Analysis of Aircraft Fittings

Fittings for aircraft panels are described.

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.

Model Files

Before you begin, copy the file(s) used in this example to your working directory.

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