During the vehicle development process, usually we find difficult compromises between a good stability and roll control levels and an acceptable comfort for secondary ride, i.e., the noise and vibration insulation provided by the suspension system.
During a recent development for MMC Automotores do Brasil (Mitsubishi), similar difficulties were found. One of the engineering actions taken to achieve a good secondary ride level was to develop new suspension bushings, to allow better vibration insulation.
In this work it was decided to make use of a new procedure, based on instrumented subjective evaluations, with posterior analysis done by the NHT consultancy, using the Pulse software, from BRUEL & KJAER (B&K).
Based on previous experience, we know that, using more conventional methods, measuring the vibrations before and after the bushing to be studied, and comparing the input and output spectra, it will result in a very difficult task, and a very time consuming analytic work. In the other hand, trusting only in subjective evaluations, it will lead to a longer development time, with greater number of experimental samples, selected only in a trial and error basis.
To increase the quality and speed up the development process, it was decide to use the resources provided by the “transfer function analysis”. This paper describes the use of such method, in comparison with more traditional ones, and its correlation with laboratory and subjective evaluations data from the several experimental bushings.