XFEM-Based Analysis for Crack Growth Characteristics of Diffusion Bonded Laminates of Titanium Alloy with Localized Nonwelded Zone

Titanium-alloy laminates fabricated by sheet materials using diffusion bonding process have drawn more and more attention in the recent years. Proper placement of nonwelded zones on the diffusion bonding (DB) interface within titanium-alloy laminates as crack arrest zones can improve damage tolerance. To achieve the optimal damage tolerance via designing non-welded zones, it is necessary to study fatigue crack growth characteristics for this type of laminates by adjusting all the relevant parameters such as geometrical sizes, locations, and the number of the nonwelded zones, which is highly time consuming. Therefore it is essential to develop a reliable and quick method to analyze the fatigue crack growth characteristics for titanium-alloy laminates with non-welded zones. In this paper, the extended finite element method (XFEM) which was employed to simulate the fatigue crack growth process and the applicability of this method to capture fatigue crack growth characteristics of titanium-alloy laminates with localized non-welded zones was also studied. The numerical results were compared with the experiment data, and the agreement on numerical and experimental results illustrated that the specific crack growth characteristics can be captured by using XFEM, thereby verifying the applicability of XFEM in the analysis of fatigue crack growth of the laminates with non-welded zones. The influence of non-welded zones on the fatigue crack growth was then discussed.