Two wheelers are widely used as a medium of transportation in Asia. The increased competition challenges automotive manufacturers' to deliver the high quality product to the market. Better acoustic performance of vehicle conveys the impression of a superior quality to the customer. The better acoustic performance of the vehicle gives the competitive edge to the manufacturers. This is putting pressure on the automotive manufactures' to achieve the superior NVH performance of the vehicle.
In a two wheeler, apart from the power train noise, transmission noise and exhaust tonal quality; the structure-borne rattle noise threatens to achieve the better acoustic performance of the vehicle. Because of the presence of audible structure borne rattle noise in a motorcycle can convey the impression of poor quality to the customer.
In this paper, the focus is on experimental methodology for evaluation and elimination of structure-borne rattle noise in motorcycle. Emphasis is given to new techniques in the efforts made by Mahindra Two wheelers to move from “Road to Lab to Desk”. The structures like headlamp, odometer console, style panels are the major source for rattle noise. A motorcycle frame structure with all the suspected sub-assemblies for the structure-borne rattle noise is mounted on Electro-Dynamic Shaker (EDS). A sine sweep from 20-150 Hz was used as the input vibration for the test to simulate the real-world driving condition. The acoustic signature during test is measured and analyzed using state of the art equipments and software packages. The critical excitation frequencies and the sound pressure levels are identified. The similar noise experimentation with the “Method of elimination of the source” is used on actual vehicle in operating condition.
From the lab experimentation, the critical subassemblies are modified for reduced rattle noise. The CAE help is taken for the evaluation of the durability of the modified parts.
This approach has helped in reduction of the development time and achieving the superior NVH quality by eliminating the rattle noise.