Vehicle Crash Tests Research Articles

Real-world performance of vehicle crash test: the case of EuroNCAP

ObjectiveTo investigate whether the occupants in vehicles with better safety ratings according to EuroNCAP sustain fewer fatal and severe injuries than occupants in vehicles with worse experimental safety ratings when...

The Researches of Effectiveness of Road Restraint Systems

The Researches of Effectiveness of Road Restraint SystemsThe work describes model and experimental tests on the road restraint systems with particular attention to vehicle collisions with a concrete protective barrier. Vehicle and protective barrier crash tests include the experiment results in three basic fields: intensity of influence of the collision effects on vehicle passengers, collision impact on a vehicle and the road restraint system. It presents a test track concept as well as criteria for performing and evaluating the crash tests with a passenger vehicle and a safety barrier. The experimental tests were performed according to the test methodology recommended by the standard [2]. Examples of model test results were compared with experimental test results obtained on the test track.

Vehicle crash test simulation of roadside hardware using LS-DYNA: a literature review

A great deal of progress has been achieved during the past several years in integrating advanced non-linear finite element programs into the design and analysis phases of roadside hardware. Most of the progress in this area can be attributed to the pioneering work by Lawrence Livermore National Laboratory (LLNL) along with extensive financial support by the Federal Highway Administration (FHWA) and other institutions. There is still, however, much work remaining before analytical methods achieve their full potential in roadside safety research. The computer software tools are available and computing capabilities continue to improve at a rapid pace making analysis of complex systems possible. The application of Finite Element Analysis (FEA) has evolved from relatively simple impacts to highly realistic interaction problems. With continued progress, FEA is expected to play a vital role in the design and analysis of new generation cost-effective roadside hardware in coming years. This literature review attempts to summarise the major achievements and key developments on crash test simulation of roadside hardware over the past years and inform readers about the current state of knowledge in roadside hardware simulation. Successful crash test simulations on different applications are reviewed based on roadside hardware type. Specific models used in the virtual crash tests are explained. Due to the nature of the paper, many of the details that go into the successful simulations are not discussed herein. References for those details previously discussed in the literature are provided.

Roadway Departure and Impact Conditions

In-depth accident data were collected to investigate vehicle impact conditions (e.g., crash severity, impact speed, impact angle, and orientation) for crashes with roadside obstacles and features. Descriptive statistics of these variables are presented, including statistics for the data segregated by highway class, speed limit, and access control. Relationships between impact conditions and these segregating factors were explored. Statistical tests were applied to investigate the association between speed and angle, and univariate distributions were fitted for these two variables. Impact speed and impact angle are independent for most highway classes when segregated by highway class, and they have a relatively weak negative correlation. Both impact speed and angle data for all highway classes follow a normal distribution. Joint impact distributions were then determined using the bivariate normal distribution. The findings of this study are of significant importance to the establishment or reinforcement of full-scale vehicle crash testing guidelines, to benefit–cost analysis procedures, and to highway designers who seek more detailed information on probabilities of impact conditions for different highway classes.

Approach Slopes for Midwest Guardrail System

The American Association of State Highway and Transportation Officials’ Roadside Design Guide recommends that W-beam guardrails should not be placed on roadside slopes steeper than 10H:1V. With the development of the Midwest Guardrail System (MGS), the higher mounting height and deeper blockout may provide sufficiently improved performance to relax that recommendation. An LS-DYNA simulation study was conducted to determine that an 8:1 slope, with a barrier placement of 1.5 m down from the slope-break point, was the critical condition for determining the maximum allowable slope for the MGS. Subsequently, two full-scale vehicle crash tests were performed on the system according to Test Level 3 specified in the National Cooperative Highway Research Program Report (NCHRP) No. 350, Recommended Procedures for the Safety Performance Evaluation of Highway Features. The first test was with a pickup truck, impacting the system at a speed and angle of 100.4 km/h and 25.9 degrees, respectively. The second test was performed using a small car, impacting the system with a speed and angle of 99.6 km/h and 21.6 degrees, respectively. Both tests successfully passed all evaluation criteria. Therefore, the research has shown that the MGS may be placed anywhere on an 8:1 or shallower slope and meet NCHRP 350 safety recommendations.

Characterization of Crash-Induced Thoracic Loading Resulting in Pulmonary Contusion

Pulmonary contusion (PC) is commonly sustained in motor vehicle crash. This study utilizes the Crash Injury Research and Engineering Network (CIREN) database and vehicle crash tests to characterize the occupants and loading characteristics associated with PC. A technique to match CIREN cases to vehicle crash tests is applied to quantify the thoracic loading associated with this injury. The CIREN database and crash test data from the National Highway Traffic Safety Administration were used in this study. An analysis of CIREN data were conducted between three study cohorts: patients that sustained PC and any other chest injury (PC+ and chest+), patients with chest injury and an absence of PC (PC- and chest+), and a control group without chest injury and an absence of PC (PC- and chest-). Forty-one lateral impact crash tests were analyzed and thoracic loading data from onboard crash tests dummies were collected. The incidence of PC in CIREN data were 21.7%. Crashes resulting in PC demonstrated significantly greater mortality (23.9%) and Injury Severity Score (33.1 +/- 15.7) than the control group. The portion of lateral impacts increased from 27% to 48% between the control group and PC+ and chest+ cohort, prompting the use of lateral impact crash tests for the case-matching portion of the study. Crash tests were analyzed in two configurations; vehicle-to-vehicle tests and vehicle-to-pole tests. The average maximum chest compression and deflection velocity from the dummy occupants were found to be 25.3% +/- 2.6% and 4.6 m/s +/- 0.42 m/s for the vehicle-to-pole tests and 23.0% +/- 4.8% and 3.9 m/s +/- 1.1 m/s for the vehicle-to-vehicle tests. Chest deflection versus time followed a roughly symmetric and sinusoidal profile. Sixteen CIREN cases were identified that matched the vehicle crash tests. Of the 16 matched cases, 12 (75%) sustained chest injuries, with half of these patients presenting with PC. Quantified loading at the chest wall indicative of PC and chest injury in motor vehicle crash is valuable boundary condition data for bench-top studies or computer simulations focused on this injury. In addition, because PC often exhibits a delayed onset, knowing the population and crash modes highly associated with this injury may promote earlier detection and improved management of this injury.

Dynamic responses of connections in road safety barriers

Bolted road safety barrier connections utilise slotted holes that are perpendicular to the direction of the safety barrier beam. Due to the clearance between the slotted holes and the bolts, a varying amount of slippage is seen before contact with the edge of the slot is made. The stiffness characteristics of bolted road safety barrier connections have been examined with a representative test coupon that incorporates a full size safety barrier connection slot to industry standard dimensions. Previous research work has successfully determined the stiffness characteristics of the bolted connections at quasi-static strain rates. Representative non-linear finite element models of the bolted test coupons have been constructed. When compared to the laboratory results the initial stiffness, maximum force and displacement of the bolted connections are similar to the finite element model predictions. Current investigations have moved onto strain rates comparable to those observed in actual vehicle crash tests. Explicit dynamic finite element (FE) models have been constructed and validated, using experimental data produced using a series of high strain rate laboratory tests for a number of bolt configurations.

Comparison of roadside and vehicle crash test injury criteria in frontal crash tests

The flail space model is widely used to assess occupant injury risk potential in full-scale crash tests of roadside safety hardware, e.g. guardrail. A fundamental assumption of this model is that the occupant is unbelted and not airbag restrained. In the early 1980s, these were valid assumptions in the US: cars were not airbag equipped and belt usage rates were around 11%. In today's US vehicle fleet, however, these assumptions are questionable: the belt usage rate is approximately 80% and airbags are required equipment. These changes have significant implications on injury risk computed using the original flail space model. The objective of this study is to contrast flail space model injury risk with the widely accepted dummy-based injury criteria in frontal crashes involving unbelted, belted or airbag restrained occupants. In an analysis of 39 frontal crash tests of speeds ranging from 40 to 97 km/hr, the flail space model was unable to account for variations in occupant risk due to the presence and per...

Safety Grates for Cross-Drainage Culverts

This paper presents findings of an investigation of the safety performance of culvert safety grates when installed on slopes as steep as 3:1, as recommended by the AASHTO Roadside Design Guide (RDG). LS-DYNA modeling was used to identify critical impact conditions for roadside culvert grates installed on 3:1 slopes. Two full-scale vehicle crash tests were conducted under the guidelines of NCHRP Report 350 on a 6.4- × 6.4-m (21-×21-ft) culvert safety grate installed on a 3:1 slope. The full-scale crash tests demonstrated that the AASHTO RDG recommended safety grates provide acceptable safety performance when installed on 3:1 slopes.

Restrained occupant protection performance under rollover conditions using an intelligent rollover protection subsystem

The evaluation of the biomechanical performance that can be expected by restrained occupants from the incorporation of an intelligent rollover protection subsystem (IRPS) into a production vehicle has been conducted. This paper reports on the evaluation of such a system based on finite element modeling. Finite element models of vehicle designs and the Hybrid III dummy were used to evaluate the subsystem under manufacturer-created rollover conditions for a production roof structure. Results from a rollover crash test of a production vehicle were utilized to validate the model, using the production vehicle crash test. The IRPS design was then integrated with the production vehicle and the results were compared with the baseline neck biomechanical injury measures. Neck loads were utilized to validate the model against the test results. The results of the study show that the IRPS resulted in substantial reduction of head and neck loads with the production roof and even greater reductions with a strengthened roof. The results illustrate opportunities available to improve rollover crashworthiness performance for restrained occupants.

A new crash test configuration for car-to-car frontal collisions with small lateral overlap

This article investigates the current accident statistics using data provided by GIDAS and Austrian databases. It shows that among frontal crashes between cars, the impact configuration with small lateral overlap (<30%) reveals risk for severe injuries and casualties as well as in significant numbers. Among the Austrian databases, 20 in-depth accident reconstructions were performed, evaluating each detail of the accident. The study shows that the impact configuration with small lateral overlap is especially dangerous since a. energy absorbing structures such as the longitudinal beams are not involved; b. the “rim locking effect” (impacted wheels are being caught up in each other during the crash and are pushed into the occupant compartment) endangers the safety cage. Based on the accident data, the relevant parameters (collision speed, overlap, and angle of impact) are investigated and a representative impact configuration is proposed. The proposed test configuration is developed in a manner so as to account for as many collision scenarios as possible. Based on this configuration, computer simulations will be done, transforming this impact scenario into a single vehicle crash test impacting against an especially designed object.

Analysis of a safety barrier connection joint post-testing

The purpose of this paper is to examine the effect of a full impact vehicle crash test on the joint material and the mechanical fasteners that form part of the safety barrier beam to beam connection joint. Corrugated beam safety barriers have been installed on Britain’s roads for several decades. New legislation introduced in 2004 has had a direct impact on the UK safety barrier market. Many companies have embarked on extensive testing and development programmes to produce fully compliant safety barrier systems that are both low cost and high performance. The results showed that there is significant deformation of the barrier material surrounding the slotted holes in the safety barrier beam of tested components. The mechanical fasteners faired slightly better but they sustained some damage to the threaded portion of the bolts that were in contact with the barrier section. The results show changes in the safety barrier beam material microstructure in the area of the slotted holes where the mechanical fasteners were subjected to shear loads due to tension forces in the safety barrier beam. Additional information is presented to demonstrate that changes in the material microstructure have not been caused by cold work deformation sustained in the manufacturing process.

Performance of Steel-Post, W-Beam Guardrail Systems

On the basis of the proposed changes to the NCHRP Report 350 guidelines, NCHRP Project 22-14(2) researchers deemed it appropriate to first evaluate two strong-post W-beam guardrail systems before finalizing the new crash testing procedures and guidelines. For this effort, the modified G4(1S) W-beam guardrail system and the Midwest Guardrail System (MGS) were selected for evaluation and comparison. Five full-scale vehicle crash tests were performed with the two longitudinal barrier systems, in accordance with the Test Level 3 (TL-3) requirements presented in the NCHRP Report 350 Update. For the modified G4(1S) testing program, two 2,270-kg pickup truck vehicles (2270P vehicles) were used: one 3/4-ton, two-door vehicle and one 1/2-ton, four-door vehicle. For the MGS testing program, two 2,270-kg pickup truck vehicles (2270P vehicles) and one 1,100-kg small-car vehicle (an 1100C vehicle) were used, with both pickup truck configurations being evaluated. On the basis of several findings, the NCHRP Project 22-14(2) researchers determined that the 1/2-ton, four-door pickup truck was better suited for use as a surrogate light truck test vehicle than the 3/4-ton, two-door pickup truck. The modified G4(1S) W-beam guardrail system, mounted at the top rail height of 706 mm, provided acceptable safety performance when it was crashed into by the 1/2-ton, four-door pickup truck vehicle, thus meeting the proposed TL-3 requirements presented in the NCHRP Report 350 Update. Testing of the modified G4(1S) W-beam guardrail system was not successful with a 3/4-ton, two-door pickup truck under the TL-3 impact conditions. The MGS was found to meet the TL-3 criteria presented in the NCHRP Report 350 Update for Test Designations 3-10 and 3-11. Satisfactory safety performance was observed with the MGS with both the 1/2-ton, four-door and 3/4-ton, two-door pickup truck vehicles.

Innovative test method for seat belt D-ring

Seat belt assemblies are tested prior to vehicle crash tests in accordance with the UNECE R16 regulation. Thanks to these tests, global verifications of the restraint system performance are performed. Nevertheless, this common method is inadequate to analyse the local behaviour of seat belt components such as D-ring stability, because small variations of the dummy or the belt positions can create high perturbations in the test results. Besides, the cost of classical crash tests prevents planning test campaigns from focusing on the effect of these tiny variations. In this paper, an innovative test method is proposed to analyse webbing/D-ring/retractor subsystem of a seat belt assembly in a fully controlled manner. A test method is studied and evaluated by finite element analysis. An experimental bench is described and validated during a drop test campaign. Several load cases are described and a case of seat belt bunching phenomenon is reproduced.

Systematic design process for frontal crashworthiness of aluminium-intensive electrical vehicle bodies

In the design of an aluminium-intensive body used for an electrical vehicle, a systems engineering approach, composed of system analysis, an optimization task to support the requirements, functional analysis, and a synthesis task, is introduced. Using these systems engineering concepts, the mounting and package requirements were determined through the estimation of force distribution and energy absorption of the front structure. The average acceleration, the effective crash spaces, and the collapse characteristics of an aluminiumintensive body were used for the idealization of the plastic collapse stiffness curve of the front longitudinal member. The geometric dimensions of rectangular and circular front longitudinal members in axial and bending collapse were determined by quasi-static simulations based on the approximation equations of axial and bending collapse modes. In the development process, a full vehicle crash test was performed to verify computer aided engineering (CAE) simulation and assess the feasibility of the design process.

Injury potential of a three-year-old Hybrid III dummy in forward and rearward facing positions under CMVSS 208 testing conditions

This research focuses on the injury potential of children in forward and rearward facing child restraint seats in frontal collisions. Vehicle crash tests were completed following the guidelines outlined in the Canadian Motor Vehicle Safety Standard 208 using a Hybrid III three-year-old dummy in a convertible forward/rearward facing child restraint seat. The seat was equipped with a five-point restraining system and the experimental test was completed in the forward facing configuration. A numerical model employing a similar set-up as the experimental crash test was developed and numerically simulated using LS-DYNA. To verify the numerical simulations, the head and chest accelerations as well as neck loads and moments were compared to the experimental findings and it was observed that a reasonable correlation between the experimental and numerical observations existed. Further numerical simulations were completed to investigate the influence of positioning the three-year-old dummy in the rearward configuration on the head and neck injury potential during frontal crash. Through an analysis of injury criteria, using neck loads and head accelerations, it was observed that the rearward facing child dummy sustained significantly lower levels of neck injury criteria while exhibiting similar levels of the head injury criteria as the forward facing child dummy.

Development of a Three-Year-Old Child FE Model

Objective. Child crash dummies are conventionally used for safety performance evaluations of the child restraint system (CRS) in vehicle crash tests. To investigate injuries to various body regions of a child in detail, mathematical models are useful, and provide information that cannot be analyzed by crash dummies. Therefore, in the present research, a finite element (FE) model of a 3-year-old child has been developed by model-based scaling from the AM50 human FE model, THUMS (Total HUman body for Safety). Methods. The dimensions of each body region were based on the anthropometry data of United States children, and material properties of child bone were estimated from data reported in the literature. Neck flexion, thorax impact responses, and torso flexion were validated against the response corridor of the 3-year-old Hybrid III dummy in calibration tests. A test of lap belt loading to the abdomen was also conducted. FE models of two different types of CRS, a 5-point harness and a tray shield CRS, were also made, and ECE R44 sled impact test simulations were conducted using the child FE model. Results. The characteristics of the child FE model proved to be close to the Hybrid III and child volunteer corridor. In the ECE R44 sled test simulations using the child FE model, the head movement down and head rotation were large in the 5-point harness CRS, and chest deflection was large in the tray shield CRS. In both CRS types, the whole spine flexed in the child FE model. This behavior is different from that of the Hybrid III, where the thorax spine is stiff and only the cervical spine and lumbar spine flex. Conclusions. Although this child FE model has several limitations in areas such as the anatomical shapes and material properties of a child, this model can be a useful tool to examine the behavior of a child in impacts, which may be difficult to predict by using the Hybrid III dummy with its stiff thorax spine box.

Development and structural testing of a composite-reinforced timber highway guardrail

Various government agencies install timber guardrails on scenic highways and roads in lieu of conventional steel guardrails for aesthetic reasons. Most acceptable timber guardrails rely on a continuous steel backing member to carry the large tensile forces caused by vehicle impact and transfer load to the posts. However, these guardrails are relatively expensive and heavy due to their use of large, solid-sawn timber sections. This study focuses on the development and structural testing of a novel timber guardrail that consists of a hardwood glued-laminated member strengthened with a fiber-reinforced polymer (FRP). The FRP acts in place of steel to carry the impact-induced tension and the guardrail is significantly shallower and lighter than conventional timber guardrails. This paper details the analysis of the guardrail response under vehicle impact, the development and testing of a unique and easily installed rail-to-rail field splice connection capable of carrying the tensile forces caused by vehicle impact, and the evaluation of guardrail durability in exterior conditions. In addition, the structural performance of the guardrail was assessed using experiments that produced the simultaneous tension and flexure forces expected during vehicle impact using a single hydraulic actuator and a three-point bending test apparatus. Based on the development and testing documented in this paper, the FRP-reinforced timber guardrail is expected to be capable of passing required vehicle crash tests.

The effect of using universal anchorages in child restraint seats on the injury potential for children in frontal crash

This paper focuses on the efficacy of various methods used for anchoring child safety seats in vehicles. An experimental vehicle crash test was conducted incorporating two three-year-old Hybrid III crash test dummies, restrained in a five-point child restraint seats, in accordance to Canadian Motor Vehicle Safety Standard 208. One Child Restraint Seat was affixed to the vehicle seat using the car seat belt and the second was anchored using the lower anchorages provided in the vehicle for child seats. A top tether was used in addition to both the anchoring techniques to provide additional support to the child safety seat. The vehicle crash test was completed to investigate the head, neck, and thoracic injury potential of the Hybrid III crash test dummies due to change in anchoring methods. Similarities and differences were noted in the response of the two dummies to the same crash conditions. Peak values of the neck injury criteria, calculated from the observations obtained from the lower neck loads cell ranged from 1.7 to 1.9. The head injury criteria calculated over a 15 ms evaluation period were observed to lie between 250 and 350, and the values computed over a 36 ms evaluation period ranged between 450 and 600. Percentage reduction of approximately 10% to 20% was observed in the neck forces and moments and head accelerations by using the adult seat belt instead of the ISOFIX for CRS anchoring. A high probability of neck and cervical injuries was estimated for both child restraining configurations.

Recognition by symmetry derivatives and the generalized structure tensor

We suggest a set of complex differential operators that can be used to produce and filter dense orientation (tensor) fields for feature extraction, matching, and pattern recognition. We present results on the invariance properties of these operators, that we call symmetry derivatives. These show that, in contrast to ordinary derivatives, all orders of symmetry derivatives of Gaussians yield a remarkable invariance: They are obtained by replacing the original differential polynomial with the same polynomial, but using ordinary coordinates x and y corresponding to partial derivatives. Moreover, the symmetry derivatives of Gaussians are closed under the convolution operator and they are invariant to the Fourier transform. The equivalent of the structure tensor, representing and extracting orientations of curve patterns, had previously been shown to hold in harmonic coordinates in a nearly identical manner. As a result, positions, orientations, and certainties of intricate patterns, e.g., spirals, crosses, parabolic shapes, can be modeled by use of symmetry derivatives of Gaussians with greater analytical precision as well as computational efficiency. Since Gaussians and their derivatives are utilized extensively in image processing, the revealed properties have practical consequences for local orientation based feature extraction. The usefulness of these results is demonstrated by two applications: 1) tracking cross markers in long image sequences from vehicle crash tests and 2) alignment of noisy fingerprints.