Frontal Crash Tests Research Articles

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.

Evaluation of brain injury criteria based on reliability analysis

Among the proposed brain injury metrics, Brain Injury Criteria (BrIC) is a promising tool for performing safety assessment of vehicles in the future. In this paper, the available risk curves of BrIC were re-evaluated with the use of reliability analysis and new risk curves were constructed for different injury types based on literature data of tissue-level tolerances. Moreover, the comparison of different injury metrics and their corresponding risk curves were performed. Tissue-level uncertainties of the effect and resistance were considered by random variables. The variability of the tissue-level predictors was quantified by the finite element reconstruction of 100 frontal crash tests which were performed in Simulated Injury Monitor environment. The applied tests were scaled to given BrIC magnitudes and the injury probabilities were calculated by Monte Carlo simulations. New risk curves were fitted to the observed results using Weibull and Lognormal distribution functions. The available risk curves of diffuse axonal injury (DAI) could be slightly improved, and combined AIS 4+ risk curves were obtained by considering subdural hematoma and contusion as well. The performance of several injury metrics and their risk curves were evaluated based on the observed correlations with the tissue-level predictors. The cumulative strain damage measure and the BrIC provide the highest correlation (R² = 0.61) and the most reliable risk curve for the evaluation of DAI. Although the observed correlation is smaller for other injury types, the BrIC and the associated reliability analysis-based risk curves seem to provide the best available method for estimating the brain injury risk for frontal crash tests.

Optimasi Parameter Desain Multi-Cell Hexagonal Crash Box terhadap Absorbsi Energy Impact dengan Metode Taguchi

The crash box is a passive safety system placed between the bumper and the mainframe of the car that functions as an energy absorber to reduce the impact of driving accidents. The purpose of this study is to determine the optimal level of factors and analyze the factors that provide the most significant effect on energy absorption in a multi-cell hexagonal crash box. Identification of parameters that affect the crash box in energy absorption, namely: the position of placement hole (P), the distance of position hole (L), the thickness of crash box (t), and the hole diameter (D). The modeling method has used the design of the crash box by utilizing a computer simulation with software ANSYS 17.0. This research uses aluminum material type AA 6061-T4 and impactor material uses structural steel. Modeling loading using the frontal crash test method. In this modeling, the impactor with a speed of 7.67 m/s with a deformation length of 100 mm. This research uses the experimental design of the Taguchi method with the L27 orthogonal array. The optimization result were obtained optimum design parameter multi-cell hexagonal crash box with parameter settings P = inner wall; L = 112.5 mm; t = 2 mm, and D = 6.6 mm. Based on the calculated F value ≥ F Table, the factors P, t, and D affect the ability to absorb energy. Thickness crash box (t) has the highest contribution of 98.10% in increasing the value of energy absorption.

The influence of coach interior partitions and seat leaf-tables on occupant injury in a frontal collision

For a typical coach, interior seats and partitions are considered as secondary collision objects in the event of a frontal collision. When a seat back has a deployable leaf-table, the additional effect of the leaf-table should be considered too. To investigate the effect of occupant collision with these objects, a full-scale frontal crash test of a coach was conducted with an impact velocity of 30 km/h. For virtual tests, a coupling model of partition-seat-occupants on a sled was established using the combination of LS-DYNA and MADYMO. It was validated using the full-scale test. The injury severity of the first row occupants was evaluated under different restraint conditions. Results show that occupants who are not belted and those with a lap belt only have the highest injury severity. A comparison of kinematics and injury characteristics between the first row occupants and the non-first row occupants was conducted to provide a comparative analysis.

A Sensor Suite for Toeboard Three-Dimensional Deformation Measurement During Crash.

This paper presents the development of a sensor suite that is used to measure the toeboard threedimensional (3D) dynamic deformation during a crash test, along with the methodology to use the sensor suite for toeboard measurement. The sensor suite consists of three high-speed cameras, which are firmly connected through a rigid metal frame. Two cameras, facing directly towards the toeboard, measure the shape of the toeboard through stereovision. The third camera, facing the ground, is equipped with a three-axis gyroscope and a three-axis accelerometer and localizes the sensor suite globally for removing the vibration of the sensor suite. The sensor suite was mounted onto the car through car seat mounting bolt holes, and a hole was made on the floor to let the downward camera see the ground. A pipeline using the data collected by the sensor suite is also introduced in this paper. A 56 km/h frontal barrier crash test was conducted to validate the capability of the sensor suite and a sled test was conducted to test the measuring accuracy of the purposed system. The results show that the proposed sensor suite identified its position and orientation, which allowed the removal of vibration of the stereo camera. The measuring accuracy, which is neither temporal nor positional, was 1.3 mm. The proposed methodology, as a result, has measured the global 3D deformation of the toeboard during crash with a measuring accuracy of 1.3mm.

Determining vehicle pre-crash speed in frontal barrier crashes using artificial neural network for intermediate car class

This paper introduces a new, innovative approach to pre-crash velocity determination, namely the artificial neural networks. A perceptron based on a database obtained from NHTSA (National Highway Traffic Safety Administration) with numerous data concerning frontal vehicle crash tests: i.e. vehicle mass, deformation zone and deformation coefficients C1-C6. Part of the database entries were used to train the network to develop consistent accuracy and the remainder was used as validation and training sets.

Frontal Crash Injury Metrics Are Below Mandated Limits for a Spica Casted Child Dummy in Currently Available Restraints.

There is a paucity of data defining safe transport protocols for children treated with hip spica casting. Although restraint devices for casted children are available, all federally mandated testing uses a noncasted anthropomorphic test device (ATD or crash dummy). The purpose of this study was to evaluate current restraint options in simulated frontal crash testing using a casted pediatric ATD to determine injury risk to the head, cervical spine, chest, and pelvis. Using a 3-year-old ATD, dynamic crash sled tests simulating frontal crash were performed in accordance with government safety standards. The ATD was casted in a double-leg spica and the following restraint devices were tested: a seat designed for spica casted children, a restraint vest-harness, a traditional booster seat, and 2 traditional forward-facing car seats. Although the presence of the cast increased many of the injury metrics measured, all seats passed current federal guidelines for the head and chest. No single seat performed best in all metrics. The greatest magnitude of neck loading and second-highest head injury criterion values were observed for the booster seat. The vest-harness produced the highest head injury criterion and the chest compression exceeded proposed federal limits. The results suggest safe transport in commercially available seats is possible with the child properly restrained in a correctly fitting seat. However, parents should not assume a child restraint system is appropriate for use just based on fit as, for example, seats with harnesses outperformed an easy to fit booster seat. Each child and the position of the child's cast are unique and discharge planning involves consideration of safe transportation. Although this study suggests several seats used to transport spica casted children pass the federal head and chest injury prevention requirements, it is important to recognize that some children may still require emergency vehicle transport.

Suitability of enhanced head injury criteria for vehicle rating

Objective: Euro NCAP is considering the implementation of a new head injury assessment with the introduction of THOR in the mobile progressive deformable barrier frontal impact crash test. The objective of this study is to assess the suitability of enhanced head injury criteria for practical application in consumer rating programs.Method: AIS2+ risk predictions from nine selected head injury criteria where calculated for 27 pairs of crash test results representing small and moderate overlap frontal crashes. The capability of each injury criteria to predict the real-world injury rates of these crash modes was evaluated. Next, the correlation coefficients between the head injury candidates were calculated and individual predictions were compared for all tests in scatter plots.Results: The results show that none of the crash tests head injury assessment predicted the four-times higher head injury rates observed in the accident data for small overlap crashes compared to moderate overlap crashes. Poor correlation was demonstrated between many leading brain injury metrics, and the risk predictions for individual vehicles differ quite substantially depending on the criterion considered. Conclusions: While preliminary, the results of this study demonstrate that more evaluation of the most suitable brain injury criteria is necessary before consideration into a consumer evaluation program. Convergence of the head injury criteria risks for individual cases should be part of the validation process for enhanced head injury criteria, since identical head signals should yield similar injury risks.

Safe Transport of Spica Casted Children in Passenger Vehicles is Possible: A Frontal Crash Test Analysis of Child Restraint Systems Using Spica Casted Crash Test Dummies

Purpose: There is a paucity of data defining safe transport protocols for children treated with hip spica casting. No current restraint device has been tested using casted anthropomorphic test devices (ATDs). Our goal was to evaluate current restraint options in simulated frontal crash testing using a casted pediatric ATD.
 Methods: Using an ATD simulating a 3-year-old child, dynamic crash sled tests simulating a frontal crash were performed in accordance with Federal Motor Vehicle Safety Standards 213 (FMVSS 213). Sensors within the ATD recorded: HIC36 (Head Injury Criterion score; predictive of skull fracture), neck injury assessment (Nij), chest compression, chest acceleration, and pelvic injury assessment. Test crash video visual assessment was performed (Figures 1&2). The ATD was casted in a double-leg spica. Five restraint devices were tested: seat designed for spica-casted children (Merrit Wallenberg), modified restraint harness (Modified EZ-On-Vest), commercially available booster seat (Britax Parkway SGL Booster), and two commercially available forward-facing car seats able to accommodate the casted ATD (Diono Radian R100, Graco Nautilus 65 LX). One test was performed for each restraint system. All tests were performed at 30 MPH on a deceleration sled.
 Results: Although the presence of the cast increased many of the injury metrics measured, all 5 seats that were tested passed current FMVSS 213 federal guidelines for the head and chest. However, there were marked differences between the 5 restraint options (Figures 3-5). No single seat performed best in all metrics. Additionally, visual analysis of the video from the test crash of the EZ-On-Vest demonstrated that the face and upper extremities of the ATD are impacted during the crash. The ATD does not have a way to record injury to the extremities, thus this is not captured in the quantitative data.
 Conclusions: Per the FMVSS 213 standard, these results suggest safe transport in the five evaluated restraint systems is possible with the child properly fitted and restrained. However, the Nautilus and Diono were found to have both the lowest HIC36 and chest acceleration values, suggesting casted children may not need specially designed seats. Additionally, review of the video of the EZ-On Vest appears to demonstrate that the vest may expose the casted child to additional facial and extremity injuries compared to systems that allow the child to sit upright.
 Significance: Parents should not assume a restraint system is automatically appropriate for use with their child. While there were differences in the performances of the tested restraint systems, each child is unique and a trained healthcare provider should be consulted to ensure the child is properly restrained.

Nonlinear method of determining the vehicle pre-crash speed based on B-spline with propabilistic weights - subcompact car class

A new non-linear method utilizing the work W of car deformation is considered in this study. The car deformation is defined as an algebraic function of deformation ratio Cs. The method of variable correlation is exploited in order to develop experimental data. To determinate mathematical model parameters, data from the NHTSA database including frontal crash tests are used. Such database is comprised of substantial number of crash cases and main focus was put on frontal impacts. In the non-linear method used so far, the so-called energetic approach, collisions are considered non-elastic. The speed threshold defining the elastic collision was set to be 11 km/h. This simplistic approach is used to determine the linear relation of energy loss during deformation on deformation coefficient Cs. Deformation points C1-C6 are taken into account while calculating a mean value that defines this coefficient. A more accurate non-linear method as well as more complex form of deformation coefficient is suggested to determine the work of deformation in this paper. The focus of those methods is to establish the value of nonlinear coefficient b_k which is the slope factor of precrash velocity Vt and deformation ratio Cs function.

Performance of Rear Under-Ride Protection Device (RUPD) During Car to Heavy Truck Rear Impact

Passenger vehicles crashes with Under-ride rear end of heavy vehicles result in fatal injuries due to sliding of passenger car beneath heavy trucks frames. This is related to an improper structure design of rear under-ride protection device (RUPD) that is mounted to the rear of the heavy vehicles. The design of effective RUPD must be taken into consideration during the design stage of truck chassis frame. There are two types of analyses used to investigate the performance of trucks RUPDs such as experimental tests and numerical analysis or simulation. This review aims to discuss the available research methods on the performance of RUPDs during car to heavy truck rear impact, and record their lack and potential areas. Moreover various crash velocities will be discussed for the car-to-heavy truck rear impact tests, as well as different scales of car frontal crash tests are included. Furthermore energy absorption capability of different truck RUPDs designs will be presented in this paper.

Cross-chest clips in child restraints: A crash testing study

Objective: Cross-chest clips are widely used in North American child restraints but are less common in other countries, partially due to concerns over anterior neck contacts in frontal crashes. They have recently been reported to be associated with lower odds of injury in real-world crashes, but there is a paucity of crash test performance information. This study aimed to compare the dynamic performance of a small child occupant in frontal crash tests with and without cross-chest clips in place.Methods: Frontal sled tests at 49 km/h were conducted to compare 2 cross-chest clip designs to nonuse of a chest clip. Tests using a P3/4 anthropomorphic test device (ATD) to represent the smallest occupant in a forward-facing child restraint were conducted with the chest clips in the recommended position and also in an incorrect lower position and with and without additional harness slack present.Results: Though contacts were observed between the chest clips and the base of the ATD’s neck, there was little difference observed in head excursion or ATD sensor loads in the presence of the chest clips. No detectable change in the neck forces or moments was detected at the time of the neck contacts. The position of the clips did not affect the results. Harness slack increased head excursion, as expected, but this effect did not differ between the tests with and without the clips.Conclusions: Cross-chest clips do not appear to greatly influence the dynamic performance of a forward-facing child restraint in a simulated frontal crash. Taken together with recent research suggesting a potential benefit in injury reduction from the clips in the real world, possibly due to maintaining the harness straps in place on a child’s shoulders, it may be appropriate to re-evaluate safety standards that prevent their use.

Small overlap assessment for early design phases based on vehicle kinematics

Assessing the effectiveness of a vehicle structure concerning the minimisation of intrusions during the early phase of crashworthiness design is challenging because of the lack of a detailed layout of the structural components. In the case of the IIHS Small Overlap Frontal (SOF) crash test, the vehicle kinematics, specifically, the instantaneous positions of the occupant compartment relative to the barrier, are available even early in the development. Hence it is proposed here to use these vehicle kinematics as a predictor of the resulting structural intrusions at the occupant compartment. For this, a method is presented to distinguish between two kinematic responses, glance-off and deformation mode, and identified them by an automated video analysis. This is validated by an example using 182 vehicles subjected to the SOF crash test. This categorical definition is used along with the inbuilt kinematic parameters to derive a linear model for the prediction of the intrusions at the Upper and Lower Hinge Pillar, Upper Dash and Left Instrument Panel providing a first estimate of the vehicle structural rating and thus, overcoming the lack of knowledge uncertainties inherent to this design phase.

Driver head kinematic analysis under frontal offset collision during the rebound phase

Frontal offset crash test, either regulator or NCAP, only focus on evaluating the primary impact during the collision phase. The rebound phase is not counted in the assessment. This study focused on the rebound phase. In this phase, vehicle will rotate to the side, causing occupant's head move toward the window door glass. At an impact velocity from 6 m/s to 9 m/s against tempered glass windows, HIC values can stand over a limit of 1000. However, the severity of the head injury cannot be evaluated in the offset collision test because the window glass winded down for the high speed camera recording purpose. The analysis from the video shows head are moving towards the b pillar and side windows glass during frontal offset crash test. The resultant head rebound velocities varies in the range of 4.63 to 10.18 metre per second.

Behavior of ATD, PMHS and Human Volunteer in Frontal Crash Test

Behavior of ATD, PMHS and Human Volunteer in Frontal Crash Test

System-level Sled Test Methodology to Optimize Restraints for Small Overlap Frontal Crash Tests

System-level Sled Test Methodology to Optimize Restraints for Small Overlap Frontal Crash Tests

Nonlinear methods of vehicle velocity determination based on inverse systems and tensor products of Legendre polynomials in compact car class

The article presents research on the methods of crash velocity determination based on the Compact car class. The database used in the research is provided by the NHTSA (National Highway Traffic Safety Administration) and includes numerous frontal crash tests, which allowed the determination of the mathematical model parameters.Two methods are presented that enable the determination of vehicle velocity before the collision. The first researched method is the so-called inversed system method and is based on the assumption that the relationship between bk coefficient Cs is an inverse function. The second line of research focuses on the tensor product method, which is grounded in the Legendre polynomials, orthogonal on the interval [–1, 1] (Axler, 1997; Cheney and Kincaid, 2002).The article presents the calculation algorithm for both cases and the results with reference to the NHTSA database (Sharma et al., 2007; Siddall and Day, 1996). The application of the least square method provides more precise results in both cases than in previously researched solutions, with a slight advantage of the tensor product method. The obtained mean relative error of the velocity determination using the inverse system method is approximately 16,22% for the linear model and 10,58% for the nonlinear model. In the case of the tensor product method the errors for linear and nonlinear models are respectively 6,74% and 6,3%.

次世代前突用ダミー THOR の胸部応答人体忠実性に関する一考察

次世代前突用ダミー THOR の胸部応答人体忠実性に関する一考察

Non-linear method of determining vehicle pre-crash speed based on tensor B-spline products with probabilistic weights — Intermediate Car Class

In the following study we consider the Intermediate Car Class. We apply a novel non-linear method, where the work W of car deformation is defined as an algebraic function of deformation ratio Cs.We use the data from the NHTSA (National Highway Traffic Safety Administration) database comprising numerous frontal crash tests. On the basis of this database, we determine the mathematical model parameters. In the so-called energetic approach, collisions are treated as non-elastic.The velocity threshold that defines the elastic collision was set to be 11km/h. Such an approach, which greatly simplifies our considerations, determines the linear dependence of energy lost during deformation on deformation coefficient Cs.The coefficient Cs is calculated as a weighted mean value of deformation points C1–C6. In this paper, the authors suggest a more precise non-linear method in order to determine the work of deformation.

Sensitivity analysis and optimization for occupant safety in automotive frontal crash test

Abstract Nowadays, safety is a competitive advantage for automotive products and therefore receives considerable attention by automotive research centers. In this paper, a frontal crash test of sedan product of an under development platform is simulated and occupant head injuries are investigated based on ECE R94 regulation. First, an initial evaluation of the crash behavior of the sedan car is carried out and then airbag, dummy and seat belt are added to the model to study occupant head injuries under crash test. In this study, peak head acceleration and head injury criteria (HIC36) are considered as two output parameters based on ECE R94 regulation. Considering these two output parameters, sensitivity analysis and optimization are performed using Taguchi and analysis of variance (ANOVA) methods. In this way, airbag distance to dummy, trigger time, initial inflator gas temperature and tank pressure are considered as input parameters. Obtained results show that in all computer experiments designed by Taguchi responses values satisfy the requirements of ECE R94. Two different out-of-position conditions are considered by reducing the distance between dummy and airbag relative to the optimum design obtained by Taguchi. The worst case of design and its response values are also predicted using Taguchi. Finally, re-evaluating finite element analyses are performed based on the optimum and the worst cases. The results of these simulations show the validity of approach of this paper.