Abstract

The internal lattice structures common to laser powder bed fusion parts pose significant challenges for x-ray computed tomography scans, which are the current default post-process inspection technique. In this work, we present an alternative in-process inspection technique that acquires a full-field ultrasonic response measurement for each layer of the build via ultrasonic excitation of the build plate and non-contact measurement with a scanning laser Doppler vibrometer. We implement a maximum a posteriori detection technique based on those ultrasonic response measurements that can detect malformed lattice elements by combining the information available from the measurements with the ideal part geometry as encoded in the part STL file. We demonstrate successful detection of extra sintered material in the part as well as lattice strut member breakage. Further development of this inspection method in laser powder bed fusion production environments will aide qualification of latticed parts with increased confidence.

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