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To estimate the behaviour of the thorax of the human cadaver and Hybrid III a total of 33 belt impact tests were performed with the two surrogates. These tests have shown that the Hybrid III thorax is stiffer than that of the cadaver and that the internal thoracic deflection transducer may not necessarily record the maximum thoracic deflection. The belt load was lower value with the cadavers, which confirms the differences in stiffness. A belt force of 10 KN in the cadaver tests was associated with an average of 6 rib fractures. If we consider the relationship between the thoracic deflection and the number of rib fracture cadavers showing 5 or more rib fractures sustained an external thoracic deflection at least of 7.5 cm measured at the mid sternum. The analysis of V*C parameter indicates an average V*C value of 0.77 for 6 rib fractures, and the values of V*C measured on Hybrid III are sligthly lower than those of cadaver tests.

Finite element simulation of air bags as part of the automotive occupant restraint system is rapidly evolving as a new CAE tool in support of car product development. The majority of occupant computer simulations are concentrated around the study of occupant impact into the air bag when the air bag is substantially inflated. Further, the initial air bag representation in the simulation prior to deployment is of an unfolded configuration. These simplifications do not compromise simulation of crashes wherein the dummy comes in contact with the air bag after it is substantially full. The situation wherein the dummy interacts with the air bag early during the inflation is of interest when the occupant is located close to the air bag prior to deployment. In such cases the predeploy-ment geometry of the air bag in the model needs to be representative of the actual air bag folded configuration and the unfolding of the air bag needs to be simulated.

A PC based interactive program was developed to simulate the unfolding and deploying process of a driver side airbag in the sagittal plane. The airbag was represented by a series of nodes. The maximum allowable stretch was less or equal to one between any two nodes. We assumed that the airbag unfolding was pivoted about folded points. After the completion of the unfolding process the airbag would begin to deploy. During the deploying process, two parameters were used to determine the nodal priority of the inflation. The first parameter was the distance between the instantaneous and final positions of a node. Nodes with longer distances to travel will have to move faster. We also considered the distance between the current nodal position and the gas inlet location. For a node closer to the gas inlet, we assumed that the deploying speed was faster. A graphical procedure was used to calculate the area of the airbag.

INRETS has performed in its Crash and Biomechanics Research Laboratory (LCB) series of frontal impact barrier tests with modern passenger cars in different test conditions. Three tests are made with each selected models: On the cars decelerations are recorded in different points for crashworthiness analysis. Two fully instrumented Part 572 dummies are installed in the front seats and are restrained using the vehicles belts. It is proposed to correlate the values of protection criteria with the parameters defining the test conditions and those characterizing the car behaviour during the crash test.

This study identified the mechanical properties of ten cadaveric lumbar spines and two Hybrid III lumbar spines. Eight tests were performed on each specimen: tension, compression, anterior shear, posterior shear, left lateral shear, flexion, extension and left lateral bending. Each test was run at a displacement rate of 100 mm/sec. The maximum displacements were selected to approximate the loading range of a 50 km/h Hybrid III dummy sled test and to be non-destructive to the specimens. Load, linear displacement and angular displacement data were collected. Bending moment was calculated from force data. Each mode of loading demonstrated consistent characteristics. The load-displacement curves of the Hybrid III lumbar spine demonstrated an initial region of high stiffness followed by a region of constant stiffness.

A three-dimensional finite element model of a human neck has been developed in an effort to study the mechanics of cervical spine while subjected to impacts. The neck geometry was obtained from MRI scans of a 50th percentile male volunteer. This model, consisting of the vertebrae from C1 through T1 including the intervertebral discs and posterior elements, was constructed primarily of 8-node brick elements. The vertebrae were modeled using linear elastic-plastic materials, while the intervertebral discs were modeled using linear viscoelastic materials. Sliding interfaces were defined to simulate the motion of synovial facet joints. Anterior and posterior longitudinal ligaments, facet joint capsular ligaments, alar ligaments, transverse ligaments, and anterior and posterior atlanto-occipital membranes were modeled as nonlinear bar elements or as tension-only membrane elements. A previously developed head and brain model was also incorporated.

The WorldSID is a new, advanced Worldwide Side Impact Dummy that has the anthropometry of a mid-sized adult male. It has a mass of 77.3 kg, a standing height of 1753 mm and a seated height of 911 mm. Almost every body region is a new, innovative design, setting the WorldSID apart from all existing side impact dummies. It incorporates over 200 available data channels, in-dummy wiring, and an in-dummy data acquisition system (DAS). The dummy is designed to be used for research and future harmonized side impact test procedures as defined by the International Harmonized Research Activities (IHRA) and other organizations. It is expected to have a biofidelity classification of “good” to “excellent” using the International Organization for Standardization (ISO) dummy classification scale. The WorldSID will be the basis for the future development of a side impact dummy family.

Lower extremity injuries in frontal automotive crashes usually occur with footwell intrusion where both the knee and foot are constrained. In order to identify factors associated with tibial shaft injury, a series of numerical simulations were conducted using a finite element model of the whole human body. These simulations demonstrated that tibial mid-shaft injuries in frontal crashes could be caused by an abrupt change in velocity and a high rate of footwell intrusion.

A nonlinear foam was added to a previously created three-dimensional finite element model of the Hybrid III dummy chest which consisted of six steel ribs, rib damping material, the sternum, a spine box and a pendulum. Two standard calibration pendulum impact tests for a Hybrid III dummy chest were used to validate the new model. An explicit finite element analysis code PAM-CRASH was utilized to simulate the dynamic process. At impact velocities of 6.7 m/s and 4.3 m/s, the force and deflection time history as well as the force-deflection plots showed good agreement between model predictions and calibration data. Peak strains also agreed well with experimental data.

To help predict the injury responses of child pedestrians and occupants in traffic incidents, finite element (FE) modeling has become a common research tool. Until now, there was no whole-body FE model for 10-year-old (10 YO) children. This paper introduces the development of two 10 YO whole-body pediatric FE models (named CHARM-10) with a standing posture to represent a pedestrian and a seated posture to represent an occupant with sufficient anatomic details. The geometric data was obtained from medical images and the key dimensions were compared to literature data. Component-level sub-models were built and validated against experimental results of post mortem human subjects (PMHS). Most of these studies have been mostly published previously and briefly summarized in this paper. For the current study, focus was put on the late stage model development.

Auto racing has been in vogue from the time automobiles were first built. With the dawn of modern cars came higher engine capacities; the speeds involved in these races and crashes increased as well. However, the advent of passive restraint systems such as the helmet, HANS (Head and Neck Support device), multi-point harness system, roll cage, side and frontal crush zones, racing seats, fire retardant suits, and soft-wall technology, have greatly improved the survivability of the drivers in high-speed racing crashes. Three left lateral crashes from Begeman and Melvin (2002), Case #LAS12, #IND14 and #99TX were used as inputs to the Wayne State Human Body Model (WSHBM) in a simulated racing buck. Twelve simulations with delta-v, six-point harness and shoulder pad as design variables were analyzed for the average maximum principal strain (AMPS) in the aorta. The average AMPS for the high-speed crashes were 0.1551±0.0172 while the average maximum pressure was 110.50±4.25 kPa.

Since many years, the vehicle industry is interested in occupant safety. The dummy use in crash tests allowed to create protective means like the belt and the airbag that diminished the injuries of the head and the thorax, which are often lethal for the car occupant. An other objective appears now: to improve the car safety to avoid the injuries which are not fatal but which can cause disability and which cause great cost in hospitalization and rehabilitation. The lower extremity protection, in particular the one of the ankle and the foot region, has become the subject of diverse research efforts by its high percentage of injuries in car crashes. But the dummy mechanics cannot reproduce the accurate ankle and the foot kinematics during an impact loading like in vehicle crash. Therefore, ankle/foot complex numerical models are an essential tool for the car safety improvement.

In occupant safety simulations it is desirable to extend existing rigid body occupant models towards deformable Finite Element models. Thereby a wider range of occupant / structure interactions can be covered and a better accuracy can be achieved. This paper describes some aspects of the FE modelling of the EUROSID thorax for use in an explicit Finite Element code. First a single rib model is evaluated, then a full thorax is generated and inserted into a rigid body Dummy model. Experimental results from impactor tests serve as a basis for the validation of the model.

A three-dimensional finite element model of the Hybrid III dummy head-neck complex was created to simulate the Amended Part 572 Head-Neck Pendulum Compliance Test, of the Code of Federal Regulations. The model consisted of a rigid head and five circular aluminum disks joined together by butyl elastomer rubber. Contact surfaces were defined to allow the anterior neck to separate upon an application of extension moments. Two mounting positions, one for flexion and the other one for extension, were used to simulate the head-neck calibration tests. An explicit finite element code PAM-CRASH was utilized to simulate the model dynamic responses. Simulation results were compared to experimental data obtained from First Technology Safety Systems Inc. Model predictions agreed well in both flexion and extension. This model can be used to study the head-neck biomechanics of the existing dummy as well as in the development of new dummies.

Injuries to the thorax in frontal impact accidents remain an important problem even for restrained occupants. During a frontal accident a significant portion of the forces restraining the occupant pass through the thoracic belt and deform the chest with the possibility of serious thoracic injuries. It is therefore important to understand the deformation of the human thorax when loaded by a thoracic belt and to understand how accurately crash dummies used in standard tests reproduce these deformations. This paper describes results of 19 tests in which a diagonal shoulder belt dynamically loaded the thorax of unembalmed cadavers and dummies (1). In all the tests, thoracic external deformations were measured using string potentiometers and two External Peripheral Instrument for Deformation Measurement (EPIDM) transducers (2).

Numerical simulation of the airbag can be used as a powerful tool in the development of a SIR (Supplemental Inflatable Restraint) system leading to an optimized design and to reduce the development time. However, modeling flattened or folded airbags from the 3D CAD geometry and simulating exact airbag shapes during the deployment is a very complex problem. Especially for the passenger side airbags, generating a flattened and folded mesh from the CAD geometry of the airbag is a very difficult task as these airbags are made of non-developable surface and can not be flattened easily without introducing secondary folds, wrinkling or distortions of mesh. A novel approach called as Initial Metric methodology effectively addresses these problems. The initial metric method uses two types of meshes, A CAD reference mesh and a mapped or a scaled (compressed) mesh constructed from a CAD mesh of the airbag. In the simulation, mapped or scaled (compressed) mesh is used for airbag inflation.

After a rear end impact, various clinical symptoms are often seen in car occupants (e.g. neck stiffness, strain, headache). Although many different injury mechanisms of the cervical spine have been identified thus far, the extent to which a single mechanism of injury is responsible remains uncertain. Apart from hyperextension or excessive shearing, a compression of the cervical spine can also be seen in the first phase of the impact due to ramping or other mechanical interactions between the seat back and the spine. It is hypothesized that this axial compression, together with the shear force, are responsible for the higher observed frequency of neck injuries in rear end impacts versus frontal impacts of comparable severity. The axial compression first causes loosening of cervical ligaments making it easier for shear type soft tissue injuries to occur.

The mechanisms of knee fracture were studied experimentally using cadaveric knees and analytically by computer simulation. Ten 90 degree flexed knees were impacted frontally by a 20 kg pendulum with a rigid surface, a 450 psi (3.103 MPa) crush strength and a 100 psi (0.689 MPa) crush strength aluminum honeycomb padding and a 50 psi (0.345 MPa) crush strength paper honeycomb padding at a velocity of about five m/s. During rigid surface impact, a patella fracture and a split condylar fracture were observed. The split condylar fracture was generated by the patella pushing the condyles apart, based on a finite element model using the maximum principal stress as the injury criterion. In the case of the 450 psi aluminum honeycomb padding, the split condylar fracture still occurred, but no patella fractures were observed because the honeycomb provided a more uniform distribution of patella load. No bony fractures in the knee area occurred for impacts with a 50 psi paper honeycomb padding.

Since numerous years, the vehicle industry is interested in occupant safety. The dummy use in crash tests allowed to create protective means like the belt and the airbag that diminished the injuries of the head and the thorax, which are often lethal for the car occupant. An other objective appears now: to improve the car safety to avoid the injuries which are not fatal but which can cause disability and which cause great cost in hospitalization and rehabilitation. The lower extremity protection, in particular the one of the ankle and the foot region, has become the subject of diverse research efforts by its high percentage of injuries in car crashes. But the dummy mechanics cannot reproduce the accurate ankle and the foot kinematics during an impact loading like in vehicle crash. Therefore, ankle/foot complex numerical models are an essential tool for the car safety improvement.

Previously, a 10-year-old (YO) pediatric thorax finite element model (FEM) was developed and verified against child chest stiffness data measured from clinical cardiopulmonary resuscitation (CPR). However, the CPR experiments were performed at relatively low speeds, with a maximum loading rate of 250 mm/s. Studies showed that the biomechanical responses of human thorax exhibited rate sensitive characteristics. As such, the studies of dynamic responses of the pediatric thorax FEM are needed. Experimental pediatric cadaver data in frontal pendulum impacts and diagonal belt dynamic loading tests were used for dynamic validation. Thoracic force-deflection curves between test and simulation were compared. Strains predicted by the FEM and the injuries observed in the cadaver tests were also compared for injury assessment and analysis. This study helped to further improve the 10 YO pediatric thorax FEM.