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1976-02-01
Technical Paper
760805
Kenneth J. Saczalski, John D. States, Ivan J. Wagar, Edward Q. Richardson
The basic physical mechanisms underlying recent experimentally observed anomalous behavior in the impact performance of safety helmets evaluated with soft (human-like) and hard (magnesium alloy) headform surrogates are qualitatively and quantitatively explained in this paper. The principal and physical mechanisms brought to light in the headform surrogate investigation are directly applicable to the utilization of other forms of surrogates (head -neck, thorax, whole body). In particular the results raise a serious question as to the validity of using non-human responding surrogates, with human generated injury tolerance data, for the purpose of assessing safety system performance. The implications of the results are that good crash-impact protective devices (helmets, restraints, etc.) could be penalized and, equally important, less safe crash-impact protective system designs could result from improper assessment of safety system performance.
1976-02-01
Technical Paper
760802
J. Harris
Abstract The lack of a suitable means of measuring levels of protection for car occupants in side impacts has hampered development of satisfactory designs of car to withstand impacts of this type by cars or other objects. The TRRL side impact dummy described in the paper has been designed specifically for this task and its use has been demonstrated in achieving a high level of protection for occupants of the Leyland Marina cars developed in the international car safety programme. The dummy makes possible the matching of each part of the energy absorbing inner face of the donor structure to the different loadings on the human frame, which can be safely tolerated at the shoulder, chest and pelvic regions.
1976-02-01
Technical Paper
760809
D. Orne, E. Barak, R. F. Fisch
Abstract A contoured rear-facing restraint couch has been designed, fabricated and tested which protects wheelchair-confined passengers in simulated frontal barrier collisions at velocities of up to at least 25 mph and in simulated rear-end collisions. A cable system secures the wheelchair to the base of the restraint couch and is automatically engaged when the wheelchair is backed against the couch. A three-point belt system secures the passenger in rear-end collisions or during elastic rebound in frontal collisions. Plastic deformation of the couch framework limits g-loadings on passenger and couch even during severe impacts.
1976-02-01
Technical Paper
760808
L. M. Patrick, W. D. Wickersham
Abstract Children riding on the bed over the cab in campers can be injured in forward force collisions from striking the glazing material and/or being ejected through the opening. The two types of glazing commonly used are acrylic and laminated. A comparison of the performance of the two types of glazing in simulated forward force collisions at velocities up to 30 mph showed the acrylic material to pose threats of neck and back injury and the laminated material to result in lacerations. Ejections occurred with the acrylic that were not present with the laminated windshields when correct glazing techniques were used. With poor installation procedures, ejections occurred in both types of glazing materials. It is concluded that the best way to avoid injury is to prevent the child from riding in the over-the-cab bunk. If the child does ride there, his body axis should be positioned at an angle to the longitudinal axis of the vehicle.
1976-02-01
Technical Paper
760807
L. M. Patrick, C. C. Chou
Abstract An improved windshield with a special, thin, plastic inner surface attached to the inner surface of a three layer windshield similar to those used in the United States minimizes lacerations from occupant impact to the windshield during a collision. The plastic coats the sharp edges of the broken glass preventing or minimizing laceration. It was evaluated by comparing its laceration performance with that of a standard windshield in simulated barrier crashes at velocities up to 65 km/h. No lacerations resulted from impact to the Securiflex windshield at Barrier Equivalent Velocities up to 65 km/h. Substantial laceration resulted at velocities above 20 km/h with the standard windshield. It is concluded that the Securiflex windshield essentially eliminates lacerations in the particular vehicle involved at velocities up to at least 65 km/h.
1976-02-01
Technical Paper
760813
K. W. Krieger, A. J. Padgaonkar, A. I. King
A series of 10 full-scale experimental simulations of pedestrian-vehicle impact was carried out using cadavers and a 95th percentile anthropomorphic dummy. The test subjects were impacted laterally and frontally at 24, 32 and 40 km/h (15, 20 and 24 mph). Each subject was extensively instrumented with miniature accelerometers, up to a maximum of 53 transducers. The nine-accelerometer scheme was used to measure angular acceleration of body segments from which it was possible to compute the head injury criterion (HIC) for cadaver head impact. A full-size Chevrolet was used as the impacting vehicle. The impact event was three-dimensional in nature during which the body segments executed complex motions. Dummy impacts were more repeatable than cadaver impacts but the response of these test subjects were quite different. The HIC was higher for head-hood impact than for head-ground impact in two of the cases analyzed.
1976-02-01
Technical Paper
760817
Charles K. Kroell, Dennis C. Schneider, Alan M. Nahum
The purpose of this paper is to present a comparison of whole body, target impingement knee impact response for a Part 572 dummy versus that for anthropometrically similar embalmed human cadavers. “Response” is defined here to include the impact force-time history as sensed by 1) femur load cells, and 2) impingement target load cells for the dummy and by the target load cells for the cadavers. The data presented demonstrate significantly higher peak forces and correspondingly shorter pulse durations for the dummy than for the companion cadaver subjects under similar test conditions and at all velocity levels investigated. For the dummy, the ratio of forces measured by the femur load cells to those measured by the impingement target load cells averaged eight tenths.
1976-02-01
Technical Paper
760819
N. S. Hakim, A. I. King
Previous work on biodynamic response to whole-body +Gz (caudocephalad) acceleration gave ample evidence of facet loads in intact cadaveric spines. The computation of facet loads was based on an assumption that the total spine load was proportional to the measured seat pan load. In this study, the aim is to investigate the magnitude of the facet load during static and dynamic loading of an exised spinal segment. The applied loads resulted in a close simulation of those experienced by the intervertebral disc during whole-body impacts. An intervertebral load cell was used as the controlling mechanism in the duplication of the whole-body run in a testing machine. During these tests, both the total spine load and the intervertebral load were measured and thus the facet load was determined without relying on any assumptions.
1976-02-01
Technical Paper
760620
Allen Coombs, William Lippert, Larry Lowden, David Michaels, Charles J. Owen, Tom Thomas
On January 10th, 1972, an S. A. E. Paper “Lighting System Performance and the Computer as a Maintenance Tool” (720087) was presented by Charles J. Owen. This was a paper presented on the causes, effects, corrections and a study in good and bad electrical wiring, presented pictorially as well as editorially. We recommend that paper to you for reading. On November 4th, 1974, S. A. E. Paper “A Case for Standardization” (741143) was presented by Charles J. Owen. The purpose of this paper was intent on “improving the breed”. The recommendations and specifications were very specific. In view of the two previous papers, this paper is presented specifically for the designer with back-up data involving recommendations that the industry have generally accepted as applied to the electrical wiring systems The practical data included, is a first in relating indexes of performance and indexes to cost comparisons. The usefulness of this paper in aiding a Designer is the target of the authors.
1976-02-01
Technical Paper
760769
Jeffrey C. Huston, Sunder H. Advani
A comprehensive three dimensional model of the human head and neck is formulated. This model predicts the center of mass displacements, velocities, and accelerations of the head and neck resulting from contact and/or inertial impact forces. Key anatomical components are incorporated in this model along with a joint stopping mechanism. Known acceleration profiles are inputed to the torso and/or head force time histories are specified. The equations of motion are then derived using d'Alembert's form of Lagrange's Principle and are numerically integrated using a fourth order Runge-Kutta technique. Validation is accomplished by the comparison of responses from (i) direct frontal and occipital impact experiments on human cadavers, and (ii) sled tests conducted on human volunteers.
1976-02-01
Technical Paper
760768
Nicholas Perrone
The significant correlation of skull fracture with fatal head injury suggests such fracture prevention to be a useful minimal design criterion. A spherical cap under dynamic local loading is recommended as an effective mathematical model to assess skull fracture. With finite difference techniques in space and time, the governing large deformation cap equations are solved for a circular load area. For load pulses of practical significance, the only parameters of concern are load area, load amplitude, skull thickness and maximum allowable stress. Curves are presented of fracture load with load area for various skull thicknesses. Results suggest that increasing the load area greatly diminishes the possibility of fracture. Hence, helmet and vehicle designers should aim towards this end.
1976-02-01
Technical Paper
760771
S. A. Tennyson, A. I. King
A biodynamic model of the spine simulated the action of spinal musculature on the head, vertebral bodies and pelvis in the midsagittal plane. Muscle was treated as a force generator whose contractile force was dependant on muscle stretch, stretch rate and neural delay time. Eight model runs were conducted with and without muscle, simulating +Gz and -Gx impact acceleration. The model predicted that spinal musculature was incapable of affecting overall spinal column kinematics. However, as a result of muscle contraction, significantly higher local axial forces were predicted in the discs and facets than were predicted when muscle was absent.
1976-02-01
Technical Paper
760770
U. R. Pontius, Y. K. Liu
A computer model of the neuromusculature and passive elements of the cervical spine during whiplash is presented. The model indicates that the neuromusculature increases the rotational stability of the cervical spine during low level accelerations. This results in decreased bending but increased axial compressive stresses in the passive structures and increased axial tensile stresses in the neuromusculature. Increased neural feedback augments peak acceleration and stress because the “active” neuromusculature causes a flexion response near the end of the acceleration pulse. A decrease in neural delay time allows the muscles to act earlier and decrease peak accelerations and bending stresses.
1976-02-01
Technical Paper
760772
Joseph C. Free, James W. Hall, Cesar A. Montano
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1976-02-01
Technical Paper
760773
David C. Viano, Tawfik B. Khalil
The mechanical response of a plane strain finite element model depicting an axial midsection of a human femur is investigated for both static and dynamic condylar loadings. An elastic bi-medium structure composed of compact and cancellous bone is used to represent the femur. Critically stressed locations are identified and associated static and dynamic load levels which may initiate femur fracture are calculated. The predicted fracture sites and load levels are found to be in good agreement with published data for cadaver knee impacts. An important conclusion of this investigation is that the peak stress or strain and therefore femoral tolerance significantly depends on the impact duration due to stimulation of structural resonances.
1976-02-01
Technical Paper
760527
H. W. Carhart, I. Pinkel, J. H. Warren
At the request of the FAA the CRC initiated a study to investigate the effect of fuel volatility on aircraft fire safety. The primary objective was to use new data which have become available over the last ten years to revise and update the 1964 CRC Report on Aviation Fuel Safety. The huge increase in jet aircraft utilization provided a data base for a statistical analysis of accidents; and new data on non-equilibrium conditions involving fuel-air mixtures and fuel electrification facilitated a more complete laboratory study. The results of these two studies were then used to prepare the final report which is summarized in this paper.
1976-02-01
Technical Paper
760486
James Shaw
This paper is submitted to insure that every basic precaution is taken in the design of the installation for an aircraft filler cap and adapter for lightning protection. The axiom in the industry of installing a lightning proof cap solves the problem of a lightning safe installation. However, designers sometimes disregard the problem of the installation of the adapter and the adapters mating parts. Adherence to the FAA and military specifications are considered acceptable while these specifications contain only the bare minimal requirements. This design criteria of only using a lightning safety cap and disregarding the installation of the adapter sometimes leads to an expensive redesign or retrofit of the aircraft after the plane is in production.
1976-02-01
Technical Paper
760500
Robert H. Stanton
The FAA is involved in aircraft design for safety and continued airworthiness, its certification functions consisting of making preoperational findings or determinations that a product design, a facility, an operation, or a person satisfies the applicable Federal Aviation Regulation. This paper, in discussing safety systems, places particular emphasis on the design of aeronautical hardware for regulatory compliance.
1976-02-01
Technical Paper
760494
D. C. Johnston
Civil litigation arising out of claims of defect in design and/or manufacture causing injury has now expanded into a new arena giving rise to claims of defect in design and/or manufacture, increasing the injuries complained of, although not causally related. This new doctrine of “CRASHWORTHINESS” or “second injury” evolved first out of automobile accidents, but in the last few years, has been extended to aircraft. Recent Court decisions have indicated a trend toward the adoption of this new doctrine by a majority of the Courts in this Country. This trend will obviously affect the future planning of aircraft manufacturers and engineers who are responsible for programs of research, development and production changes in the field of crashworthy design. Secondly, this paper discusses the possible personal liability exposure of the engineer and the method and means by which the engineer may protect himself.
1976-02-01
Technical Paper
760480
Brent W. Silver
This paper represents the results of a computer study of General Aviation accidents, particularly stall and spin accidents. In an introductory review, five transportation modes are compared on the basis of deaths per 100,000,000 passenger-miles. Of these, General Aviation has the highest accident rate, and domestic airlines the lowest. Descriptions of four “stall-related” accident types (stall, spin, spiral and mush) are given. A summary for these four accident types over the years 1965 through 1973 is given for both twin- and single-engine aircraft. The patterns are found to be similar. Stall/spin accident patterns are reviewed for a group of 31 single-engine aircraft (1965-1973) by: kind of flying, phase of flight, turning flight, airport proximity, weather, daylight, pilot experience and age, stall warning indicator, and cause of accident. Individual results are presented for the 31 aircraft by make and model.
1976-02-01
Technical Paper
760503
Claude P. J. Frantzen
Differences in safety objectives and lack of confidence are the two major obstacles which could have prevented the international development of civil aviation. From the Chicago Convention to the European Joint Airworthiness Requirements, these obstacles have been overcome to the satisfaction of all nations. This stands as an example not only for other aviation matters, but for any field of technical activities faced with international regulatory problems.
1976-02-01
Technical Paper
760800
C. L. Ewing, D. J. Thomas, L. Lustick, W. H. Muzzy, G. Willems, P. L. Majewski
Abstract The parameters of duration, rate of onset and peak acceleration of the sled have been identified by other investigators as determinants of the dynamic and injury response of man. A series of human experiments have been conducted to measure the response of the head and the first thoracic vertebrae to these parameters. Each subject was run at three conditions defined as high rate of onset-long duration (HOLD), high rate of onset-short duration (HOSD) and low rate of onset-long duration (LOLD) at peak accelerations of 6, 10 and 15G. Comparison time profiles of angular acceleration, angular velocity and linear resultant acceleration at the head anatomical origin and horizontal linear acceleration at the T1 origin are presented for 5 to 8 subjects at each of the three peak sled acceleration levels.
1976-02-01
Technical Paper
760219
U. W. Seiffert, H.-G. Marks, K.-H. Ziwica
Two hydraulic brake system regulations, the U.S. Federal Motor Vehicle Safety Standard 105-75 and the European Economic Community Directive 71/320/EEC with its respective amendments, became effective with the introduction of 1976 model year passenger cars. This paper highlights some of the most difficult requirements in terms of braking stability and stopping distances a passenger car has to meet in the U.S. and Europe. Further, it shows the impact these two regulations have on the brake system layout in the U.S. and Europe. For that purpose a specific vehicle model, the Volkswagen Rabbit, is used to demonstrate the brake systems layout. Since international standard unification is of major importance, some suggestions are made to achieve this goal with a minimum of cost and optimum brake system performance without sacrifice in safety.
1976-02-01
Technical Paper
760821
Gerald W. Nyquist, Lawrence M. Patrick
An X-ray radiographic study of two volunteers in a vehicle seated configuration was performed to gain insights into the lower torso skeletal geometry associated with this posture. A pseudo three-dimensional analysis of each radiogram was utilized to obtain quantitative results. The analyses provided indications of the pelvis and femur relative and absolute orientations. Further, the geometry of the lumbar spine and its location relative to the pelvis were defined. The relevance of the data from the standpoint of anthropomorphic dummy design is discussed, and recommendations are offered for further studies of vehicle seat/vehicle occupant interfacing biomechanics. Anthropometric data on each volunteer are included.
1976-02-01
Technical Paper
760049
Max H. Alexander, Ruth E. DeWald
. Using the systems approach, the human factors engineer stands ready to assist the design engineer in providing the vehicle driver with an optimum workplace. A human factors checklist has been devised for the design engineer to alert him to the major areas where troubles for the human operator generally develop. This preliminary checklist has been applied to the design of a pickup truck cab to illustrate its use. The terms “average” and “percentile” are explained. Sources of human factors data are suggested where the design engineer may find specific information as to spatial requirements for U.S. adult men and women, automotive driver controls, driver seating, environmental considerations within the vehicle, including conditions of heat, cold, and high humidity, ventilation, noise, vibration, and vision capability. When a particular component or control is the subject of a Federal Motor Vehicle Safety Standard, the pertinent standard is identified by number and title.
1976-02-01
Technical Paper
760082
Thomas L. Black, James A. Mateyka
Concern for the accommodation of the elderly and handicapped in all public facilities has in the past decade become a new design challenge for architects and engineers. In the past five years, based in part upon legislative actions at the Federal and state levels, considerable research and development activities have been initiated related to this problem in mass transportation. This paper focuses on the design problems associated with accommodating the ambulatory elderly and handicapped as well as individuals in a wheelchair on full-size urban transit buses. The results of research activities during the development, testing, and public demonstrations of advanced prototype transit buses is presented. The focus of the paper is on the technical feasibility of bus design features and does not deal with operational or economic questions related to transportation of the handicapped.
1976-02-01
Technical Paper
760823
David C. Viano, Charles Y. Warner
Abstract Five anesthetized porcine subjects were exposed to blunt thoracic impact using a 21 kg mass with a flat contact surface traveling at 3.0 to 12.2 m/s. The experiments were conducted to assess the appropriateness of studying in vivo mechanical and physiological response to thoracic impact in a porcine animal model. A comprehensive review of comparative anatomy between the pig and man indicates that the cardiovascular, respiratory and thoracic skeletal systems of the pig are anatomically and functionally a good parallel of similar structures in man. Thoracic anthropometry measurements document that the chest of a 50 to 60 kg pig is similar to the 50th percentile adult male human, but is narrower and deeper. Peak applied force and chest deflection are in good agreement between the animal's responses and similar impact severity data on fresh cadavers.
1976-02-01
Technical Paper
760816
Heinrich F. von Wimmersperg, Waldemar J. Czernakowski
Abstract The most important biomechanical characteristics of infants from birth to about six months are compiled in view of the development of adequate restraining devices for this group. The conventional engineering approaches are discussed, also a new method, a swinging bed. The long axis of the shell of this bed is placed perpendicular to the main axis of the vehicle on the rear seat. The top of the shell is attached at both sides by a strap to the vehicle frame for example by the adult belt. As the center of gravity of the shell plus infant is below the attachment points, the shell turns in a frontal crash. This transfers the impact load over a large area of the infant and also reduces the duration of maximal impact for each area element. The development from the first models for studying the kinematics to the final models for production is discussed. Results from European and United States sled tests are included.
1976-02-01
Technical Paper
760814
G. Sturtz, E. G. Suren, L. Gotzen, S. Behrens, K. Richter
Abstract An optimisation of the vehicle exterior with regard to the pedestrian accident is only sensible with a view of the main groups of pedestrians. Contrary to dummy tests, of which advantages as well as disadvantages are sufficiently known, the correlation of dummy versus living human body versus dead tissue is eliminated in the analysis of real accidents, but gets extended by the parameter of age. Compared with laboratory tests, this method suffers from the disadvantage of middle errors in the estimated initial data, for instance the collision speed of the vehicle, which vary with every accident. Based on 230 medically and technically thoroughly worked out single-case analyses of real pedestrian accidents, including 128 accidents involving children, the influence of various parameters of vehicles and traffic participants on kinematics, injury mechanisms, and traumatising of the pedestrian accident are outlined.
1976-02-01
Technical Paper
760812
D. G. C. Bacon, M. R. Wilson
Abstract Impacts of bumpers on the legs of pedestrians are analysed by simulating accidents using comprehensively instrumented adult and child dummies with free-standing ability. The friction force between the feet and ground is found to be a significant factor in the kinematics of the pedestrian and his interaction with the bumper, vehicle and ground. The effects of bumper height, lead and deflection characteristics are evaluated experimentally in conjunction with a mathematical model of leg impact. Bumper impacts are not considered in isolation; results indicate that bumper positional requirements for reduced leg injury would be 12-14 in height and 5 in lead, but vehicle front end height is a more important factor in determining critical impacts of other body areas with the vehicle and ground. An energy absorbing bumper system with the facility to lift the leg on impact presents further possibilities of reducing loads on the leg.
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