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It is well known that rotational loading is responsible for a spectrum of diffuse brain injuries spanning from concussion to diffuse axonal trauma. Many experimental studies have been performed to understand the pathological and biomechanical factors associated with diffuse brain injuries. Finite element models have also been developed to correlate experimental findings with intrinsic variables such as strain. However, a paucity of studies exists examining the combined role of the strain-time parameter. Consequently, using the principles of finite element analysis, the present study introduced the concept of sustained maximum principal strain (SMPS) criterion and explored its potential applicability to diffuse brain injury. An algorithm was developed to determine if the principal strain in a finite element of the brain exceeded a specified magnitude over a specific time interval.

This study was conducted to resolve discrepancies and fill in gaps in the biomechanical impact response of the human abdomen to frontal impact loading. Three types of abdominal loading were studied: rigid-bar impacts, seatbelt loading, and close-proximity (out-of-position) airbag deployments. Eleven rigid-bar free-back tests were performed into the mid and upper abdomens of unembalmed instrumented human cadavers using nominal impact speeds of 6 and 9 m/s. Seven fixed-back rigid-bar tests were also conducted at 3, 6, and 9 m/s using one cadaver to examine the effects of body mass, spinal flexion, and repeated testing. Load-penetration corridors were developed and compared to those previously established by other researchers. Six seatbelt tests were conducted using three cadavers and a peak-loading rate of 3 m/s. The seatbelt loading tests were designed to maximize belt/abdomen interaction and were not necessarily representative of real-world crashes.

European safety community has been actively involved in side impact research and has made significant contributions. One of the most recent is the development of the Euro-SID (European Side impact Dummy) which contains an abdominal injury detection element. This report details an analysis of the dummy abdomen and the cadaver tests upon which it is based. Specifically, the analysis examines the empirical basis, and final design of the Euro-SID abdomen with the following conclusions proffered: 1) The inclusion of an abdominal injury prediction element in the European Side impact Dummy is an important advancement in anthropomorphic dummy design. 2) The peak force-maximum compression criterion chosen as the predictor of injury is valid, given the results from the 8 cadaver tests upon which it is based.

It is well known that the ability of the human body to withstand trauma is a function of its inherent strength, i.e., the strength of the bones and soft tissues. Yet, the properties of the bones and tissues change as a function of the individual's age. In this paper age effects on thoracic injury tolerances are studied by analyzing the mechanical properties of human bones and soft tissues and by examining experimental results found in the literature of thoracic impact tests to human cadavers. This work suggests that the adult age range can be divided into three age groups. Using piece-wise linear regression analyses, it has been determined that the reduction in injury tolerance from the “young” age group to the “elderly” group is approximately 20% under blunt frontal impact loading conditions and is as much as 70% under belt loading conditions.

In this study, three-dimensional nonlinear finite element models of age-specific one year old, three year old, and six year old pediatric human cervical spine (C4-C5-C6) structures were developed. Their biomechanical responses were compared with the adult human cervical spine behavior under different loadings and at all load levels. The adult human cervical spine model was constructed from close-up computed tomography sections in the axial and sagittal planes, and sequential anatomic cryomicrotome sections. The adult model was validated with experimental moment-rotation data under flexion-extension and compression by correlating bilateral strains in the vertebral body and the lateral masses, and the force-deflection responses with experiments conducted in our laboratory. The adult model was modified to create one, three and six year old pediatric spines by incorporating the local geometrical and material characteristics of the developmental anatomy.

The purpose of the study was to identify all small overlap impacts using published coded NASS-CDS data. Three sets of criteria were used: CDC measurements; crush profiles for frontal impacts; and crush profiles for oblique side impacts to the fender component. All criteria were applied to passenger and non-passenger cars and their different vehicle class sizes. Data were analyzed based on fatalities and different levels of MAIS trauma. The overall data set based on CDC codes for 2005 to 2008 NASS-CDS data had 9,206 MAIS=0; 13,522 MAIS=1-2; 3,600 MAIS=3-6; 1,092 MAIS=7; and 961 fatal cases. For the weighted ensemble, these data were: 5,800,295; 4,324,773; 269,042; 219,481; and 44,906 cases, respectively. However, these cases reduced to 1071, 1468, 364, 82, and 87 raw cases with the application of the CDC criteria for frontal impacts.

The biofidelity of the Ford Motor Company human body finite element (FE) model in side impact simulations was analyzed and evaluated following the procedures outlined in ISO technical report TR9790. This FE model, representing a 50th percentile adult male, was used to simulate the biomechanical impact tests described in ISO-TR9790. These laboratory tests were considered as suitable for assessing the lateral impact biofidelity of the head, neck, shoulder, thorax, abdomen, and pelvis of crash test dummies, subcomponent test devices, and math models that are used to represent a 50th percentile adult male. The simulated impact responses of the head, neck, shoulder, thorax, abdomen, and pelvis of the FE model were compared with the PMHS (Post Mortem Human Subject) data upon which the response requirements for side impact surrogates was based. An overall biofidelity rating of the human body FE model was determined using the ISO-TR9790 rating method.

Lower extremity injuries caused by floor plate impacts through the axis of the lower leg are a major source of injury and disability for civilian and military vehicle occupants. A collection of PMHS pendulum impacts was revisited to obtain data for paired booted/unbooted test on the same leg. Five sets of paired pendulum impacts (10 experiments in total) were found using four lower legs from two PMHS. The PMHS size and age was representative of an average young adult male. In these tests, a PMHS leg was impacted by a 3.4 or 5.8 kg pendulum with an initial velocity of 5, 7, or 10 m/s (42-288 J). A matching LS-DYNA finite element model was developed to replicate the experiments and provide additional energy, strain, and stress data. Simulation results matched the PMHS data using peak values and CORA curve correlations. Experimental forces ranged between 1.9 and 12.1 kN experimentally and 2.0 and 11.7 kN in simulation.

This paper details the development of an abdominal injury assessment device for loading due to belt restraint submarining in the Hybrid III family of dummies. The design concept and criteria, response criteria, choice of injury criterion, and validation are explained. Conclusions of this work are: 1) Abdominal injury assessment for belt loading due to submarining is now possible in the Hybrid III family of dummies. 2) The abdomen developed has biofidelity in its force deflection characteristics for belt loading, is capable of detecting the occurrence of submarining, and can be used to determine the probability of abdominal injury when submarining occurs. 3) Installation of the abdomen in the Hybrid III dummy does not change the dummy kinematics when submarining does not occur. 4) When submarining does occur, the dummy kinematics are very similar to baseline Hybrid III kinematics, except for torso angle.

The Frangible Abdomen is a crushable Styrofoam insert for the abdominal region of the Hybrid III family of dummies, which has biofidelity, and assesses the occurrence of submarining and its risk of injury. It was first developed for the mid-sized male Hybrid III dummy. This paper describes the design of the Frangible Abdomen for the small female Hybrid III dummy, and how to use it to assess the occurrence and the risk of injury from submarining. The force-deflection properties of the mid-sized male insert were scaled to the small female dimension using equal stress/equal velocity scaling. Sled tests were run to compare the kinematic and dynamic performance of the baseline small female Hybrid III dummy with the same dummy modified to incorporate the Frangible Abdomen. The kinematic and submarining performance of the small female Hybrid III dummy was unchanged by the addition of the Frangible Abdomen. The Frangible Abdomen was easy to install and use, and had excellent repeatability.

Hyge sled tests were conducted using a rear-seat sled fixture to evaluate submarining responses (the lap belt of a lap-shoulder belt restraint loads the abdominal region instead of the pelvis). Objectives of these tests included: an evaluation of methods to determine the occurrence of submarining; an investigation into the influence of restraint system parameters, test severity, and type of anthropomorphic test device on submarining response; and an exploration of the mechanics of submarining. This investigation determined that: 1. Slippage of the lap belt off the pelvis due to dynamic loading of the dummy and the resulting kinematics can cause abdominal loading to the dummy in laboratory crash testing. 2. The 5th female dummy submarined more easily than did the Hybrid ill in the test environment. 3. Motion of the pelvis was controlled using a “pelvic stop”, which reduced the submarining tendency for both the 5th female and Hybrid III dummies. 4.

Spinal trauma produced from motor vehicle accidents, diving accidents, or falls occur at high rates of loading. This study was undertaken to reproduce clinically relevant cervical spine injuries under controlled conditions. Six isolated head - T2 human cadaveric preparations were tested using an electrohydraulic piston actuator at loading rates from 295 to 813 cm/sec. The Hybrid III head-neck was tested similarly at rates from 401 to 683 cm/sec. The input forces for specimen tests were of higher magnitude and shorter duration than the distally measured forces. In contrast, the Hybrid III head-neck revealed similar magnitude and duration force traces from input to output. The specimen preparations were analyzed kinematically at 1200 frames/sec with 20 to 30 retroreflective targets fixed to each level of the cervical spine. With this technique it is possible to temporally follow cervical damage as a function of applied force.

This study applies a detailed finite element model of the human body to simulate occupant knee impacts experienced in vehicular frontal crashes. The human body model includes detailed anatomical features of the head, neck, chest, thoracic and lumbar spine, abdomen, and lower and upper extremities. The material properties used in the model for each anatomic part of the human body were obtained from test data reported in the literature. The total human body model used in the current study has been previously validated in frontal and side impacts. Several cadaver knee impact tests representing occupants in a frontal impact condition were simulated using the previously validated human body model. Model impact responses in terms of force-time and acceleration-time histories were compared with test results. In addition, stress distributions of the patella, femur, and pelvis were reported for the simulated test conditions.

Head injury is a serious threat to lives of people working around farm machinery. The consequence of head injuries are costly, paralytic, and often fatal. Clinical and biomechanical data on head injuries are reviewed and their application in the analysis of head injury risk associated with farm tractor discussed. A significant proportion of tractor-related injuries and deaths to adults, as well as children, is due directly or indirectly to head injury. An improved injury reporting program and biomechanical studies of human response to tractor rollover, runover, and falls, are needed to understand mechanisms of the associated head injury.

There is an increasing need to accurately define the soft tissue components of the human cervical spine in order to develop and exercise mathematical analogs such as the finite element model. Currently, a paucity of data exists in the literature and researchers have constantly underscored the need to obtain accurate data on cervical spine ligaments. Consequently, the objective of the study was to determine the geometrical and biomechanical properties of these ligaments from the axis to the first thoracic level. A total of thirty-three human cadavers were used in the study. Geometrical data included the length and cross-sectional area measurements; and the biomechanical properties included the force, deflection, stiffness, energy, stress, strain, and Young's modulus of elasticity data. Data were obtained for the following ligaments: anterior and posterior longitudinal ligaments, joint capsules, ligamentum flavum, and interspinous ligament.

This study evaluated the biomechanical performance of a rear-seat inflatable seatbelt system and compared it to that of a 3-point seatbelt system, which has a long history of good real-world performance. Frontal-impact sled tests were conducted with Hybrid III anthropomorphic test devices (ATDs) and with post mortem human subjects (PMHS) using both restraint systems and a generic rear-seat configuration. Results from these tests demonstrated: a) reduction in forward head excursion with the inflatable seatbelt system when compared to that of a 3-point seatbelt and; b) a reduction in ATD and PMHS peak chest deflections and the number of PMHS rib fractures with the inflatable seatbelt system and c) a reduction in PMHS cervical-spine injuries, due to the interaction of the chin with the inflated shoulder belt. These results suggest that an inflatable seatbelt system will offer additional benefits to some occupants in the rear seats.

While seat belts are the most effective safety technology in vehicles today, there are continual efforts in the industry to improve their ability to reduce the risk of injury. In this paper, seat belt pretensioners and current trends towards more powerful systems were reviewed and analyzed. These more powerful systems may be, among other things, systems that develop higher belt forces, systems that remove slack from belt webbing at higher retraction speeds, or both. The analysis started with validation of the Ford Human Body Finite Element Model for use in evaluation of abdominal belt loading by pretensioners. The model was then used to show that those studies, done with lap-only belts, can be used to establish injury metrics for tests done with lap-shoulder belts. Then, previously performed PMHS studies were used to develop AIS 2+ and AIS 3+ injury risk curves for abdominal interaction with seat belts via logistic regression and reliability analysis with interval censoring.

NHTSA estimates that more than half of the lives saved (168,524) in car crashes between 1960 and 2002 were due to the use of seat belts. Nevertheless, while seat belts are vital to occupant crash protection, safety researchers continue efforts to further enhance the capability of seat belts in reducing injury and fatality risk in automotive crashes. Examples of seat belt design concepts that have been investigated by researchers include inflatable, 4-point, and reverse geometry seat belts. In 2011, Ford Motor Company introduced the first rear seat inflatable seat belts into production vehicles. A series of tests with child and small female-sized Anthropomorphic Test Devices (ATD) and small, elderly female Post Mortem Human Subjects (PMHS) was performed to evaluate interactions of prototype inflatable seat belts with the chest, upper torso, head and neck of children and small occupants, from infants to young adolescents.

In vitro biomechanical studies were conducted on fresh human cadaveric thoracolumbar spines to establish the limits of tolerance, explain the mechanism of failure, and investigate the effects of improvement in strength and stability of the injured column using Harrington distraction rods, Luque rods and modified Weiss springs. Quasistatic axial tensile loading on ligaments, compressive loads on vertebra) bodies and intervertebral discs, and flexure and compression-flexion force vectors on ligamentous columns, intact torsos and injured spines were applied to delineate the biomechanical and functional patho-anatomic characteristics. Vertical drop tests were conducted with the Hybrid II manikin to predict the forces and accelerations on the vertebral column.

A new anthropomorphic test device (ATD) is being developed by the US Army to be responsive to vertical loading during a vehicle underbody blast event. To obtain design parameters for the new ATD, a series of non-injurious tests were conducted to derive biofidelity response corridors for the foot-ankle complex under vertical loading. Isolated post mortem human surrogate (PMHS) lower leg specimens were tested with and without military boot and in different initial foot-ankle positions. Instrumentation included a six-axis load cell at the proximal end, three-axis accelerometers at proximal and distal tibia, and calcaneus, and strain gages. Average proximal tibia axial forces for a neutral-positioned foot were about 2 kN for a 4 m/s test, 4 kN for 6 m/s test and 6 kN for an 8 m/s test. The force time-to-peak values were from 3 to 5 msec and calcaneus acceleration rise times were 2 to 8 msec.