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With the increasing necessity of reducing the development time of new products, and also the need to evaluate product reliability levels, a trend to rationalize field tests through test benches has been noted. These tests have proved more and more representative and carried out in much lower times and with lower costs. In the automotive industry this trend has generated considerable effort towards making these bench tests more representative of actual conditions towards the increase of their reliability. The quantity of simulated parameters is growing and it becomes necessary to collect more data from ground measurements signal (acceleration, temperature, pressure, flow, etc.) in experimental vehicles.

Since the rising of the automotive industry, the concern with the driving itself has been the main task of the developments, which have improved the safety-related vehicle systems, such as headlamps and signalling devices that have received significant investments in technology. The paper deals with some functional and durability tests applied to illumination and signalling devices used in the automotive industry. We describe some durability tests like: vibrations, sealing tests, vehicles tests, …… emphasizing the research regarding headlights internal pressure variations relative to the protection against adverse environmental conditions. Concerning functional tests we focus those related to Photometry and Colorimetry, using Psychophysical parameters and the CIE International System XYZ (Commission International de l'Eclairage).

Competition in Automotive Market is driving the need for more time - and cost - effective testing methods. In the fatigue life analysis of new passenger and commercial vehicle designs, laboratory testing through servohydraulic equipment plays a very important role. In DaimlerChrysler do Brasil, the Durability Test Laboratory represents an important basis to assure high endurance reliability for all kinds of our commercial vehicle applications. In order to respond to the above mentioned testing tasks, this paper will focuse what we call our “New Policy of Durability Tests for Commercial Vehicles”, based on development of simple and low cost Road Simulators, fully dedicated and customized to testing of vehicle components and chassis. Experimental results as well as other data related to consumption of laboratory's: area, utilityes, pressurized hoses and test time, will be used in order to illustrate advantages and disadvantages of the new testing resource.

In order to attend the more demanding expectations of the commercial vehicles customers, it is being looked for improvements in order to reach better comfort on driving. Among the systems that interact with the driver, the shifting system can be distinguished. The development of a commercial vehicle shifting system is getting complex, because besides making possible the gear changes, it should follow comfort, ergonomics and durability parameters, balancing the necessary robustness for heavy applications with the shift smoothness desired by the user. At the start of the development of commercial vehicles shifting systems, the concept to be applied is analyzed, defining the model. Then it starts the study of the system construction, according to layout parameters of the vehicle project. This stage is predominantly accomplished by computer models. Then the prototypes are manufactured, in which functional tests are made for refinement.

The paper looks for the degree of linear correlation of some acoustic parameters concerning Speech Intelligibility in vehicles. The Articulation Index (AI) was originally a criterion to characterize the influence of parasite noise on the Intelligibility of a conversation in the design of speech communication systems. Introduced in the automobile acoustics, it is more and more commonly used by vehicles manufacturers to estimate the middle and high frequency content of spectra noise inside various types of vehicles driven under several running conditions. The correlation with Speech Intelligibility, measured through subjective measurements is well known. Presently we have more sophisticated parameters like STI, RASTI, SII… directed mainly to architectural acoustics and sometimes used in vehicle acoustics. They require specific hardwares and softwares and are more complicated to deal with and often are called machine measures of Speech Intelligibility.