The effect cold expansion on the fatigue of aluminium alloy specimen containing fastener hole simulated using Finite Elements Method and Boundary Elements Method
Cedric Maranta-Sinigaglia (Glyndwr University)
Crack initiation and growth: methods, applications, and challenges
Wed 1:30 - 2:50
Barus-Holley 161
On an aircraft structure, one of the most vulnerable areas for the initiation and propagation of fatigue cracks is where the fastener holes are located. To reduce fatigue cracking at these points, a number of methods have been developed (such as cold expansion, hardening and tempering operations, etc.). One such idea is to introduce residual stresses, or induced stress fields, at the fastener holes. This work aims to give confidence in the ability to simulate the process of creating stress fields and then the prediction of fatigue crack growth behaviour through complex stress fields. Such confidence will be gained by comparison with *experimental data so offering a means of validation and also resulting in a better understanding of crack behaviour. It is more common than not to use numerical simulation to drive the design of a given product; however, the extension of such analysis techniques into the damage regime is currently far less common. The work presented shows the latest developments in coupling ABAQUS (Finite elements Analysis) to BEASY (boundary element analysis). From a users’ point of view the technical aspects of transferring ABAQUS input and output database files to BEASY is shown addressing a number of issues which arise from modelling a continuum with volumes and then surfaces; including suggested work-a-rounds to, for instance, enable the model to be loaded appropriately in BEASY. Such loads may have been generated within an ABAQUS simulation, such as residual stresses, or are applied within a BEASY analysis. A number of technical issues are still to be resolved regarding the ability of BEASY to automatically define and predict the path of a three-dimensional crack and this is exacerbated in the presence of residual stress fields. Again, typical issues will be shown which can be seen to stem from the complex geometries which may arise from a crack formed in a continuum. *Data is provided by P.Wagsaff, Kingston University, UK.