Qualification Tests of Aerospace Composite Materials with Embedded Optical Fibers

Due to the high reliability requirements in aerospace components a test campaign to qualify composite materials with embedded optical fibers has been carried out. The majority of the tests performed are standard ones since they are described in ASTM specifications. Selection and choice of the tests to be performed is done in order to obtain mechanical data that can be used for structural analysis by designers and for process control by manufacturers. More specific tests, for aerospace applications, have been performed to study the effect thermal cycling has on the mechanical characteristics of the materials. These tests are important because they simulate the effects that space structures could have when subjected to not uniform heating such as when they move in and out from the Earth’s shadow. A fiber optic network embedded into a structure is on principle a nervous system capable to sense the external environment through the changes of the properties or of the path length of coherent light. In order to be able to actually measure the strain in the structure, the fiber should be perfectly bonded on the hosting material. Therefore further non conventional tests have been devised to check this important aspect both before and after thermal cycling.