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A radiometric method has been developed for the determination of camshaft wear during engine operation. After a radioactive tracer is induced at the tips of one or more cam lobes by the technique of surface layer activation, calibration procedure are performed to determine the amount of radioactive material remaining versus the depth worn. The decrease in γ-ray intensity measured external to the engine is then directly related to cam lobe wear. By incorporating a high-resolution detector and an internal radioactive standard,measurement accuracy better than ±0.2 μm at 95% confidence has been achieved. Without the requirement of engine disassembly, this method has provided unique measurements of break-in wear and wear as a function of operating conditions. Because this approach requires only low levels of radiation, it has significant potential applications in wear control.

Utilizing unembalmed cadaver test subjects, a series of tests was carried out to characterize quantitatively the resistance of the skin, the soft underlying tissue of the scalp, and certain other typical areas of the body to impact loading. The impacts were delivered by the use of an instrumented free-fall device similar to that previously employed for facial bone fracture experiments. In one group of tests, metal and glass edges were affixed to the impacting device to produce localized trauma under conditions which were standardized with respect to variables affecting the degree of the injury. In the second group of experiments, specimens of skin, together with underlying tissue of uniform thickness, were subjected to compressive impact between the parallel surfaces of the impacting weight and a heavy metal platen. From these latter experiments the force-time histories, coefficient of restitution, and hysteresis loops of load versus deflection were obtained for the specimens.

Noise produced by automotive ignition systems can deteriorate the performance of nearby communication systems. An important step toward alleviating this difficulty is to characterize the ignition noise. Measurements have been made of the noise peak amplitude distribution of a number of identically equipped vehicles over a fixed period of time. Both vertical and horizontal polarizations were used, and measurements were made at two frequencies, 145 and 230 MHz. These statistics were then compared to various probability distributions to attempt to characterize the amplitude distribution of the noise. The distributions studied were: the log-normal, the exponential, the Rayleigh, and the Weibull distributions. It was concluded that the best fit was provided by the Weibull distribution. The parameters of the best fitting distribution are primarily a function of the antenna's polarization, with frequency having only a minor effect.

This paper evaluates the tendency of lip seals to fracture in a test apparatus in which dynamic runout is 0.010 in and the temperature is cycled between -30 and 0 F. Seals made of eight different polyacrylate polymers were soap-sulfur cured with various types and amounts of carbon black. Physical tests included room-temperature flexibility defined by Young's modulus at small strains, standard tensile tests at room temperature, flexibility at sub-zero temperatures determined by a Gehman test, and sub-zero starting torques of the seals. Primary determinant of successful fracture resistance is a low starting torque resulting from good low-temperature flexibility. The effect of adding graphite to some of these formulations is described and some current commercially available seals are evaluated.

This paper summarizes an analysis, design, and test project in which a dummy chest structure was developed. The chest consisted of mechanical elements that had been characterized by computer simulations as giving responses to blunt frontal impacts necessary for biofidelity. An analysis of mechanical rib structures indicated that materials having a high ratio of yield stress to modulus of elasticity were required. Only metals having unusually high yield strengths, such as spring steels, qualified. A mechanical system was developed with steel ribs pivoted at each end as a primary spring. A secondary spring was a pair of commercially available die springs acting in parallel with the ribs after 25.4 mm (1.00 in) deflection. A fluid damper was developed to provide the damping. The chest structure was tested under conditions modified from those used by Kroell. The modifications were holding the spine rigidly and reducing the impact masses.

At the 1970 SAE International Automobile Safety Conference, the first experimental chest impact results from a new, continuing biomechanics research program were presented and compared with earlier studies performed elsewhere by one of the authors using a different technique. In this paper, additional work from the current program is documented. The general objective remains unchanged: To provide improved quantification of injury tolerance and thoracic mechanical response (force-time, deflection-time, and force-deflection relationships) for blunt sternal impact to the human cadaver. Fourteen additional unembalmed specimens of both sexes (ranging in age from 19-81 years, in weight from 117-180 lb, and in stature from 5 ft 1-1/2 in to 6 ft) have been exposed to midsternal, blunt impacts using a horizontal, elastic-cord propelled striker mass. Impact velocities were higher than those of the previous work, ranging from 14-32 mph.

A professional high diver, instrumented with accelerometers, performed sixteen dives from heights between 27-57 ft. For each dive, he executed a 3/4 turn and landed supine on a 3-ft deep mattress which consisted of pieces of low-density urethane foam encased in a nylon cover. Using FM telemetry, sagittal plane decelerations were recorded for a point either on the sternum or the forehead. Impact velocities and corresponding stopping distances for the thorax and the head were calculated from high-speed movies of the dives. For a 57-ft dive, the impact velocity of the thorax was 41 mph with a corresponding stopping distance of 34.6 in. The peak resultant deceleration of the thorax was 49.2 g with a pulse duration of 100 ms. The maximum rate of change of the deceleration of the thorax was 5900 g/s. No discomfort was experienced as a result of this impact. The maximum forehead deceleration occurred during a 47.0-ft drop and exceeded 56 g with a Gadd Severity Index greater than 465.

To lower emissions from a multicylinder engine, the air-fuel ratio must be optimized in all cylinders. If uniform fuel distribution is achieved, then the cylinder-to-cylinder air distribution is of particular interest. A probe system has been developed to measure mass flow rates to individual cylinders during operation of a complete engine. Fast response measurements of pressure, temperature, and flow velocity are made in the intake port near the valve during the intake portion of the cycle. High-speed collection of the large volume of data was accomplished through on-line use of an IBM 1800 computer. A V8 455 CID (7457 cm3) engine with stock intake and single exhaust system was used in the initial application of the mass flow probe. Measurements of 30-40 individual cycles were combined to calculate the mean volumetric efficiency for each cylinder.

Platinum, palladium, and copper-chromium oxidation catalysts for exhaust emission control were exposed to exhaust gases from a steady-state engine dynamometer test in which the amount of oil consumed per unit volume of catalyst was high. When unleaded gasoline (0.004 Pb g/gal, 0.004 P g/gal) was used, conventional SE oil caused somewhat greater loss of catalyst activity than an ashless and phosphorus-free (“clean”) oil. Chemical analysis of the catalyst indicated that phosphorus from the conventional oil was probably responsible for the difference. However, a test run with low-lead (0.5 Pb g/gal, 0.004 P g/gal) gasoline and “clean” oil caused much greater catalyst activity deterioration than either of the tests with unleaded gasoline.

A five-vehicle, 64 000-km test with 7.45 litre V-8 engines was conducted to determine if synthetic engine oils provided performance sufficiently superior to that of conventional engine oils to permit longer oil change intervals. The results show better performance in two areas of deposit control; inferior performance with respect to wear protection; and essentially equivalent performance in the areas of fuel and oil economies. Based on these data, it was concluded that synthetic engine oils do not provide the necessary performance required to safely recommend their use for extended oil change intervals. In addition, a cost analysis shows that the use of synthetic engine oils, even at a change interval of 32 000 km, will essentially double the customers' cost compared with conventional engine oils at GM's current 12 000-km change interval.

Several polymeric materials were developed and evaluated for possible inclusion in the neck structure of state-of-the-art anthropomorphic dummies. These included three types of foam-polyvinylchloride, polyethylene, and polyurethane, and two flexible polymers-polyurethane and a polyvinylchloride chlorinated polyethylene blend (PVC-CPE). Two materials, the polyurethane elastomer and the PVC-CPE blend, were found to be satisfactory in their dynamic response. Because of the ease of casting, the polyurethane material will be used in the GMR 1 state-of-the-art dummy.

One of the prime requisites for automobile radar systems is obstacle hazard evaluation, the extent needed being dependent upon the particular system application. Much of the information necessary for a radar system to assess the degree of hazard of a target must come from characteristics which can be measured by the radar itself. While the hazard evaluation capacity has not yet been developed for automobile radar systems, research to provide this capability is in progress. Continuous wave (CW) scattering measurements have been made in a manner which is consistent with automobile radar operation. Various aspects of simple targets and of an automobile were measured in a microwave anechoic chamber. Both horizontal and vertical linear polarizations were transmitted and their co-linear and cross polarizations received. These data have been used to confirm the existence of and to understand certain scattering mechanisms.

During development of the General Motors rotary engine, the lubricant was recognized as important to its success because certain lubricants produced deposits which tended to stick both side and apex seals. Consequently, it was decided to develop a rotary engine-dynamometer test, using a Mazda engine, which could be used for lubricant evaluation. In an investigation using an SE engine oil with which there was rotary engine experience, engine operating variables and engine modifications were studied until the greatest amount of deposits were obtained in 100 h of testing. The most significant engine modifications were: omission of inner side seals, plugging of half the rotor bearing holes, pinning of oil seals, grinding of end and intermediate housings, and using a separate oil reservoir for the metering pump. Using this 100 h test procedure, three engine oils and five automatic transmission fluids were evaluated.

Automatic transmission fluids can oxidize with use, causing marginal transmission performance and eventual transmission malfunction. Periodic fluid changes are presently recommended to alleviate this problem. Fluid oxidation is promoted in current transmissions because they breathe air freely through a vent tube. To reduce fluid oxidation, and thereby improve fluid and transmission durability, a one-way check valve, called the Transmission Air Breathing Suppressor (TABS), was designed to restrict the intake of air into the transmission and to replace the conventional vent tube. The effectiveness of the TABS valve in reducing fluid oxidation was determined in high temperature transmission cycling tests and in taxicab tests. Fluid oxidation results with the TABS valve-equipped transmissions were compared to those with normally-vented transmissions. By reducing the amount of oxygen in the transmission gas, the TABS valve nearly eliminated fluid oxidation.

Interactive graphics is an aid which eliminates the data management problems that arise when manually preparing finite element models. Line and surface data representations of sheet metal automotive stampings are displayed on a cathode ray tube (CRT), and these data are then used for building finite element models. Elements are built by creating node points with the light pen or by using automatic mesh generating techniques. By using the interactive capability, the user immediately sees the results of his modeling decisions and can make changes in his model as a result of viewing his work. The interactive graphics system allows the user to define his elements, load cases, boundary conditions, and freedom sets without worrying about the grid point or element numbers. All information is communicated through the use of either the light pen or the keyboard. As information is supplied about the model, it is stored in a data base for review and possible change.

The assembly and particularly the reduction of the mass and stiffness matrix for a large system can be a significant portion of the computational cost of finding the mode shapes and natural frequencies. Therefore, parameter studies for design purposes can be prohibitive if these matrices are reassembled and reduced for each change. The purpose of this paper is to outline the procedure for using the modes of the original system to determine the dynamic characteristics of the changed system. The method also results in computational savings for boundary condition changes and for large systems that are nearly-symmetric except for a few mass and stiffness changes. To illustrate the method several changes are made to a ladder frame. The results from an analysis using the reconstructed mass and stiffness matrices and the modal synthesis technique are compared to show the accuracy and freedom requirements.

To compute the tearing energy of nicked rubber strips in extension, one has to solve first the associated stress-deformation involving finite elasticity. In the past, this was a formidable task so that the tearing energy had been determined solely by experiments and only for a few testpieces. With the aid of the finite element method (FEM), it is shown that this may now be done simply through the use of the Rice's J integral. Tearing energy for two testpieces are computed and results compared with existing experimental data. The agreement is good. Because of FEM's ability to treat general geometric and loading conditions, the use of the J integral in combination with FEM to cmpute the tearing energy now allows a wider application of the tearing energy concept to more complex units than hitherto known.

This paper illustrates by way of two practical examples, namely, transmission gears and crankshafts, how the automotive industry applies basic approaches and methods for achieving fatigue resistant design. Analytic, laboratory, and field studies necessary in the development of these components are briefly outlined.

This paper describes a computer study made by the General Motors Corp. Research Laboratories to determine what percentage of the energy supplied to the axle of a passenger car is available for recovery through regeneration. Several weight classes of passenger cars were studied using three driving schedules-city, suburban, and highway. For each vehicle run in accordance with the prescribed driving schedules, two ratio percentages were obtained: (1) the ratio of energy available for recovery to the total energy supplied to the axle, and (2) the above ratio modified by assumed efficiencies in the propulsion and regeneration systems.

Renewal theory concerns itself with the replacement of randomly failing parts. In the simplest case we have a one component system which is kept running continuously by replacing a failed component at the instant of failure with an identical “new” component. The random variable N(t) = the number of failures (or replacements) to time t is then of interest in many types of reliability analysis. In this paper the distribution of N(t) is considered when the underlying failure law is a Weibull distribution. Tables of the mean and standard deviation of N(t) for various values of the Weibull slope parameter are presented. Applications to warranty and spare parts analyses are also noted.