Automatic Damage Detection and Monitoring of a Stitch Laminate System Using a Fiber Bragg Grating Strain Sensor

Abstract

There are numerous aspects and questions related to the use of composite materials for primary structures in aircraft where the structural integrity is the most important factor. This is especially true if the main concerns are that the material should have good reliability and durability for the primary structural application. Composite laminates are highly sensitive to out-of-plane failure due to their low inter laminar fracture toughness. An alternate method to increase the damage resistance is through three-dimensional fibrous reinforcement such as through-the-thickness stitching with a single fiber as the thread. Recent studies have shown that the stitching of standard laminates can enhance damage tolerance to levels obtainable with toughened resin systems. However, for next-generation aircraft, material improvement alone is not enough to assure or increase the safety and reliability of the structure.