Search Results

The purpose of the present study is to improve the on-street exhaust noise measurement technique for regulating vehicles emitting unacceptably large exhaust noise. The method under development uses racing operation of engines with a wide-open throttle. Due to the high engine acceleration in this operation, exhaust pulsation amplitudes at resonant speeds may not increase sufficiently to represent the amplitudes under full-load acceleration conditions. To investigate the seriousness of this problem, experiments and numerical simulations were conducted. As a result, the sound level measurement error caused by the insufficient resonance growth was found to be sufficiently small for on-street tests.

A formula type racing-car was designed and built for the “Formula SAE” competition. Lightweight design was achieved separately in two areas, i.e. the pipe frames and bulkheads, by employing two different strategies. In the pipe frame design, the stretch method was used. The baseline design employed the minimum number of pipes required to make the structure statically stable. After this, reinforcements were attached one-by-one, until the rigidity reached a satisfactory level. In the bulkhead design, weight reduction was achieved using a voxel approach and topology optimization. The bulkhead was divided into finite elements that have the same shape and size. Starting from a solid board, relatively low-stress parts were removed from the model in a step-by-step manner. The weight of the final design is less than 50% of that of the solid board.