Effect of laser beam welded reinforcement on integral skin panel fatigue life. (July 2019)

• Record Type: Journal Article
• Authors: Grbović, Aleksandar; Sedmak, Aleksandar; Kastratović, Gordana; Petrašinović, Danilo; Vidanović, Nenad; Sghayer, Abulgasem
• Is Part Of: Engineering failure analysis. Volume 101(2019)
• Page Start: 383
• Page End: 393
• Publication Date: 2019-07
• Subjects: Integral skin-stringer structures -- XFEM -- SIFs -- Fatigue crack growth -- Fatigue life; System failures (Engineering) -- Periodicals; Fracture mechanics -- Periodicals; Reliability (Engineering) -- Periodicals; Pannes -- Périodiques; Rupture, Mécanique de la -- Périodiques; Fiabilité -- Périodiques; Fracture mechanics; Reliability (Engineering); System failures (Engineering); Periodicals; Electronic journals; 620.112
• DOI: 10.1016/j.engfailanal.2019.03.029
• Languages: English
• ISSNs: 1350-6307

Abstract

Abstract: In this paper, numerical analyses of fatigue crack growth in integral skin-stringer panel produced by means of laser beam welding (LBW) are presented along with fatigue results verified by previously conducted experiments. Skin-stringer panel is fail-safe structure widely used in aircraft industry, which requires a good estimate of fatigue life after crack initiation. In the past, experimental work was the only successful method for fatigue life estimation of complex damaged structure, but nowadays researches have powerful numerical tools, such as extended finite element method (XFEM), for three-dimensional crack growth analysis. In research presented here, XFEM was initially used for crack growth simulation in simple flat plate made of aluminium 6156 T6 and 6156 T4 for the purpose of procedure verification, since fatigue life for simple plate was known from experiment. Then, XFEM was used to simulate fatigue crack growth in the panel reinforced with four stringers. Fatigue life obtained on the basis of calculated stress intensity factors (SIFS) along the crack fronts on LBW skin-stringer panels was, as expected, significantly longer than experimentally measured life of simple flat plate. Finally, several numerical simulations were performed in order to analyse the influence of mesh size on accuracy of estimated fatigue life of damaged LBW skin panels. For that purpose, average element sizes of 1, 2 and 4 mm were used. Highlights: XFEM may play a significant role in structure fatigue life estimation. Effect of mesh size on fatigue life estimation is evident, but not dominant. Coarser mesh provides better agreement with experimental results. Small changes in material properties significantly change fatigue life.