Frontal Collision Research Articles

Safety Study of High-Speed Collisions between Trains and Live Intruder.

To investigate the safety of train collisions with live intruders under high-speed operation, a new 3D finite element laminated model of live intruder filling was constructed based on reconstruction using physical 3D scanning, with three outer layers of the model simulating the skin, three inner layers simulating bone, and internal filling simulating internal organs. The model was simulated in LS-DYNA with pendulum side collision, and the force-time and force-displacement curves of the collision between the pendulum and the living intruder were obtained, which were consistent with the curve trend of the results of the cadaver pendulum collision test by Viano in 1989, and the accuracy of the finite element model of the intruder was verified. Through the simulation calculation of high-speed collision between the train and two kinds of living intrusions, the maximum acceleration of the train body, the maximum lifting of the wheel pair, the deformation of the cowcatcher, and the maximum central load on the cowcatcher during the collision can be obtained. The results of the study show that at a collision speed of 110 km/h and different collision positions, the collision risk factor between the train and heavier organisms is relatively high, and the risk arising from frontal collisions is generally greater than that of offset collisions; despite this, all the indicators such as the maximum acceleration of the train, the maximum lift of the wheel pairs, the reduction in the length of the cowcatcher discharge per 5 m of space, and the maximum central load borne by the cowcatcher discharge are lower than the EN15227 standard. Additionally, the safety of the train is not affected and the components can work reliably.

Weber number and the outcome of binary collisions between quantum droplets

A theoretical analysis of binary collisions of quantum droplets under feasible experimental conditions is reported. Droplets formed from degenerate dilute Bose gases made up from binary mixtures of ultracold atoms are considered. Reliable expressions for the surface tension of the droplets are introduced based on a study of low energy excitations of their ground state within the random phase approximation. Their relevance is evaluated considering an estimation of the expected excitation energy having in mind the Thouless variational theorem. The surface tension expressions allow calculating the Weber number of the droplets involved in the collisions. Several regimes on the outcomes of the binary frontal collisions that range from the coalescence of the quantum droplets to their disintegration into smaller droplets are identified. Atoms losses of the droplets derived from self-evaporation and three-body scattering are quantified for both homo- and hetero-nuclear mixtures. Their control is mandatory for the observation of some interesting effects arising from droplets collisions.

정면충돌을 고려한 전동 킥보드 연결부의 2차원 위상최적설계

Electric kickboards provide personal mobility with a simple structure and easy operation. With these advantages, the number of users is increasing annually. However, as the number of users of electric kickboards increases, related accidents are also increasing. To prevent accidents, this study proposes the topological optimization of an electric kickboard connecting part to improve structural strength during a front collision. The results confirmed that as the volume fraction increased, the structure connecting the board and the bottom of the handle support changed to a toroidal shape, thereby lowering the maximum stress and improving the uniformity of the stress distribution. In addition, the topological optimization was safer than the connecting parts of two typical electric kickboards sold in the Korean market. These findings can contribute to improving the safety and optimizing the design direction of electric kickboards.

The effect of crash pulse on occupant injury in frontal coach collisions

The effect of crash pulse on occupant injury in frontal coach collisions

Severity of Placental Abruption in Restrained Pregnant Vehicle Drivers: Correct Seat Belt Use Confirmed by Finite Element Model Analysis.

Despite wearing a seat belt, pregnant drivers often suffer from negative fetal outcomes in the event of motor accidents. In order to maintain the safety of pregnant drivers and their fetuses, we assessed the severity of placental abruption caused by motor vehicle collisions using computer simulations. We employed a validated pregnant finite element model to determine the area of placental abruption. We investigated frontal vehicle collisions with a speed of 40 km/h or less involving restrained pregnant drivers with a gestational age of 30 weeks. For a crash speed of 40 km/h, the placental abruption area was 7.0% with a correctly positioned lap belt across the lower abdomen; it was 36.3% with the belt positioned at the umbilicus. The area of placental abruption depended on collision speed, but we found that with a correctly positioned belt it likely would not lead to negative fetal outcomes. We examined the effects on placental abruptions of reconfiguring seat belt width and force limiter setting. A wider lap belt and lower force limiter setting reduced the area of placental abruption to 3.5% and 1.1%, respectively; however, they allowed more forward movement upon collision. A 2.5 kN force limiter setting may be appropriate with respect to both forward movement and reduced placental abruption area. This study confirmed the importance of correctly using seat belts for pregnant drivers. It provides valuable evidence about improving safety equipment settings.

Injury effects of knee airbags on Chinese human dummy

Two kinds of knee airbags and dummy crash simulation models are established, and the accuracy of the models is verified by comparing the knee module impact test data and CAE simulation data. A knee airbag and dummy crash simulation system is established, and the frontal collision finite element simulation of the Chinese 50th percentile dummy is carried out under the three conditions of no knee airbag, bottom-mounted knee airbag, and rear-mounted knee airbag. According to the regulations of China-New Car Assessment Program (CNCAP), the injury data of major body parts such as the head, chest, femur, and legs are compared and analyzed, and the differences in damage to the dummy caused by the bottom-mounted knee airbag, the non-knee airbag and the rear-mounted knee airbag are focused on. Conclusion: Compared with the HIII dummy with knee airbag, the chest compression and tibia compression force of the Chinese dummy with knee airbag are larger, and the compression force of femur is smaller; compared with the condition without knee airbag, the value of head acceleration, tibial index, chest deformation, etc of Chinese dummy can be reduced with knee airbag, but the tibial axial force and knee side displacement have increased; compared with the condition of the rear-mounted knee airbag, the bottom-mounted knee airbag has better protection performance for the dummy’s head, chest, upper leg, and lower leg, but the knee side displacement of bottom-mounted knee airbag is greater, and the axial compression of the tibia is greater. This paper can provide a theoretical basis for the design of knee airbag in the Chinese market and the development of Chinese human dummy.

Evaluation of a coach door under a frontal impact

PurposeThe vehicle´s body front pillar should absorb most of the striker kinetic energy, while only a fraction of that is absorbed by the door structure. This study aims to discuss the aforementioned issue. In this test the striker is a virtual entity. Six uniaxial strain gauges are installed throughout the door. Additionally, contactless 3D digital image correlation (DIC) allows to assess the major door panel’s continuous deformation and strain fields.Design/methodology/approachA coach is a large and heavy long-distance passenger transport vehicle. Their structural certification, classifies coaches as M3 Class III vehicles. New coach structures’ designs need analyses of each sub-system for critical pre-validation of the entire structure, aiming driver and passenger carrier safety. Also, a thorough examination due to increased travel speed is needed.FindingsExperimental pseudo-dynamic (PSD) results were compared and validated using finite element method (FEM) with two pieces of distinct FEM software (Abaqus® and PamCrash®). The time dependent solution was carried out by explicit techniques. Results by FEM and PSD test showed good agreement, evidencing the reliability of the tools selected. Results by PamCrash® were closer to the experimental data.Practical implicationsR-29 is truck-only regulation, however can be adapted to coaches in case of a frontal collision. The present work focuses on the impact behavior of the passenger front door subsystem.Originality/valueAs a first validation the entire structure, the behavior of a vehicle door, under in-plane impacts was studied. The corresponding deformation energy absorbed by the frontal passenger coach door under virtual impacts of a swinging striker was assessed using a PSD approach.

Formation of prestellar regions in collisions of molecular clouds simulations on heterogeneous computers

The processes occurring in near and far space have a significant impact on the safety of space flights. Processes such as explosions of supernovae and relativistic jets have a particularly great impact. They arise in quasars, black holes, protostars. Often such structures are observed during the formation of new stars. Such jets have a great impact on the safety of space flights. For example, there is currently no radiation shelter on the International Space Station, so astronauts are at serious risk of getting radiation sickness. In addition, the skin of the orbital station modules consists of aluminum, which accumulates secondary radiation. The formation process of new star systems is the result of complex processes that occur in interstellar gas. These processes include nonlinear interactions of turbulence, gravity, collisions of molecular clouds with each other, as well as rotation and several other factors. The evolution of the formation of superdense substance begins from the moment when it gathers in turbulent flows or is formed by supersonic collisions of molecular clouds with each other, or are formed during the intereaction of molecular clouds with supersonic waves, which are formed during the explosions of supernovae, until the moment when these superdense areas reach the prestellar density. Further, depending on several factors, these superdense formations either collapse or disintegrate and return to the interstellar medium. The analysis of observations allows to conclude that a significant part of the molecular clouds is not gravitationally bound. These conclusions are made based on the virial theorem, which expresses the connection between gravitational and kinetic energy. In this paper, a simulation of large molecular clouds collision in a three-dimensional formulation on ultra-high-resolution grids is carried out. Execution of such calculations requires a lot of computer capacity. The paper presents the results of computer modeling of large-scale processes of filament formation and superdense, gravitationally coupled structurally parallel computation clusters with hybrid architecture. Parallel simulation on supercomputers was conducted with author’s software, which uses a modified second-order Godunov method of accuracy of the Total Variation Diminishion type. Calculations were conducted on grids that contain more than one billion cells (1024 × 1024 × 1024). The gravitational potential is calculated on graphic processors. To refine the calculations, the method of adaptive refinement of the AMR grid is used. Simulation results are presented for cases of frontal collision of two molecular clouds, which density is distributed along the radius according to certain laws.

Safety Assessment and Crash Compatibility of Heavy Quadricycle under Frontal Impact Collisions

An electric heavy quadricycle, categorized as an L7e vehicle, is an alternative solution for sustainable mobility with a lower carbon footprint and high energy consumption efficiency. However, accidental crashes of quadricycles with larger vehicle opponents can cause extensive damage to their structures and fatal injury to the occupants due to their geometry drawback in limited space in the front crumple zone. This work investigates the crashworthiness performance and safety assessment of the L7e vehicle under rigid wall crash tests and crash compatibility in car-to-car collisions with a sedan and an SUV. Crash scenarios are simulated using a nonlinear finite element analysis via LS-DYNA to evaluate structural crashworthiness and occupant injuries of a hybrid III 50th percentile male dummy. The compatible vertical alignment of the primary energy-absorbing structure substantially affects the safety of the quadricycle under a frontal crash. A secondary energy-absorbing component should be adapted to the L7e vehicle to achieve vertical alignment with different vehicle sizes. In addition, the typical rigid-wall frontal crash test at 50 kph considerably underestimates the structural damage and occupant injury of the L7e vehicle compared to car-to-car collisions. Thus, additional crash tests representing car-to-car collisions that account for the car’s smaller size and lighter mass should be included in the safety regulation for the L7e vehicle.

Review on Functional Testing Scenario Library Generation for Connected and Automated Vehicles.

The advancement of autonomous driving technology has had a significant impact on both transportation networks and people’s lives. Connected and automated vehicles as well as the surrounding driving environment are increasingly exchanging information. The traditional open road test or closed field test, which has large costs, lengthy durations, and few diverse test scenarios, cannot satisfy the autonomous driving system’s need for reliable and safe testing. Functional testing is the emphasis of the test since features such as frontal collision and traffic sign warning influence driving safety. As a result, simulation testing will undoubtedly emerge as a new technique for unmanned vehicle testing. A crucial aspect of simulation testing is the creation of test scenarios. With an emphasis on the map generating method and the dynamic scenario production method in the test scenarios, this article explains many scenarios and scenario construction techniques utilized in the process of self-driving car testing. A thorough analysis of the state of relevant research is conducted, and approaches for creating common scenarios as well as brand-new methods based on machine learning are emphasized.

Effectiveness analysis of a foldable booster safety seat with integrated seatbelt buckle for reducing children’s vehicle accident injury risk

Vehicle collisions may result in severe injuries to child passengers. These accidents are of concern to the automotive community; hence child restraint systems are now subjected to legislative requirements. New foldable child safety seats are a new technology that has the potential for space-saving whilst protecting children from injuries. For the first time, this paper proposes to evaluate the safety of such a foldable seat, considering multiple frontal impact directions. The research created a baseline 6-year-old HybridIII child sled test computer model, built from a correlated vehicle rear seat cabin interior environment model and including its crash pulse characteristics, in which various seat safety configurations were evaluated. A total of seven scenarios were investigated, considering no booster seat, a traditional booster seat, and a foldable booster seat, combined with different impact angles, including frontal impact (0°), near and far side impacts (15° and 30°). In each scenario, the child kinematics, seatbelt to neck interaction, head acceleration, HIC15, and chest acceleration were extracted as metrics to determine the safety effectiveness of the foldable booster seat. The study concluded that the foldable booster seat reduced the risk of neck entrapment as well as better restrained the dummy in its seat. While the head acceleration, HIC15, and chest acceleration may slightly increase, injury responses caused by the foldable booster seat are still well within safe margins. This study suggests that foldable booster seats are innovative and practical and have the potential, pending more research, to protect children in frontal collisions better.

Dynamic Weighted and Heat-map Integrated Scalable Information Path-planning Algorithm

Smart storage is widely used for its efficient storage and applications. For making dynamic decisions when robots conflict and eliminating robot conflicts and improving efficiency from a global perspective, path-planning Algorithm will be analyzed and improved by integrating dynamic weighted and heat-map algorithm based on the scalable information of multi-robot in this paper. Firstly, a small storage grid model applicable to a variety of storage modes is established. Second, in order to solve the frontal collision problem of robots, an improved reservation table is established, which greatly reduces the storage space occupied by the reservation table while improving the operation efficiency; the A* algorithm is improved to achieve the purpose of avoiding vertex conflict and edge conflict at the same time; dynamic weighting table is added to solve the multi-robot driving strategy of intersection conflict and ensure that the most urgent goods are out of the warehouse firstly; the heat map algorithm is appended to reasonably allocate tasks, avoiding congested areas and realizing the dynamic assignment of tasks. Finally, the simulation was done by the proposed path planning method, the average transportation time was reduced by 14.97% comparing with the traditional path algorithm.

Selected Problems in a Two-Vehicle Impact Collision Modeling

In this paper, a potential use of the basic parameters of a road collision in a forensic activity was analyzed. A selected case of a frontal, eccentric, and oblique collision between two motor vehicles was analyzed from the point of view of both a computer simulation and a model. The case has been presented as an attempt to identify the collision parameters necessary to conduct the analytical calculations useful in analyzing specific road accidents. The simulation results were obtained in V-SIM software, which is widely used in collision reconstructions by forensic experts and appraisers. It was further analyzed from the point of view of a mathematical model, with the use of the force–impulse method and avoiding the use of the coefficients of restitution in the normal and tangential directions versus the adopted coordinate frame. In the analytical calculations, apart from the masses and the velocities of vehicles, the collision angles and the vicarial coefficient of adhesion between the colliding vehicles (µ) are also important. The approach presented in the article enables an expert to verify the obtained results of a computer program simulation.

Effects of Seat Belts and Shock Absorbers on the Safety of Racing Car Drivers

This paper aimed to study the behavior of a body (dummy) that was in a race car in the event of a frontal collision with a wall in order to see what loads were acting on the dummy. Based on a complex car model, equipped with two safety system seat belts and a shock absorption system, the behavior of the dummy was obtained following frontal collision of the car–dummy assembly. The accelerations were obtained at different points of the dummy’s body and the force that appeared on the seat belts were determined. The Gibbs–Appell method was used to assess the response of the system based on the equations of motion in a problem involving shocks. This paper demonstrates that the revisited old principle of mechanics can offer an interesting and convenient means to obtain results in a short time. FEM and Altair Hyperworks software II was used to model the system. It can be used to determine whether a seat belt is able to work if it has defects during use, such as scratches, cigarette burns or animal bites.

Simulation of a frontal vehicle collision in order to study the comparison between a forward facing and rear facing child occupant

Child occupants are considered very vulnerable in the case of vehicle accidents due to the fact that their bodies are not fully developed and thus they have a higher risk of injury. Because of this, child seats have been developed to be mounted on the backseat of the vehicle and have 2 seating positions, facing the rear of the vehicle or facing the front of it. This paper aims to analyse the two seating positions of a child seat and to determine the injury risk of a child occupant using a virtual simulation of a vehicle crash at different velocities and a multibody model for the occupant. The results of the simulation show that a rear-facing child seat has better occupant protection and overall could reduce the injury probability in case of frontal vehicle collisions.

Injury severity analysis of electric bike crashes in Changsha, Hunan Province: taking different lighting conditions into consideration

Abstract With the increasing use of electric bikes, electric bike crashes occur frequently. Analysing the influencing factors of electric bike crashes is an effective way to reduce mortality and improve road safety. In this paper, spatial analysis is performed by geographic information system (GIS) to present the hot spots of electric bike crashes during daylight and darkness in Changsha, Hunan Province, China. Based on the Ordered Probit (OP) model, we studied the risk factors that led to different severities of electric bike crashes. The results show that the main influencing variables include age, illegal behaviour, collision type and road factors. During daylight and darkness, elderly electric bike riders over the age of 65 years have a higher probability of fatal crashes. Not following traffic signals and reverse driving are significantly related to the severity of riders' injuries. In darkness, frontal collisions are significant factors causing rider injury. In daylight, more serious crashes will be caused in bend and slope road segments. In darkness, roads with no physically separated bicycle lanes increases the risk of riders being injured. Electric bike crashes are mainly concentrated in the commercial, public service and residential areas in the main urban area. In suburbs at darkness, electric bike riders are more likely to be seriously injured. Adding protection measures, such as improved lighting, non-motorized lane facilities and interventions targeting illegal behaviour in the hot spot areas can effectively reduce the number of electric bike crashes in complex traffic.

Biomechanical effects of a halo orthotic on a pediatric anthropomorphic test device in a simulated frontal motor vehicle collision

Objective: Cervical spine injuries in children under 10 frequently involve the craniocervical junction. In patients too small for conventional spinal instrumentation, treatment may involve placement of a halo orthotic, and these patients will frequently be discharged home in a halo orthotic. To date, little research has been done on the biomechanics of motor vehicle collisions involving young children in halo orthotics. To better understand possible safety concerns, we applied a halo orthotic to an appropriately sized anthropomorphic test device (ATD, or crash test dummy) on an acceleration sled to simulate a frontal motor vehicle collision. Methods: For the tests, a Hybrid III 3-year-old ATD was instrumented with head and chest accelerometers, head angular rate sensors, a six-axis upper neck load cell, and a chest linear potentiometer. Four tests were conducted on an acceleration sled, and kinematics were recorded with high speed video. Testing variables included 1) with or without a halo orthotic and 2) with a standard booster seat or a commercially available harness vest. Results: The halo orthotic reduced flexion and extension but was associated with increased rotation, especially in the condition of a halo orthotic with a standard booster seat. Increased cervical distraction was noted with the halo orthotic, and this was especially increased in the condition of a halo orthotic with the harness vest. Conclusions: The biomechanics of a child involved in a motor vehicular collision may be dramatically altered with a halo orthotic, as modeled by an acceleration sled test. While cervical spine flexion and extension are reduced with the halo orthotic, rotation appears to increase. Immobilization from a halo orthotic also appears to increase cervical distraction, especially when used in conjunction with a harness vest. Further testing is needed to determine the safest restraints for this small, but at-risk, population.

Protection challenges in seat positions with large rearward adjustment in frontal collisions: An approach using stochastic human body model simulations

Novel seat positions enabled by self-driving cars have been investigated in various studies in recent years. However, there is little research on the effect of increased rearward seat adjustments. To predict challenges associated with the possibility to move the seat further backwards in the car than currently possible as driver, appropriate methods have to be defined. A detailed human body model, a THUMS v4.1 in particular, tissue-based injury risk evaluation methods, a generic vehicle interior and a Latin hypercube design of experiments taking the variability of real-world crashes into account was established. In a first step, 200 simulations at current representative seat positions and a driving occupant posture were performed. The results were then compared to field data from an accident database to evaluate the accuracy of the method. The predictions exceeded the injury risks for the abdomen, head, and upper extremities, while underestimating the risk for thoracic and lower extremity injuries. A good match was observed for injuries of the neck and spine. In a second step, the 200 simulations were run again, but with the seat adjusted rearwards significantly. In this seat configuration, with the exception of the head and the upper extremities, increased injury risks were predicted for all body regions. The highest increases affected the lower extremities (+28%)—predominantly pelvic fractures—and the neck (+9%). In addition, (partial) submarining occurred in almost 50% of cases with the rearward adjusted seat—as opposed to none in the conventional seat position. The established method could be used in future studies to design safety measures addressing these identified potential safety risks.

Body mass index influence on lap belt position and abdominal injury in frontal motor vehicle crashes

Objective As obesity rates climb, it is important to study its effects on motor vehicle safety due to differences in restraint interaction and biomechanics. Previous studies have shown that an abdominal seatbelt sign (referred hereafter as seatbelt sign) sustained from motor vehicle crashes (MVCs) is associated with abdominal trauma when located above the anterior superior iliac spine (ASIS). This study investigates whether placement of the lap belt causing a seatbelt sign is associated with abdominal organ injury in occupants with increased body mass index (BMI). We hypothesized that higher BMI would be associated with a higher incidence of superior placement of the lap belt to the ASIS level, and a higher incidence of abdominal organ injury. Methods A retrospective data analysis was performed using 230 cases that met inclusion criteria (belted occupant in a frontal collision that sustained at least one abdominal injury) from the Crash Injury Research and Engineering Network (CIREN) database. Computed tomography (CT) scans were rendered to visualize fat stranding to determine the presence of a seatbelt sign. 146 positive seatbelt signs were visualized. ASIS level was measured by adjusting the transverse slice of the CT to the visualized ASIS level, which was used to determine seatbelt sign location as superior, on, or inferior to the ASIS. Results Obese occupants had a significantly higher incidence of superior belt placement (52%) vs on-ASIS placement (24%) compared to their normal (27% vs 67%) BMI counterparts (p < 0.001). Notable trends included obese occupants with superior placement having less abdominal organ injury incidence than those with on-ASIS belt placement (42% superior placement vs 55% on-ASIS). In non-obese occupants, there was a higher incidence of abdominal organ injury with superior lap belt placement compared to on-ASIS placement counterparts (Normal BMI: 62% vs 41%, Overweight: 57% vs 43%). Conclusions In CIREN occupants with abdominal injury, those with obesity are more prone to positioning the lap belt superior to the ASIS, though the impact on abdominal injury incidence remains a key point for continued exploration into how occupant BMI affects crash safety and belt design.

Head Kinematics in Youth Ice Hockey by Player Speed and Impact Direction

Hockey is a fast-paced sport known for body checking, or intentional collisions used to separate opponents from the puck. Exposure to these impacts is concerning, as evidence suggests head impact exposure (HIE), even if noninjurious, can cause long-term brain changes. Currently, there is limited understanding of the effect of impact direction and collision speed on HIE. Video analysis was used to determine speed and direction for 162 collisions from 13 youth athletes. These data were paired with head kinematic data collected with an instrumented mouthpiece. Relationships between peak resultant head kinematics and speeds were evaluated with linear regression. Mean athlete speeds and relative velocity between athletes ranged from 2.05 to 2.76m/s. Mean peak resultant linear acceleration, rotational velocity, and rotational acceleration were 13.1g, 10.5rad/s, and 1112rad/s2, respectively. Significant relationships between speeds and head kinematics emerged when stratified by contact characteristics. HIE also varied by direction of collision; most collisions occurred in the forward-oblique (ie,offset from center) direction; frontal collisions had the greatest magnitude peak kinematics. These findings indicate that HIE in youth hockey is influenced by speed and direction of impact. This study may inform future strategies to reduce the severity of HIE in hockey.