Search Results

An overview of the analytical noise, vibration, and harshness (NVH) simulations performed to support the design and development of the Nissan Quest mini-van is presented. The use of analytical techniques on this project was unique in that analytical results were used to drive the pre-prototype design efforts, as well as to assist in the prototype development phase. Analytical models were developed, and simulations performed, prior to the release of prototype drawings. The simulation results identified necessary changes which were incorporated into the design. Once prototype vehicles became available, analytical simulations and development testing were used hand-in-hand to minimize development time as well as to optimize the cost, weight, and performance of NVH countermeasures. The extensive use of analytical simulations in the design and development process was critical in achieving the aggressive NVH performance objectives set for the vehicle.

An acoustic control technique for reducing booming noise caused by road surface roughness is described. This noise, mainly in the frequency range between 25 and 40Hz and accompanied by a pressure sensation, is closely related to suspension vibration characteristics and the acoustic response of the vehicle compartment. A reduction method which separates the highest acoustic response from suspension resonance in this frequency region is proposed. An acoustic simulation model is used to estimate the effects of the luggage compartment on this noise and of trunk lid vibration characteristics in optimizing acoustic properties of the compartment. As a result, a frequency region for trunk lid resonance which lowers booming noise is obtained. Estimated booming noise reduction is experimentally confirmed in road tests. A study of human auditory characteristics is also conducted to ascertain the frequency range and booming noise level which produce uncomfortable sensations.