Rationalizing Current Product Range
The first stage in this project was to examine the existing designs for compactor chassis. It was found that some models were far easier to manufacture while others were more robust. Production staff felt that it would be possible to create a standardized hybrid design that could be used across the product range.
A concept design for a standard chassis was agreed. This would combine ease of fabrication with robustness.
Design optimization
The basic design was then refined using 14 separate FEA models. This allowed material use and welding to be minimised. At this stage relatively simple FEA models were used; unstructured Tet element meshing of solid geometry. Some localized refinement was carried out in areas of high stress but generally the models were optimized to allow rapid changes to the underlying SolidWorks geometry.
At this stage the main concerns were to:-
- Make efficient use of steel in terms of evenly stressing the structure and therefore minimise material use.
- Minimise part complexity - ideally sectional steel should be simply cut to length.
- Facilitate rapid fabrication through self-jigging with tabs and the auto-alignment of components.
- Minimise welding time
Detailed FEA Optimization & Verification
Following the initial design optimisation more structured modelling was carried out to further optimize the design and obtain more reliable results. Geometry was initially simplified by making use of symmetry.
Meshing with 1D Beam Elements
The geometry was approximated to a simple wire frame and series of beam cross sections. This idealized geometry was created in SolidWorks and then imported into FEMAP for meshing. Beam element properties were defined using the cross section data imported from SolidWorks.
The wire frame geometry was then meshed using these beam elements. The imported cross section data was again used to verify the correct alignment of beam elements. This model was then solved for linear stress and buckling in NEi Nastran.
Meshing with 2D Plate Elements
The SolidWorks data was first modified so that component midplanes would intersect. Unnecessary details were also removed. The geometry was then exported as a Parasolid assembly and midplane geometry created in FEMAP for each component. These surfaces were intersected meshed with 2D plate elements.
The model was solved for linear stress and buckling in NEi Nastran.
Final Design Presentation
The final design was delivered as a set of detail drawings. Material use and fabrication time were reduced considerably across the product range.
