Advanced Potting Solutions for Lightweighting and Improved FST Performance
Honeycomb composite sandwich structures are now extensively employed in a variety of high performance engineering applications across several key industries, including aerospace. The advantage of such configurations is the ability to reduce weight, with increased strength and stiffness and very effectively carrying distributed loads along the normal direction of the core shell. One disadvantage of honeycomb core is the inherent weakness along the transverse direction making them unsuitable for point loads. As result of this, structural reinforcement of the core is required when mechanical fasteners are being used. This reinforcement can be accomplished with the use of a potting compound. Potting compounds are lightweight composite materials formulated from a polymer matrix, typically epoxy or phenolic, and various fillers, including hollow microspheres. However, among the many challenges of developing high performance potting compounds, is the ability to balance the high mechanical and compression strength with low density required to reduce the overall weight of the fabricated structure. This paper discusses the development of very low density potting materials (< 0.75g/cc) with excellent mechanical strength, including compression > 48 MPa (7000psi) at 180°C (350°F). Furthermore, developments in Flame Retardants, Smoke Density & Toxicity (FST) will be presented as opportunities for improved health & safety properties of potting materials for interior applications. Additionally, a detailed investigation of the rheology of the formulations will be presented, demonstrating superior handling and processing of the materials particularly focused towards automated dispensing to meet the increasing production demands and structural challenges of next generation aircraft design.
Author: Ruairi O'Kane
Conference: SAMPE Seattle 2017