Development of Ultrasonic Vibration Augmented Hybrid Additive Manufacturing Setup for Improving Interlayer Adhesion

Abstract

This work develops an in-situ hybrid additive manufacturing approach that couples ultrasonic vibration (USV) with fused deposition modeling (FDM) to strengthen interlayer adhesion and improve mechanical performance. Designated as Contour Scanning Mode (CSM), this approach facilitates the travel of an ultrasonic horn across deposited layers by following image-derived toolpaths while the printing is paused and the printer bed remains stationary. A legacy FDM platform was retrofitted to accommodate the three-axis motion of the ultrasonic-horn applicator, and a Raspberry Pi with additional components was utilized to execute image processing to extract object contour and tool paths and to direct the horn movement. To test the developed system, ASTM D256 Izod impact specimens were prepared by using poly(lactic) acid (PLA) and tested. Compared to control samples, CSM USV applied samples displayed ∼25% increase in impact resistance. This indicates enhanced interlayer adhesion through improved polymer chain diffusion via squeeze flow of remelted material. Digital microscopy revealed reduced voids and more consolidated layers, corroborating the results. As the preliminary data demonstrate the efficacy of the developed hybrid method, more in-depth experiments are in progress to characterize the associated effects for different layer combinations through tensile, impact, and morphological property testing. But this article will broadly focus on the iterative details of the CSM USV application system development rather than on the detailed results. In the future, an effort to improve the current method for adapting to different 3D geometrical shapes will be undertaken.