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as acoustic emission and acousto- ultrasonics. These both rely on high- frequency, structure-borne surface waves to detect and classify damage in structures, including composite andmetallic engineering components. Dr Phil Anderson of theWolfson Centre

forMagnetics also supported the application and his research interests include the characterisation ofmagnetic materials, the properties, processing and application of softmagneticmaterials, magnetostriction and transformer noise. Dr Pearson comments: “The CUSP

group research includes detection and classification of damage using high frequency structural borne waves. I am currently developing a highly novel and independent area of research within the group aimed at non-contact damage detection techniques using audible acoustics for compositematerials. The acoustic camera will be fundamental to the development of this independent research theme and crucial in realising the greatest impact fromthis work.”

AEROSPACE STRUCTURE TESTING The development of a non-contact AA damage detection systemis aimed at certification testing of large scale composite structures. The AA technique utilises an array ofmicrophones to detect and locate sound waves emitted froma variety of sourcemechanisms. The AA damage detection technique has considerable benefits as it is completely non-contact and can potentiallymonitor large areas with relatively short set-up times, significantly reducing down time and associated costs for testing programmes. This is especially relevant in the aerospace sector. Dr Pearson continues: “The acoustic

camera will allow online guiding of testing programmes to increase confidence of success, avoid any unexpected and potentially costly failures, reduce test downtime andmonitor hard to access locations.” Airbus has expressed a strong desire for

the development of AA for damage detection in structural and in-service testing, and sees definite benefits from using the equipment to facilitate this research. The acoustic camera will enable Cardiff to develop a new collaborative venture between the university and the Materials/Processes & Structures Group at Airbus. The group has a global reputation for

research with direct application in industry. This highly novel research combined with the unique test facility will

36 /// Environmental Engineering /// October 2017

 Cardiff University is applying the acoustic camera technology to the non-contact testing of aerospace composite constructions

enable laboratory results to be translated quickly into applications which will be of significant benefit to Airbus and others.

POTENTIAL STEM CANDIDATES Acoustic detection hasmany clear links into everyday experience,making it an accessible topic for a non-technical audience. It uses a number of basic scientific andmathematical principles which link into the national curriculum and are highly appealing to teachers. Dr Pearson says: “On the basis of

current research into factors affecting attitudes towards STEMcareers we are keen to workmore closely with parents and primary school children. Acoustic detection is a strong candidate for a family activity that can be tailored to different levels of skill and knowledge, providing ample opportunity to discuss current research at Cardiff University with a wider audience. “We are thrilled to have secured the

funding for the acoustic camera, which will deliver a new area of research within the School of Engineering supporting an early career researcher and allow Cardiff University to become internationally recognised for audible acoustic research. It will also enable us to increase industrial partnerships and academic collaborations

within the EU and USA and provide a greater learning experience for undergraduate students and impact the National Student Survey (NSS).”

WIDER CAPABILITIES Cardiff University’s acoustic camera package also comprises acoustic photo capability and soundmapping on 2D photo, data recorder, compactPCI and Windows XP embedded. It also has seven slots for Gfai tech expansion cards and two additional slots including CPU, hard disk and power array. Plus a streaming capable card formicrophone array connection, 24 differentialmicrophone channels, 24-bit resolution and 32-bit recording. Allmicrophones in the arrays are

calibrated for amplitude and phase, traceable to National Standards. The calibration factors for each set of microphones are stored in EPROMwithin the array itself. “The technical help and overall service

provided by Gfai tech and AcSoft has been excellent. Nothing has been toomuch trouble and we look forward to collaborating with both businesses as the acoustic camera becomes operational, and we start to feed back the results of our research.” EE

 To readmore online about acoustics, scan the QR code or visit

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