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This paper outlines the critical factors that must be considered in obtaining good torque control of threaded fasteners when using power tools: torque and tension and control of friction, torque rate, relaxation, multiple fasteners, and measurement errors. The construction of the various pneumatic power tools available to industry today are described, along with their applications. Included are impact wrenches, torque control impact wrenches, screwdrivers, angle wrenches, and assembly machines.

On high-speed, dual-lane expressways, such as the interstate highway system, drivers encountering problems usually park their vehicles on the highway shoulder in close proximity to the outer lane. If a tire change is required, then the vehicle must be jacked up and the aerodynamic inputs from passing vehicles become a design criteria for jacking systems. The study covered by this paper was carried out to determine the magnitude and time history of these aerodynamic forces and moments.

The aerodynamic features of the race version of the Charger Daytona, an aerodynamically modified 1970 Charger, are discussed. Effects of major specific modifications are evaluated individually and as a total package. Wind tunnel techniques and philosophy employed in the Daytona Development Program are also discussed.

A complete survey covering the almost 50 years of automotive aerodynamic research that began in the early 1920's details the development and use of wind tunnel facilities for cars in Germany, Great Britain, Italy, and the United States. Contributions of key researchers are described and referenced, as are the automobiles that stand as landmarks in the reduction of drag coefficients from as high as 0.66 to a modern low of 0.11.

The effects of aircraft-loading parameters on the fatigue behavior of titanium alloy have been investigated for a schedule of stresses representing the flight-by-flight variation of stress at a point in the lower wing surface of a supersonic airplane. The effects on fatigue life of design mean stress, minimum stress for ground-air-ground cycles, taxi stress, thermal stress, elevated temperature, salt corrosion, and flight duration were investigated. Of the loading parameters studied, the design mean stress and the minimum stress for ground-air cycles had the greatest effects on fatigue life. Simulated taxiing and thermal stresses, elevated temperature, and salt corrosion had smaller effects on fatigue life. Fatigue lives at 550 F (560 K) were about half as long as at room temperature for most conditions investigated. The effect of the difference in flight duration on fatigue life was less than a factor of 2.

The corrosion performance of alloys considered suitable for automotive terminal systems are examined. General corrosion is insignificant when copper alloys are used. The designer can avoid stress corrosion by choosing from a complete range of mechanical and electrical property combinations in less sensitive and even immune copper alloys. Crevice corrosion can be minimized chiefly by designing to eliminate crevices and also by choice of less susceptible alloys. Finally, dezincification can be overcome by using less susceptible modified brasses or inhibited brasses; lower zinc alloys or alloys not containing zinc may also be used.

Load spectrum testing is an advance toward the ultimate purpose of fatigue testing, that is, prediction of life in advance of service. The relative merits of the three basic approaches to load spectrum testing, the Programmed Fatigue Test, the Service Duplication Test, and the Random Load Spectrum Test, are discussed and compared to the conventional Constant Amplitude Test technique. Practical examples from car and truck engineering are given for each of the three test techniques, and a general introduction to the new test concept of random load spectrum testing is included. Advantages cited are: good correlation to service life, low scatter of results, and reduction of overall test time. Detailed knowledge of service load histories is required, as is test machinery with suitable frequency response.

The design and development of a new series of V-type diesel engines featuring air cooling and direct injection is described. With this family of 6, 8, 10, and 12 cyl powerplants, which are available as naturally aspirated, turbocharged, and turbocharged engines with intercooling, an output range of 150-500 hp is covered. A one cylinder unit is standard for all engines. Details are given of the development work of some assemblies, especially crankcase, connecting rod, and cylinder head and its bolting. Extensive field and bench testing of the engines have revealed excellent durability, good fuel economy, and low noise level.

Problem areas in producing a range of multicylinder, aircooled diesel engines for universal application are described. If the manufacturer has dealt with water-cooled engines the design expertise between water cooling and air cooling is inter-related to a certain point and it is from this point that the technique required must be changed to satisfy the aircooled unit. A multipurpose design has more inherent problems than a design aimed for a specific application and it is necessary to consider all the side effects involved. Problems faced in the development of the cooling system, piston design, valve mechanisms, engine ratings, etc. for the range of Dorman's “DA” aircooled engines are highlighted. Ideal applications for the 6 and 8-cyl engines are in short haul work with maximum stop and start operation. Many installations have been made in earthmoving and snow-blowing equipment. Additions in the 8-cyl unit are planned.

Uses of solvent and evaporative type adhesives in the automotive industry are reviewed. The use of adhesives is traced from the earliest days when fasteners were screws, nails, and wood glue to the development of neoprene type adhesives used during late 1940's, and to the evaporative adhesives made from synthetic elastomers and resins in use today. Specifications are presented covering requirements of a sprayable, fast air-drying rubber based solvent type adhesive, as well as requirements for a fast-setting synthetic water dispersion adhesive system. Problems facing automotive engineers in selection of adhesives are demands for safety, elimination of toxicity, danger of flammability, and air pollution control. The future of automotive solvents and evaporative adhesives is an exciting one and new developments such as irradiation activation and ultrasonic curing will help meet challenges of the future.

Many mechanical properties of composite materials are affected by the nature of the adhesion between the phases. Adhesion plays an especially important role in determining the stress-strain behavior of composites, but quantitative theories have been developed only for the elastic moduli. Dynamic mechanical properties (especially damping) are also strongly dependent upon the type of adhesion between the phases.

A case is made for the consideration of the effects of boundary layers on the mechanical properties of composite structures such as adhesive joints. Because boundary layers do exist (for example, oxides on metals, transcrystallinity in certain polymers), it is not sufficient to consider that only surface chemical and bulk mechanical properties determine joint behavior. Several different kinds of boundary layers are shown to exist in polymeric materials and certain of their properties are described. Illustration of their relevance to adhesive joint behavior is given.

The different types of intermolecular forces that can act across an interface are reviewed. In the case of the dispersion force and the dipole-dipole force, quantitative calculations can be made, to predict the energy of adhesion and the interfacial free energy. The relationship between the “interaction parameter” method of Girifalco and Good and the “dispersion component of surface tension” method of Fowkes is discussed. Forces across interfaces due to hydrogen bonds, to ionic attraction, to metallic forces, and to covalent bonds are also discussed.

A method of calculating mass burning rates for a single cylinder spark-ignition combustion engine based on experimentally obtained pressure-time diagrams was used to analyze the effects of fuel-air ratio, engine speed, spark timing, load, and cyclic cylinder pressure variations on mass burning rates and engine output. A study of the effects on mass burning rates by cyclic pressure changes showed the low pressure cycles were initially slow burning cycles. Although large cyclic cylinder pressure variations existed in the data the cyclic variations in imep were relatively small.

The effect of knock intensity on exhaust emissions was examined in a single cylinder spark ignition engine. The exhaust components surveyed were carbon monoxide, carbon dioxide, oxides of nitrogen (as NO), and total unburned hydrocarbons. Knock was induced solely by changing the spark timing. To describe knock intensity quantitatively, the magnitudes of the rate of pressure irregularities occurring during the combustion process were utilized. The use of the rate of pressure change to define a quantitative knock intensity scale is supported by an apparent generalization of the stoichiometric air-fuel ratio data. Graphs are presented that indicate the dependency of power output as well as exhaust emissions on knock intensity for various air-fuel ratios.

Race car designers have relied heavily upon mechanical creativity to gain a competitive edge in racing. The Armco/McKee Can-Am car is not short in its mechanical innovations, but the program objective was to demonstrate the merits of special aircraft steels and titanium in a road racing vehicle. The design advantages gained in the use of these very high specific strength and specific modulus materials are shown. Their use in future racing cars will be more in the area of highly stressed components, rather then complete vehicle concepts. Their use in passenger cars will also be in highly stressed components, and will depend upon the emphasis placed on power/weight ratios of specialty vehicles.

The importance of ceramic cutting tools in machining operations is briefly discussed. The fabrication, properties and microstructure of ceramic tools are reviewed. Ford dispersion strengthened ceramic cutting tools are described in some detail along with some performance data in both laboratory and field tests.

The paper describes the development of new methods of turbocharging 2-stroke cycle engines. Work on the normal simple system, which has a turbocharger alone, and the series turbocharging system which employs a Roots blower after the turbocharger, showed their limitations and potentialities. In developing a system incorporating the best features of each, the throughput of the engine driven blower was controlled to make the air delivery of the series turbocharging system more similar to that obtained with simple turbocharging, thus greatly improving the fuel consumption and torque curve of a vehicle sized engine. A second change was to use the two types of charging systems on the same engine, thereby halving the size and parasitic losses of the engine driven blower. This gave further improvement in fuel consumption and is suitable for engines large enough to use two turbochargers.