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Technical Paper

Lower Abdominal Tolerance and Response

Twelve unembalmed human cadavers were tested for lower abdominal injury tolerance and mechanical response. The impacts were in an anterior-to-posterior direction and the level of impact was primarily in the lower abdomen at the L3 level of the lumbar spine. The impactor mass was either 32 kg or 64 kg. The impactor face was a 25 mm diameter aluminum bar, with the long axis of the bar parallel to the width of the cadaver body. In this paper, mechanical response is presented in terms of force-time and penetration-time histories, and force vs. abdominal penetration cross-plots. Injury tolerance is described in terms of post-impact necropsy findings and AIS ratings. Based on our studies, the lower abdomen of the unembalmed human cadaver is much less stiff than is suggested by previous research, and the stiffness is velocity and mass dependent, as is suggested by the correlation coefficients presented in this paper. Force-time history and force-penetration response corridors are presented.
Technical Paper

Facial Impact Tolerance and Response

Facial impact experiments were conducted on eleven unembalmed human cadavers. A 32 kg or 64 kg impactor with a 25 mm diameter, rigid, cylindrical contact surface was oriented in the left-right direction relative to the face and contacted the nose at the elevation of the infraorbital margins. The impactor was propelled toward the race along an anterior-to-posterior path, with contact velocities ranging from 10 to 26 km/h. Accelerometers mounted on the impactor and the occiput provided data for analyzing the dynamics of the impacts. While the threshold for nasal bone fractures was not determined, it appears that a peak force of about 3 kN (filtered 180 Hz) is a representative threshold for more severe fracture patterns. A preliminary dynamic force vs penetration response specification for the above mode of loading is offered.
Technical Paper

Injury Tolerance Characteristics of the Adult Human Lower Extremities Under Static and Dynamic Loading

A review of the literature dealing with the injury tolerance of the lower extremities in quantitative terms is provided. The data stem from sources ranging from Weber (1859) to as recent as Culver (1984) and in all cases involve tests of embalmed or unembalmed cadaveric specimens. The strength of the femur (thigh bone) and tibia (shin bone) have been depicted primarily in terms of the peak axial compressive force or bending moment associated with fracture-producing tests. Peak forces involved in fracturing the patella (knee cap) are reported for static and dynamic distributed loads involving both padded and rigid contact surfaces. One study is described where patella data are available for punch-through type fractures resulting from loading by small diameter impactors. Limited data are provided for hip joint dislocation and/or pelvic fracture as a result of loading through the femur. Finally, limited data are also included for injury at the knee and ankle joints.
Technical Paper

Tibia Bending: Strength and Response

Unembalmed human tibias were subjected to static and dynamic three-point bending tests using the Wayne State Translational Impactor. Simple supports potted to the bone near the proximal and distal epiphyses were attached to force transducers and load was applied at midspan by a 32-kg impactor that had a rigid 25-mm diameter cylindrical contact surface. Loads were applied through the normal flesh covering the bone, and were directed from the anterior to posterior or from lateral to medial. Each bone was loaded once and sustained fracture at or near mid-span. Peak bending moments, impact speeds and load-deflection data are presented. Data regarding cross-sectional properties adjacent to the fracture site and mineral content of the specimens are included, along with a study of the correlations of strength with these various parameters.
Technical Paper

Pick-Up Truck Rear Window Tempered Glass as a Head Restraint—Head and Neck Loads Relative to Injury Reference Criteria

A series of rear impact tests of varying severity was performed using a mini pick-up truck with an instrumented Hybrid III dummy at the driver position. Head, neck and chest loads were monitored. The severities of these loads from an injury standpoint were assessed using biomechanically based reference criteria that are particularly suitable for the Hybrid III. The glass Installation performed well as a head restraint. Glass fracture from head impact was achieved only when the glass was predamaged, with surface scratches on the outer (tensile) side. The amazing strength and flexibility of tempered glass and the dramatic reduction in strength caused by small surface scratches are demonstrated.
Technical Paper

Lumbar and Pelvic Orientations of the Vehicle Seated Volunteer

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.
Technical Paper

Static Bending Response of the Human Lower Torso

This report defines humanlike quasi-static bending response characteristics of the lower torso. Six volunteers were subjected to a total of 72 tests to define response characteristics for sagittal flexion and extension bending. The effects of muscle tensing and knee bend on the response are evaluated. Sixteen loading corridors of moment of applied force about the H-point axis versus thorax-pelvis and pelvis-femur angles are suggested. The significant differences between the relaxed and tensed muscles results illustrate the need for a philosophical decision regarding which of these conditions should be adopted to define lower torso bending response for the human surrogate used in automotive safety studies.
Technical Paper

Static Force-Penetration Response of the Human Knee

Biomechanical guidelines for the development of an anthropometric dummy knee have been lacking. Quasi-static tests were performed on adult male volunteers and embalmed cadavers to define the force-penetration characteristics of the knee when loaded by a rigid, crushable foam of known crush properties. The test subject was seated erect with the thigh horizontal and lower leg unrestrained. Axial thigh (femur) force and knee penetration were recorded as a block of foam was pressed against the knee. The test was conducted incrementally with increasing peak load, and a new foam block was used for each increment. This enabled evaluation of the foam indent volume as a function of peak load. Pertinent anthropometric data are presented for each subject, and normal distribution theory is used to develop percentile scaling rules for the knee response. Loading corridors for biomechanically sound 50th percentile performance are suggested.
Technical Paper

Safety Performance of Shaped Steering Assembly Airbag

This paper discusses a program wherein studies were made of forward force simulations of crashes and destructive barrier crashes using a shaped steering assembly airbag. It was shown that the airbag offered the best protection when compared with the performance of lap belts and lap and shoulder belt combinations. This shaped airbag deploys between the abdomen and the steering wheel and between the head and the steering wheel, thus providing protection of these two important areas.