Impact Damage Detection of Curved Stiffened Composite Panels by Using Wavy Embedded Small-Diameter Optical Fibers

摘要

It is well known that barely visible damage is often induced in composite structures subjected to out-of plane impact, and the mechanical properties of the composites decrease markedly. So far, for the significance of the damage monitoring, the impact tests of the CFRP laminate plates with embedded small-diameter optical fibers were conducted, and it was found possible to detect impact load and impact damage in real-time by measuring the optical loss and strain responses. But the stiffened composite panels, which are the representative structural elements of airplane, are characterized by different impact damage from that of the composite plates. In this study, single-mode and multi-mode optical fibers are used as a sensor for detecting impact load and impact damage in curved/ stiffened composite panels. Those fibers have polyimide coating and about 40 micron hi diameter which will have no serious effect on the mechanical properties of composites. Impact tests are performed using the panels with wavy embedded optical fibers. The characteristics of impact damage are investigated. The impact load, the strain measured by FBG sensors and the optical intensity of the optical fibers embedded in the composites are monitored as a function of time. And we discuss the relationship between optical responses, impact load and impact damage.