In this paper, the experimental determination of the stress intensity factor in thick walled cylinders subject to uniform internal pressure and having longitudinal non-penetrating cracks is presented. Photoelastic measurements were used together with the expressions of the stress field near the crack tip for Mode I crack extension and a specific methodology for stress intensity factor determination. Two types of longitudinal cracks - internal and external - were considered. Four plane models were manufactured and analyzed in a plane polariscope at different values of the applied internal pressure. The values of the normalized stress intensity factor were calculated and the results were compared to those reported by other authors. A good accuracy was noticed, showing the reliability of the experimental procedure.
Structural Health Monitoring (SHM) represents a method of monitoring and assessment of the structural state of a certain component, in terms of damage identification, damage classification and monitoring of deformations and loads. The structure and purpose of different SHM methods are presented, with a review of the main types of sensors and monitoring methods available. Recent trends in implementing SHM methods in composite applications are presented, especially in aerospace structures. Also, the main advantages and disadvantages of SHM methods are being highlighted and the potential that these systems have in the technological future. The main purpose of the presented survey is to assess the best method to realize a future model of a new composite blade, equipped with sensors, that will replace the current metal tail rotor blade which equips the IAR330 military transport helicopter used by the Romanian Air Force.