Design Optimization of Scooter Engine Hanger for Maximizing Stiffness to Weight Ratio 2015-01-1366

In scooters, the engine is a dynamic component. It is directly connected to the rear wheel and it also acts as a swing arm. Such behavior of an engine entails a requirement of a dynamic link connecting it to the frame. The link employed for this is an engine hanger. An engine hanger sustains a direct load and vibrations from the engine and allows swinging motion of the engine, thereby reducing the vibrations generated by the road undulations. The length of the engine hanger is chosen to minimize the transmission of forces generated by the rear wheel and engine arrangement to the chassis. Whereas, its shape is dictated by the forces acting on it, manufacturing process, available packaging space and its manufacturing cost. An engineer aims at developing an engine hanger that can withstand such loads and vibrations, as well as optimize its weight to meet the cost target. Improper design may lead to failure of the part in running condition.

This research aims at optimizing the shape of an existing engine hanger, in order to minimize its weight without compromising on the required stiffness and at the same time ensuring manufacturability, strength and low cost. Packaging constraints, boundary and loading condition have been carried over from an existing design. The design has been modified for achieving the optimum balance between strength and cost. The design is then further validated and analyzed keeping all the manufacturing constraints and packaging space in mind.

The results provide a better understanding of the distribution of stresses in the engine hanger and the effects of the manufacturing process on its shape, size and cost. The study of stress distribution helps in formulating designs with minimum weight as well as meeting the required stiffness criteria and cost target.