Overview
Aerospace structures are currently inspected using traditional non-destructive inspection (NDI) techniques such as visual inspection, fluorescent penetrant, eddy current, etc. In recent years new sensing techniques were developed for damage detection in metallic and composite materials. This includes acousto-ultrasonic waves based technologies that utilise piezoelectric sensors. These techniques are capable of achieving continuous or discrete structural health monitoring (SHM) for aircraft maintenance and operation. The attractive potential of such technologies arise from the following:
• increase of fleet availability (i.e. operational readiness)
• reduction of maintenance inspection efforts (i.e. costs)
• improvements in inspection reliability (i.e. safety)
• overall reduction of life cycle costs and extended life of structures (i.e. sustainability)
Composite light weight structures in modern aircraft are based on damage tolerant design and require maintenance by NDI. The replacement of an existing NDI by a retrofitted SHM system could enable to achieve above benefits. However, significant hurdles remain in the implementation of SHM systems even after many years of development efforts by the sensor suppliers.
This project aims to demonstrate a path for the implementation of a piezoelectric sensor system for a specific aircraft composite structure for the detection of damages due to fatigue or accidental impact. As the safety, or integrity, of an aircraft is determined via deterministic or probalistic substantiation analysis, one must consider the reliability of an inspection method. The key input is the probability of detection (POD). The lack of POD assessments for SHM systems is a significant barrier to the adaptation of this form of NDI. As part of this project a POD study which includes the targeted damage mode in representative structural configuration shall be carried out with an advanced piezoelectric sensor system.
