Search Results

EuroSID-2 and EuroSID-2re are among the most frequently used side impact dummies in vehicle crash safety. Radioss is one of most widely applied finite element codes for crash safety analysis. To meet the needs of crash safety analysis and to exploit the potential of the Radioss code, a new generation of EuroSID-2 (ES2) and EuroSID-2re (ES2_RE) Radioss dummies was developed at First Technology Safety System (FTSS) in collaboration with Altair. This paper describes in detail the development of the ES2/ES2_RE dummies. Firstly whole dummy meshes were created based on CAD data and intensive efforts were made to obtain penetration/intersection-free models. Secondly FTSS finite element certificate tests at component level were conducted to obtain satisfactory component performances. These tests include the head drop test, the neck pendulum test, the lumbar pendulum test and the thorax drop test [ 1 , 2 ].

Accident data show that the injury risks to children seated in child restraint systems (CRSs) are higher in side collisions than any other type of collision. To investigate child injury in the CRS in a side impact, it is necessary to understand the occupant responses in car-to-car crash tests. In this research, a series of full car side impact tests based on the ECE R95 test procedure was conducted. In the vehicle's struck-side rear seat location, a Q3s three-year-old child dummy was seated in a forward facing (FF) CRS, and a CRABI six-month-old (6MO) infant dummy was seated in a rear facing (RF) CRS and also was placed in car-bed restraint. In the non-struck side rear seat location, the RF CRSs also were installed. In addition to testing the CRSs installed by a seatbelt, an ISOFIX FF CRS and an ISOFIX RF CRS were tested. For the evaluations, occupant kinematic behavior and injury measures were compared.

Injuries to the lower extremities are one of the major issues in vehicle-to-pedestrian collisions. To evaluate pedestrian lower extremity protection, the Transport Research Laboratory (TRL) legform impact tests have been conducted according to the specifications in the EU directive. The TRL legform impactor consists of a tibia and a femur steel shaft connected by deformable knee bars. A Flexible Pedestrian Leg-form Impactor (Flex-PLI), which has flexible femur and tibia, is examined in the Global Technical Regulation (GTR). Previous studies compared the responses of both impactors; however, the relation between the tibia acceleration in the TRL legform impactor and the maximum bending moment in the Flex-PLI (both injury measures are for the tibia fracture) is not understood sufficiently.

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.

In order to prevent lower extremity injuries to a pedestrian when struck by a car, it is important to elucidate the loadings from car front structures on the lower extremities and the injury mechanism caused by these loadings. In this study, using a human finite element (FE) model, a bending moment diagram and a stress diagram of tibia were introduced to examine the effects of loading from car structures. By the lower absorber of the car, the bending moment was distributed over the tibia with small moment at the upper tibia location that can reduce knee injury risk. Certain positions of the lower absorber reduced the tibia fracture risk. An FE analysis of a legform impact test using the TRL legform impactor was also conducted, and a relation was found between the injury criteria of the TRL legform impactor and the human FE model. High acceleration of the TRL legform impactor corresponded to the tibia fracture or MCL rupture of the human FE model.

This paper describes the development of new advanced Finite Element (FE) models of the World SID series, namely World SID 50th and 5th, the new generation of side impact Anthropomorphic Test Devices (ATD). The model development follows the FTSS's rigorous quality assurance (QA) procedure and uses the manufacture's product data and test facilities extensively. The models are validated at material, component & assembly, full dummy certification and sled test application levels. A detailed modeling methodology is described. The models correlate well with both the component and whole dummy level test results.

The THUMS (Total HUman Model for Safety) 3-year-old child finite element (FE) model was developed by Toyota Central R&D Labs (TCRDL) by model-based scaling from the AM50 (50 percentile male) human FE model. The objective of this paper is to present a comparison between the kinematics of a child FE model developed from the adult THUMS model and a HYRID III 3-year-old child dummy using observations from numerical simulations of a CMVSS 208 frontal crash. Both the child models were positioned in a forward facing, five point child restraint systems (CRS). An acceleration pulse acquired from a vehicle crash test in accordance with Canadian Motor Vehicle Safety Standards (CMVSS) 208 was applied to the seat buck supporting the CRS. Numerical simulations with both the child model and the Hybrid III child dummy were conducted using LS-DYNA version 970.

This research focuses on the response of the Q3, Hybrid III 3-year-old dummy and a child finite element model in a simulated 213 sled test. The Q3 and Hybrid III 3-year old child finite element models were developed by First Technology Safety Systems. The 3-year-old child finite element model was developed by Nagoya University by model-based scaling from the AM50 (50 percentile male) total human model for safety. The child models were positioned in a forward facing, five-point child restraint system using Finite Element Model Builder. An acceleration pulse acquired from an experimental 213 sled test, which was completed following the guidelines outlined in the Federal Motor Vehicle Safety Standard 213 using a Hybrid III 3-year-old dummy, was applied to the seat buck supporting the child restraint seat. The numerical simulations utilizing the Q3, Hybrid III 3-year-old and the child finite element model were conducted using the explicit non-linear finite element code LS-DYNA.

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.

This research focuses on the further development of a child finite element model whereby implementation of pediatric cadaver testing observations considering the biomechanical response of the neck of children under tensile and bending loading has occurred. Prior to this investigation, the biomechanical neck response was based upon scaled adult cadaver behaviour. Alterations to the material properties associated with ligaments, intervertebral discs and facet joints of the pediatric cervical spine were considered. No alteration to the geometry of the child neck finite element model was considered. An energy based approach was utilized to provide indication on the appropriate changes to local neck biomechanical characteristics. Prior to this study, the biomechanical response of the neck of the child finite element model deviated significantly from the tensile and bending cadaver tests completed by Ouyang et al.

The modular dummy model is a new concept to represent a crash dummy in computer simulation. The modular dummy model could be a solution with combination of acceptable responses and quick run times. The approach of the modular dummy model is to take an existing standard model and create rigid modules of all major dummy components (Head, Thorax, Pelvis, Femurs, Tibias, Feet, etc.), which are fully interchangeable between deformable and rigid modules. The special run time efficient component models for the neck and lumbar spine are also developed for the modular dummy. Mass and inertial properties of each rigid module are derived from the corresponding deformable part. The joint and connection definitions are shared between the rigid and deformable modules. The users only need to decide and select which modules should be used in order to achieve the best compromise between CPU time and accuracy for the specific application.

In the current Japanese and European side impact regulation, occupant protection is evaluated based on anthropomorphic test device (hereafter referred to as the more commonly used term “dummy”) measurements recorded in a stationary car impacted by a moving deformable barrier (MDB). In order to validate and improve the side impact test procedures of the regulation and the associated new car assessment program, it is necessary to compare the side impact test procedure with car-to-car side impact tests conducted in various conditions. In this research, a series of car-to-car side impact tests using a small sedan as the target vehicle was conducted as follows: (1) A striking car impacted against the stationary car at 50 km/h at an impact angle of 90 degrees. (2) A 1BOX vehicle impacted the stationary car at 50 km/h at an impact angle of 90 degrees. (3) Both cars were moving, and the striking car impacted the struck car at an impact angle of 90 degrees.

Current accident analysis shows that the head of the pedestrian impacts most frequently into or around the windscreen since cars in recent have a short hood. Therefore, the injury risks to the head in contact with various locations of the car including the windscreen and its frame were examined on the basis of headform impact tests. The HIC is high from contact with the cowl, lower windscreen frame or A pillar, and it is low with increasing distance from these structural elements. In the windscreen center, the HIC is less than 500. The headform impact test results were compared between earlier and current car models. The HICs in the bonnet top area are similar in either type car except for the car built especially for pedestrian safety. However, on the A pillar, the HICs are much greater for current cars. From child headform impact tests for the WAD of 1000 mm, the HIC of SUV is higher than cars, and the SUV with steel bull bar leads to high injury risk.

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.

Accurate prediction of the responses from the anthropomorphic test devices (ATDs) in vehicle crash tests is critical to achieving better vehicle occupant performances. In recent years, automakers have used finite element (FE) models of the ATDs in computer simulations to obtain early assessments of occupant safety, and to aid in the development of occupant restraint systems. However, vehicle crash test results have variation, sometimes significant. This presents a challenge to assessing the accuracy of the ATD FE models, let alone improving them. To resolve this issue, it is important to understand the test variation and carefully select the target data for model improvement. This paper presents the work carried out by General Motors and Humanetics Innovative Solutions (formerly FTSS) in a joint project, aimed at improving the FE model of the Hybrid III-50 ATD (HIII-50) v5.1.

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.

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.

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.