Abstract
This paper introduces an aviation industrial application of digital image correlation (DIC) technique on the measurement of residual tensile strength (RTS). In order to investigate multi-site damage (MSD) that is common in the fuselage of aging aircraft, RTS of 2024-T4 aluminum alloy sheet with MSD was evaluated using DIC technique. Firstly, the four-factor and three-level orthogonal experiment was designed to optimize the DIC method to control the strain calculation error by considering subset size, interpolation tap, calibration score and step size. Secondly, RTS and strain fields were generated to analyze the path of crack propagation. The results show the optimal factor combination is 0.018 of calibration score, 23 pixels of subset size, step size is 1/4 of subset size and the filter size of interpolation calibration is 8 pixels. With the increase of spacing between adjacent holes, the RTS increases and the collinear cracked specimen becomes more perilous than that of non-collinear cracked while the hole spacing is 25 mm from the statistical analysis. Based on the Net section yield criterion, the RTS was calculated, which can give a conservative prediction of RTS.
Highlights
Technique on the measurement of residual tensile strength (RTS)
2024-T4 aluminum alloy is highly attractive for mechanical properties such as high strength ratio, low density, machining, plastic forming and brilliant heat performance [1,2,3]
Multi-site damage (MSD) is a special kind of failure that is commonly found in aging aircraft structures, it leads people to realize what is called the aging aircraft problem, which has developed into the main concern for research on airframe strength [4]
Summary
Technique on the measurement of residual tensile strength (RTS). In order to investigate multi-site damage (MSD) that is common in the fuselage of aging aircraft, RTS of 2024-T4 aluminum alloy sheet with MSD was evaluated using DIC technique. 2024-T4 aluminum alloy is highly attractive for mechanical properties such as high strength ratio, low density, machining, plastic forming and brilliant heat performance [1,2,3]. These properties have led to its extensive use in aircraft components and structures that undergo loading, including the fuselage, airframe, wing ribs and scar. Overloading extended effectively the fatigue life of riveted joints with a constant amplitude while bending and under-loading had a significant reduction of mechanical performances on the MSD structures of the fuselage [9]. By comparing the changes of random speckle pattern covered on the specimen before and after deformation, DIC can provide full-field strains and displacements with sub-pixel accuracy
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
