Vehicle automation and intelligent transportation systems will be the cornerstones of sustainable smart cities of the future. People movers seem to be at the heart of technology development, field trials and on-road testing, and strategic business partnerships when it comes to connectivity and automated driving. Majority of the focus has been on unmanned operation and door-to-door service in urban environments and not on highways. Highways are relatively simpler to handle from an engineering stand-point, but vehicles typically operate at higher speeds, so the cost of accidents is worse.
In today's automobile industry refined NVH performance is a key feature and of high importance governing occupant comfort and overall quality impression of vehicle. This paper interior noise measurement is done on one of the light truck and few dominant low frequency noise booms were observed in operation range. Modal analysis was done for the cabin at virtual as well as experimental level and few modes were found close to these noise booms. Vibrations were measured across the various cabin mounts and it was found that the isolation of front mounts is not effective at lower boom frequencies. Taking this as an input, the mount hardness and profile optimized to shift the natural frequency and hence improve the isolation behavior at the lowest dominant boom frequency. This was followed by static and dynamic measurement of the mounts at test rig level and finally the interior noise measurement after fitment on truck.
In current automotive industry, it is well known that the driveline subsystem and components are normally from different automotive suppliers for OEMs. In order to ensure proper system integration and successful development of driveline system NVH performances, collaboration efforts between OEMs and suppliers are very demanding and important. In this paper, a process is presented to achieve successfulness in developing and optimizing vehicle integration through effective teamwork between a driveline supplier and a major OEM. The development process includes multiple critical steps. They include target development and roll down, targets being specific and measurable, comprehension of interactions of driveline and vehicle dynamics, accurate definition of sensitivity, proper deployment of modal mapping strategy, which requires open data sharing; and system dynamics and optimization.
In recent truck applications, single-piece large-diameter propshafts, in lieu of two-piece propshafts, have become more prevalent to reduce cost and mass. These large-diameter props, however, amplify driveline radiated noise. The challenge presented is to optimize prop shaft modal tuning to achieve acceptable radiated noise levels. This paper will cover the development of a two-step CAE method to predict modal characteristics and airborne noise sensitivities of large-diameter single piece aluminum propshafts fitted with different liner treatments. The first step is the use of a traditional CAE software to calculate prop surface response. The second step is a boundary element simulation to calculate prop surface radiating noise under the excitation obtained from the first step. Finally, test data, acceleration and acoustic, in both subsystem and vehicle levels are presented to assess the accuracy of the CAE method.
Cabin acoustic comfort is a major contributor to the potential sales success of new aircraft, cars, trucks, and trains. Recent design challenges have included the increased use of composites, and the switch to electrically powered vehicles, each of which change the interior noise spectral content and level. The role of acoustic absorption in cabins is key to the optimisation of cabin acoustic comfort for modern vehicles, with acoustic impedance data needed in order to assess and optimise the impact of each component of a given lay-up. Measurements of absorbing interior trim are traditionally performed using either sample holder tests in a static impedance tube (impedance and absorption), or through tests in reverberation rooms (absorption only). Both of these procedures present challenges. In-tube absorption and impedance measurements are destructive, requiring highly accurate sample cutting and sealing.
Increased public pressure to improve commercial truck safety and new stopping distance regulations have intensified the need to better understand the factors influencing heavy vehicle braking performance. To assist individuals and their organizations in preparing for these new truck braking standards, this seminar focuses attendees on understanding medium-duty hydraulic brake systems and heavy-duty air brake systems and how both systems' performance can be predicted, maintained and optimized.