancing procedure can be based on fast Fourier transform (FFT) or on order tracking, for the most accurate results.
> Two-plane and Multi-plane Balancing Consultant (Product Data)
In rotating and reciprocating machines, varying load conditions and imperfections in the moving parts cause vibrations and associated sounds. The vibrations are shaped by the structural properties of the moving and stationary parts of the machine. Order analysis relates measurements to revolutions of a rotating part, improving knowledge about machinery such as aircraft and automotive engines, powertrains, pumps, compressors and electric motors.
Typical applications include rotating machinery analysis and processing vehicle or engine speed sweeps (run‐up/down) with respect to RPM or other time‐varying quantities. Fixed-bandwidth FFT order analysis is best suited for situations where sweep rates are relatively small or, for faster speed sweeps where the lower order numbers are of interest. Tracked order analysis is recommended for high-accuracy analyses of higher orders and fast-speed sweeps.
Our Order Analysis and PULSE Reflex Order Analysis software provide PULSE with tachometers, autotrackers, order analyzers and related post-processing functions, as well as a wide range of display facilities and three additional trigger types – tacho, speed and speed interval – providing a complete diagnostic toolbox for everything from basic real-time order analysis (with and without tracking) to advanced order analysis with PULSE Reflex.
Moving parts in any rotating machine will eventually cause annoying vibrations that ultimately lead to breakdowns due to production and assembly tolerances, wear, and load variation.
By using various diagnostic techniques that use vibration measurement as an indicator, the root cause of the deteriorating machine condition can be established and corrective measures planned. Diagnostic techniques are extremely effective because they directly use the information contained in the machine vibration signature. The signature is obtained by frequency and time analysis of the machine vibration signal from a sensor fixed on the surface of or inside the machine. It enables troubleshooting of rotor dynamic problems, rotating component deterioration and structural problems.
PULSE machine diagnostics used in run-up/down sessions can diagnose multiple faults. All analyses can be performed simultaneously and the raw signals recorded for subsequent analysis using PULSE Time Data Recorder. Diagnostics on transients is then performed with PULSE Time Capture. Results are shown in relation to data tagged with auxiliary parameters like temperature, oil pressure, position and wind speed. The system comprises Order Analysis Type 7702-N with multi-tachometer, FFT order analysis, order tracking, signal enhancement, envelope analysis on bearings, cepstrum analysis on gearboxes and process data/auxiliary parameter logging. Any LAN-XI data acquisition module is suitable, giving up to 12 input channels. Auxiliary parameter logging requires LAN-XI module Type 3056.
Health and usage monitoring systems (HUMS) are being used more frequently in monitoring critical helicopter gearboxes and also, increasingly, for gas-turbines – both in helicopters and in certain fixed-wing aircraft.
Vibration monitoring is a well-proven method for preventing catastrophic failures of rotating components, with the piezoelectric accelerometer proving to be the best sensor for these applications
HUMS accelerometers typically have very specialized performance and reliability requirements. Strict development and production standards such as AS/EN 9100 and environmental standards, such as DO-160 ‘Environmental Conditions and Test Procedures for Airborne Equipment’ must be adhered to, together with aircraft specific requirements.
Brüel & Kjær supplies a range of HUMS and engine-monitoring accelerometers, whose design is focused on guaranteeing a highly robust and highly reliable sensor. Sensors must operate continuously in demanding environmental conditions yet be sensitive enough to be able to detect incipient bearing and gear failures. Size and ease of mounting are equally important considerations for these applications.
> AgustaWestland safeguards helicopter reliability with HUMS (Solution summary)
> Airbus Helicopters: Monitoring gearboxes with HUMS accelerometers (Solution summary)
Airframers face stringent requirements to reduce fuel burn, environmental emissions and engine noise, drawing engine performance into central focus. Gas turbines are highly complex machines that need comprehensive testing and analysis during development in order to understand and optimize their dynamic behaviour. Engine testing takes considerable resources. With huge engine test facilities, data acquisition requirements and many involved staff, each test is a large operation with tight schedules and test commitments.
The LAN-XI based data-acquisition system provides data recording of many hundreds of dynamic channels, together with highly detailed real-time monitoring of test data and the capability of sharing data throughout the test facility for post-test analysis. Instant feedback to ensure the validity of the test data is provided to operators in the form of detailed real-time analysis and alarm information at multiple networked monitoring stations.
The system is highly scalable and easily transportable. It can be combined into high-capacity centralized data-acquisition or split into smaller, highly mobile systems for easy transport between sites and test facilities.
PULSE Reflex data processing software provides a toolbox of post-analysis functions supporting a wide range of formats for importing from and exporting to native and third-party systems.
> Leap through jet engine testing (Waves article)
> Software for PULSE LabShop (System Data)