Crack Propagation Simulation on Composite Wing Subjected to Gust Load by Means of XFEM

The utilisation of composite in aircraft industry is increasingly higher in the recent decades. The flexibility to optimise weight and strength by using composite is a great benefit for lightweight structure applications. However, as highlighted by many companies, i.e., Boeing and Airbus, further works need to be done on understanding the composite behaviours especially its damage evolution prior to structural failure.
In the current research, the development of a more accurate tool is focused to predict the structural integrity of a composite wing under operational loads. In the first part of the present work, a custom subroutine containing three-dimensional (3D) Puck failure criterion combined with exponential damage degradation model is developed. This subroutine aims to extend the capability of the finite element analysis (FEA) software to accurately model composite structures. Two benchmark studies are conducted, the single-element test and the open hole test. The results from both cases indicate good agreements with the experimental outcomes.
The second part of the present work focuses on improving the search algo rithm for the Inter-Fibre Failure (IFF) on 3D Puck failure criterion. Hence, a novel fast fracture plane orientation angle (FPOA) search algorithm is proposed as a replacement for the standard linear search algorithm. The results demonstrate the proposed fast FPOA search algorithm is significantly more accurate than that of the other fast FPOA search algorithms, although
this comes with a slight penalty in computational speed.
Finally, the third part of the present work focuses on the integration of the 3D Puck criterion with fast FPOA search algorithm into the Extended Finite Element Method (XFEM) framework. A benchmark test using XFEM shows that the crack propagates in similar orientation with an experimental result. Furthermore, computational analysis is conducted to evaluate the structural integrity of the composite lifting structure (wing) subjected to cruise and gust loads.