Thermal characterization of aerospace structures

Predicting the thermal performance of complex aerospace structures requires accurate knowledge of the thermal properties associated with the structure . It is desired, in this case, to measure the in situ properties of a compl ex as-built structure, not only to capture the thermal properties of each c omponent hut also to capture interaction of components in the as-built stru cture. The overall goal of this study was, therefore, to develop and implem ent a nondestructive methodology to estimate the thermal properties associa ted with a complex aerospace structure. The structure considered was an out er wing subcomponent design fur the high-speed civil transport made from fo ur different materials, including a honeycomb blanket. The thermal properti es sought included both effective and individual material through-the-thick ness thermal conductivities and volumetric heat capacities (product of dens ity and specific heat) and the in-plane thermal conductivities of each mate rial in the structure. In the estimation procedure an objective function co ntaining both theoretical and experimental temperature histories was minimi zed using a genetic algorithm. One-dimensional experiments were implemented to estimate the through-the-thickness thermal conductivities and volumetri c heat capacities, and two-dimensional experiments sere conducted to estima te the in-plane conductivities. These properties were successfully estimate d despite the high degree of correlation and low sensitivity evident for ma ny of the properties.