Direct 3D wholefield strain imaging to determine structural integrity and residual life

摘要

The manufacture of aircraft wheels requires quality control procedures and mechanisms to identify potentially defective units during manufacture, testing stages as well as during service life. Defects can be formed due to random or systematic errors within the manufacturing process and comprise tiny fractures within the wheel structure. Use of such defective wheel and tyre units by an aircraft operator leads to growth of these fractures, which in turn can generate sudden unexpected catastrophic failure on landing. Qualification and approval of all wheel units is mandatory under UK Civil Aviation Authority (CAA) and US Federal Aviation Authority America (FAA) regulations as well in the aircraft manufacturer's standards. The regulatory authorities and manufacturers were requesting improvement in, and traceability of, analysis methods during manufacture and during routine in-service maintenance checks. They were thus considering alternative technologies. Speckle shearing interferometry is a non-contact wholefield sensor system used primarily within the aerospace industry, for analysis of defects in composite materials, including the analysis of manufacturing defects in aircraft tyres. This methodology has traditionally been used qualitatively to identify the location of faults such as disbonds. Through laser technology and image processing technology advances, it has become more common for this type of instrumentation to deliver quantitative data. However, there has been concern about data integrity, data quality and issues of defects being missed due to instrument sensitivity.