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Acoustics and Diagnostic of Materials and Structures
(Ref. TEP-232)
marzo 2019
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Motivation and proposal

The acoustic emission method is a technology used for the diagnosis and evaluation of the integrity of structures in real time, under non-destructive conditions. Acoustic emission consists in the analysis and recording of the elastic waves released by a material or structure by the sudden redistribution of the internal stress-strain field when external load is applied. This occurs in the initiation and growth of cracks, opening and closing of cracks, material deformation, movement of dislocations, formation of voids, interfacial failure, corrosion, fiber-matrix separation in composite materials, delaminations, etc. These waves propagate through the material and if their energy is large enough, they can reach the surface, thus producing small surface displacements which can be picked up by piezoelectric transducers (acoustic emission sensors). The elastic waves are low amplitude and high frequency (usually working between 20 kHz and 1 MHz). The sources of EA are directly related to structural damage, when it progresses. Therefore, its detection and analysis can be used to evaluate the behaviour of the material and structure under load conditions and thus anticipate its failure, in order to carry out possible repairs and/or stop the activity.

Advantages over other NDT methods

  • It allows the early detection and evaluation of active defects in the entire structure.
  • It is sensitive to the growth of defects and changes in the structure of the material.
  • It allows the detection of active defects up to several meters away (depending on the material and number of sensors used).
  • Limited access to the structure is required.
  • Many tests can be performed without stopping the activity.


Limitations of the method

  • Sometimes it is difficult to discriminate between genuine AE signals and spurious signals.
  • Influence of external climatic, mechanical, electromagnetic, etc. factors.
  • It requires a high degree of specialization and skill in data analysis and interpretation.


Services offered

  • Testing of pressure vessels (metallic and FRP), according with the current standards or customer requirements.
  • Tests for assessing the bottom metallic-tanks conditions.
  • Testing of wind turbine blades.
  • Other tests proposed by the client, after prior evaluation.
  • Monitoring of laboratory tests.
  • Technical consulting, testing projects, and ellaboration of reports.
  • Training courses for technicians and professionals.


Previous services performed

  • Test on a large beam made with carbon fibre composite material subjected to bending. Client: ACCIONA Infrastructure and NDT-Ingenieros. R+D+i Centre in Alcobendas, Spain.
  • Test on a wind turbine blade. Consulting and testing. Client: CEDER (CIEMAT) Centro de Desarrollo de Energías Renovables. Altos de Lubia, Soria, España.
  • Tests on GRP vessels (fiberglass). Project Jazan. Client: OLLEARIS. SA. Barcelona, Spain.
  • Test of metal fuel storage tanks. Client: IEC (Israel Electrical Corporation). Eilat, Israel. Work done in cooperation with Integrity Diagnostics Ltd.



  • Testing and characterization of materials.
  • Chemical and oil industry: integrity tests on pressure vessels, storage tank tests, cryogenic tanks, reuse time tests of thermal reactors, towers, columns and piping systems, tank bottom tests, real-time corrosion detection, FRP tank testing, pipeline network inspection, valve and buried pipeline leak detection, offshore pipeline sand detection and offshore platform monitoring.
  • Monitoring and diagnosis of power plants.
  • Partial discharge testing on transformers.
  • Aerospace and aerospace industry: aircraft testing, aircraft aging tests, component fatigue testing, corrosion detection under the wings, in-situ inspection of landing gear parts, helicopter blade and blade testing, crack detection in the fuselage, etc.
  • Metallurgical industry: tool wear and breakage detection, contact detection between parts, quality control of metal working processes, collision detection and prevention in manufacturing processes.
  • Civil engineering: inspection of the structure of concrete buildings, tests on bridges and tunnels, continuous monitoring of damage or propagation of cracks, crane tests, etc.
  • Transport: detection and location of faults in trailers, wagons and tank trucks, crack detection in railway materials and structures, integrity testing of bridges and tunnels, monitoring of the condition of rolling bearings and bearings in trucks and trains, detection of cracks in wheels and axles of trains, etc.
  • Other applications: welding control, crop and forest drought control, geological and seismological applications, engine condition monitoring, on-line process control of rotating machines, medical applications such as osteoporosis detection, etc.

Publications of the group

A. Gallego, E. Martínez. Emisión Acústica. Niveles 1 y 2. AEND y FC Editorial, ISBN: 978-84-15781-43-1, vol (1), 2015.

Ti and Cr nitride coating/steel adherence assessed by acoustic emission wavelet analysis. NDT & E International, vol. 38 (260-267), 2005.

Coating adherence in galvanized steel assessed by acoustic emission wavelet analysis. Scripta Materialia, vol 52 (1069-1074),2005.

Identification of coating damage processes in corroded galvanized steel by acoustic emission wavelet analysis. Surface and Coating Technology, vol. 201 (4743-4756), 2007.

Wavelet power, entropy, bispectrum applied to AE signals for damage identification, evaluation of corroded galvanized steel. Mechanical Systems and Signal Processing, vol 23 (432-445), 2009.

AE monitoring for damage assessment of RC exterior beam-column sub assemblages subjected to cycled loading. Structural Health Monitoring-An International Journal, vol. 8 (175-189), 2009.

Evaluation of low-cycle fatigue damage in RC exterior beam-column subassemblages by acoustic emission. Construction and Building Materials, vol. 24 (1830-1842), 2010

Health monitoring of reinforced concrete slabs subjected to earthquake-type dynamic loading via measurement and analysis of acoustic emission signals. Smart Structures and Systems, vol. 8 (385-398), 2011.

An acoustic emission energy index for damage evaluation of reinforced concrete slabs under seismic loads. Structural Health Monitoring-An International Journal, vol. 11 (69-81), 2012.

Discrimination of acoustic emission signals for damage assessment in a reinforced concrete slab subjected to seismic simulations. Archives of Acoustics, 38 (303-310), 2013.

Simulation and Experimental Investigation on the AE Tomography to Improve AE Source Location in the Concrete Structure. Mathematical Problems in Engineering, 2014.

Modified Gutenberg–Richter Coefficient for Damage Evaluation in Reinforced Concrete Structures Subjected to Seismic Simulations on a Shaking Table. Journal of Nondestructive Evaluation, vol. 33 (616-631), 2014.

Real-time damage mechanisms assessment in CFRP samples via Acoustic Emission Lamb wave modal analysis. Composites Part B: Engineering, vol. 68 (317-326), 2015.

Damage assessed by Wavelet scale bands and b-value in dynamical tests of a reinforced concrete slab monitored with acoustic emission. Mechanical Systems and Signal Processing, vol. 60-61 (75-89), 2015.

Concrete-Galvanized Steel Pull-Out Bond Assessed by Acoustic Emission, Journal of Materials in Civil Engineering, vol. 28, 2016.

Correlation of Plastic Strain Energy and Acoustic Emission Energy in Reinforced Concrete Structures. Applied Sciences, vol. 6-84, 2016.

Acoustic emission energy b-value for local damage evaluation in reinforced concrete structures subjected to seismic loadings. Mechanical Systems and Signal Processing, vol. 102 (262-277), 2017.

Monitoring of Carbon-fiber Reinforced Old Timber-beams Via Strain and Multiresonant Acoustic Emission Sensors. Sensors, vol., 2018.

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