Abstract: A system for sensing fractures in a structural component that has a plurality of light conductor fibers attached to or incorporated in the structural component, such as an aircraft body or wings made of fiber reinforced material. The light conductor fibers function as fracture sensors. For this purpose the light supply to each individual fracture sensing light conductor and the interrogation whether a light signal has passed through the light conductors is controlled by a computer. The absence of a light signal at a particular conductor signifies a fracture and this fact may be indicated on a display in the cockpit of an aircraft.

Abstract: An arrangement for detecting cracks within a construction or structure part made of multiple lamina in a compound fashion and wherein at least some of said lamina are made of fibres, being at least partially embedded in synthetic resin, includes light conducting fibres in said lamina taking the place of regular ones of said fibres within a pattern of such fibres either as part of the weaving pattern or as particular interposed layer.

Abstract: The invention relates to a measuring device for determining cracks. Light conductive fibers or film are provided as crack detectors in this measuring device which fibers or films are applied directly upon the construction parts. Light is coupled into these light conductive fibers by means of a coupler and the passage of light is monitored at the free end. A fiber fracture serves as irreversible crack indication.

Abstract: Laminated parts of structural material receive as embedment light transmitting fibers, preferably in addition to reinforcing fibers, and light transmission through the light transmitting fibers is monitored for purposes of determining pattern irregularities and formation of cracks.