In an ultrasonic welding operation of plastic parts,
a system of internal electrical conductor strips were fatigue failing due
to natural resonance excitation. A detailed parametrically
based model was created to optimism the dynamic response thus tuning
the connectors. The model included a melt front model due to frictional
heating at the connector-plastic interface. Correlation to physical test
data was completed and fracture behavior identified resulting in redesign
and improvement of the device.