Evolving fuel efficiency and emissions standards, along with consumer demand for performance, are strong pressures for light-weighting of performance oriented motorcycles. The field of topology optimization (TO), with the extension of multi-material topology optimization (MMTO) provide manufacturers with advanced structural light-weighting methodology. TO methodology has been adopted in many industries, including automotive where light-weighting assists in meeting efficiency regulations. The development of process specific manufacturing constraints within MMTO is a critical step in increasing adoption within industries dealing with manufacturing cost restrictions. This capability can decrease design complexity, lowering manufacturing costs of optimization solutions.
A conventional all-aluminum perimeter style motorcycle chassis is analyzed to develop baseline compliance (total strain energy) metrics. An MMTO design space is created and optimized with steel and aluminum, such that results match the baseline design weight. This formulation demonstrates increased structural efficiency through stiffer structures at equivalent weight. Results are generated with standard MMTO, symmetry, and extrusion constraints to demonstrate utility of these manufacturing constraints. Material ratios are used to enforce lower cost material distribution selections.
The usage of MMTO with manufacturing and material ratio constraints has resulted in up to 60.4% reduction in structural compliance of designs, and a multitude of lower cost alternative designs. The usage of symmetry constraints provides effectively identical results to standard MMTO, with a computational time reduction of 29%. Extrusion constraints demonstrate decreased manufacturing difficulty with a computational time reduction of 52% and structural performance penalty of 58.6% from the lowest compliance MMTO result. The enforcement of steel has demonstrated a decrease in structural performance (increase in compliance) and material costs, with varying degrees depending on manufacturing constraints and enforcement limits. The MMTO based designs provide a range of solutions to designers, which can be selected based on the importance of structural efficiency, manufacturing difficulty, and material costs.