Modeling of ultrasonic processing

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2005.Includes bibliographical references (leaves 53-55).This paper presents a finite element analysis (FEA) of ultrasonic processing of an aerospace-grade carbon-epoxy composite laminate. An ultrasonic (approximately 30 kHz) 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 over 100⁰C in approximately Is 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 intractable, and the FEA approach is valuable in process development and optimization.by Wenguang Zhao.S.M