Low-speed Collisions Research Articles

FEA and Quasi-static Test on Energy Absorption Characteristic of Space Orthogonal Concave Honeycomb Structure with Negative Poisson’s Ratio

As a representative of metamaterials, negative Poisson’s ratio (NPR) material possesses special mechanical properties such as expansion, negative compression ratio and so forth. As a result, it is widely used in the fields of vehicles, aerospace, et al. In this paper, a novel space orthogonal concave honeycomb structure (OC) is designed based on traditional concave honeycomb structure (CHS). In order to explore the influence rule of OC structure on the deformation and energy absorption capacity of crash box under low-speed collision, mechanical analysis and parameter research on OC structure are conducted through quasi-static compression test and numerical simulation. The results suggest that the finite element results of OC structure fit well with the experimental results, and the FEM is highly credible. In addition, the novel OC sandwich structure can effectively enhance the deformation capacity and improve the energy absorption performance of the crash box. When the wall thickness ? of OC structure is 1mm and angle ? is 50°, the deformation and energy absorption capacity of the crash box increased by 25.6% and 19.3% respectively.

Factors Affecting the Severity of Placental Abruption in Pregnant Vehicle Drivers: Analysis with a Novel Finite Element Model

We clarified factors affecting the severity of placental abruption in motor vehicle collisions by quantitively analyzing the area of placental abruption in a numerical simulation of an unrestrained pregnant vehicle driver at collision velocities of 3 and 6 m/s. For the simulation, we constructed a novel finite element model of a small 30-week pregnant woman, which was validated anthropometrically using computed tomography data and biomechanically using previous examinations of post-mortem human subjects. In the simulation, stress in the elements of the utero–placental interface was computed, and those elements exceeding a failure criterion were considered to be abrupted. It was found that a doubling of the collision velocity increased the area of placental abruption 10-fold, and the abruption area was approximately 20% for a collision velocity of 6 m/s, which is lower than the speed limit for general roads. This result implies that even low-speed vehicle collisions have negative maternal and fetal outcomes owing to placental abruption without a seatbelt restraint. Additionally, contact to the abdomen, 30 mm below the umbilicus, led to a larger placental abruption area than contact at the umbilicus level when the placenta was located at the uterus fundus. The results support that a reduction in the collision speed and seatbelt restraint at a suitable position are important to decrease the placental abruption area and therefore protect a pregnant woman and her fetus in a motor vehicle collision.

Dynamic derailment behaviour of urban tram subjected to lateral collision

ABSTRACT The urban tram is theoretically likely to be laterally collided by the automobile during operation due to their shared right of roadway. The collision occurrence is fortuitous, but the consequence is commonly disastrous induced by the collision and subsequent derailment accidents. This article presents an investigation into the derailment performance of the tram when the automobile impacts laterally onto the tram flank. A comprehensive dynamic model to simulate derailment behaviours of the tram under this collision scenario is built, in which the complicated contact relation of wheel/rail system is treated. The contribution of several affecting factorsto the derailment response is reported. It is shown that the guardrails of the grooved rail track play a key role in preventing the tram derailments due to low-speed collision. The violent lateral and rolling motions of the tram body caused by the great lateral impact is the root cause of the derailments.

Prediction of neck injury using multiple linear regression and bumper damage: Case study for low-speed rear-end collisions

The most frequent type of traffic accident is a low-speed rear-end collision, which can damage parts of the vehicle, including the bumper, and cause neck injury to the occupants. Even in minor damage accidents, such as scratches on bumper covers, 26.3% of occupants received treatment for bodily injuries whose main symptom was neck injuries through auto insurance. This study was conducted to evaluate the potential for neck injuries in low-speed accidents. Fifty-nine low-speed rear-end impact tests were conducted, and the motion of the struck vehicle and the neck injury criterion (NIC) of the occupant according to the test conditions were predicted using multiple linear regression derived via supervised machine learning. It was confirmed that the NIC can be predicted using vehicle motion values that can be obtained through an event data recorder. The coefficients of determination of the regression equations were 0.67–0.83. Lastly, we investigated whether neck injuries can be predicted through bumper cover damage that can be checked immediately after a vehicle accident. In the case of the vehicle damage type 1/2/3 category applied to auto insurance by the Korean government, an occupant would have a very low possibility of neck injury or symptoms. No symptoms or injuries were reported in the volunteer tests conducted for this study.

Accident Detection and Reporting System

A significant rise in the number of road accidents has been observed due to the increasing number of vehicles. Significant research has been conducted on accident for the rescue, particularly on the use of Information and also Communication Technologies for efficient and prompt rescue or saving operations. The majority of such works will provide us the sophisticated solutions that focus on reducing response times. However, such solutions can be very expensive and are not available in all forms of vehicles. Our approach aims to take advantage of the advanced specifications of smartphones to design and develop a low-cost solution for enhanced transportation systems that are deployable in legacy vehicles. In this topic, a customized Android application is developed to collect information regarding speed, attraction, pressure, sound, and location. Speed is one of the factor which is used to improve the identification of the accidents. It arises because of clear differences in environmental conditions or changes (e.g., noise, deceleration rate) that arise in low-speed collisions, versus higher-speed collisions). The information collected is again further processed to detect road incidents. Furthermore, a navigation system is also constructed to report the incident to the nearby hospital. Furthermore, a navigation system is constructed to send and report the accident location and patients details to the nearby hospital! The proposed approach is validated through simulations and comparison with a real data set of road accidents acquired from the Road Safety Open Repository and shows promising results in terms of accuracy.

Research on lower extremity injury characteristics of elderly pedestrians under different impact loads

The safety protection of elderly pedestrians has always been the focus of passive safety research in car collision accidents. Lower limb protection efficiency for pedestrians is lower than occupants inside the vehicle. In particular, lower limb injuries account for a large proportion of pedestrian accident injuries. This study aims to determine the trend and primary characteristics of pedestrian lower limb injuries under the different impact speeds and impact angles. The elderly lower limb model based on Chinese structure is used. Then, the control variable method is used to simulate the collision process with four impact speeds and three impact angles, and the influence of the impact load difference on the characteristics is analysed. Results show that in low-speed collisions, the most vulnerable part of the elderly pedestrians’ lower limbs is the knee joint, and the collision speed is positively correlated with the injuries level of lower limbs. In a vehicle-pedestrian collision, the load from the side direction of the limbs is slightly higher than the load from the front direction for the elderly. The injury risk caused by the load from the inner side of the lower limb is higher than that from the outer side collision. The research results can provide a reference for the study on the protection of the lower limb.

Research on low-speed collision performance of Collision resistance of different materials

In order to explore the impact of lightweight materials and structures on the performance of anti-collision beams, this paper selects aluminum alloy and carbon fiber as the research objects, and analyzes the difference in low-speed impact performance of open and closed anti-collision beams for these two materials. Based on the structure of carbon fiber materials, the mechanical properties of carbon fiber materials are analyzed. At the same time, a low-speed collision model is established using numerical simulation to study the maximum intrusion amount, intrusion acceleration and intrusion force changes with time during the collision of aluminum alloy and carbon fiber anti-collision beams, And finally use experiments to verify. The research results show that the impact of the open aluminum alloy anti-collision beam and carbon fiber anti-collision beam on the fluctuation range of the collision acceleration is less than that of the closed aluminum alloy anti-collision beam; at the same time, compared with the closed aluminum alloy anti-collision beam, the open aluminum alloy anti-collision beam and carbon fiber, the maximum intrusion of the anti-collision beam is reduced by 8.2% and 18.6%; the carbon fiber anti-collision beam has the greatest force during the collision, followed by the closed anti-collision beam and the open anti-collision beam. The test results are consistent with the numerical simulation, which further illustrates the rationality of the exploration results.

Study of the Measurement of Generation 2 Toyota Event Data Recorders in Low-Speed Side Impacts

<div class="section abstract"><div class="htmlview paragraph">Automotive Event Data Recorders (EDRs) are often utilized to determine or validate the severity of vehicle collisions. Several studies have been conducted to determine the accuracy of the longitudinal change in velocity (ΔV) reported by vehicle EDRs. However, little has been published regarding the measurement of EDRs that are capable of reporting lateral ΔVs in low-speed collisions. In this study, two 2007 Toyota Camrys with 04EDR ECU Generation modules (GEN2) were each subjected to several vehicle-to-vehicle lateral impacts. The impact angles ranged from approximately 45 to 135 degrees and the stationary target vehicles were impacted at the frontal, central, and rear aspects of both the driver and passenger sides. The impact locations on the bullet vehicles were the front and rear bumpers and the impact speeds ranged from approximately 7.9 to 16.1 km/h. Instrumentation was mounted at the approximate center of gravity (CG) of the target vehicles, as well as on the front reinforcement bar, rear body panel, airbag ECU, B-pillars, and C-pillars to evaluate the varying lateral ΔV (ΔV<sub>y</sub>) readings from the 3 sensor locations (ECU, B-pillar, C-pillar) represented in the Toyota EDR and to account for rotational (yaw) effects on the data. The lateral ΔVs reported by the Toyota EDRs were then compared to the recorded ΔV<sub>y</sub>s from the reference instrumentation mounted within the test vehicles. A comparison of the data revealed a general under-reporting of impact severity from the Toyota EDRs at the ECU sensor when compared to reference instrumentation at the vehicle CG for impacts near the center of the target vehicle where the vehicle typically rotated about its frontal aspect. There was a general over-reporting of impact severity from the Toyota EDRs at the ECU sensor when compared to reference instrumentation at the vehicle CG for impacts near the front (heavy) axle of the target vehicle where the vehicle rotated about its rear aspect. Rotational data from the reference instrumentation and the distance between the ECU and reference instrumentation at the CG was also utilized to calculate the corresponding ΔV<sub>y</sub> at the ECU location for a direct comparison to the Toyota EDR measurement at the ECU (maximum of 12.0% difference). A comparison of the data recorded at the Toyota ECU sensors and the reference instrumentation mounted to the ECUs revealed accurate measurements by the Toyota ECU sensor (maximum of 7.6% difference). Differences in reported values between the 3 aforementioned Toyota sensor locations, as well as non-recordings and longitudinal ΔV recordings from the Toyota EDRs were also evaluated.</div></div>

Performance Analysis of Front Bumper under Frontal Low Speed Impact

In this paper, the front bumper of a certain model was simulated and analyzed in low-speed frontal collision. HyperMesh software was used as the pre-processor, LS-DYNA was submitted for simulation calculation, and HyperView was used as the post-processor to view the output results, so as to analyze the performance of the automobile front bumper in low-speed frontal collision. At the same time, the influence of different beam thickness on collision performance is compared under the same condition, which provides an effective reference for subsequent bumper optimization and design.

Energy absorbers in automobile bumper system for pedestrian safety and low-speed impact: a review

Bumper is a structure attached to the vehicle at both front and rear end to dissipate the kinetic energy generated by an impact and protect the vehicle components and its occupants. An ideal bumper energy absorbing system should be crash-worthy at both low-speed and high-speed collisions as well as meet the requirement of pedestrian safety. Energy absorbers are used between the bumper fascia and bumper beam to improve crashworthiness. Key areas of research focused to optimise the bumper energy absorbing systems are the selection of material and the structural design/geometry. Different materials and structural designs are being tried out to optimise the bumper energy absorbing system to meet the requirements. The characteristics, advantages and disadvantages of these materials and structures are reviewed in this paper.

Combined with finite element analysis of car seat safety performance improvement

Neck injuries caused by low-speed rear-end collisions are a worldwide problem. The reasonable design of car seat can effectively prevent or reduce the passenger neck injuries. In this paper, the finite element analysis (FEA) and whiplash test are combined to optimize the seat structure parameters to enhance the safety. The whiplash test results of the existing car seats according to C-NCAP (2015) were matched with FEA, and the optimization scheme was developed by computer simulation. For the improvement of seat safety, the optimizations are applied to determine backrest stiffness, backrest rotational stiffness, headrest rotational stiffness and headrest stiffness. The retest results of optimized seat show that its safety performance is greatly improved. Furthermore, it shows that the combination of finite element analysis and whiplash test can optimize seat structure to improve safety performance.

Mechanisms of Negative Fetal Outcome in Frontal Vehicle Colli-Sions Involving Unbelted Pregnant Drivers.

To determine the cause of negative fetal outcomes and the causative mechanism in a frontal collision, we analyzed the kinematics and mechanisms of injuries using an unbelted pregnant dummy, the Maternal Anthropometric Measurement Apparatus dummy, version 2B. Sled tests were performed to recreate frontal impact situations with impact speeds of 13, 26, and 40 km/h. Overall kinematics of the dummy were examined through high-speed video imaging. Quantitative dummy responses—such as time courses of the abdominal pressure, chest deflection, neck injury criteria (Nij), and displacement of the pelvis during impact—were also measured. The maximum abdominal pressure of 103.3 kPa was obtained at an impact speed of 13 km/h. The maximum chest deflection of 38.5 mm and Nij of 0.36 were obtained at an impact speed of 26 km/h. The highest maximum chest deflection of >40.9 mm, Nij of 0.61, and forward pelvis displacement of 478 mm were obtained at an impact speed of 40 km/h. Although the kinematics and mechanism of injuries of the dummy were different for different collision speeds, we found that unbelted pregnant drivers suffer severe or fatal injuries to the fetus even in low-speed collisions.

Grain Damage in Low­Speed Collision with the Surfaces of the Hoisting­and­Transport Machines Working Parts

To reduce the damage level of wheat grains during its post-harvest processing, it is proposed to replace steel working parts in lifting and transporting machines with polymer ones. ( Research purpose ) Experimentally determine the dependence of the degree of wheat grain damage on the number of collisions, the incidence angle and the hoisting-and-transport machines working parts surface material when the grain moves at a speed of up to 3.5 meters per second. ( Materials and methods ) Experiments were carried out on a unit that reproduced the low-speed collision conditions of wheat grains with a smooth steel or plastic surface plate at various angles of incidence and the number of impacts. ( Results and discussion ) The authors identified a significant reduction in grain damage in a collision with a plastic plate compared to a steel plate – by 8-10 percentage points – is observed only at incidence angles of 60-90 degrees and the number of strokes from 5 to 10. It was found that at incidence angle up to 60 degrees, the specified difference didn’t exceed 4 percentage points and reached zero at an angle of 45 degrees. The low efficiency of replacing steel working parts with plastic ones to reduce grain damage when driving at low speed was explained by the weak manifestation of the decrease effect in the potential energy of grain deformation upon impact on a plastic surface at a collision low speed. ( Conclusions ) The authors determined that when grains moved at a speed of less than 3.5 meters per second in a rarefied stream without interaction between them, when individual grains collided with the hoisting-and-transport machines working parts, replacing steel working parts with plastic ones was impractical.

Modelling traumatic brain injury in pedestrian involved in backover collisions

Backover collisions causing Traumatic Brain Injuries (TBIs) are underreported, and its severity may have been overlooked and underestimated. We conducted a series of pedestrian impact simulations involving backover collisions with a reversing vehicle, at a low speed of 10 km/h, to determine the risk of sustaining severe TBIs. Our modelling studies revealed a significant risk despite the 'moderate' impact configuration applied. By systematically performing injury analyses based on selected mechanical parameters, we found that TBI risk involved in primary head strike with a striking vehicle was almost negligible because of the low-speed collision, but significant injuries result from ground impact. Our study also demonstrated that pedestrians are potentially at a greater risk for TBI when struck by a Sport Utility Vehicle (SUV) than a conventional sedan, because the impact energy would be effectively transmitted from the SUV via its flat rear surface with a steep angle.

PSEUDO ELASTIC METHODS FOR DAMAGE ASSESSMENT OF COMPOSITE TUBES

Rapid urbanization globally has led to increased traffic congestion within cities which often result in low speed collisions. These low speed collisions can happen during parking of Vehicles also. Bumpers provided for the Vehicles primarily absorb the impact energy during these low speed collisions. However, a portion of this, impact could get transferred to the thin walled tubular structures attached to the bumpers whose main purpose is to effectively absorb the Impact energy and compliment occupant safety, in the event of an accident. These structures are usually provided with notches of specific sizes at select locations to improve crush (energy absorption) efficiency and result in uniform crushing pattern. These notches could experience localized damage during low speed collisions. Such a scenario could make the crush tubes ineffectual as energy absorbers, after few such collision cycles due to localized partial damage. Hence it is desirable to check the design for possibility of localized damage during low speed collisions. Computation of damage requires prediction of notch energy or associated strains. Usage of Finite Element methods for damage evolution prediction of composite elements poses several challenges, especially for anisotropic materials like Composites. Several approximate methods have been proposed and are being used for evaluation of Elasto-Plastic strains, for isotropic materials. The adaptability and relative accuracies of these methods namely The ESED rule, arc Length Method and Neuber’s rule under axial compressive loads for anisotropic composite materials have been investigated and presented.

Low-velocity motor vehicle collision characteristics associated with claimed low back pain

Objective: Up to 50% of individuals involved in low-velocity motor vehicle collisions report low back pain (LBP). A major limitation in such cases is the lack of knowledge of injury mechanisms linking the collision characteristics to the pain and pathology associated with LBP reporting. Thus, the objective of this investigation was to characterize the physical circumstances of low-velocity motor vehicle collisions that resulted in claims of LBP.Methods: Eighty-three forensically assessed cases were analyzed to identify specific collision and claimant characteristics.Results: Seventy-seven percent of reviewed cases involved a claim of LBP. Of these LBP claim cases, 70% of cases involved a rear-end collision configuration, and 40% of all cases were low-velocity collisions, with severities ranging between 10 and 12 km/h. The most common pre-existing medical condition was prior LBP or evidence of disc degeneration.Conclusions: The results of this investigation provide knowledge of collision characteristics that can be employed in future studies on the mechanisms of low back injury in low-speed motor vehicle collisions.

Quasi-static impact of origami crash boxes with various profiles

The crash box is a structural component which is widely used in transport vehicles. It is designed to collapse and absorb kinetic energy in a low-speed collision. In this paper, we present a family of new origami crash boxes with rectangular, polygonal cross sections, and tapered shapes, through pre-folding the surface of thin-walled tubes according to a set of developable origami patterns. We have demonstrated through quasi-static impact experiments and numerical simulation that these origami crash boxes collapse into a diamond-shaped mode with a doubled number of traveling plastic hinge lines. The proposed optimal design leads to a maximum increase of 107.1% in terms of the energy absorption per unit mass and a maximum reduction of 68.3% of the initial peak force when compared with the conventional crash box. The substantial gain in overall energy absorption and the decrease in peak reaction force makes the proposed origami patterns attractive for energy absorption applications.

A Novel Internet of Things-Enabled Accident Detection and Reporting System for Smart City Environments.

Internet of Things-enabled Intelligent Transportation Systems (ITS) are gaining significant attention in academic literature and industry, and are seen as a solution to enhancing road safety in smart cities. Due to the ever increasing number of vehicles, a significant rise in the number of road accidents has been observed. Vehicles embedded with a plethora of sensors enable us to not only monitor the current situation of the vehicle and its surroundings but also facilitates the detection of incidents. Significant research, for example, has been conducted on accident rescue, particularly on the use of Information and Communication Technologies (ICT) for efficient and prompt rescue operations. The majority of such works provide sophisticated solutions that focus on reducing response times. However, such solutions can be expensive and are not available in all types of vehicles. Given this, we present a novel Internet of Things-based accident detection and reporting system for a smart city environment. The proposed approach aims to take advantage of advanced specifications of smartphones to design and develop a low-cost solution for enhanced transportation systems that is deployable in legacy vehicles. In this context, a customized Android application is developed to gather information regarding speed, gravitational force, pressure, sound, and location. The speed is a factor that is used to help improve the identification of accidents. It arises because of clear differences in environmental conditions (e.g., noise, deceleration rate) that arise in low speed collisions, versus higher speed collisions). The information acquired is further processed to detect road incidents. Furthermore, a navigation system is also developed to report the incident to the nearest hospital. The proposed approach is validated through simulations and comparison with a real data set of road accidents acquired from Road Safety Open Repository, and shows promising results in terms of accuracy.

Aperture judgement in fire-appliance drivers

Low-speed collisions are a common occurrence for UK Fire and Rescue Services, with frequent bumps and scrapes adding up to create a significant drain on emergency service budgets, and damaging public faith in the service. We hypothesised that the decision to drive through a gap, or aperture, created by other vehicles and/or road furniture, may be related to driver experience and risk-level. To create a test to assess this skill, video clips were recorded from a fire appliance on blue-light training runs. Eighteen clips were selected on the basis that they culminated in a narrow aperture that the film-driver either navigated through, or stopped and waited for other vehicles to move and the gap to widen. Drivers were required to watch these clips, which paused at the point that the film-driver made the decision to either go though, or to wait. The participants rated their belief that the appliance would fit through the gap, and how confident they would be to drive through that aperture themselves (on a 1–8 scale). Novice fire-appliance drivers were less accurate in deciding whether to proceed or not, though their criterion threshold did not differ to that of more experienced drivers. All drivers favoured looking at the right edge of the aperture (either a vehicle or road furniture), but low-risk, experienced fire appliance drivers had the shortest fixations on this area. The results suggest that a video-based test of aperture judgement can differentiate between fire-appliance driver groups based on experience, opening the way for future testing and training tools using this methodology.

Characterizing trunk muscle activations during simulated low-speed rear impact collisions

Objective: The purpose of this study was to evaluate the activation profiles of muscles surrounding the lumbar spine during unanticipated and braced simulated rear-end collisions.Methods: Twenty-two low-speed sled tests were performed on 11 human volunteers (V = 4 km/h). Each volunteer was exposed to one unanticipated impact and one braced impact. Accelerometers were mounted on the test sled and participants’ low back. Six bilateral channels of surface electromyography (EMG) were collected from the trunk during impact trials. Peak lumbar accelerations, peak muscle activation delay, muscle onset time, and peak EMG magnitudes, normalized to maximum voluntary contractions (MVCs), were examined across test conditions.Results: Though not statistically significant, bracing for impact tended to reduce peak lumbar acceleration in the initial rearward impact phase of the occupant’s motion by approximately 15%. The only trunk muscles with peak activations exceeding 10% MVC during the unanticipated impact were the thoracic erector spinae. Time of peak muscle activation was slightly longer for the unanticipated condition (unanticipated = 296 ms; braced = 241 ms).Conclusions: Results from this investigation demonstrate that during an unanticipated low-speed rear-end collision, the peak activation of muscles in the lumbar spine are low in magnitude. As such, muscle activation likely has minimal contribution to the internal joint loads that are experienced in the lumbar intervertebral joints during low-speed rear impact collisions. These findings justify the use of simplified joint models in estimating the joint loads in the lumbar spine during low-speed rear impact collisions and support the application of cadaveric and anthropomorphic test device (ATD) testing in understanding the resultant joint loads in the lumbar spine associated with rear-end collisions.