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Search Publications by: Ward L. Johnson (Fed)

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Displaying 1 - 25 of 105

Evidence for contributions of lack-of-fusion defects and dislocations to acoustic nonlinearity and loss in additively manufactured aluminum

February 2, 2024
Author(s)
Ward L. Johnson, Paul R. Heyliger, Jake Benzing, Orion Kafka, Newell Moser, Derek Harris, Jeremy Iten, Nik Hrabe
Resonant acoustic nonlinearity and loss have previously been found to be correlated with porosity in additively manufactured (AM) commercially pure aluminum and stainless steel, and this effect offers a potential basis for rapid nondestructive

Novel or Improved NDE Inspection Capabilities for Additively Manufactured Parts

February 26, 2022
Author(s)
Ward L. Johnson, Anne-Francoise Obaton, Alex Van den Bossch, Bryan Butsch, Imane Zouggarh, Olivier Burnet, Florent Soulard
Additive manufacturing (AM) enables the production of parts with extremely complex shapes, such as lattice structures and internal structures (cavities, channels). As a result of this geometric complexity, the applicability of most conventional

Mechanisms of Anelastic Loss in Langasite at Temperatures from 113 K to 1324 K

May 4, 2021
Author(s)
Ward L. Johnson, Yuriy Suhak, Holger Fritze
Synthetic piezoelectric crystals with the structure of langasite (LGS) are being pursued for resonant acoustic sensors that can operate at temperatures exceeding the range of conventional piezoelectric materials. The optimization of these crystals is

Resonant acoustic nonlinearity and loss in additively manufactured stainless steel

May 8, 2019
Author(s)
Ward L. Johnson, Justin G. Whiting, Felix H. Kim, Paul R. Heyliger, Nikolas W. Hrabe
Resonant acoustic nonlinearity and loss in additively manufactured stainless steel were measured with the aim of assessing the potential of such measurements for nondestructively sensing defects that degrade mechanical performance. The material was

Phase noise generated by vibration of bacteria adhered to a quartz resonator

September 22, 2017
Author(s)
Ward L. Johnson, Danielle C. France, F L. Walls, William T. Cordell, Nikki S. Rentz
An approach is presented for sensing mechanical fluctuations of bacteria, with potential application in monitoring microbial responses to changes in chemical environment, such as antimicrobial intervention. Bacteria are tethered to a quartz crystal