Design of an equipment for permeability estimation of composite materials for the aeronautical industry

• Novel equipment developed to measure composite permeability for aerospace. • Hybrid O-ring and rubber gasket sealing ensures accurate leak-free testing. • Validation performed using Teflon® and carbon/PA6 composite samples. • PA6 composite showed negligible permeability at 9 bar, fit for pressure vessels. • Cost-effective design accessible to labs while meeting aeronautical standards. Nowadays, composite materials are a hot topic due to their exceptional mechanical properties that allow structures to achieve high mechanical strength with low weight. Along this type of applications, pressure vessels to store hydrogen, fuel or liquid natural gas are thriving in the industry. This study aims to develop an equipment capable of measuring the composite permeability. The proposed equipment includes a fastening system that was designed to be resilient to stress and easy to use, leading to the use of a bolt system. To guarantee the system sealing, multiple approaches were considered depending on the test conditions and on material nature, with a hybrid system composed of O-Ring and rubber gasket being chosen. Equipment validation was accomplished by experimental testing to ensure no gas leaking the capability of measuring the permeability correctly. A material with known high permeability, Teflon®, was tested and its result compared with literature data, confirming the equipment reliability in measuring composite permeability. Moreover, a composite made polymeric PA6 matrix reinforced with carbon fibre in a 0/90° orientation, with a thickness of 2 mm was tested, and its suitability for aerospace applications was confirmed, since had null permeability over approximately 6 h.