Evaluation of Aerogel as a Material Additive for the Creation of Synthetic Defects in Carbon Fiber Reinforced Plastics

摘要

Damage within CFRP composites (commonly used in the aerospace industry) is often difficult to locate and identify, often occurring beneath the surface of the material. Many methods are used in an attempt to isolate these unseen defects, from thermography to a wide array of ultrasonic techniques. Real damage can be used to train personnel and calibrate inspection equipment, however synthetic damage is favorable for the same uses as it can be manufactured at will to any specification desired. Current methods are capable of creating foreign body defects, impact damage, and delaminations, however these methods can require expensive equipment and/or a great amount of time to manufacture. Aerogel was investigated to determine if the material could be used to simulate several types of damage common to CFRP. Samples were created by mixing Aerogel and Epoxy Resin and placing it within composite laminate layups. These samples were used to determine the material characteristics of Aerogel in relation to NDI and the response of the material under UT and Thermographic inspection. The Aerogel/epoxy mixture was optimized to achieve best ultrasonic response which could be a replacement of delamination. It was found that Aerogel was not only ultrasonically visible within the composite panel samples but had a pronounced signature compared to pure epoxy. By altering the amount of Aerogel used, the shape and size of the artificial defects could be controlled. Comprehensive scans of the samples revealed that Foreign Body Inserts (FBI) and delaminations could be matched almost exactly in UT signature and physical appearance, therefor the Aerogel method could be used in place of the current methods. Though in terms of time and cost the original method was better for creating FBIs, substantial savings could be attained with the Aerogel methods when creating synthetic delaminations.