Monitoring of the elements of aviation structures using strain-gauge measurement

Abstract

Analysis of the kinetics of the stress-strain state was carried out using data of tensometry as one of the methods for monitoring the integrity of the aircraft structure and a promising approach to ensure safety of aviation equipment during long-term operation. The advantages of condition monitoring using on-board systems prior to routine procedures aimed at maintaining the airworthiness (which consist mainly in periodic inspections) are presented. The results of using monitoring when studying the fatigue characteristics of the aircraft structure elements at the Central Aerohydrodynamic Institute (Russia) are shown. The study was carried out on samples of longitudinal fuselage joints. Several types of fatigue damages typical for operation of longitudinal joints are considered. The possibility of detecting defects by monitoring of the local stress-strain state with the help of strain gauges under various modes of destruction is assessed. Data on the of fracture surfaces of the damaged elements, fronts and crack propagation rates corresponding to different number of applied cycles were used. The assessment of the controllability of several typical structural and technological variants of longitudinal joints is presented. The results of determining zones of changes in stress-strain state in a bearing sheet with a single main crack are presented, which is the most typical fatigue damage to the longitudinal fuselage joints. The optimal location of the sensors for monitoring the integrity of the joint is proposed. Studies proved that the method of structural health monitoring using tensometry data can be successfully applied to tests for durability and has a prospect of being used in maintaining the integrity of joints and other places of limited access by instrumental non-destructive test methods.