The effects of welded clips on fatigue crack growth in AA6156 T6 panels

Fatigue crack growth simulation by extended finite element method: A review of case studies

“…Here, we focus on some new results in numerical analyses of FCG in integral skin‐stringer panel produced by means of laser beam welding (LBW). Except for the good agreement of numerical and experimental results, one should notice significant effect of Paris law coefficient on remaining life, 112 and the fact that the fatigue life obtained on the basis of calculated SIFs along the crack fronts on LBW skin‐stringer panels was significantly longer than experimentally measured life 111 …”

“…This approach was presented in literature, 90 where XFEM results for FCG in the case of the base panel (without stringers and welded clips) were verified by experimental measurements. Afterward, two additional issues were covered, the effect of mesh size (1, 2 and 4 mm), as described in literature, 110,111 and the effect of clips on fatigue life. 112,113 Here, we focus on some new results in numerical analyses of FCG in integral skin-stringer panel produced by means of laser beam welding (LBW).…”

“…Except for the good agreement of numerical and experimental results, one should notice significant effect of Paris law coefficient on remaining life, 112 and the fact that the fatigue life obtained on the basis of calculated SIFs along the crack fronts on LBW skin-stringer panels was significantly longer than experimentally measured life. 111 The effect of mesh size on the fatigue life was investigated with three differently sized hexahedral meshes, resulting in different FCGs, as shown in Figures 18-20 for 1-, 2-, and 4-mm FE mesh sizes, respectively. As for the remaining life, it was found that results for 2-and 4-mm FE mesh sizes were similar (279,052 and 289,841 loading cycles to reach crack length 220 mm, respectively), while for the mesh size of 1 mm, the remaining life was about 15% lower (243,460 cycles).…”

“…Number of cycles for panel with additional three clips was higher than for panel with just four-stringer (278,476 cycles vs. 264,987) cycles, improving fatigue life for cca 5%, as shown in literature. [111][112][113] Having in mind additional cost of clips welding, such a small improvement is not justified!…”

“…Few other examples of XFEM application to solve practical problems were briefly described in previous review paper of this author 39 . Rather, we focus our attention on series of papers on XFEM application published recently by Grbovic and coworkers, in the scope of the activities of the Belgrade school of XFEM simulation, 82–134 presented as case studies in the following chapters, more or less in chronological order.…”