Acoustic emission monitoring

A study is at present being carried out to check and validate the feasability of acoustic emission monitoring of the pneumatic testing of tanks. This study is being carried out in the context of the CIAPES program. This article gives only a brief summary of the results obtained on various materials, and different types of vessels, under different operating conditions. 

The AEBIL acoustic emission monitoring system installed on site has shown a good level of functional reliability no instrumentation failure is to be recorded in over 1 year of continuous in-plant operation. 

Daugela A, Kutomi H, Wyrobek T. Nanoindentation induced acoustic emission monitoring. Ziff Fur Metallkunde 2001 92 1052-1056. 

Mono vs. polycrystalline diamond lapping of ceramics ID PMMC 1703. Acoustic emission monitoring of lapping process ID PMMC 1704. 

A system for evaluating the physical state of machinery and equipment over time, to prevent a failure that could lead to an incident Readings and parameters are plotted to give a characteristic trend. The objective is to identify evidence of deterioration at an early stage so that corrective maintenance can be undertaken before failure. There are a range of techniques that may be employed that include strain measurement, corrosion monitoring, vibration measurement, and acoustic emission monitoring. It is considered a type of preventive maintenance or predictive maintenance. 

Serious work on acoustic emission monitoring started in the 1950s. This mainly featured NDT of composite materials, storage vessels, and aircraft structures. 

Acoustic impedance is an important parameter. When an acoustic wave passes from one medium to another, some of the energy is transmitted and some is reflected. The acoustic impedance controls the ratio of transmitted to reflected energy. In acoustic emission, monitoring the acoustic impedance explains the need for an acoustic coupling agent between the sensor and the surface on which it is mounted. Without this the detected signal will be very low, as most of the energy will be internally reflected at the wall. 

Some chemical reactions produce acoustic emission directly. These require a phase change, i.e., liquid to gas, liquid to solid. Crystallization is a likely target for acoustic emission monitoring. There is some evidence that certain crystallization processes intrinsically produce acoustic emission. However, crystallization may be detected by the impact of the crystals on the walls of the reactor. As long as the fluid is well agitated acoustic emission gives a good estimate of the solid yield. 

Fowler TJ (1986) Ejq)erience with acoustic emission monitoring of chemical Process industry vessels. Progress in AE III, pp 150-162 Kaiser VJ (1953) Knowledge and research on noise measurements during the tensile stressing of metals. Archiv fur das Eisenhiittenwesen, 24 43-44 ISO 12716 (2001) Nondestmctive testing-acoustic emission inspection Vocabulary. ISO... 

Balazs GL, Grosse CU, Koch R, Reinhardt HW (1993) Acoustic emission monitoring on steel-concrete interaction. Otto Graf Journal 4 56-90... 

J Stractmal Division, ASCE 102(ST2) 387-400 Hearn SW, Shield CK (1997) Acoustic emission monitoring as a nondestractive testing technique in reinforced concrete. ACI Materials Journal 94(6) 510-519... 

Applying a combination of NDT methods is advisable in many cases. A useful guiding principle is to choose NDT methods that yield complementary information, eg, based on different probe types (Table 2). One example is acoustic emission monitoring with high sensitivity for potentially critical areas, followed by high spatial resolution inspection of such areas by, eg, ultrasonic or X-ray methods to quantitatively locate and size the indication. 

E. Verstrynge, M. Weavers, A novel technique for acoustic emission monitoring in civil structures with global fiber optic sensors. Smart Mater. Str. 23 Article Number 065022 (2014)... 

Robert, J.L. and Brachel-Rolland, M. (1992). Survey of structures by using acoustic emission monitoring, lABSZ Symposium, Washington, 39,33-38. 

S.A.S. Akers and G.G. Garrett, Acoustic emission monitoring of flexural failure of asbestos , int J. Cem. Comp. Ltwt. Concr. 5,1983,97-104. 

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