Search Results

In the present investigation a tractor wheel runover accident was simulated to obtain biomechanical information relating to mechanism of injury. Twelve cadaver porcine specimens were runover with the right front wheel of a tractor. Specimens were placed on a six-axis force plate and thorax contours were recorded temporally. Results indicated up to 68% compression of the chest occurred during the runover event. The shear force in the direction of travel was a significant factor in the type of fractures that occurred to the rib cage. Pathology determined from x-ray revealed multiple fractures per rib in the area directly below the path of the tire. Autopsy evaluation revealed soft tissue contusion on the left side in the area of wheel path. There was often extra blood in the pericardial space and examination of the brain showed petechial hemorrhaging subdurally.

A series of twenty-nine tests was completed by conducting static deployment of side airbag systems to an out-of-position Hybrid III three-year-old dummy. Mock-ups (bucks) of vehicle occupant compartments were constructed. The dummy was placed in one of four possible positions for both door- and seat-mounted side airbag systems. When data from each type of position test were combined for the various injury parameters it was noted that the head injury criteria (HIC) were maximized for head and neck tests, and the chest injury parameters were maximized for the chest tests. For the neck injury parameters, however, all of the test positions produced high values for at least one of the parameters. The study concluded the following. Static out-of- position child dummy side airbag testing is one possible method to evaluate the potential for injury for worst-case scenarios. The outcome of these tests are sensitive to preposition and various measurements should be made to reproduce the tests.

The objective of the present study was to determine the thorax and abdomen deflections sustained by post mortem human surrogate (PMHS) in oblique side impact sled tests and compare the responses and injuries with pure lateral tests. Oblique impact tests were conducted using modular and non-modular load-wall designs, with the former capable of accommodating varying anthropometry. Tests were conducted at 6.7 m/s velocity. Deflection responses from chestbands were analyzed from 15 PMHS tests: five each from modular load-wall oblique, non-modular load-wall oblique and non-modular load-wall pure lateral impacts. The thorax and abdomen peak deflections were greater in non-modular load-wall oblique than pure lateral tests. Peak abdomen deflections were statistically significantly different while the upper thorax deflections demonstrated a trend towards significance.

The objective of the study was to document the thoracic deformation contours in a simulated frontal impact. Unembalmed human cadavers and the Hybrid III anthropomorphic manikins were tested. Data from the newly developed External Peripheral Instrument for Deformation Measurement (EPIDM) was used to derive deformation patterns at upper and lower thoracic levels. Deceleration sled tests were conducted on three-point belt restrained surrogates positioned in the driver's seat (no steering assembly) using a horizontal impact test sled at velocities of approximately 14.0 m/s. Lap and shoulder belt forces were recorded with seat belt transducers. The experimental protocol included a Hybrid III manikin experiment followed by the human cadaver test. Both surrogates were studied under similar input and instrumentation conditions, and identical data acquisition and analysis procedures were used. All six testedcadavers demonstrated multiple bilateral rib fractures.

The objective of the present study was to determine the biomechanics of the human thorax in a simulated frontal impact. Fourteen unembalmed human cadavers were subjected to deceleration sled tests at velocities of nine or 13 m/s. Air bag - knee bolster, air bag - lap belt, and air bag - three-point belt restraint systems were used with the specimen positioned in the driver's seat. Two chest bands were used to derive the deformation patterns at the upper and lower thoracic levels. Lap and shoulder belt forces were recorded with seatbelt transducers. After the test, specimens were evaluated using palpation, radiography, and a detailed autopsy. Thoracic trauma was graded according to the Abbreviated Injury Scale based on autopsy findings. Peak thoracic deformations were normalized with respect to the initial chest depth to facilitate comparison between the specimens.

Studies were conducted on twenty-two fresh human cadavers to determine the probability of facial bone fracture following dynamic contact with steering wheel assemblies of both standard (a commercially available) and energy absorbing (EA) types. Using a specially designed and validated vertical-drop impact test system, either zygoma was impacted once onto the junction of the lower left spoke and rim with velocities ranging from 2.0 to 6.9 m/s. Generalized force histories were recorded with a six-axis load cell placed below the hub. The wheel was inclined 30 degrees to the horizontal. Steering wheel deformations were recorded with a system of potentiometers placed below the impact site on the wheel. Dynamic forces at the zygoma (impact site) were computed using transformation principles. A triaxial accelerometer was placed at the posterior parietal region of the specimen opposite to the impact site to record acceleration histories. High speed photography documented the kinematics.

The objective of the present study was to determine the kinematics of the human head-neck complex with specific reference to posterior facet joints as a function of rear impact acceleration. Six intact human head-neck complexes were prepared by fixing the first thoracic vertebra in polymethylmethacrylate. The specimens were oriented such that the Frankfurt plane was horizontal and the cervico-thoracic disc was at an angle of 25 degrees to simulate the normal driving position. Retroreflective targets were inserted to the cervical vertebrae. The specimens were subjected to simulated rear impact accelerations using a minisled apparatus. A series of tests were conducted with velocities of 2.1, 4.6, 6.6, 9.3, and 12.4 km/h. In this study, to achieve the objective, results are presented on the facet joint motions at the C4–5, C5–6, and C6–7 levels as a function of change in velocity.

The objective of the present exploratory study is to understand occupant responses in oblique and side-facing seats in the aviation environment, which are increasingly installed in modern aircrafts. Sled tests were conducted using intact Post Mortem Human Surrogates (PMHS) seated in custom seats approximating standard aircraft geometry. End conditions were selected to represent candidate aviation seat and restraint configurations. Three-dimensional head center-of-gravity linear accelerations, head angular velocities, and linear accelerations of the T1, T6, and T12 spinous processes, and sacrum were obtained. Three-dimensional kinematics relative to the seat were obtained from retroreflective targets attached to the head, T1, T6, T12, and sacrum. All specimens sustained spinal injuries, although variations existed by vertebral level.

With the widespread use of supplemental restraint systems (airbags), occasional rare injuries have occurred because of the force associated with these systems upon deployment. Recent case studies have demonstrated forearm fractures associated with airbag deployment. The present study was conducted to determine the tolerance of the human forearm under a dynamic bending mode. A total of 30 human cadaver forearm specimens were tested using three-point bending protocol to failure at 3.3 m/s and 7.6 m/s velocities. Results indicated significantly (p < 0.01) greater biomechanical parameters associated with males compared to females. The bending tolerance of the human forearm, however, was found to be most highly correlated to bone mineral density, bone area, and forearm mass. Thus, any occupant with lower bone mineral density and lower forearm geometry/mass is at higher risk. The mean failure bending moment for all specimens was 94 Nm.

Thirty-six lateral PMHS sled tests were performed at 6.7 or 8.9 m/s, under rigid or padded loading conditions and with a variety of impact surface geometries. Forces between the simulated vehicle environment and the thorax, abdomen, and pelvis, as well as torso deflections and various accelerations were measured and scaled to the average male. Mean ± one standard deviation corridors were calculated. PMHS response corridors for force, torso deflection and acceleration were developed. The offset test condition, when partnered with the flat wall condition, forms the basis of a robust battery of tests that can be used to evaluate how an ATD interacts with its environment, and how body regions within the ATD interact with each other.

Fracture to the lumbo-pelvis region is prevalent in warfighters seated in military vehicles exposed to under-body blast (UBB). Previous high-rate vertical loading experimentation using whole body post-mortem human surrogates (PMHS) indicated that pelvis fracture tends to occur earlier in events and under higher magnitude seat input conditions compared to lumbar spine fracture. The current study hypothesizes that fracture of the pelvis under high-rate vertical loading reduces load transfer to the lumbar spine, thus reducing the potential for spine fracture. PMHS lumbo-pelvis components (L4-pelvis) were tested under high-rate vertical loading and force and acceleration metrics were measured both inferior-to and superior-to the specimen. The ratio of inferior-to-superior responses was significantly reduced by unstable pelvis fracture for all metrics and a trend of reduced ratio was observed with increased pelvis AIS severity.

While numerous studies have been conducted to determine side impact responses of Post Mortem Human Surrogates (PMHS) using sled and other equipment, experiments using the biological surrogate in modern full-scale vehicles are not available. The present study investigated the presence of oblique loading in moving deformable barrier and pole tests. Three-point belt restrained PMHS were positioned in the left front and left rear seats in the former and left front seat in the latter condition and tested according to consumer testing protocols. Three chestbands were used in each specimen (upper, middle and lower thorax). Accelerometers were secured to the skull, shoulder, upper, middle and lower thoracic vertebrae, sternum, and sacrum. Chestband signals were processed to determine magnitudes and angulations of peak deflections. The magnitude and timing of various signal peaks are given. Vehicle accelerations, door velocities, and seat belt loads are also given.

The objective of the study was to determine the thorax and abdomen deflection-time corridors in oblique side impacts. Data were analyzed from Post Mortem Human Surrogate (PMHS) sled tests, certain aspects of which were previously published. A modular and scalable anthropometry-specific segmented load-wall system was fixed to the platform of the sled. Region-specific forces were recorded from load cells attached to the load-wall plates. The thorax and abdomen regions were instrumented with chestbands, and deflection contours were obtained. Biomechanical responses were processed using the impulse-momentum normalization method and scaled to the mid-size male mass, 76-kg. The individual effective masses of the thorax and abdomen were used to determine the scale factors in each sled test, thus using the response from each experiment. The maximum deflections and their times of attainments were obtained, and mean and plus minus one standard deviation corridors were derived.

The American population is getting heavier and automated vehicles will accommodate unconventional postures. While studies replicating mid-size and upright fore-aft seated occupants are numerous, experiments with post-mortem human subjects (PMHS) with obese and reclined occupants are sparse. The objective of this study was to compare the kinematics of the head-neck, torso and pelvis, and document injuries and injury patterns in frontal impacts. Six PMHS with a mean body mass index of 38.2 ± 5.3 kg/m2 were equally divided between upright and reclined groups (seatback: 23°, 45°), restrained by a three-point integrated belt, positioned on a semi-rigid seat, and exposed to low and moderate velocities (15, 32 km/h). Data included belt loads, spinal accelerations, kinematics, and injuries from x-rays, computed tomography, and necropsy. At 15 km/h speed, no significant difference in the occupant kinematics and evidence of orthopedic failure was observed.

This study presents a design concept for a multi-configuration modular medical evacuation fixture that can be used to retrofit standard utility vehicles for emergency medical transport. The fixture has been designed so that when installed in a vehicle and configured for litter transport, it provides mounting structure for a single patient on a North Atlantic Treaty Organisation (NATO) style litter as well as for a variety of emergency medical equipment. When installed in a vehicle and configured for ambulatory patient transport, the device provides safe seating for multiple patients as well as mounting surfaces for medical equipment. When not installed, the fixture can be collapsed for ease of shipping and warehousing. A survey of potential host vehicles was conducted to evaluate the feasibility of the proposed design. Given a preliminary concept, factors such as expected patient anthropometry, and physical data of medical equipment were used to perform basic structural analyses.

This study was conducted to collect data and gain insights relative to the mechanisms and factors involved in hip injuries during frontal crashes and to study the tolerance of hip injuries from this type of loading. Unembalmed human cadavers were seated on a standard automotive seat (reinforced) and subjected to knee impact test to each lower extremity. Varying combinations of flexion and adduction/abduction were used for initial alignment conditions and pre-positioning. Accelerometers were fixed to the iliac wings and twelfth thoracic vertebral spinous process. A 23.4-kg padded pendulum impacted the knee at velocities ranging from 4.3 to 7.6 m/s. The impacting direction was along the anteroposterior axis, i.e., the global X-axis, in the body-fixed coordinate system. A load cell on the front of the pendulum recorded the impact force. Peak impact forces ranged from 2,450 to 10,950 N. The rate of loading ranged from 123 to 7,664 N/msec. The impulse values ranged from 12.4 to 31.9 Nsec.

Lower cervical spine injuries are more common in survivors of motor vehicle crashes sustaining neck trauma. Injury criteria are determined using upper neck loads in dummies although a lower neck load cell exists. Due to a paucity of lower neck data from post mortem human subject (PMHS) studies, this research was designed to determine the head-neck biomechanics with a focus on lower neck metrics and injuries. Sixteen frontal impact tests were conducted using five belted PMHS. Instrumentation consisted of a pyramid-shaped nine accelerometer package on the head, tri-axial accelerometer on T1, and uniaxial accelerometer on the sled. Three-dimensional kinematics of the head-neck complex were obtained using a 20-camera high-speed motion analysis system. Testing sequence was: low (3.6 m/s), medium (6.9 m/s), repeat low, and high (15.8 m/s) velocities. Trauma evaluations were made between tests. Testing was terminated upon confirmation of injuries.

The patho-anatomic alterations due to vertical loading of the human cervical column were documented and correlated with biomechanical kinematic data. Seven fresh human cadaveric head-neck complexes were prepared, and six-axis load cells were placed at the proximal and distal ends of the specimens to document the gross biomechanical response. Retroreflective markers were placed on bony landmarks of vertebral bodies, articular facets, and spinous processes along the entire cervical column. Targets were also placed on the occiput and arch of C1. The localized movements of these markers were recorded using a video analyzer during the entire loading cycle. Pre-test two-dimensional, and three-dimensional computerized tomography (CT), and plane radiographs were taken. The specimens were loaded to failure using an electrohydraulic testing device at a rate of 2 mm/s.

In 1989, the EUROSID-1 was accepted in the European regulation ECE-R95. After a steady period of use, an upgraded version of this dummy: ES-2 is now considered as a step towards harmonization of side impact occupant regulations. The upgrades to the dummy include, amongst others, a modification of its torso back plate and a change in rib module guidance (piston-cylinder), especially to overcome anomalous rib deflection responses referred to as ""flat-top.'' Presented here are results of lateral and oblique pendulum tests, conducted on the EUROSID-1 and ES-2 to verify the modified torso back plate and to study the responses of three proposed rib module designs for ES-2. Particularly, rib deflections, rib VC responses, and thorax force-deflection responses are analyzed. The current study primarily addresses sensitivity of the ES-2 thorax to oblique loading.

This study was conducted to quantify intracranial biomechanical responses and external blast overpressures using physical head model to understand the biomechanics of blast traumatic brain injury and to provide experimental data for computer simulation of blast-induced brain trauma. Ellipsoidal-shaped physical head models, made from 3-mm polycarbonate shell filled with Sylgard 527 silicon gel, were used. Six blast tests were conducted in frontal, side, and 45° oblique orientations. External blast overpressures and internal pressures were quantified with ballistic pressure sensors. Blast overpressures, ranging from 129.5 kPa to 769.3 kPa, were generated using a rigid cannon and 1.3 to 3.0 grams of pentaerythritol tetranitrate (PETN) plastic sheet explosive (explosive yield of 13.24 kJ and TNT equivalent mass of 2.87 grams for 3 grams of material).