Composite Radome Design

One of the core competencies at Metis Design is the insertion of composite materials into non-traditional markets. Thermoplastic Composite Designs, Inc. (TCD) commissioned MDC's expertise in this area in the redesign of a radome, using thermoplastic composite material to be manufactured using the TPF Process. TCD had been asked by the Ogden Air Logistics Center (OO-ALC), located at Hill Air Force Base in Utah, to develop a composite radome panel that would have similar weight and strength to existing designs but would be significantly more durable. To meet these goals TCD, who plans to manufacture these panels, has partnered with MDC to design and analysis these parts.

At the start of the project, basic geometry of an existing panel was provided by TCD as well as loading requirements. The radome design had to withstand wind speeds up to 200 mph and might be exposed to severe point loading by repair workers repelling down the dome. The engineers at Metis Design developed a mathematical model of the wind loading condition and used the resulting forces in a FE model for the overall radome structure. Used this model, the nominal panel cross sectional stiffness was determined. Next, a Matlab code was developed to identify a skin thickness and rib pattern that would provide the required stiffness for a minimum of weight. A finite element analysis was performed on this optimized geometry to determine if any thicknesses needed to be adjusted to withstand the expected dynamic load of someone repelling down the structure. Once the final geometry had been established using FEA, a detailed solid model suitable for molding was created.

Current radomes are generally manufactured using composite sandwich structure designs. This means that an impact event could occur that would not affect the visible surface, but could damage the interior core, separating the sandwich layers. This damage mode would dramatically reduce the stiffness of a given radome panel and could ultimately result in failure of the part. These sandwich panels are also often manufactured by hand, resulting in variation between parts, slow lead times and high manufacturing costs. By using a thermoplastic composite material and the TPF process, the panel can be manufactured as a single piece, increasing the durability of the part while reducing the manufacturing time and cost.

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