Vehicle Crash Tests Research Articles

Evaluation of lap belt-pelvis load transfer in frontal impact simulations using finite element occupant models

Objective The goal of this study was to examine the relationship between lap belt tension and force measured at the iliac wing and the effects of model type and torso posture on this relationship. From this analysis, preliminary transfer functions were developed to predict loads applied to the iliac wing as a function of lap belt tension at magnitudes typically measured in sled and vehicle crash tests. Methods A DOE study was conducted to provide a robust assessment of the lap belt-pelvis load relationship under various conditions. The GHBMC, THUMS, and THOR FE models were positioned in upright and reclined postures with several other intrinsic and extrinsic parameters varied for a total of 360 simulations. For the HBMs, instrumentation was developed to measure ASIS load at each iliac wing. Simulations that resulted in submarining were identified and removed from the subsequent development of lap belt-ASIS force transfer functions. Results The GHBMC exhibited submarining more frequently than the THUMS and THOR models. In addition to submarining, there were several cases in which the lap belt remained below the ASIS instrumentation or roped during the model’s forward excursion. These phenomena, particularly prevalent in the THUMS model, also influenced how the lap belt engaged the ASIS instrumentation and were thus eliminated from the transfer function development. Transfer functions relating peak lap belt tension and corresponding ASIS force magnitudes were developed for the GHBMC and THOR models in upright and reclined postures. In the upright posture, the THOR showed a higher level of ASIS load measured for a given level of lap belt tension than the GHBMC; however, in recline the lap belt-pelvis load relationship was similar between the two models. Conclusions The lap belt-pelvis load relationship was found to be affected by model type, posture, the area in which the ASIS instrumentation was defined, and occupant kinematics. This study showed it was possible to minimize the ASIS force by having the lap belt engage low on the pelvis and upper thighs, though further study is needed to determine if this loading mechanism is truly protective from an injury standpoint or an artifact of bypassing the ASIS instrumentation. The transfer function that showed the highest ASIS force measured for a given level of lap belt tension is recommended for future use.

A study on the application of diffuse axonal multi-axis general evaluation for brain injury assessment in small overlap barrier crash test

PurposeHead injury criterion (HIC) companied by a rotation-based metric was widely believed to be helpful for head injury prediction in road traffic accidents. Recently, the Euro-New Car Assessment Program utilized a newly developed metric called diffuse axonal multi-axis general evaluation (DAMAGE) to explain test device for human occupant restraint (THOR) head injury, which demonstrated excellent ability in capturing concussions and diffuse axonal injuries. However, there is still a lack of comprehensive understanding regarding the effectiveness of using DAMAGE for Hybrid Ⅲ 50th percentile male dummy (H50th) head injury assessment. The objective of this study is to determine whether the DAMAGE could capture the risk of H50th brain injury during small overlap barrier tests. MethodsTo achieve this objective, a total of 24 vehicle crash loading curves were collected as input data for the multi-body simulation. Two commercially available mathematical dynamic models, namely H50th and THOR, were utilized to investigate the differences in head injury response. Subsequently, a decision method known as simple additive weighting was employed to establish a comprehensive brain injury metric by incorporating the weighted HIC and either DAMAGE or brain injury criterion. Furthermore, 35 sets of vehicle crash test data were used to analyze these brain injury metrics. ResultsThe rotational displacement of the THOR head is significantly greater than that of the H50th head. The maximum linear and rotational head accelerations experienced by H50th and THOR models were (544.6 ± 341.7) m/s2, (2468.2 ± 1309.4) rad/s2 and (715.2 ± 332.8) m/s2, (3778.7 ± 1660.6) rad/s2, respectively. Under the same loading condition during small overlap barrier (SOB) tests, THOR exhibits a higher risk of head injury compared to the H50th model. It was observed that the overall head injury response during the small overlap left test condition is greater than that during the small overlap right test. Additionally, an equation was formulated to establish the necessary relationship between the DAMAGE values of THOR and H50th. ConclusionIf H50th rather than THOR is employed as an evaluation tool in SOB crash tests, newly designed vehicles are more likely to achieve superior performance scores. According to the current injury curve for DAMAGE and brain injury criterion, it is highly recommended that HIC along with DAMAGE was prioritized for brain injury assessment in SOB tests.

Comparison of frontal crash compatibility metrics between battery-electric and internal-combustion-engine passenger vehicles

Objective The objective of this study was to determine if there are any emerging issues related to battery-electric vehicles’ (BEVs’) geometry, force distribution, and extra weight that may make them more aggressive partners in front-to-front crashes through comparisons of stiffness metrics derived from crash tests. Methods We examined load cell wall data from the National Highway Traffic Safety Administration’s (NHTSA’s) New Car Assessment Program full-width frontal crash test at 56 km/h. Fourteen BEVs, ranging in class from small cars to large SUVs, were compared with 92 internal-combustion-engine (ICE) vehicles, ranging in class from small cars to midsize pickups. We selected vehicles based on the test results available in the NHTSA Vehicle Crash Test Database, and there were no tests of battery-electric (BE) pickups. Data included load-cell-wall force-time histories and longitudinal vehicle acceleration from the body structure. We constructed force-displacement diagrams and calculated static, dynamic, energy-equivalent, and initial front-end-stiffness metrics from load cell wall forces, vehicle acceleration, and static front-end crush measurements for each vehicle. Linear regression models were applied to the metrics for comparison between powertrains. Results BE cars and BE SUVs weighed more than their ICE counterparts, on average 369 kg and 286 kg more, respectively. Initial (200 mm and 400 mm), energy-equivalent and dynamic front-end-stiffness metrics, average height of force, and individual maximum forces, when compared with vehicle shadow, were not statistically different between powertrains. Static stiffness (p = 0.04) and initial stiffness (300 mm; p = 0.05) decreased for BEVs with greater shadow and increased with greater shadow for ICE vehicles. When controlling for vehicle shadow, dynamic crush was greater (p = 0.01), the percentage of center force was lower (p < 0.001), and maximum peak force was higher (p = 0.01) for BEVs compared with ICE vehicles. For the Kia Niro BEV and ICE pair, the 329 kg heavier BEV had a 165 mm longer crush distance, which resulted in lower forces and stiffness metrics compared with the traditional ICE counterpart. Conclusion Overall, this study indicates that current BEVs are not excessively aggressive in terms of stiffness metrics for frontal crash compatibility compared with ICE vehicles.

Test and application of movable steel barrier with grade SB light composite corrugated beam

In this study, movable steel barrier with grade SB light composite corrugated beam is designed, which addresses the problems of the prior central partition belt portable guardrail in terms of easy mobility, local safety, easy construction, and other indications. This guardrail employs explicit algorithms to conduct a dynamic finite element simulation analysis and a real vehicle crash test, and verifies the guardrails' blocking, guiding, and buffering functions in accordance with the SB level collision conditions listed in the Standard for Safety Performance Evaluation of Highway Barriers (JTG B05-01-2013). According to the results, the safety performance of SB grade lightweight composite corrugated beam movable steel guardrail meets the requirements of the Standard for Safety Performance Evaluation of Highway Barriers (JTG B05-01-2013). In addition, the guardrail can be opened for 12 meters in 1 minute and returned to close in 2 minutes. The opening and restoration of the movable guardrail is superior to the previous central divider movable guardrail. This guardrail has been tried for some high-speed and its safety performance has been verified again in actual high-speed vehicle collisions.

Study on evaluation indexes of the full width deformable barrier test

In order to evaluate the crash compatibility of vehicles, the full width deformable barrier is introduced into the vehicle crash test. Real car to car frontal collision is better simulated by installing deformable barrier on the load-cell wall . By the load-cell wall data, the values and distribution of vehicle frontal collision loads can be further obtained. Based on this, the full width deformable barrier tests are conducted for different structural sedans and SUV. The height index, homology index, horizontal structure interaction index(HSI), vertical structure interaction index(VSI), and minimum load-cell index are analyzed and compared. The results indicate that there is uncertainty when calculating the homology index RH and the evaluation indexes proposed by FIMCAR repeat the first step of VSI and HSI. Therefore, the height index, VSI, and HSI indexes are selected as effective indexes for evaluating the compatibility of the full width deformable barrier test.

Comparison of Head, Neck, and Chest Injury Risks between Front and Rear-Seated Hybrid III 50th-Percentile Male ATDs in Matched Frontal NCAP Tests

&lt;div&gt;The objective of this study was to compare head, neck, and chest injury risks between front and rear-seated Hybrid III 50th-percentile male anthropomorphic test devices (ATDs) during matched frontal impacts. Seven vehicles were converted to rear seat test bucks (two sedans, three mid-size SUVs, one subcompact SUV, and one minivan) and then used to perform sled testing with vehicle-specific frontal NCAP acceleration pulses and a rear seated (i.e., second row) Hybrid III 50th male ATD. Matched front seat Hybrid III 50th male ATD data were obtained from the NHTSA Vehicle Crash Test Database for each vehicle. HIC15, Nij, maximum chest acceleration, and maximum chest deflection were compared between the front and rear seat tests, as well as between vehicles with conventional and advanced three-point belt restraint systems in the rear seat. Additionally, a modified version of the NCAP frontal star rating was calculated for the front and rear seat tests. All injury metrics, except for chest acceleration, were higher in the rear seat compared to the front. In addition, injury thresholds were exceeded or nearly exceeded in the rear seat for Nij in three vehicles, chest acceleration in one vehicle, and chest deflection in three vehicles, while no thresholds were exceeded in the front seat. When comparing advanced and conventional restraints in the rear seat, all injury metrics were higher in the vehicles with conventional restraints. All vehicles with conventional restraints in the rear had a star rating of 1, while those with advanced restraints in the rear ranged from 2 to 3. Conversely, all vehicles had 5 stars for the front seat, except one that had 4 stars. Overall, these data highlight the disparity between front and rear seat occupant protection and the benefits of advanced rear seat safety restraints, and the need for future testing.&lt;/div&gt;

Analysis of Driver Departure and Damage in Frontal 100% Overlap Rigid Barrier Crash Conditions with AEB Intervention.

A braking robot and an in-vehicle HD camera were used to study the influence of emergency braking systems on the passive safety of vehicles, to conduct real vehicle tests on volunteers. The dynamic responses of 18 groups of volunteers under different braking deceleration speeds and different test speeds were collected, and the change rule of the driver’s forward tilt displacement during AEB braking was analyzed. The x-direction displacement of the head and shoulder of the volunteers increased with the increase of the braking deceleration speed, and there was no obvious correlation with the initial speed. Madymo was used to build a restraint system model, verified against the real vehicle crash test data. The maximum off-position state of the volunteer’s real car test was input into the restraint system model. The injury of drivers in frontal 100% overlap rigid barrier crash conditions with or without AEB effect was analyzed through simulation and comparison. It was concluded that AEB interventions do not increase the damage value with the existing passive safety development strategy.

Construction of Collision Equivalent Scaled Model for Locomotive Using Multi-Parameter Nondimensional Method

At present, the research on crashworthiness of locomotive mainly adopts the method of theoretical analysis, numerical simulation and component test, it is too expensive and less repeatable to carry out vehicle crash tests. Therefore, a method to construct the collision equivalent scaled model (SM) for locomotive based on multi-parameter nondimensional is presented in this paper. Firstly, an equivalent method of structural dynamic responses was proposed. The extraction process and analysis method of dynamic responses for thin plate structures widely existing in locomotives were studied. Then, according to the structural characteristics of the locomotive, the partition equivalent design was carried out, and a dimensionless analysis model of impact dynamic responses for SM was established. Finally, the SM crash test was carried out to verify the effectiveness of collision equivalent SM established, it was found that the SM has high reliability, it can achieve equivalence with the locomotive for energy absorption, average impact force, average acceleration of cab and center of gravity of vehicle body. Carrying out the SM crash test can study the reasonable configuration of energy absorption parameters for locomotives and obtain the impact dynamic responses of locomotives under different configurations of energy absorption parameters.

Incorporation of motion prediction and state estimation to track dots for vision-based in-crash toeboard deformation measurement

This paper presents a marker-based stereovision method to measure toeboard deformation during a crash test. The method tracks a set of colored dots marked on the surface for stereovision using recursive state estimation that consists of a prediction step and a correction step. Prediction is based on a motion model derived by feature matching and mapping in the stereo image. In the correction step, the dots are first tracked using a dot centroid tracking (DCT) algorithm that weights the color, saturation, and brightness of pixels in a search kernel predicted by the motion model. An extended Kalman filter (EKF) subsequently fuses the prediction and the DCT measurement for the most likely dot centroid. The accuracy and robustness of the proposed method for in-crash toeboard deformation measurement are presented in a vehicle crash test. The experiment shows the proposed technique tracks the deformed surface accurately and is robust in varied light conditions and conditions when the field of view (FOV) is temporarily blocked.

Head injury criteria assessment using head kinematics from crash tests and accident reconstructions

Objective The aim of this study was to assess head injury criteria based on their correlation to brain strain in a Finite Element (FE) head model (the KTH Royal Institute of Technology model), by simulation of head kinematics data from frontal and side crash tests with Anthropomorphic Test Devices (ATDs), and from Human Body Model (HBM) accident reconstructions. Methods Six Degrees of Freedom (DoF) head kinematic data was extracted from 221 crash tests, consisting of frontal impacts with the THOR-50M ATD, near-side and far-side impacts with the WorldSID-50M ATD, and from 19 FE HBM accident reconstructions. The head injury criteria HIC15, HIP, BrIC, UBrIC, DAMAGE and CIBIC were calculated, and FE head model simulations were conducted using the six DoF kinematics data. The 100th, 99th, and 95th percentile Maximum Principal Strains (MPS) of the brain were extracted and linear regression models with respect to the injury criteria were created. The injury criteria were then evaluated based on the coefficient of determination, R2, and the Normalized Root Mean Square Error (NRMSE) of each regression model. Results For all the data sets combined and for the WorldSID far-side data, CIBIC had the best goodness of fit, with R2 of 0.76 and 0.85. For frontal impacts with THOR and the combined ATD data set, DAMAGE had highest R2, 0.83 and 0.78, respectively. Injury criteria including translational accelerations were ranked lower, and BrIC were among the three lowest ranked for most data sets evaluated. UBrIC generally ranked after DAMAGE and CIBIC with respect to the goodness of fit but had the lowest NRMSE for all data sets. Conclusions The two mass-spring-damper brain surrogate model criteria, DAMAGE and CIBIC, were best in capturing the head model MPS response for both the THOR and WorldSID data sets. BrIC had lower correlation to the head model MPS and performed marginally better than the linear acceleration only criteria for all the data sets combined. This study supports the suitability of DAMAGE and CIBIC as brain injury criteria to be used with THOR-50M and WorldSID-50M in vehicle crash test conditions, as they outperform BrIC.

Dynamic Behaviors of Optimized K12 Anti-Ram Bollards

Since terrorist attacks pose a great threat, protective structures need to be applied in terms of the safety of buildings and personnel. The installation of anti-ram bollards around buildings and infrastructures could block potential hazards, including the damage caused by car bombs and vehicular impacts on the buildings. In order to provide effective protection for buildings, the dynamic behaviors of anti-ram bollards should be examined, which is under insufficient research. In this paper, by adopting the FE program LS-DYNA, the FE models of corresponding anti-ram bollards are established, and the FEMs are validated by comparison with the experimental results of five existing vehicle crash tests. On this basis, the dynamic response of the optimized K12 anti-ram bollards under vehicular impact is numerically analyzed, and the influences of various parameters on the deformation of anti-ram bollards, as well as the displacement of the vehicle is studied.

Criteria inadequacy of the vehicles used for the calculation of safety parameters in the EN1317-TB11 test

Road restraint systems-RRS are passive safety designs installed on roadsides to ensure the safety of errant vehicle passengers as well as pedestrians. The adequacy of these systems is assessed through full-scale vehicle crash testing for which evaluation criteria are determined by standards such as EN1317. Recently the same RRS is crash tested two times with two different 900 kg passenger cars and test results varied significantly. After a failed crash test instead of modifying the barrier test vehicle was replaced and the same test was repeated. It was surprising to see that the failed RRS this time satisfied the EN1317 evaluation criteria. Despite the use of the same mass vehicle in the crash tests, the different results obtained were a source of motivation for investigating the inadequacy of EN1317. In this study, the adequacy of the 900 kg vehicle criteria used in the determination of the safety parameters in the EN1317-TB11 test was investigated by creating validated finite element-FE models. After the FE analysis it was concluded that test vehicle properties, such as vehicle mass and velocity provided in EN1317 are deemed to be insufficient and more explicit vehicle selection parameters, given in the study, are needed to provide safer and more uniform crash testing results.

Research and Design of a Wing-Wall-Free Guardrail in Transition Between the Subgrade and the Bridge

Considering the difficulty and high cost of guardrail installation in the transition between the highway subgrade and the bridge, this paper proposes a wing-wall-free guardrail based on comprehensive research. It has carried out a performance analysis of material Q690 before proposing the scheme. It is found that this type of material has high yield strength and tensile strength as well as high plasticity. Accordingly, the guardrail structure of the transition section of the wing-wall-free guardrail is designed, and the DYNA numerical simulation is carried out to optimize the structure. Moreover, vehicle crash tests are used to verify the performance of the newly designed guardrail. The results of the above-mentioned research methods are as follows: the vehicle crash tests show that the wing-wall-free guardrail can reach a protection level of Grade SB, with a collision energy of 280 KJ. All performance indicators meet the industry standards. The guardrail can be used in the transition between W-beam subgrade guardrails and concrete or combined bridge barriers. This proposed guardrail is beautifully designed with low cost and great conveniency for installation and maintenance.

Design and manufacture of thermoplastic carbon fiber/polyethylene terephthalate composites underbody shield to protect the lithium-ion batteries for electric mobility from ground impact

Recently, the electric mobility has emerged with great prospects as there has been a growing interest in and demand for eco-friendly energy. The electric vehicle uses a large number of lithium batteries as sources of power, and the lithium battery poses a risk of fire and explosion when the external impact is loaded. Therefore, in this study, an underbody shield (UBS) was designed and manufactured using carbon fiber reinforced thermoplastic composites for battery protection. The underbody shield is composed of two parts, which are the main shield plate and collision protection bar (CPB). Mechanical behavior against impact was analyzed through finite element analysis considering the position of the CPB and the shape of the underbody shield plate. For the UBS, the hybrid composites (Carbon fiber (CF)/polyethylene terephthalate (PET) and self-reinforced polypropylene (SRPP) composites) were used and the ratio between the CF/PET and SRPP was optimized. Through a finite element analysis, the optimal underbody shield was designed with a thickness of 2.4 mm and a hybrid ratio of CF/PET:SRPP as 1:2. Finally, the designed underbody shield was manufactured using a thermo-forming process and mounted to an electric vehicle, and then a vehicle crash test was performed with a concrete obstacle. The developed underbody shield could protect the battery against the impact damage successfully, showing that the deformation of a rear part was within 5 mm and no battery leakage occurred.

Localization of Stereovision for Measuring In-Crash Toeboard Deformation.

This paper presents a technique to localize a stereo camera for in-crash toeboard deformation measurement. The proposed technique designed a sensor suite to install not only the stereo camera but also initial measurement units (IMUs) and a camera for localizing purpose. The pose of the stereo camera is recursively estimated using the measurement of IMUs and the localization camera through an extended Kalman filter. The performance of the proposed approach was first investigated in a stepwise manner and then tested in controlled environments including an actual vehicle crash test, which had successfully resulted in measuring the toeboard deformation during a crash. With the oscillation motion in the occurrence of the crash captured, the deformation of the toeboard measured by stereo cameras can be described in a fixed coordinate system.

Influential crash conditions leading to injury differences experienced by female and male drivers

IntroductionRobust occupant protection is critical for the longevity and quality of life of the diverse driving population. Studies have shown that the vehicle crash testing process has greatly assisted in decreasing the severity of injuries experienced by occupants. However, female occupants are not equitably accounted for in the current testing processes while experiencing a significantly increased risk of higher severity injuries compared to male occupants in comparable crash conditions. Given the increased safety concern for female occupants, it is critical to investigate the conditions that result in injuries occurring in specific locations in cases of female occupants compared to male occupants. MethodsIn this study, an investigation is made to uncover potential influential crash conditions that lead to injury location differences experienced by female and male drivers using a novel linked dataset of emergency medical services and crash data. Logistic regression methods were used to develop robust analyses. ResultsThe results revealed that female and male drivers experience injuries in different locations to a significant degree depending upon vehicle model year, airbag deployment, and driver age when considering all crash types. The results included the finding that as vehicle model year increases, neck injury risk decreases for male drivers while it increases for female drivers. ConclusionsThis study highlighted the crash conditions and vehicle components that lead to different injury outcomes for female and male drivers. From a policy perspective, the results emphasize the importance of including both representative female and male anthropometry in vehicle testing and design. From a practitioner and research perspective, this study provides the data needed to understand the components of vehicle design that must be further considered to provide optimal occupant protection for the entire driving population, leading to more equitable, positive long-term health outcomes for all drivers.

Simulation and Optimization of Crash Performance of Movable Barrier at Median Strip

To better evaluate the crash performance of the guardrail and reduce the number of actual vehicle crash tests, this paper uses mechanical analysis and finite element simulation technology to evaluate the typical movable guardrail and optimize the structure. It's of great significance for improving the crashworthiness of this type of guardrail and enhancing its safety performance. Firstly, the vehicle-barrier mechanical model was established to calculate the vehicle collision force on the barrier. Secondly, the collision force model was used to calculate the collision of a 10-ton truck, and a finite element model of a typical movable barrier was established for a collision simulation. Finally, the wall thickness and column spacing were optimized according to the results. The simulation results show that the maximum lateral dynamic deformation of the barrier was 1,818 mm, which agrees with the actual vehicle test results (1,600 mm). When the wall thickness of the barrier increases by 2 mm, the maximum lateral dynamic deformation was 1,419 mm; When the spacing of strengthened columns was reduced to 15 m, the deformation was 1,364 mm; After optimization, the deformation was reduced by more than 20%, and the crashworthiness of barrier was improved obviously.

Motor Vehicle Crash Testing Regulations for More Inclusive Populations

There is a stark disparity in motor vehicle crash deaths and injuries between male and female drivers. Female drivers are 13% more likely to be killed than their male counterparts in similar motor accidents. However, vehicle safety test practices do not account for diverse body proportions when assessing safety outcomes. Vehicle crash testing standards only require testing of two variations of adult-sized crash test dummies: a 50th percentile male and a 5th percentile female. Automotive companies are not required to test safety outcomes in crash test model’s representative of average female proportions or of non-average body sizes and physiological compositions. Current crash test standards are regulated by the National Highway Traffic Safety Administration (NHTSA) under the US Department of Transportation. This memo proposes three actions for the NHTSA and the Department of Transportation to address disparities in vehicle safety outcomes: 1) update safety standard requirements to include a 50th percentile female crash test dummy, 2) implement a federal tax incentive program for companies to include a greater diversity of vehicle occupant models, and 3) allocate funds for research and development of virtual crash testing models. These proposed initiatives seek to raise the minimum safety requirements and prioritize wider representation of vehicle occupants to improve parity in vehicle safety outcomes.

Determining vehicle pre-crash speed in frontal barrier crashes using genetic algorithm model adjustment techniques for intermediate car class

This paper introduces another approach to pre-crash velocity determination by the means of genetic algorithm model adjustment (GAMA). This innovative method is based on the standard genetic algorithm approach applied to the problem of determining the dependency of predicted variable on given parameters. The experiment is performed on a database obtained from NHTSA (National Highway Traffic Safety Administration), which contains potent number of data samples regarding frontal vehicle crash tests: i.e. vehicle mass, deformation zone and deformation coefficients C1-C6. Various classes of possible functions are considered and the model for determining the pre-crash speed based on the given parameters is obtained.

Modeling and Simulation of a Vehicle Crash Test

Modeling and Simulation of a Vehicle Crash Test