Reducing the Weight of a Bus Frame by 17%
Lighter vehicles require less energy to move and can retain the required performance characteristics while making use of a lighter, smaller, less polluting engine. As part of its research activities, NEPTECH, an institution within Vietnam’s Department of Science and Technology, became involved in a development program for a local mass transportation vehicle manufacturer. The client wanted to explore new methods to reduce the weight of the vehicle in an effort to meet its fuel efficiency and cost targets.
NEPTECH approached Altair ProductDesign to assist with the project based on its experience of developing lightweight structures for public transport vehicles. As well as being lightweight, the final design of the structure had to meet ‘ECE R66’, a set of standards which dictates that the superstructure of any oversized vehicle should have enough strength to avoid large deformations during a rollover event.
After an initial research period, it was decided that the most effective way to deliver a weight saving was to adjust the thickness of the steel frame. In order to identify where the thickness of the frame could be altered, Altair conducted a ‘gauge optimization’ study which uses load cases based on real world use conditions to suggest where the thickness of the frame could be safely removed to save weight but without compromise to passenger safety. Once the optimized design had been produced and reviewed by the engineering team, inertia relief analysis was used to validate the new design.
The weight of the frame was successfully reduced by 17% while maintaining all design and performance characteristics. For rollover analysis, both the baseline and optimized designs were ‘stable’ at 30 degrees which met the requirement for the ECE R66 standards. In addition, the intrusion values were successfully kept low when considering the overall dimensions of the bus in the optimized model. By successfully reducing the weight of the frame, NEPTECH’s bus manufacturer client can be confident that the new design will help to minimize fuel consumption and CO2 emissions.