Fittings involving aircraft panels, the bulkhead, angle, tee, skin and lateral panels
are meshed using quadrilateral elements. The fittings are meshed using tetrahedral
elements. The fasteners are defined using RBE2 and
CBUSH elements. Figure 1. DFEM Model
The above fitting is analyzed for tensile and compressive loads, in two different
load steps.
The details of loading and the boundary conditions for the model are: Figure 2. Details of Loads and Boundary Conditions
The analysis is performed with different analysis types.
Linear Static Analysis
The element forces for the CBUSH elements are then reviewed in the
Tension and Compression cases. Figure 3. DFEM Model Results from Linear Static Analysis
Nonlinear Analysis with Pre-loaded Fasteners
Nonlinear material property is defined using TABLED1 for aluminum
and a pre-tension of 6000 lbs. is applied to the fasteners using the
DEFORM card. Figure 4. DFEM Model Results from Nonlinear Static Analysis. (a) before applying an external load; (b) after the application of
external load
Large Displacement Nonlinear Analysis with Pre-loaded Fasteners
Large displacement nonlinear analysis can be activated with PARAM,
LGDISP in OptiStruct. Figure 5 shows the results from a Nonlinear Large
Displacement Analysis. Figure 5. DFEM Model Results from Nonlinear Large Displacement Static
Analysis
