A model for weld strength in ultrasonically consolidated components

Abstract

• Abstract: Ultrasonic consolidation (UC) is a solid freeform fabrication technique developed for the manufacture of metal parts. The mechanisms by which bonds are formed, during the UC process, are based on a combination of the surface effect and the volume effect. Based on the outcomes of peel tests and microstructural analysis, this paper will consider the influence of these two phenomena on the weld strength of specimens. A model is presented to describe how calculations for weld strength may be derived on the basis of the theory of surface and volume effects. Through the application of the model, it was possible to demonstrate that the weld strength may be 7 per cent greater than the tensile strength of the base metal. The identification of the phenomena and the development of a model for weld strength have led to the modification and production of an enhanced test procedure which is described in this paper.

Thermal modeling during continuous ultrasonic welding

“…The repetitive stick/slip mechanism at the interface is the best way to explain the bonding mechanism of ultrasonic consolidation [4]. The applied normal force of the sonotrode as shown in Figure 5 generates a frictional shear stress at the interface of materials to be welded.…”

“…However, surface preparation is recommended since it has been reported to improve the bonded area by approximately 45% [1]. The ultrasonic bonding mechanism is reported to be a repetitive stick-slip [4] mechanism. The surface asperities bond together by means of friction during the stick phase and create contact points.…”

The effect of ultrasonic excitation on the electrical properties and microstructure of printed electronic conductive inks

“…A high degree of material plastic flow is encountered during the welding process, as well as various surface and volume effects, such as stick-slip phenomena at the welding interface and acoustic softening on the volume of the material [1]. The temperature developed during UAM has been experimentally measured by placing a thermocouple between two layers of foil for relatively low levels of oscillation amplitude [2], and with an infrared camera for higher levels of amplitude [3].…”

The Effect of Ultrasonic Additive Manufacturing on Integrated Printed Electronic Conductors

“…The sonotrode is then rolled over the foil with a linear speed (S), while it oscillates at an ultrasonic frequency (20 kHz) at a pre-set amplitude (A) perpendicular to the direction of rolling. This process causes the mating surfaces at the foilfoil interface to come in close metal contact and form solid state metal bonds [3,4].…”

“…Bonding in UAM occurs in the presence of a high degree of plastic metal flow, due to the ultrasonic softening phenomenon [4]. This allowed researchers in the past to create composite metal matrix structures with embedded functional materials and other smart features, such as optical fibres [5,6], shape memory alloy fibres [7,8], other shape memory and magnetostrictive materials for embedded sensing applications [9] and smart switches for a structural antenna [10].…”