14. starptautiskā konference 2012 - Latvijas Jūras akadēmija

Proceedings of 14th International conference „Maritime Transport and Infrastructure - 2012”Measurements can be taken also with a portable AE based CM instrument. Today thisinstrument has its own standard - ISO 22096 (Condition monitoring and diagnostics of machines –Acoustic Emission) and is specifically listed in the CM standard ISO 18436 (Condition monitoringand diagnostics of machines – Requirements for qualification and assessment of personnel) as one ofthe four main CM techniques, together with Infra-Red Thermography, Lubrication Management &Analysis and Vibration Analysis.Furthermore, AE based technology can be used to forecast such important metal defects as: Crack propagation Fatigue Corrosion, Stress corrosionTypes of monitoring: Continuous monitoring (preferable) Periodical testingCurrently the following types exist: Traditional acoustic emission Source-function and waveform analysis1. Typical AE system setup. The AE sensors are generally very sensitive piezoelectricdevices. As the traditional AE technique only uses AE features, the actual waveforms arenot critical to this method2. In recent years, due to the improvement of transducer technology, wide-band, highsensitivitysensors have been developed to capture the whole waveform.As already relayed above, one of the biggest advantage of the EA system is the flexibility ofthe sensors allocation on the hull and machinery elements, which can be placed in convenient spots.Fig. 1 shows an example of the allocation of the sensors on a ship’s hull for monitoring the integrity ofsame.SensorsSensorsSensorsabFig. 1. Allocation of AE sensors on ship’s hull:a – side view; b – top viewFig. 2 provides an example of how the readings of AE sensors are received, visualized and caneventually be interpreted. The “spike” draws interpreter`s attention and allows for certain conclusions.114