Prestressed concrete aerospace autoclave ovens: feasibility and opportunities for the industry

With the current and future growth of composites in the aeronautic industry, market pressure is increasing for fabricants to obtain the largest possible composite sections, in order to reduce the use weight and complexity of the final product. In this scenario, autoclaves remain as the main constraint to determine the maximum size of a composite element that can be produced and thus, the question on how larger autoclaves can be built is ever more relevant. This research aims to explore the possibilities, strengths and weaknesses that prestressed concrete presents as a possible material for a new generation of super large autoclaves. To determine the feasibility of the concept, the current state of the art in prestressed structures was studied to determine a viable design scope and the behavior of the structure in key areas, such as fatigue and comparative material consumption. Then, estimations were performed in consideration to the applicable construction codes as well as simplified numerical models, in order to obtain a rough estimate in terms of stresses and material demand. Finally, a study case was considered for an ultra large autoclave (10m diameter, 84m length) using the previously estimated designs, to study the static and dynamic behavior of the structure.