Finite Element Analysis of Ultrasonic Processing of a Polymer- Matrix Composite

Viscoelastic heating induced by ultrasonic loading is an attractive method of consolidating polymer-matrix composites. An ultrasonically oscillating loading horn is applied to a small region at the laminate surface, which produces a spatially nonuniform strain energy field within the material. A fraction of this strain energy is dissipated during each ultrasonic loading cycle depending on the temperature-dependent viscoelastic response of the material. This dissipation produces a rapid heating, yielding temperature increases near 100C in approximately 1s and permitting the laminate to be consolidated prior to full curing in an autoclave or other equipment. The spatially nonuniform, nonlinear, and coupled nature of this process, along with the large number of experimental parameters, makes trial-and-error analysis of the process difficult, and this paper demonstrates how a finite-element simulation can be valuable in process development and optimization.