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This paper outlines the nature of the measuring equipment used in the investigation of tire-road interactions and presents the results of a study of the interfacial stress distributions of a radial-ply, a bias-belted, and a 4-ply bias-angle tire. There is a discussion of tractive ratios and effective coefficients of friction. Distributions of tractive ratios are displayed for all of the conditions treated and for the three types of tires. The paper also covers the changes in stress distributions that result from steering and the relation of these alterations to the lateral thrust and self-aligning torque of the tires.

This paper discusses the development of adequate criteria and evaluation methods for seat belt restraint design. These criteria should include the effect of seat belts in abdominal injury as well as head injury. It is concluded that belt load limiters and energy-absorbing devices should limit head-to-vehicle contact, ensure that the lap belt maintains proper contact with the bony pelvic girdle, and limit the belt loads. Studies are made of pulse shape and belt fabrics. Currently available mathematical models are used for the studies included in the paper.

In automobile structures some box sections cannot be adequately defined using beam finite elements. These sections require detailed plate models to represent holes and rapid changes in cross sections. Complications arise in connecting these detailed sections to those sections that can be adequately defined using beam elements. This paper shows one technique for connecting the two sections together. An example of this technique is demonstrated on a section of an automobile frame, and the results are compared to experimental data.

A method is presented for the transient analysis of structures including nonlinearities in material behavior and geometry. A system of convected coordinates that rotate and translate with each element is used to simplify the governing equations so that an efficient computer code could be developed. For purposes of applying the method to problems with moderately large relative rotations within an element, this paper introduces additional terms to account for these variations of the rotation. Results are presented for a variety of elastic and elastic-plastic problems.

Automotive frames frequently consist of thin-tube members thick enough for much of the structure to be modeled adequately by bar elements. However, previous results show that a typical welded joint cannot be handled by the classical "rigid joint" assumption of frame analysis. Those results include tests of a joint type common in passenger car frames, and establish errors of over 60% in analytical predictions for some of the lower natural frequencies. The present paper attempts to see how much improvement can be achieved by simply accounting for the actual tubular shape in the vicinity of the joint, without allowing for the flexibility of the weld line itself. The study uses the NASTRAN computer program. The joint region is treated as a small substructure in a model otherwise composed of bar elements. This procedure is economical because only those portions which really have to be analyzed using plate elements are so treated.

It is very difficult for small cars to protect occupants in high-speed collisions. The Nissan ESV is of lightweight monocoque construction, and its body possesses crashworthiness designed to match the occupant protection system. This vehicle has experimentally proved to be effective in occupant protection. This paper primarily deals with the most difficult problem of crashworthiness in frontal collisions, first referring to the basic analyses and test results acquired in the development process, and then setting forth the body construction and test results of the two types of Nissan ESV (E1 and E2).

The objective of this paper is to study the applicability of the finite element method in calculating both small and large deflections of sheet metal shells subject to concentrated loads in the elastic range. In the small deflection case, three types of elements -- the Hsieh-Clough-Tocher triangular plate element, the Felippa quadrilateral plate element, and the Dupuis triangular shell element -- are used to calculate the stiffness of two simple panels (a sectional circular cylinder and a paraboloid) and a spherical cap. The calculated results show that all three elements give solutions converging to the exact shell solutions. For large deflections, load-displacement curves of the spherical cap are computed for deflections up to three shell thicknesses using the Dupuis element.

A static analysis of the front-end structure of an experimental vehicle which identified the high stress areas is presented in this paper. NASA Structural Analysis (NASTRAN), a finite element computer program, was used for the analysis. The size of the mathematical model was large (17,000 degrees of freedom); therefore, substructuring techniques were utilized. Procedures pertinent to NASTRAN substructuring are described, and the theoretical relationships are summarized. Interpretation of results, comparison between analytical and experimental results, as well as computer cost and manpower requirements, are also discussed.

This paper describes the procedure and instrumentation used to telemeter, record, and analyze in-service truck tire accelerations. The tire sound signal monitored at a point approximately 1 ft to the rear of the tire was recorded simultaneously with the acceleration signal on board the test vehicle. Subsequent time domain, frequency domain, and level analyses of the signals show the importance and relationship of tire acceleration to the tire noise generated. The results reported are for a 10:00-20 cross-bar type tire with three states of wear, two load conditions and three speeds.

The paper presents data showing the effects of the state of wear, structure, load, and inflation pressure on the cornering stiffness and aligning torque stiffness of typical passenger tires. A method is introduced and applied for assessing contributions of local elements of the tread interface to the cornering force, the cornering stiffness, the aligning torque, and the aligning stiffness. There is also a further identification of the contributions to the aligning torque from fore and aft interfacial stress distributions and from lateral stress distributions. Pneumatic trail is redefined in the light of the interfacial measurements, and values are established for various operating conditions, states of wear, and tire types.

This paper presents a new criterion for comparing the performance of catalytic monoliths of various channel geometries and a better geometry for analyzing channels of wave-like pattern. Under mass transfer rate controlling conditions, the performance of ducts of different geometry is analyzed and compared on the basis of equivalent duct open area. Results indicate that the monolith length required for a 99% CO conversion is in the following ascending order: conduits of rectangular cross section, wave ducts, equilateral triangles, squares, circles and hexagons.

This paper identifies and analyzes steady-state and transient tire properties affecting vehicle directional response characteristics. The study is limited to the relationship between lateral force and slip angle. It shows fundamental differences between steady-state and transient properties. An interrelationship between cornering stiffness and dynamic lateral force offset resulting from the time lag between lateral force and slip angle is shown. Rapm steer techniques for measuring transient tire properties on a road trailer and on an external drum machine are described. A need for transient tire data for computer simulations of vehicle transient steer maneuvers is shown. Subjective evaluations of a vehicle equipped with different tires are described and compared with results of evaluations of 21 foreign and domestic vehicles. The significance to vehicle handling of tires having different characteristics, as determined by subjective evaluations in a lane change maneuver, is shown.

The Crash Test Dummy Task Force of the Human Factors Engineering Subcommittee (the SAE Automotive Safety Committee) during the 1968 meetings decided to establish master models of seated human body forms, representing the 95th and 50th percentile male and 5th percentile female United States adult size population. A seating posture and basic measurements were adopted for sculputuring of the models which, after being verified by anthropometrists, were reproduced in fiberglass gold-painted shells, therefore named "golden shells." The golden shells were measured steroemetrically, which yields a quantification of body shape and size in the form of point coordinates in three dimensional space and cross-sectional profiles throughout the body. The procedures employed in obtaining stereometric measurements of the master models and use of these data for extraction of desired information are described in this paper.

This paper presents a set of procedures that the stress analyst can use in laying out a finite element grid such that a near optimum mesh of elements will result. These grids lead to marked improvement in the displacement and stress estimates, especially in high gradient regions. Examples are given of direct application to problem encountered in automotive stress analysis.

This paper presents an objective technique for estimating the severity of automobile collisions. The vehicle damage and the dynamic force-deflection characteristics of the vehicle structure are used to estimate the energy absorbed in plastic deformation of the vehicle. The energy can then be expressed as an "equivalent barrier speed" (EBS). Data are presented relating residual crush and impact speed for full frontal barrier tests to provide the basis for a simple model of the force-deflection characteristics of the vehicle front structure. The results of this model are compared with test data to indicate the types of damage patterns for which the model appears valid.

Of all the automobile safety studies made, one that has received much attention is tire design. Comfort, service life, and reliability have been the guideposts in the development of better and safer tires. The investigation of the forces that affect reliability is the subject of this paper, and emphasis is placed on determination of the parameters at the particular area where tire and road are in contact.

The biodynamic response of cadaver torsos subjected to -Gdx impact acceleration is discussed in this paper, with particular emphasis on the response of the vertebral column. The existence of an axial force along the spine and its manifestation as a load on the seat pan are reported. Spinal curvature appears to be an important factor in the generation of this spine load. In anthropometric dummies, the spine load does not exist. Details of the testing and results are given, and the development of a mathematical model is shown.

Direct impact to the larnyx is usually prevented in accidents by ths]protective nature of the chin. In some situations, the occupant motions leave the larnyx unprotected and susceptible to impact by the steering wheel rim or instrument panel. As one of the unpaired vital organs of the body, there is no easy way to provide an alternative for its functions when the larnyx is lost or damaged. Information available on the tolerance of the unembalmed human larnyx to force is quite limited. This paper describes a multidisciplinary study to determine the response of unembalmed human larynges to blunt mechanical loading and to interpret the response with respect to clinical data. Fresh intact larynges were obtained at autopsy and tested at either static or dynamic loading conditions utilizing special test fixtures in materials-testing machines. Load and deformation data were obtained up to levels sufficient to produce significant fractures in both the thyroid and cricoid cartilages. Additional information was obtained in the form of permanent dimensional changes through direct measurements and location of fracture sites by use of xeroradiography. Final evaluation of the damage was performed following dissection of the laryngeal structure. The results of the tests are analyzed and interpreted in relation to establishing tolerance criteria for laryngeal loading.

This paper details the design and development of a new child restraint system recommended for children from 20-40 lb and under 40 in. The child is restrained in a seat by a five-belt harness system that utilizes a single quick-release buckle. The seat is restrained by the vehicle lap belts and a top anchor strap. It satisfactorily meets the standards of FMVSS 213 in static testing, and it reduces excursion of the child in front and side impact testing. The seat has padded forward-projecting walls at the side of the head. The seat retained its integrity during impact testing.

This paper describes an investigation that was undertaken to evaluate the lateral forces and moments produced on a vehicle with large, flat lateral faces when it is passing or being passed by a large vehicle in an adjacent traffic lane. The forces and moments were determined from tests that were conducted in the University of Tennessee subsonic wind tunnel. They were, then, input to a computerized vehicle model to find the resulting dynamic response of the vehicle. These forces and moments were sufficiently strong to produce a significant lateral deviation from the desired path of the vehicle. Resulting from this investigation, several recommendations were made to improve highway safety. /Author/

The analysis presented in this paper indicates that while 1700 lbf (7560 N) is a realistic femur fracture load for 30-50 ms duration impacts, the human femur can withstand higher loads for shorter-duration impacts. Experimental femur fracture data from cadaver and bone specimen tests are reviewed. These data are used to develop femur load fracture tolerance as a function of impact duration. On the basis of a measured 10% amplification of 1-2 ms input forced by the dummy, the cadaver fracture tolerance is proportionately adjusted to arrive at equivalent load levels for forces measured on current dummy test devices. Experimental dummy test device data are included and compared to the theoretical response of a mathematical model of the human upper leg. This comparison demonstrates that even neglecting the 10% amplification, there are still significant differences in the response of dummy and human upper leg structures for impact durations less than 3 ms.

Sandwich construction has been used for many years in aircraft and missiles, because of its ability to provide strong, stiff, lightweight structures. While the technology is well-developed for certain combinations of materials, there are many new developments which will have a significant impact on future applications. These new developments can be grouped into five following categories: (1) Joining methods. (2) Materials. (3) Geometries. This paper describes new technologies being developed in each of these categories and the impact they will have on sandwich construction. (MM)

With highly complex structures, it is sometimes desirable to derive a dynamic model of the system from experimental vibration data. This paper presents algorithms for synthesizing the mass and stiffness matrices from experimentally derived modal data in a way which preserves the physical significance of the individual mass and stiffness elements. The synthesizing procedures allow for the incorporation of other mass and stiffness data, whether empirical or based on the analyst's insight. The mass and stiffness matrices are derived for a cantilever beam example and are compared with those obtained using earlier techniques.

THIS PAPER DISCUSSES THE PROBLEM OF OCCUPANT PROTECTION IN SEVERE REAR END COLLISIONS FROM THE STANDPOINT OF HIGH PERFORMANCE SEAT STRUCTURES AND HEAD RESTRAINTS. CONSIDERATION IS GIVEN TO BOTH FIXED HEAD RESTRAINTS AND TO DEPLOYABLE HEAD RESTRAINTS. TWO-DIMENSIONAL COMPUTER SIMULATIONS OF OCCUPANT KINEMATICS IN A VARIETY OF REAREND COLLISIONS ARE UTILIZED TO PROVIDE INITIAL PERFORMANCE CRITERIA FOR HEAD RESTRAINT DESIGN CONFIGURATIONS. THE RESULTING PROTOTYPE SYSTEM UNDERWENT A TEST AND DEVELOPMENT PROGRAM ON AN IMPACT SLED. THE RESULTS OF THE VARIOUS PROTOTYPE PERFORMANCES AND GENERAL CRITERIA FOR HIGH PERFORMANCE HEAD RESTRAINT SYSTEMS ARE DISCUSSED. /SAE/

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. The response of the mechanical system was similar to that predicted by the mathematical model. It satisfied the 4.92 m/s (11 mph) response corridor and was very near the 7.15 m/s (16 mph) corridor. Further adjustments are necessary to adapt the chest to a crash test dummy. The chest must still be tested as part of the total dummy structure under the impact conditions specified by Kroell. Testing under these conditions is necessary, but not sufficient, to assure biofidelity.

The Lewis Research Center cold-flow model externally blown flap (EBF) noise research test program is summarized. Both engine under-the-wing and over-the-wing EBF wing section configurations were studied. Ten large scale and nineteen small scale EBF models were tested. A limited number of forward airspeed effect and flap noise suppression tests were also run. The key results and conclusions drawn from the flap noise tests are summarized and discussed.

A full nonlinear analysis, geometric as well as constitutive, of cracked plates in plane stress and strain is given. The theory is formulated in a Lagrangian frame of reference. The Newton-Rahpson method is used to solve for generalized displacements in the resulting nonlinear equilibrium equations. An elastic-perfectly plastic bahavior is assumed. An example of a plate containing a sharp crack and subjected to tensile load is solved using a developed finite element computer program. The analysis reveals the extent to which linear elastic-plastic approximation can be used with confidence.

Frequency response and power spectral density analyses are implemented on the NASTRAN computer program for the purpose of assessing the vibratory response of automotive vehicles. A review of theoretical concepts related to the frequency domain techniques is presented, followed by a derivation of the equations of vertical motion for a linearly elastic automotive vehicle. Special emphasis is given to the discussion of random loading, and the cross-spectral density matrix for the terrain input to a four-wheel vehicle is derived. Example calculations are performed for a compact-size vehicle exposed to moderately severe road roughness.

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 parameters of vehicle components is investigated and the technical criteria for improvement of vibration/acoustic characteristics are clarified.

An impact model of the human head characterized by an elastic spherical shell (skull) containing a low modulus core (brain) is studied using experimentally determined geometric, material, and structural properties. Injury criteria represented by skull fracture, brain cavitation, and brain shear deformation are interpreted and investigated in terms of effective acceleration-time thresholds. Contact stresses and durations are identified for head impacts typical in automobile collisions. In addition, selected comparisons of results with experimental data and head severity indices are given.

During this test program a series of during and human tests were carried out on a prototype lateral body support system at levels up to 15.6 g. The prototype system utilized an inflatable airbag for torso and head support. The purpose of the test program was to demonstrate the feasibility of using this approach in protecting against the severe accelerations encountered during the ground landing phase of escape from high-performance aircraft with escape capsules. The program has definitely demonstrated this feasibility. Tests were conducted with human subjects beyond the current specified tolerance limits in the lateral axis (1). Even at 15.6 g the subjects experienced no symptoms which would indicate an approaching endpoint. It would seem reasonable to postulate that accelerations in the 20-25 g range could be tolerated with this system. The inflatable lateral body support system tested here has some attractive advantages for retrofitting into an emergency escape capsule system. It requires no elaborate changes to current seat geometries or crew harnesses. No contours need be built into the head/neck area and the bag provides good support for both small and large subjects. The direct deployment mode selected works easily into automatic escape sequencing. The bag can be inflated after separation from the aircraft and held in position until ground contact. Deployment is slow enough so that there is no problem with bag slap or the noise which accompanies rapid deployment. Subjects during the tests indicated that they felt tightly restrained and slightly uncomfortable with the bag prior to impact, but felt they would have no problem maintaining the position for long periods.

Low speed sectional characteristics of a high lift airfoil are studied and a comparison is made of those characteristics with the predictions of the theoretical methods used in the airfoil's design. The 13.1 percent-thick, UI-1720 airfoil was found to achieve the predicted maximum lift coefficient of nearly 2.0. No upper-surface, flow separation was found below the stall angle of attack of 16 degrees; it appeared that stall was due to an abrupt leading edge flow separation.

Noise tests were conducted on new and retreaded truck tires of a wide variety of patterns using three different procedures. Single tires on the test wheel and 2-tire sets on the road were correlated with the standard 4-tire sets in accordance with the Recommended Practice SAE J57 Procedure. The correlation was analyzed and the conversion techniques were discussed with the conclusions that it is possible to convert test wheel data to equivalent road test data. The results show that retreaded truck tires are not noisier than new tires of similar construction and tread design. /HSRI/

Wind tunnel tests were conducted on a series of 1/4-scale, 1/6-scale and 1/8-scale models of various automotive configurations utilizing a wind tunnel fitted with adjustable ceiling and sidewall inserts. Force, moment, and static pressure distribution data were acquired and used to develop corrections which appear to account for the constraints imposed on the flow field about these bodies by solid tunnel walls. In addition test section size limitations are defined for the acquisition of reliable data from automotive configurations.

A method is derived and confirmed for predicting the tread wear configurations of tires positioned on nondriven axles of passenger vehicles. The method is based on laboratory measurements of the interfacial stresses of freely rolling tires and takes account of perturbations in these stresses that occur during the road test procedure. Wear is found to occur primarily at the exit end of the tire-road interface, and the degree of wear is related to the interfacial pressure and slip determining conditions at that location. The steering properties of the tire also enter into the determination.

For three given deceleration pulses of defined shape and peak magnitude, total velocity change was varied from 20 to 40 mph by changing duration of the pulse. Several restraint systems were compared, for these combinations of speed change and pulse shape, using head injury criterion, chest severity index, and femur loads to evaluate potential injury. Limit curves for each restraint are developed in terms of velocity change and peak deceleration, and the significance of these curves is discussed. /SAE/