Ultrasonic Characterization and Assessment of Bonding between Adjacent Structures in Polymeric Additive Manufacturing

Vinay Dayal and Richard Livings, Center for NDE and Department of Aerospace Engineering, Iowa State University, Ames IA 50011

Non-homogeneous, layered structures (Figure 1 & 2) were observed in the production of parts by polymeric additive manufacturing. Previous work demonstrated that these materials do not fit the isotropic material model and suggested that they may be better fitted to a monoclinic model since complimentary shear velocity measurements gave differing results [1]. This work measures the full set of monoclinic elastic constants using ultrasonic velocities and mechanical testing as well as the directional properties of the ultrasonic dispersion and attenuation. Determining the elastic constants from mechanical testing and ultrasonic measurements gives significantly different results for this material which indicates dispersion caused by the visco-elastic nature of the material, the periodic microstructure, and the bond quality between adjacent voxels. The visco-elastic properties of the material was examined by DMA testing, while the bond quality was determined with double cantilever beam samples

Figure 1. Micrograph of the printing plane showing a striated structure.

Figure 2. Micrograph of the plane perpendicular to the printing plane showing a striated structure.

References:1. R. Livings, V. Dayal, and D. Barnard, “Characterization of 3D Rapid Prototyped Polymeric

Material by Ultrasonic Methods,” in Review of Progress in Quantitative Nondestructive Evaluation, eds. D. E. Chimenti and L. J. Bond, (American Institute of Physics 1650, Melville, NY) 34, 807-816 (2015).

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