Strain and damage monitoring in CFRP fuselage panels using fiber Bragg grating sensors. Part I: Design, manufacturing and impact testing

Abstract

This is the first paper of a two-paper series describing design, implementation and validation of a strain and damage monitoring system for CFRP fuselage stiffened panels based on fiber optic Bragg grating sensors. The monitoring system was developed and tested on the basis of three load-scenarios: compression to failure of the undamaged panel, compression to failure of the impacted panel and compression to failure of the impacted and fatigued panel. This paper focuses on the design of the fuselage panel, the design of the monitoring system, the embedment of fiber sensors in the panel during manufacturing and the impact testing. The network of the sensors was designed based on a numerical buckling analysis from which the strain field of the panel was computed as a function of the applied compressive load. Embedment of fiber sensors in the panel was done so as to minimize risk of fiber breaking during manufacturing and impact testing and to effectively capture strains that are representative of damage developed in the panel due to compressive load. Barely visible and visible low velocity impact damage sites were created at different locations of the panel using a drop-weight impactor. The panels were inspected using C-scan just after manufacturing, to check quality of the material, and just after impact testing to detect impact damage at each location.

Modelling of fracture processes in laminate composite plates with embedded delamination

“…Among them are the non-destructive testing methods such as acoustic emission, ultrasonic examination and others [30][31][32][33]. Another promising direction is embedding of the sensor elements, such as piezoelectric sensors and sensors, based on optical fibers [34][35][36]. Indications of such sensors may be also used for verification of failure models as well as predictions of durability of structures based on them.…”

Bird and hail stone impact resistance analysis on a jet engine composite air inlet

“…All numerical models were calibrated on the basis of experimental results gathered with an eye towards damage initiation and propagation behaviours. Fibre Bragg grating (FBG) sensors and strain gauge measurements were used for material calibration [7,8].…”

Analysis of Fibre Bragg Gratings Sensors Optimal Placement for Monitoring of Damage Propagation in Laminate Composites

“…The solution was found with the development of the technologies based on the optical fibre sensors with Bragg gratings (fibre Bragg gratings, or FBG sensors) [2][3][4]. Such sensors can be embedded between the layers of the material during its manufacturing and are able to measure changes of magnetic, strain and temperature fields.…”