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Interest in the use of high strength cold-rolled steel sheets is growing primarily because of the greater weight reduction that can be realized in automotive vehicles when the thinner gage, higher strength cold-rolled sheets are substituted for the heavier gage hot or cold rolled sheets currently used. Today's steelmakers have considered and tried a number of metallurgical alternatives and philosophies which have resulted in the production and availability, either in commercial or developmental quantities, of formable, high-strength, cold-rolled steels with yield strengths in the range of 50 to 120 ksi. These steels have as good or better properties as the standard, lower strength, cold rolled steels.

A laboratory simulation of dawn/dusk illumination showed that following vehicles could be detected equally well in plane and convex mirrors, and a night driving test showed that low- and mid-beam headlamps of a following car produced discomfort glare responses that were independent of whether the exterior mirror was plane or convex. Visibility of the following car was rated better with the plane exterior mirror. Measures of performance of drivers relevant to safety in lane changing and passing were not different when they used a plane or convex exterior mirror in conjunction with a plane interior mirror, and did not differ in the day or at night. When the initial speed of the overtaking car was 15 mph (24 km/h) greater than the subjects' car, drivers significantly underestimated the relative speed, indicating a potential cause of collisions with a following vehicle in lane changing and passing maneuvers.

Twelve passenger and three truck rear vision systems were evaluated under real-world driving conditions using driver looking behavior as performance measures. Glance duration and frequency at each rear vision device, as well as glances made directly to the side/rear scene, by six experienced drivers during 22 traffic maneuvers were recorded using direct video recording of eye movements. Over 20,000 rear information gathering glances were analyzed with regard to glance location, frequency, duration, total glance time per maneuver, and number of glances per maneuver for each system. Superior rear vision systems were identified and design implications regarding multiple device systems, convex devices and field of view were drawn. Ground plot field of view maps and Docket 71-3a target field of view coverage for each system was determined. A secondary study used expert judgment techniques to obtain estimates of rear scene zone criticality.

Several independent studies of sound level variation with nominal microphone distance are reported for a variety of equipment types tested in accordance with SAE exterior sound level test procedures. Good correlation between levels and distance is shown, although dependent on equipment type and mode of operation. It is concluded that predictions of sound levels at distances closer to the source than the normally-specified microphone distance can be made with reasonable accuracy.

Photographic and performance studies with a Rapid Compression Machine at the Massachusetts Institute of Technology have been used to develop insight into the role of mixing in diesel engine combustion. Combustion photographs and performance data were analyzed. The experiments simulate a single fuel spray in an open chamber diesel engine with direct injection. The effects of droplet formation and evaporation on mixing are examined. It is concluded that mixing is controlled by the rate of entrainment of air by the fuel spray rather than the dynamics of single droplets. Experimental data on the geometry of a jet in a quiescent combustion chamber were compared with a two-phase jet model; a jet model based on empirical turbulent entrainment coefficients was developed to predict the motion of a fuel jet in a combustion chamber with swirl. Good agreement between theory and experiment was obtained.

Better fluid mixing in automobile engines can contribute to fuel economy, smoothness of engine operation, and reduction of emissions. It is possible to improve the uniformity of mixture of fuel with air in the induction system, of trapped burned gas with the charge in the cylinders, and of air with the exhaust gas in a reactor. Criteria of uniformity of mixing are discussed and a more stringent criterion suggested. The mixing length concept is developed. Fluid flow mixing models for different passage geometries are presented and evaluated for mixing length. Mixing performance of the induction system and cylinders of a typical engine are estimated. Improved mixing means are proposed and described. Maximum uniformity of distribution of the charge involves effective vaporization of fuel and mixing with the air ahead of the intake manifold. Maximum uniformity of mixture and turbulence prior to combustion involves the mixture of the trapped burned gas with the charge in the cylinders.

The transfer functions of a vehicle's dynamic systems, which denote the exciting force characteristics of driveline, vibration transmissibility of body structures and the characteristics of acoustic radiation from vehicle floors, are determined by forced vibration experiments. These three transfer functions are combined together into one, and frequency response characteristics of the vehicle's dynamic systems, composed of vibration and acoustic elements, are obtained by computer simulation techniques. By application of this approach, the relationship between the sound pressure in the passenger compartment and the dynamic parameters of vehicle components is investigated and the technical criteria for improvement of vibration/acoustic characteristics are clarified.

A gear noise control device for quality inspection in the production line is presented. Through analysis of the noise coming from the gear housing, this device can detect gear defects like nicks, eccentricities, and noisiness. It has proved reliable and not sensitive to external environmental condition changes.

A theoretical and experimental study of the vibrations of the conventional driveline of a car with a rear-wheel drive has identified at least 11 modes of vibration in the range 10-200 Hz. There are indications that a simple theoretical model, which ignores coupling with the vibration modes of the body, is adequate to predict the most important modes. It is found that the model can be improved by the inclusion of the dynamic characteristics of the rubber insulators in the system and the gyroscopic effects of the rotating wheel. A significant increase of the noise level in the interior of the vehicle was attributed to the first bending mode of the rear axle. Random excitation by force inputs at the road surface, and forces and couples at twice the frequency of rotation of the driveshaft and engine crankshaft, cause the major resonance.

The growing emphasis on reducing automobile weight is likely to lead to the use of increasing quantities of high-strength, cold-rolled steel sheet in the near future. The reasons for this probable trend (such as production restrictions on producing hot-rolled sheets having thicknesses below 0.070 in and potential weight savings from thinner body panels) are reviewed briefly. Because many steel producers are developing new steels and practices to expand their range of high-strength, cold-rolled sheet grades, the technical approaches available for producing high strengths in cold-rolled steel sheets are also reviewed. Possible methods for increasing the strength of steel sheets are discussed.

Four families of low-carbon, high-strength cold-rolled (HSCR) sheet are discussed, exhibiting minimum yield strengths of 40 to 140 ksi. The relative merits of the various grades are analyzed in terms of important fabricating and selection criteria: strengthening capability, planar anisotropy, formability, impact loading response, weldability and cost reduction. Paralleling the increase in strengthening capability in HSCR was an increased planar anisotropy and variation in formability within the various families. The impact loading of all cold-rolled grades showed increased yield strengths and energy absorption; the weldability of the different grades varied widely depending upon strengthening mechanisms, strength level, and chemistry; the cost reductions possible with the HSCR decreased as the degree of formability required in the finished part increased. Generally, gauge reductions of 6% to 34% were found to be necessary to offset cost extras for different grades of HSCR sheet.

High-strength cold-rolled sheet steels offer a potential to accomplish weight savings through gage reductions. However, the reduced formability which accompanies increased strength presents difficulties in the application of these steels for sheet metal stampings which require the formability equivalent of deep-drawing steels. A new deep-drawing sheet steel is being developed which overcomes the formability limitations of high-strength cold-rolled steels. Parts made from this steel can be uniformly strengthened to a high yield strength, up to 120,000 psi (827 MPa). Strengthening is accomplished by a 1200°F (921°K) heat treatment in a controlled atmosphere which results in internal nitridation. The nitrides formed by the alloying elements in the steel provide precipitation hardening. No distortion of the parts results from the heat treatment. The effect of heat-treating variables on tensile properties, weldability, fatigue, and toughness, are discussed.

Increasing secondary powerloads, advanced technology components, varied installations, and increased emphasis on cost and performance provide the requirements against which the engine project engineer must seek a balance during the conceptual, design, and development phases of an engine program. This paper reviews the requirements for advanced engine secondary power systems and some of the trends which are developing for future propulsion systems.

A new NATO patrol hydrofoil missile (PHM) is being developed, with the first lead ship nearing completion. The automatic control system (ACS), which provides the foilborne vehicle control, is newly developed for PHM. The ACS development evolved primarily from two previous hydrofoil control systems: Tucumcari and High Point. The ACS functional configuration was evolved using a highly developed digital simulation of the craft, control hardware, and sea conditions. Extensive failure mode and effect analyses were used to evolve a ship/control system configuration which is fail-safe for single-level failures within the system. From the overall performance, stability, and failure analyses, significant evolutions in the control system configurations resulted. The ACS hardware is newly developed for PHM, building around new families of integrated circuit building blocks.

Development and application of computer analysis to the flow system of the internal combustion engine is discussed. Particular attention is directed to the crankcase-scavenged, two-stroke-cycle, spark ignition engine, with the objective of optimizing the relationships between its complex transient flow processes and its basic mechanical simplicity. The aspects of specific output and fuel consumption, as well as those of the emission of noise and other obnoxious constituents of the exhaust, are considered. A systematic procedure is presented for determining the most practical port and duct dimensions for a new engine application.

Teledyne Continental's new Red Seal industrial engine line incorporates the Controlled Pressure Combustion System (CPCS) featuring emissions control, fuel efficiency and driveability, without sacrificing maximum power. These new, low maintenance engines are based on time-proven mechanical components with a new cylinder head, carburetor and electronic ignition. The complete R & D history of the program is presented, covering cylinder head, carburetion and ignition system. The paper describes an Automotive Program with two cars, matched and optimized to meet the 1975 Light Duty Automotive Standards without using any exhaust after treatment or other emissions control devices.

In an Energy Management Bumper System (EMBS) maximum energy-absorption efficiency is achieved with a “square wave” load/deflection response. The laboratory and barrier impact tests conducted in this study show that elastomeric columns provide essentially square wave response during the buckling stage of column deflection. Of the materials tested, high diene-low Mooney EPDM (terpolymer of ethylene, propylene and a diene) materials fabricated into hollow cube absorber units exhibited square wave efficiencies of 85-90% and were found to be the most suitable elastomers for an EMBS application. The efficient use of the elastomeric absorbers in an EMBS was accomplished by placing a metal face plate in front of the units to distribute the impact force across the face of the vehicle. This concept was applied to an engineering design for a 3000 lb. vehicle EMBS that would handle impacts at 5 mph in compliance with Federal Motor Vehicle Safety Standard No. 215.

A modified version of the pneumatic air cushion bumper has been incorporated into the basic design of a prototype automobile designed to provide improved structural performance during front, side, rear, and rollover collisions. A simple air bladder, recessed within a high-strength bumper bar, was supported by the front cross member of a modified frame which also served as a supplementary volume to reduce peak pressures and loads. Check valves were located between the bladder and the frame chamber to limit energy of rebound. Test results showed that the design is suitable for incorporation into vehicles intended to withstand barrier crashes of 5-10 mph.

During the past two decades, front-wheel-drive architecture has grown enormously in Europe. This trend can be explained by the need to provide compactness, large inside space, and good road holding. The paper describes technical problems that arise when designing a front-wheel-drive car and quotes the various technical solutions in current use. The authors conclude that a preference for front-wheel drive will last for a long time.

The performance of a hydrogen-supplemented fuels system is predicted using a semiempirical model. The prediction of this model is compared to data obtained during engine dynamometer tests of a hydrogen generator/multicylinder engine system. The test data and the predictions are also compared to the fuel consumption and emissions of the same engine in its stock configuration and indicate that the hydrogen-supplemented fuels system can improve BSFC 10-15% and simultaneously reduce NOx emissions to a level consistent with the 1977 EPA standard. The performance of an optimized hydrogen generator/engine system is estimated. With these comparisons and estimates used as a basis, the potential of the hydrogen-supplemented fuels system is identified.