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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.

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.

Effective performance of functional automotive components requires fluid sealing under compatible conditions. One method of determining this compatibility is through the use of immersion testing under a variety of conditions that simulate those experienced in actual use. By measuring the changes in the physical properties of the seal materials after immersion a judgment can be made regarding seal/fluid compatibility which will be encountered later in actual use. A series of immersion tests using representative seal materials and automotive fluids; namely, gear oils, transmission fluids, and motor oils were conducted within the framework of the Technical Committee on Automotive Rubber, jointly sponsored by SAE-ASTM.

Most transducers offered commercially are suitable for laboratory, aerospace, or industrial process applications but do not meet additional, stringent automotive requirements. A need exists, both present and future, for various types of transducers in automotive powerplant control systems. Possible electronic systems and subsystems requiring transducers are discussed, and the types of transducers needed for these systems are described along with a discussion of a general set of specifications with respect to accuracy, reliability, and durability. Substantial transducer development is needed to enhance the advancement of certain automotive electronic systems. This paper points out these requirements to the electronics industry in an effort to encourage a mutual industry development that will advance the technology.

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.

EXTENSIVE TESTING by GM Research Laboratories has screened five promising transaxle fluids out of 32 mineral-oil-base fluids, 10 synthetic-base fluids, and numerous additive-base stock combination fluids. This paper discusses the findings of the testing and the continuing program on the five fluids. Transaxle fluids have a number of properties affecting performance, including: High-temperature viscosity. Low-temperature fluidity. Shear resistance. Friction properties. Oxidation resistance. Antifoam quality. Effect on seals. Fluid-clutch plate compatibility. Antiwear quality. Extreme-pressure quality. Antirust and anticorrosion qualities.*

A brief review of the testing of automatic transmission fluid for compatibility with seals is presented. The total immersion test used in fluid qualification, while apparently effective in predicting the compatibility of fluids and seals in service, does not correlate well with transmission tests with respect to hardness change of piston seals. The Dip-Cycle Test, developed to overcome this limitation, is a procedure for alternately immersing seal specimens in the test fluid and suspending them in the hot air-fluid vapor atmosphere above the fluid. Correlation of the Dip-Cycle Test with transmission piston seal results is much improved over that with the total immersion test. It is the purpose of this paper to review these developments and to present an improved test procedure (dip cycle test) for evaluating the effect of fluids on transmission piston seal materials.

The Total Immersion Test (ASTM D 471) for seal elastomers, used in evaluating the compatibility of fluids and seals for automatic transmissions, does not, produce hardness and volume change results similar to those found for rotating shaft seals in service. The Tip Cycle Test was devised to provide better agreement with service results. In the test, one side of the seal is exposed to air, and the other alternately to fluid and to air-fluid vapor. Rotating shaft seals were evaluated in both car and dynamometer transmission tests, and in various bench tests. Agreement was poor between transmission tests and both the Total Immersion and the Dip Cycle Tests. Good agreement was found with the Tip Cycle Test.

Tests were conducted using older model cars with automatic transmissions to determine the effect of fluid composition on leakage past the rotating shaft seals. It was found that seal leakage was reduced or stopped by changing to seal-swelling fluids, and increased with seal-shrinking fluids. Leakage was also reduced by adding aromatic additives to existing fluids in the transmissions. Seal volume and hardness change results from bench tests support the car data.

Conventional radial lip oil seals can be made more effective by utilizing helical grooving beneath the contact lip surface. Miniature hydrodynamic pumps so formed aid the radial lip seal in containing the oil by generating fluid forces opposite in direction to the leakage flow forces. This seal-shaft combination has been termed the Hydroseal. Four factorial experiments were conducted to evaluate the effect of helix angle, groove depth, groove width, and number of grooves on sealing performance. The criterion used as a basis for selecting the optimum design were leakage, wear, hardening of the sealing surface, and pumping capacity. These data indicated that the best hydroseal design was one with three grooves, 0.0003 in. deep, 0.014 in. wide, having a helix angle of 45 deg.

A viscoelastic neck structure that responds to impact environments in a manner similar to the human neck is described. The neck structure consists of four ball-jointed segments and one pin-connected “nodding” segment with viscoelastic resistive elements inserted between segments that provide bending resistance as well as the required energy dissipation. Primary emphasis was placed on developing appropriate flexion and extension responses with secondary emphasis placed on axial, lateral, and rotational characteristics. The methods used to design the resistance elements for the neck structure are discussed. Three variations of the resistive elements have been developed that meet the response characteristics based on the data of Mertz and Patrick. However, no single resistive element has satisfied the flexion and extension characteristics simultaneously, but such an element appears to be feasible.

Utilization of numerically controlled milling has been found particularly attractive in producing, in limited quantities, the three-dimensional curved surfaces characteristic of turbomachinery. In experimental and developmental programs its use can result in decreased fabrication cost, reduced lead time, and improved dimensional accuracy. Following a review of the general classifications of numerically controlled milling machines available for manufacture of such parts, illustrations are given of some of the procedures and techniques employed in their use. A variety of parts made using numerical control serve as examples.

THIS REPORT deals with the major parameters of a seal application which affect its efficiency and life, as determined by controlled laboratory testing in CM Research Laboratories.* A. Shaft 1. Surface Roughness 2. Machining Lead B. Assembly C. Seal 1. Seal Diameter Control Trim Interference Spring Rate 2. Seal Lip Pressure Trim Interference Spring Rate Rubber Hardness Eccentricity 3. Seal Eccentricity Mold Register Assembly Trim

The Sealometer is used for evaluating the performance of lip type oil seals and provides a dimensionless number derived from measuring the increase in temperature of a test shaft operating in a lip seal for a given time interval. With the Sealometer it is possible to study parameters that affect seal performance. As a quality control instrument, the machine provides accurate data for design. Sealometer evaluation offers a quick method of determining the life expectancy of a particular design for a particular application and eliminates the need for long life test programs.

Two Highway Safety Research Institute (HSRI) dummies were tested and evaluated. Based on the analysis given, the HSI dummy should not be used for vehicle qualification testing. However, many of its components offer viable alternatives for future dummy development. The dummy was found to have inadequate biomechanical fidelity in the head, neck, and chest, although its characteristics were very promising and, as a whole, biomechanically superior to the Hybrid II. Its repeatability and reproducibility in dynamic component tests were better than the Hybrid II dummy. In particular, the HSRI friction joints were outstanding in repeatability and had a significant advantage in usability in that they do not require resetting between tests. In three-point harness and ACRS systems tests, the values of injury criteria produced by the HSRI dummy were generally lower than those obtained with the Hybrid II, especially the femur loads in the ACRS tests.

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.