THERMAL CHARACTERIZATION OF HONEYCOMB CORE SANDWICH STRUCTURES

Honeycomb core sandwich structures are an integral part of many of tod ay's aerospace structures. The need to know the thermal properties of these structures to perform thermal stress analyses provides the motiv ation for this research. The estimation approach used here to determin e the thermal properties involves the minimization of an objective fun ction containing both measured and calculated temperature values. A on e-dimensional conductive/radiative heat transfer model was used for th e analysis of the structure. Experimental designs for the collection o f temperature response data were optimized using a scaled confidence i nterval approach. The experimental parameters optimized were the heati ng time and the total experiment time. Experiments were conducted at t emperatures ranging from 295 to 495 K. The thermal properties estimate d at these temperatures included the facesheet capacity, the conductio n area of the core, and the emissivity in the interior of the core. Th ese parameters exhibited a great deal of correlation or interaction. A penalty function method was used to perform the parameter estimation in a constrained fashion, and it was found that the parameters could b e simultaneously estimated despite the presence of correlation.