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Imaging material texture of as-deposited selective laser melted parts using spatially resolved acoustic spectroscopy

Patel, Rikesh; Hirsch, Matthias; Dryburgh, Paul; Pieris, Don; Achamfuo-Yeboah, Samuel; Smith, Richard; Light, Roger; Sharples, Steve; Clare, Adam; Clark, Matt


Matthias Hirsch

Paul Dryburgh

Don Pieris

Samuel Achamfuo-Yeboah

Roger Light

Steve Sharples

Professor of Manufacturing Engineering

Professor of Applied Optics


Additive manufacturing (AM) is a production technology where material is accumulated to create a structure, often through added shaped layers. The major advantage of additive manufacturing is in creating unique and complex parts for use in areas where conventional manufacturing reaches its limitations. However, the current class of AM systems produce parts that contain structural defects (e.g., cracks and pores) which is not compatible with certification in high value industries. The probable complexity of an AM design increases the difficulty of using many non-destructive evaluation (NDE) techniques to inspect AM parts—however, a unique opportunity exists to interrogate a part during production using a rapid surface based technique. Spatially resolved acoustic spectroscopy (SRAS) is a laser ultrasound inspection technique used to image material microstructure of metals and alloys. SRAS generates and detects `controlled’ surface acoustic waves (SAWs) using lasers, which makes it a non-contact and non-destructive technique. The technique is also sensitive to surface and subsurface voids. Work until now has been on imaging the texture information of selective laser melted (SLM) parts once prepared (i.e., polished with R a [less than] 0.1 Ra [less than] 0.1 μ μ m)—the challenge for performing laser ultrasonics in-process is measuring waves on the rough surfaces present on as-deposited parts. This paper presents the results of a prototype SRAS system, developed using the rough surface ultrasound detector known as speckle knife edge detector (SKED)—texture images using this setup of an as-deposited Ti64 SLM sample, with a surface roughness of S a ≈6 Sa≈6 μ μ m, were obtained.


Patel, R., Hirsch, M., Dryburgh, P., Pieris, D., Achamfuo-Yeboah, S., Smith, R., …Clark, M. (2018). Imaging material texture of as-deposited selective laser melted parts using spatially resolved acoustic spectroscopy. Applied Sciences, 8(10), Article 1991.

Journal Article Type Article
Acceptance Date Oct 18, 2018
Online Publication Date Oct 19, 2018
Publication Date Oct 19, 2018
Deposit Date Oct 23, 2018
Publicly Available Date Oct 23, 2018
Journal Applied Sciences
Publisher MDPI
Peer Reviewed Peer Reviewed
Volume 8
Issue 10
Article Number 1991
Keywords Laser ultrasonics; Microstructure imaging; Additive manufacturing; Selective laser melting; Rough surface imaging; Surface integrity
Public URL
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