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This paper describes the design, synthesis-analysis and development of the unique vehicle structure architecture for the fifth generation Chevrolet Corvette, ‘C5’, which starts in the 1997 model year. The innovative structural layout of the ‘C5’ enables torsional rigidity in an open roof vehicle which exceeds that of all current production open roof vehicles by a wide margin. The first structural mode of the ‘C5’ in open roof configuration approaches typical values measured in similar size fixed roof vehicles. Extensive use of CAE and a systems methodology of benchmarking and requirements rolldown were employed to develop the ‘C5’ vehicle architecture. Simple computer models coupled with numerical optimization were used early in the design process to evaluate every design concept and alternative iteration for mass and structural efficiency.

This paper describes some methods for greatly reducing or possibly eliminating subjective tuning of suspension parts for ride and handling. Laptop computers can now be used in the vehicle to guide the tuning process. The same tools can be used to select solutions that reduce sensitivity to production and environmental variations. OBJECTIVE Reduce or eliminate time required for tuning of suspension parts for ride characteristics. Improve the robustness of ride performance relative to variations in ambient temperature and production tolerances. PROBLEM REQUIRING SOLUTION AND METHOD OF APPROACH Traditional development programs for new vehicles include time-consuming subjective ride evaluations. One example is shock absorber tuning. Even if sophisticated models define force-velocity curves, numerous hardware iterations are needed to find valvings that will reproduce the curves. Many evaluation rides are needed to modify the valvings to meet performance targets.

This paper discusses four general attributes which quantify the character of an impulsive sound event. These attributes include the time duration, amplitude and frequency content of the impulsive noise. A three dimensional plot relating time, frequency and amplitude have been developed for the presentation of the measured data. This format allows graphic illustration of the noise event, providing fast interpretation and communication of the measured sound. Application of this methodology to the sound of an automotive door closing event is presented here. Representative door closing sound events are analyzed, with correlation presented between the attributes above to dynamic events of the physical hardware within the door and vehicle systems. Modifications of the door-in-white, internal door hardware, seal systems and additional content are investigated for their effect on the sound quality of the door closing event. Finally, recommended values for these attributes are presented.

In a complex system, large numbers of design variables and responses are involved in performance analysis. Relationships between design variables and individual responses can be complex, and the outcomes are often competing. In addition, noise from manufacturing processes, environment, and customer misusage causes variation in performance. The proposed method utilizes the two-step optimization process from robust design and performs the optimization on multiple responses using Hotelling's T2 statistic. The application of the T2-statistic allows the use of univariate tools in multiple objective problems. Furthermore, the decomposition of T20 into a location component, T2M and a dispersion component, T2D substitutes a complex multivariate optimization process with the simpler two-step procedure. Finally, using information from the experiment, a multivariate process capability estimates for the design can be made prior to hardware fabrication.

Microcomputer technology has added a new dimension to the design of test instrumentation, but the connotations of the name microcomputer have a tendency to build barriers rather than offer solutions to problems. Historically, computers have been treated as systems or identifiable subsystems in instrumentation applications. The implications of complex hardware and mystical programming is often sufficient to direct the user to alternate technologies. In a new light, clear of earlier prejudices, the microcomputer becomes a functional module like other LSI devices. Flexible and economical systems involving logical control, data gathering, and numerical calculations are possible utilizations of these relatively new devices. This paper discusses a facility to assist the designer in development of test instrumentation. Emphasis is placed on use of the microcomputer as an integral part of system design. Test instrument applications are cited.

From November 1970 through August 1971 an extensive program of static and dynamic air cushion inflation tests utilizing human volunteers was conducted at Holloman Air Force Base, New Mexico, sponsored by the Department of Transportation. Forty-one full cushion deployment static firings were made, with air cushion hardware and seating buck environment designed by General Motors. The static series was followed by 35 dynamic sled firings of human volunteers, beginning at 8.6 g (15.1 mph) and culminating at 21.7 g (31.5 mph). A major objective of both the static and dynamic test series was to identify changes in air-cushion design found necessary to improve its protective capability for human beings. Because of the severity of cushion deployment, one modification was made following the initial static tests: The orifice diameter size of the bag inlet was reduced from 1.0 to 0.6 in to diminish the rapidity of bag inflation. This modification proved effective in the dynamic series.

Today's world places increased emphasis on society's members to know more, to do more, to see more. Increasingly, information is thrown to the consumer that he/she has to process almost continually, regardless of their surroundings. Due to this heightened need, the customer is becoming increasingly perceptive of their vehicle surroundings, expecting their vehicle to be an extension of their home and/or office, to assist in getting things done in an environment that is as convenient and comfortable as their primary workplace. Similarly, there is also increased emphasis on vehicles to be styled so that they are visually appealing, so that all the parts work as a whole to make the environment as enjoyable as consumers' most pleasant surroundings outside the vehicle.

A methodology involving Design for Six Sigma (DFSS) and Multi-body dynamic simulation is employed to tune a body-on-frame vehicle, for improved ride (shake) performance. The design space is limited to four sets of symmetric body mounts for a vehicle. The stiffness and damping characteristics of the mounts are the control factors in the virtual experiment. Variation of these design parameters from the nominal settings, as well as axle size, tire and wheel combinations, tire pressure, shock damping, and vehicle speed constitute the noise factors. This approach proves to be an excellent predictor of the vehicle behavior, by which much insight as to influence of each parameter on vehicle performance is gained. Ultimately, specific recommendations for the control factor settings are provided. Subsequent hardware builds show excellent agreement with the analytical model and suggested tuning.

Brake squeal has been analyzed by finite elements for some time. Among several methods, complex eigenvalue analysis is proving useful in the design process. It requires hardware verification and it falls into a simulation process. However, it is fast and it can provide guidance for resolving engineering problems. There are successes as well as frustrations in implementing this analysis tool. Its capability, robustness and reliability are closely examined in many companies. Generally, the low frequency squealing mechanism is a rotor axial direction mode that couples the pads, rotor, and other components; while higher frequency squeal mainly exhibits a rotor tangential mode. Design modifications such as selection of rotor design, insulator, chamfer, and lining materials are aimed specifically to cure these noise-generating mechanisms. In GM, complex eigenvalue analysis is used for brake noise analysis and noise reduction. Finite element models are validated with component modal testing.