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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.

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 presents predictions of fatigue crack initiation life for three distinctly different, irregular load histories, each applied to keyhole-notched compact tension specimens at several maximum load levels and using two different structural steels. Three computerized prediction methods (Landgraf, Wetzel, and a Nominal Stress Range approach) are used. All predictions are based on load histories condensed to 10% of their original number of reversals by the "Racetrack Method." This method, which is described in detail, selects the most damaging overall ranges in an irregular load history while preserving the sequence of the original loading. Predictions are compared with test data for the two dozen combinations of loading type and level and steel used. Comments are made on the relative merits of the different prediction methods.

The purpose of the study is to establish which test conditions best reproduce the relative ratios of tire wear rate which exist between the different types of tires to be found in the field. Three fundamental paramenters are defined which characterize the type of wear: specific wear rate, profile shape, and ratio of wear rates between the front and rear axles. The research is developed in three phases; an examination of the various modes of wear present in actual usage, abrasion tests carried out with great precision and at various levels of acceleration severity, and the correlation between the market wear spectra and the test data. The paper concludes that the ratio of wear rates existing between any two types of tire is not generally constant, but it changes in function of the driving severity, thus explaining the disagreement sometimes found when comparing tests made at different centres. The appendix contains a survey made about the problem of the result consistency, including checks in the preparation of tests, definition and execution of the tests and the validity of the results.

Investigations in New South Wales of Passenger car crashes involving the death of wearers of lap/sash belts have led to the conclusion that head impact with a rigid part (usually in the side) of the occupied car is responsible for more deaths than any other impact. The experimental work reported in this paper consists of crash simulations to map the space swept by the head of a lap/sash belted occupant, in head-on and in a range of side impacts in which no invasion or loss of head space occurs. The simulations employed an Ogle-MIRA dummay which has a very compliant thorax, modified with the stacked ball joint neck from a Sierra 1050 dummy, this combination having been shown to closely reproduce head motion of human volunteers in frontal crashes reported in the literature. The work includes validation of the dummy and an investigation of the infleunce on head space of the angle of crash, of inertia reels in the sash straps, and of seat springing, in contrast to the hard seats used for the volunteer crashes. The results provide evidence of the value of increasing head space so as to reduce the likelihood of head impact of otherwise well restrained occupants of passenger cars. Three current model cars are tested for availability of head space which is found to be inadequate, especially in front corner impacts on the occupant's side of the car, involving 22 degree impact yaw. /Author/

This paper presents the results of direct impact tests and driving point impedance tests on the legs of seated unembalmed human cadavers. Variables studied in the program included impactor energy and impact direction (axial and oblique). Multiple strain gage rosettes were applied to the bone to determine the strain distribution in the bone. The test results indicate that the unembalmed skeletal system of the lower extremities is capable of carrying significantly greater loads than those determined in tests with embalmed subjects (the only similar data reported in the present literature). The strain analysis indicated that significant bending moments are generated in the femur with axial knee impact. The results of the impedance tests are used to characterize the load transmission behavior of the knee-femur-pelvis complex, and the impact test results are combined with this information to produce suggested response characteristics for dummy simulation of knee impact response.

A review of the existing mathematical models of a car occupant in a rear-end crash reveals that existing models inadequately describe the kinematics of the occupant and cannot demonstrate the injury mechanisms involved. The paper shows the results of a 78 degree-of-freedom model of the spine, head, and pelvis which has already been validated in plus G//z and minus G//x acceleration directions. It considers automotive-type restraint systems, seat back, and seat cushions, and the torso is free to slide up the seat back. Results of simulation runs show a good correlation with the existing data and experimental cadaveric runs made with a high seat back (or head restraint) and low seat back. The effect of seat-back stiffness and the restraint system on the response of the head and spine is studied. Language: en

This paper discusses the use of Linear and Nonlinear Curve Fitting Programs for the development of injury-prediction equations for automobile side and rear collisions. The data used are from the C.P.I.R. files at H.S.R.I. Separate equations developed for unrestrained, lap belt restrained and three-point harness restrained front seat occupants are discussed and compared. /HSRI/

Advancement in high-strength-to-weight-ratio material development have provided the automotive industry with numerous possibilities for vehicle weight reduction. The application rate of these new materials will depend upon their economic feasibility as well as their material properties. For these materials to be cost effective, the weight interaction of lighter high strength components must be considered within the environment of the total vehicle. This paper presents an analytical technique for quantifying vehicle component weight interactions and specifying the resulting iterative weight reductions that can be achieved through high strength material substitution. The technique has been applied to a typical production full-size vehicle to obtain the hypothetical, component group-weight targets that could be achieved through substitution of high strength-to-weight-ratio materials. Finite element computer models were created, representing the typical production vehicle and the resulting lightweight, high strength vehicle. These theoretical models were then computer tested, statically and dynamically, to ascertain the differences between the typical production vehicle and the lightweight, high strength vehicle. The results of this theoretical structural testing are given.

Door intrusion beams have been fabricated from an ultra high strength steel resulting in an efficient side impact protection system. Despite the ultra high strength (yield strength approximately 150 ksi) the steel may be roll formed into beams from thin gauge material (0.035 in. or 0.089 CM) resulting in significant vehicle weight savings while still meeting all federal specifications. This paper covers the development of this door intrusion beam system and includes detailed descriptions of beam design, beam testing and steel properties. /GMRL/

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.

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.

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).

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.

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.

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.

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.

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.

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.

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)

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.

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.

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 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 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.

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 international guideline is discussed in terms of safety and human tolerance. Charts for equal subjective vibration intensity, subjective judgement of equal fatigue, and severe discomfort boundaries are included.

A modified version of the pneumatic air cushion bumper has been incorporated into the basic design of a prototype automobile designed to provide improved structural performance during front, side, rear, and rollover collisions. A simple air bladder, recessed within a high-strength bumper bar, was supported by the front cross member of a modified frame which also served as a supplementary volume to reduce peak pressures and loads. Check valves were located between the bladder and the frame chamber to limit energy of rebound. Test results showed that the design is suitable for incorporation into vehicles intended to withstand barrier crashes of 5-10 mph. /HSRI/

In order to determine the best way to simulate a road in the full-scale climatic wind tunnel of the Volkswagenwerk AG, a series of comparative tests between road and tunnel have been carried out. In general, a good correlation was achieved when a rigid ground plane was used for road simulation. Only a small margin for improvement by boundary-layer control remains. From measurements reported in the literature, it can be seen that an effective reduction of the boundary-layer displacement thickness of 60% can be achieved with single-slot suction. Nevertheless, this would result in a hardly noticeable improvement of test-data correlation for cars with standard ground clearance. Therefore, it was decided not to install a boundary-layer suction in the wind tunnel of Volkswagenwerk AG.

The head, chest and femurs of three Hybrid II dummies were impacted with a ballistic pendulum at various angles to determine what differences in accelerometer and femur load cell putput would result for a constant energy input. Also evaluated were suspicious tension loads in the femur load cell putput when the legs were subjected to obvious off-center impacts during crash tests. It was found that the dummy legs can be subjected to very high torsion and bending loads which can have a significant effect on the femur load cell axial load outputs.

The overall objective of this experimental investigation of pedestrian/vehicle impacts was to conduct representative impacts of unembalmed cadavers in order to (1) pioneer the establishment of impact tolerance levels for the pelvis and legs of a standing pedestrian and (2) explore the ability of a few selected geometry and compliance modifications to the impacting vehicle to increase the impact velocities that can be tolerated. A series of 15 experimental impacts were conducted which covered a speed range from 10 to 30 mph. Dynamic data obtained included high-speed films and time histories of (1) bumper and hood edge forces, (2) horizontal and vertical ground reaction forces, and (3) pelvic acceleration. Three of the key results are that (1) injuries to the lower body of an adult pedestrian are strongly dependent upon vehicle design, (2) the pedestrian leg injury mechanism is a complex dynamic event influenced significantly by both the bumper force and the ground friction force, and (3) a threshold tolerance value of pelvic acceleration appears to exist below which pelvic injuries do not occur. Language: en

Through our development work on a bumper system that would meet the requirements of FMVSS No. 215, "Exterior Protection of Passenger Cars," the correlation between the physical properties of the compressible solid, and the mechanical structure and load-deflection characteristics of the shock isolator system has been clarified. A number of silicone rubbers were investigated and their molecular weight and cross-linking density changed. The results of these investigations have been applied to the new shock isolator system of our 1974 model vehicles. /GMRL/

A practical procedure for the optimum design of low-speed airfoils is demonstrated. The procedure uses an optimization program based on a gradient algorithm coupled with an aerodynamic analysis program that uses a relaxation solution of the inviscid, full-potential equation. The analysis program is valid for both incompressible and compressible flow, thereby making optimum design of high-speed, shock-free airfoils possible. Results are presented for the following three constrained optimization problems at fixed angle of attack and Mach number: (1) adverse pressure-gradient minimization, (2) pitching-moment minimization; and (3) lift maximization. All three optimization problems were studied with various aerodynamic and geometric constraints.

Temperature buildup tests and load deflection tests have been conducted on six tires; three sizes with one bias and one radial ply carcass construction per size. Temperature buildup curves are given for each tire at various conditions. Curves of load versus deflection are shown for each tire during both loading and unloading. Loss energies occurring during the loading-unloading cycle are tabulated. /GMRL/

Although not exhaustive, this test program has produced a set of fatigue data of sufficient generality that methods of fatigue life prediction (both crack initiation and propagation) and laboratory simulation can be reasonably evaluated. The test data also provides other insights: Generally, the stronger steel had the longer crack initiation life and crack propagation life at all load levels for all histories. The inverse slope of the variable amplitude life lines varied from -3.8 to -7.25. Compressive mean loads resulted in less steep slopes.

Dynamic tests have been performed with subcompact vehicles (Renault R 12) in which two dummies were restrained, either by three-point belts with load limiting devices, or by air bags consisting of solid gas generators and bags including porous outlets (the driver's knees were protected by a collapsible structure). Three types of crashes were chosen: frontal barrier crash at 50 km/h (13. 9 m/s); head-on crash between two vehicles with overlap at 50 km/h (13. 9 m/s); crash against a guardrail at 80 km/h (22 m/s) with 30 degree angle of incidence. The comparison drawn from commonly used biomechanical indices shows that the three-point belt ensures a protection in each analyzed crash type but it should be improved in order to reduce head deceleration. The air bag results depend on the crash type and show the problems of adaptation in a subcompact vehicle. The frontal barrier crash tests conducted with another type of dummy reveal that the results obtained for the two restraint types depend on the dummy, so that the efficiency assessment is difficult.