2.1 FEA solution process for bonded repair simulation workflow
(BRSW)
Our proposed bonded repair effectiveness evaluation methodology is
carried out in the following steps:
Aircraft structure geometry, crack geometry, repair patch geometry
preparations. In this step, a CAD drawing is first completed based on
the aircraft structure geometry and the initial crack geometry. The
repair patch geometry is dependent on the repair strategy to be
examined, e.g., stop-drill repair and damage-removal repair. An
example of the geometry is shown in Figure 1.
- Material properties preparation and assignments. In this step, the
material properties are assigned for the aircraft structure to be
repaired and the patch materials, e.g., boron patch and titanium
patch. These material properties are necessary for the evaluation of
crack growth and estimations of service life.
- Aircraft structure and patch meshing generation, crack meshing
generation. The meshing of the geometry is necessary for FEA
simulation and analysis.
- Aircraft structure loading and boundary conditions setup. This step
sets up the loading and boundary conditions. In the case of fatigue
tests, the loading is applied as cyclic loading.
- Fatigue damage quantification. This step is to evaluate the damage
using stress measurements caused by fatigue loading and to assess when
crack is initiated.
- Fatigue crack propagation simulation and service life quantification.
This step is to provide an estimated service life for each type of the
crack repair treatment.
The steps listed above is implemented through our proposed Bonded Repair
Simulation Workflow (BRSW) with setup stages, shown in Figure 2. The
BRSW process consists of three stages with building blocks which
utilizes various Ansys software tools to perform designated tasks. The
workflow starts from the definition of material properties (structures,
patches, adhesives), to the problem setup (geometry preparation, mesh
generation, loading and boundary conditions), to FEA solutions that
yield fatigue damage evaluation, crack propagation quantification and
service life estimation.