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Vehicle transmission gear rattle is one of the most critical NVH irritants for refined vehicles. It is perceived more dominantly in lower gears of vehicle running. It depends on various design parameters like engine input torque amplitude & fluctuations, driveline torsional vibrations, gear micro & macro geometry, shaft flexibility, etc. Establishing exact contribution of each of these parameters to transmission rattle, thru experimental or simulation technique, is very challenging. Current paper explains the NVH CAE benchmark approach deployed to understand difference in rattle behavior of two transmission designs. Paper focuses on simulation of gear impact power and its sensitivity to transmission shaft deflections.

A bus is integral part of public transportation in both rural and urban areas. It is also used for scheduled transport, tourism, and school transport. Buses are the common mode of transport all over the world. The growth in economy, the electrification of public transport, demand in shared transport, etc., is leading to a surge in the demand for buses and accelerating the overall growth of the bus industry. With the increased number of buses, the issue of safety of passengers and the crew assumes special importance. The comfort of driver and passenger in the vehicle involves the vibration performance and therefore, the structural integrity of buses is critically important. Bus safety act depicts the safety and comfort of bus operations, management of safety risks, continuous improvement in bus safety management, public confidence in the safety of bus transport, appropriate stakeholder involvement and the existence of a safety culture among bus service providers.

Control of powertrain radiated noise and of excitations induced by the Powertrain through the mounts are key aspects towards designing the Powertrain induced NVH performance of a vehicle. During the concept, as well as later stages of Powertrain development, use of simulation tools for MBD, FEA and Vibro-Acoustics can help to evaluate and lead the Powertrain design decisions. In the present work, the flexible MBD software packages, AVL-Excite and MSC-NASTRAN, have been used to predict upstream mount vibrations and surface vibrations of the Powertrain structure. The radiated sound pressure was predicted using LMS Virtual Lab software. In MBD simulation of the Powertrain, the linear elastic Powertrain components (Crankcase, Cranktrain, Drivetrain, etc.) were FE modeled and condensed using MSC-NASTRAN; condensed linear elastic Powertrain components were then connected by means of non-linear joints at the bearing locations.