A cantilever truss of tubular cross-sections under different load case scenarios has been selected as the demonstrator of the proposed framework. Optimisation studies, featuring numerical layout and geometry optimisation techniques, were employed to obtain a ‘line structure’ output for the given problem involving multiple load cases and considering practical and manufacturing constraints.
Cross-section optimisation was then carried out, followed by a series of geometrical operations for the design of free-form joints connecting the optimised members. The solid model of the optimised design was then exported for AM. The process followed for the generation of the optimised cantilever truss is presented in Figure 1.
To evaluate the structural behaviour of the optimised cantilever truss, detailed geometrically and materially nonlinear FE analyses were performed, accounting for initial geometric imperfections. The capacity of the equivalent standard universal beam section, taken as a reference design, was also examined.
The key aims of the conducted FE analyses were to:
(a) assess the accuracy of the proposed truss optimisation framework and workflow and
(b) investigate the overall efficiency of the developed optimisation framework in obtaining designs with improved strength and stiffness and reduced material usage.
Following validation against test results reported in the literature, the developed FE model was employed to examine the response of the optimised truss, the efficiency of which was assessed by comparing its performance against its equivalent reference design:
- A conventional cantilever was designed for the examined load case scenarios while standard cross-sections were selected from typical section tables provided by manufacturers.
- The capacity-to-mass ratio of the optimised truss was found to be three times the equivalent ratio of the corresponding reference design.
- This suggests that the proposed optimisation framework can be used to reduce material usage and improve structural performance.
