14. starptautiskā konference 2012 - Latvijas Jūras akadēmija

Proceedings of 14th International conference „Maritime Transport and Infrastructure - 2012”UTILIZATION OF ACCOUSTIC EMISSION AS A SHIP`S DAMAGEPREVENTION METHODAndris Unbedahts*, Leonid Vindergauz***Transport Claims Consultants Network cvba, Keizerstraat 66, B-2000, Antwerpen,E-mail: andris.unbedahts@tccn.be**Transport Claims Consultants Network cvba, Keizerstraat 66, B-2000, Antwerpen,E-mail: leonid.vindergauz@tccn.beAbstractWorldwide Maritime Statistics show that about 80% of marine incidents are caused by ¨the humanfactor¨. However, the remaining 20% still severely impact the economic performance of shippingcompanies. Ships` hull and engine defects caused by metal fatigue or poor construction quality areusually very expensive to repair. Additionally to the direct costs there are also indirect ones, such asforced lay-up, environmental impact etc. In certain cases, these costs can lead a shipping company tobankruptcy. Therefore hidden defect detection in at its starting point is very important. One of themost perspective methods to do so is the Acoustic Emission method.KEY WORDS: Acoustic Emission, damage, vesselIntroductionThe Acoustic Emission (AE) technique (with sensitivity ranging from 20 kHz to 1 MHz) has a40 year history of use for machinery condition monitoring. It has gained an even further widespreadthroughout the industry in the last decade. The particular strength of AE is its ability to directly detectthe processes associated with wear and degradation of the materials at their early stage (includingfriction, impacts, crushing, cracking etc.). This is achieved by detecting and reading the surfacecomponent of stress waves that these processes invariably generate. These stress waves spread all overthe hull`s and machines` surfaces, which means that sensor positioning is not critical and allowscertain freedom in placing same in more convenient spots. Obviously, this is very important forapplication on board of a ship.Main advantages of the AE technology are as follows: High sensitivity; Early and rapid detection of defects, flaws, cracks etc.; Real time monitoring; Relatively low cost; Reduces the ship`s downtime needed for inspection, since there is no need forscanning the entire structural surface.1. AE technologyWhen we talk about a vessel’s hull & machinery (H&M) condition monitoring, we meanmonitoring the vessel’s hull`s and machineries` ability to continue performing their intended functionsin an efficient manner. Sometimes it is hard to use direct measuring methods, therefore indirectmeasurement techniques have to be applied. Currently there are a range of technologies allowingindirect Condition Monitoring (CM), but we believe AE can become one of the best, due to thefollowing: time saving and efficient; instantly alerting of a presence of a fault in H&M; analysis of the trend of the damage can be used to forecast the critical time.113