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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.

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.

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.

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.

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.

This study explores the application of viscoelastic modeling for characterization of the response of the brain to impulsive loading with the objective of learning whether such models could exhibit the same time dependency of strain or likelihood of injury, as exhibited by the Severity Index, HIC Index, Wayne Tolerance Curve, and other similar representations of tolerance. The mathematical relationships between viscoelastic properties and the corresponding time dependency of tolerance are shown for Newtonian, Bingham plastic, and Pseudo-Bingham, as well as more general behavior. Preliminary static and dynamic tests upon small mammalian material are described with particular attention given to strain in the vicinity of the brainstem as a function of loading profile. Both the theoretical and experimental results show that the falling time dependency of the above indexes can be interpreted in terms of nonlinear viscoelastic response.