An investigation into using laser micro channelling to assist fibre integration via Ultrasonic Consolidation

Ultrasonic Consolidation (UC) is a layer-by-layer metal-based additive manufacturing process. Bonding between two layers is accomplished by energy transmission in form of ultrasonic oscillations inducing localised plastic deformation. The benefit of localised plastic deformation and bonding below melting temperatures has been effectively used for fibre integration. Thus, UC presents a feasible alternative to other metal-manufacturing processes as well as an attractive method for novel engineering materials production such as smart structures.Yet, high volume fibre embedding has been shown to result in delamination of foils and greater porosity at the bonding interfaces due to insufficient plastic flow around the fibres. Furthermore, post-functionality of delicate fibre types was limited. In this study a novel hybrid approach aiming to reduce the necessary plastic flow around fibres and high fibre volume embedding is presented. [Continues.

Exploring the mechanical strength of additively manufactured metal structures with embedded electrical materials

Ultrasonic Additive Manufacturing (UAM) enables the integration of a wide variety of components into solid metal matrices due to the process induced high degree of metal matrix plastic flow at low bulk temperatures. Exploitation of this phenomenon allows the fabrication of previously unobtainable novel engineered metal matrix components. The feasibility of directly embedding electrical materials within UAM metal matrices was investigated in this work. Three different dielectric materials were embedded into UAM fabricated aluminium metal-matrices with, research derived, optimal processing parameters. The effect of the dielectric material hardness on the final metal matrix mechanical strength after UAM processing was investigated systematically via mechanical peel testing and microscopy. It was found that when the Knoop hardness of the dielectric film was increased from 12.1 HK/0.01 kg to 27.3 HK/0.01 kg, the mechanical peel testing and linear weld density of the bond interface were enhanced by 15% and 16%, respectively, at UAM parameters of 1600 N weld force, 25 µm sonotrode amplitude, and 20 mm/s welding speed. This work uniquely identified that the mechanical strength of dielectric containing UAM metal matrices improved with increasing dielectric material hardness. It was therefore concluded that any UAM metal matrix mechanical strength degradation due to dielectric embedding could be restricted by employing a dielectric material with a suitable hardness (larger than 20 HK/0.01 kg). This result is of great interest and a vital step for realising electronic containing multifunctional smart metal composites for future industrial applications

Fiber laser induced surface modification/manipulation of an ultrasonically consolidated metal matrix

Ultrasonic Consolidation (UC) is a manufacturing technique based on the ultrasonic joining of a sequence of metal foils. It has been shown to be a suitable method for fiber embedment into metal matrices. However, integration of high volume fractions of fibers requires a method for accurate positioning and secure placement to maintain fiber layouts within the matrices. This paper investigates the use of a fiber laser for microchannel creation in UC samples to allow such fiber layout patterns. A secondary goal, to possibly reduce plastic flow requirements in future embedding processes, is addressed by manipulating the melt generated by the laser to form a shoulder on either side of the channel. The authors studied the influence of laser power, traverse speed and assist gas pressure on the channel formation in aluminium alloy UC samples. It was found that multiple laser passes allowed accurate melt distribution and channel geometry in the micrometre range. An assist gas aided the manipulation of the melted material