Composite material parts may experience service exposure to three-dimensional (3D) temperature gradients where temperature differences may exceed 150 C. The effect of these conditions on a glass fabric-reinforced BMI resin laminate has been analyzed as a function of location using a 3D model. According to analysis predictions, in a situation of thermal load and temperature gradients, compression stresses develop in the center of the heated zone, which is surrounded by a tensile-stressed annular region. The stresses and strains developed are small compared to the ultimate mechanical properties of the material. The analysis has been verified by subjecting an instrumented sample to nonuniform heating. This confirmed that in the absence of absorbed moisture, the damageinducing potential of local heating was small. This observation suggests that less conservative design approaches can be used for thick laminates compared to the current, with a consequent weight saving potential.

The combined use of Bragg grating and dielectric sensors has been studied for the monitoring of bonded composite repairs to metallic parts, using standard composites field repair equipment and specially built "sensing mats" Measurements retrieved via a variety of sensors were correlated, to analyze the interactions of the chemical and physical changes occurring during the bonding process. It was concluded that the combined use of Bragg gratings and dielectric sensors can provide important information for the cure monitoring of bonded composite repairs.