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Research Papers

# Statistical Characterization of Ultrasonic Additive Manufacturing Ti/Al Composites

[+] Author and Article Information
C. D. Hopkins

Department of Mechanical Engineering, Ohio State University, 201 West 19th Avenue, Columbus, OH 43210hopkins.626@osu.edu

M. J. Dapino1

Department of Mechanical Engineering, E307 Scott Laboratory, Ohio State University, 201 West 19th Avenue, Columbus, OH 43210dapino.1@osu.edu

S. A. Fernandez

Center for Biostatistics, Ohio State University, 2012 Kenny Road, Columbus, OH 43221fernandez.71@osu.edu

1

Corresponding author.

J. Eng. Mater. Technol 132(4), 041006 (Sep 29, 2010) (9 pages) doi:10.1115/1.4002073 History: Received January 16, 2010; Revised June 18, 2010; Published September 29, 2010; Online September 29, 2010

## Abstract

Ultrasonic additive manufacturing (UAM) is an emerging solid-state fabrication process that can be used for layered creation of solid metal structures. In UAM, ultrasonic energy is used to induce plastic deformation and nascent surface formation at the interface between layers of metal foil, thus creating bonding between the layers. UAM is an inherently stochastic process with a number of unknown facets that can affect the bond quality. In order to take advantage of the unique benefits of UAM, it is necessary to understand the relationship between manufacturing parameters (machine settings) and bond quality by quantifying the mechanical strength of UAM builds. This research identifies the optimum combination of processing parameters, including normal force, oscillation amplitude, weld speed, and number of bilayers for the manufacture of commercially pure, grade 1 $titanium+1100-O$ aluminum composites. A multifactorial experiment was designed to study the effect of the above factors on the outcome measures ultimate shear strength and ultimate transverse tensile strength. Generalized linear models were used to study the statistical significance of each factor. For a given factor, the operating levels were selected to cover the full range of machine capabilities. Transverse shear and transverse tensile experiments were conducted to quantify the bond strength of the builds. Optimum levels of each parameter were established based on statistical contrast trend analyses. The results from these analyses indicate that high mechanical strength can be achieved with a process window bounded by a 1500 N normal force, $30 μm$ oscillation amplitude, about 42 mm/s weld speed, and two bilayers. The effects of each process parameter on bond strength are discussed and explained.

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## Figures

Figure 1

Schematic representation of ultrasonic metal welding and detailed view of the weld zone (inset)

Figure 2

Diagram of UAM system where successive layers of metal tape are bonded together for creating bulk metallic parts

Figure 3

Schematic representation of Ti/Al bilayers

Figure 4

Figure 5

UAM shear specimen strength testing set-up

Figure 6

Loading scheme and tape diagram of transverse tensile specimens (not to scale)

Figure 7

(Left to right) transverse tensile sample grips, grips installed in jaws, and sample in grips prior to testing

Figure 8

Interval plot showing USS for shear experiments—bars are one standard error from mean (crosshair)

Figure 9

Interval plot showing UTTS for transverse tensile experiments—bars are one standard error from mean (crosshair)

Figure 10

Surface plots of USS as a function of (a) normal force and amplitude, (b) weld speed and no. of bilayers, (c) amplitude and no. of bilayers, and (d) normal force and weld speed

Figure 11

Surface plot illustrating UTTS as influenced by (a) normal force and amplitude, (b) weld speed and no. of bilayers, (c) amplitude and no. of bilayers, and (d) normal force and weld speed

Figure 12

Deviation in average USS as a function of selected levels for each parameter: (a) USS versus normal force, (b) USS versus amplitude, (c) USS versus weld speed, and (d) USS versus number of bilayers

Figure 13

Deviation in average UTTS as a function of selected levels for each parameter: (a) UTTS versus normal force, (b) UTTS versus amplitude, (c) UTTS versus weld speed, and (d) UTTS versus number of bilayers

Figure 14

UAM built Ti/Al sample 7-3 at 100x magnification

Figure 15

UAM built Ti/Al sample 12-1 at 100x magnification

Figure 16

UAM built Ti/Al sample 7-3 at 400x magnification

Figure 17

UAM built Ti/Al sample 12-1 at 400x magnification

Figure 18

(a) Location of one of the foreign particles examined and (b) the particles are composed of silicon originating from the SiC grit disks used for polishing

## Errata

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