Preform-based toughening technology for RTMable high-temperature aerospace composites

This article describes the efforts that led to the development of surface-loaded preforms that may be used to significantly improve the compression-after-impact strength of high-temperature composites and correspondingly to dramatically reduce the area of damage because of impact. Moreover, by matching the toughening polymer surface-loaded and design of the surface pattern, in-plane mechanical properties are unaffected or even improved over laminates made from the identical materials. The proprietary preforms, so-called ES™-Fabrics, may be handled and infused with the high-temperature RTMable resins such as bismaleimide and polyimide in exactly the same manner as traditional fabrics without surface modification. The RTM conditions for the preform-based toughening is fully compatible with the traditional process procedure, making the technology cost-effective in production. This technology represents a key enabler for the use of low-cost RTM processes for high-temperature resins to supplant prepreg as the building-block material of choice for aeronautical composite structures.