MANUFACTURING OF HONEYCOMB CORE SANDWICH STRUCTURES: FILM ADHESIVE BEHAVIOR VERSUS CURE PRESSURE AND TEMPERATURE

摘要

Honeycomb core sandwich structures are composed by combining fiber-reinforced polymer facesheets, film adhesive and core. During co-cure, the facesheets are consolidated and cured while simultaneously being bonded to the core, leading to potential interactions between the in-process behaviors of the three materials. In this paper, we describe studies relating material, process and structural inputs to the in-process behavior of a film adhesive and to the characteristics of the cured bond-line. The thermochemical properties of the adhesive were determined using thermal analysis and simulated using predictive models. Sandwich assemblies consisting of skin, core and adhesive were manufactured using a simplified lab-scale process, and microstructural quality was assessed in terms of fillet geometry and bond-line porosity. Finally, the adhesive bond-line morphology was observed in-situ using a novel curing tool. The resulting data shows that, for this material and processing route, the core pressure was the major factor affecting bond-line quality due to volatile release from the adhesive, and that the major morphological characteristics of the bond-line are formed prior to the minimum viscosity point of the adhesive.