Research On Self-diagnose And Self-repair Systems In Smart Structures By Hollow Optical Fiber

Monitoring damage and repairing crack are the important problems in composite materials. Optical fiber is one of sense components used in structure inspection early. Optical fiber sensors have been widely applied to measure strain, temperature and chemical change, etc. They and their networks can be also used in self-diagnose and self-repair in smart structures shown in this paper.Firstly, The manufacture and performance of hollow optical fiber are explained. Basedon the optic theory, hollow optical fibers possess the similar performance to common optical fibers. So, the sense theory of hollow optical fiber is discussed in detail. The theory of luminous intensity is also researched. Experimental research of composite materials with or without embedded optical fiber is made to compare characters each other. Results also display that if composite materials have enough size, there is no influence to use in engineering practice.Secondly, Neutral networks was applied to diagnose the degree and location of damages in this paper. It is a effective method for damages detection, which was verified in the course of its practical use. Then the development of self-diagnose program for intelligent composites, in which the Lab VIEW instrument was used jointly, is discussed in detail. A 4x4 optical fiber network embedding in composite materials is designed to determine the feasibility of the self-diagnose program.Finally, The method of self-repair using hollow optical fiber filled adhesive is put forward. Two samples are made to study the performance. There are paper honeycomb and glass/epoxy composite materials. Results show that the performance of repair is up to that of original for paper honeycomb material and about 1/3 in tensile, over 2/3 in compression for glass/epoxy composite material.