Structural optimization of Metro Honolulu under all operative load conditions


CHALLENGE - ​Working on the design for the new Metro Honolulu car body, structural engineers at AnsaldoBreda had to push technological boundaries to ensure compliance with top level quality standards and achieve weight and cost reductions. The aim of the optimization project was to maximize dynamic performance and minimize mass while fulfilling the static structural requirements for car bodies.

SOLUTION - Starting from the original CAD model, a parameterized FE model was developed using ANSYS ​and integrated within the modeFRONTIER workflow. After performing a preliminary analysis to define all the parameters, the fuselage was parametrized and boundaries and load conditions were set according to technical requirements.



Due to the high number of time-consuming simulations and input variables, the optimization analysis was carried out by adopting a progressive approach in two phases:

Phase 1 > The main objective in the first exploration step was to reduce weight. This was performed by running the optimization from a DOE of 100 random designs, allowing engineers to identify the optimal region of the design space to be used for further exploration.

Phase 2 > Using the best results obtained in the first phase as a starting point, a second optimization was performed for the purpose of refining the knowledge of the design space and respecting constraints, taking into account 26 different working load cases. 

An accurate FE post-processing phase enabled the engineering team to extract the two most promising designs. The two configurations, however, showed a considerable variation in external and internal skin thickness which could lead to technical problems in the manufacturing phase. To avoid this issue, a further post processing analysis was performed to identify the best solution with a uniform distribution of thickness along the external and internal skins. 









BENEFITS - The modeFRONTIER optimization loop, developed to improve FE parametric models from an initial configuration, took into account the technical specifications of the structural analysis, leading to an optimized geometry capable of satisfying all static, dynamic and instability constraints. While the initial goal was to reduce weight by 5%, the final design selected using modeFRONTIER exceeded the design targets, reducing weight by 6% (228 Kg) and achieving better homogeneity in thickness variation, ultimately simplifying the manufacturing phase. Moreover, the optimization methodology developed for this case is now available for reuse in future design processes.