Energy and bond strength development during ultrasonic consolidation

• Infrared thermography is successfully used to monitor weld energy during ultrasonic consolidation.
• A relationship has been established between weld energy and bond strength for aluminum.
• This work provides a framework for future use of infrared thermography in real-time monitoring and feedback control of UC bonding.

A process model was developed that couples the effects of the three adjustable ultrasonic consolidation (UC) process parameters (amplitude, force and speed) into a single term – thermal weld energy due to frictional and volumetric heat generation. Infrared thermography was used to evaluate weld energy during UC and a relationship was established between weld energy and the peel strength of ultrasonically consolidated aluminum. An optimum processing widow was identified for bonding Al 1100-0 and Al 3003-H14 based on UC processing temperature and weld time. Bonding occurred well below the material melting temperatures, confirming that thermal softening in the bulk of the material or melting are not the bonding mechanisms and that bonding takes place in the solid-state.