Frontal Collision Research Articles

Interface collisions.

We provide a theoretical framework to analyze the properties of frontal collisions of two growing interfaces considering different short-range interactions between them. Due to their roughness, the collision events spread in time and form rough domain boundaries, which defines collision interfaces in time and space. We show that statistical properties of such interfaces depend on the kinetics of the growing interfaces before collision, but are independent of the details of their interaction and of their fluctuations during the collision. Those properties exhibit dynamic scaling with exponents related to the growth kinetics, but their distributions may be nonuniversal. Our results are supported by simulations of lattice models with irreversible dynamics and local interactions. Relations to first passage processes are discussed and a possible application to grain-boundary formation in two-dimensional materials is suggested.

Injured probability assessment in frontal pedestrian-vehicle collision counting uncertainties in pedestrian movement

In probabilistic approaches, where uncertainties in pedestrian motion are counted, the distance model is important for the accurate and robust collision risks evaluation. Focusing on the typical frontal pedestrian-vehicle collision, the conflict distance model with the merit to distinguish front impacts from side ones is presented. Based on stochastic pedestrian model and Unscented Transformation (UT) method, the time-to-collision (TTC) and conflict distance are sampled, and their probability density functions (pdf) as well as the collision probability are deduced. The presented distance model and probabilistic method are verified with Monte Carlo (MC) as the reference, and show the high accuracy and potential for real-time application. Utilizing the estimated collision speed and its probability distribution, a unified model assessing the injured probabilities of pedestrian in front collision is proposed. A pedestrian-vehicle conflict scenario is constructed to evaluate the effectiveness of the probabilistic injury assessment. Simulation results show that the proposed method is sensitive to evasive maneuvers, and provides more useful cues for the optimization of collision avoidance control than the deterministic approaches.

Modeling the Vehicle-Bicycle Collision - The Analysis of the Projection Distance and Acceleration at the Cyclist's Head

The ever-growing demand for transportation and the need to carry both people and goods has led to increased congestions of road traffic networks. Subsequently, the main negative effect is the multiplication of serious road accidents. Of the total number of serious road accidents, a significant increase has been registered among cyclists, with 13.9% in 2014 of total vehicles involved in traffic accidents, compared to 6.6% in 2010. The present paper underpins a close analysis of the kinematic and dynamic parameters in the event of a vehicle - bicycle – cyclist assembly – collision type. To study the vehicle-bicycle-collision type, we carried out a comparative analysis with regard to the distance the cyclist is thrown away following the collision, the speed variation of the vehicle and of the bicycle, and the speed variation in the cyclist’s head area, as well as the variation of the acceleration recorded on the vehicle, the bicycle and the cyclist’s head area. Hence, we modelled and simulated the vehicle – bicycle collision for two distinct instances, i.e. a frontal vehicle – rear bicycle collision and a frontal vehicle - frontal bicycle collision.

Lightweight optimization of the front end structure of an automobile body using entropy-based grey relational analysis

This study deals with the multi-objective lightweight optimization of the front end structure of an automobile body, as the main assembly to withstand impact force and protect occupants from injuries in frontal collision, based on entropy-based grey relational analysis (EGRA). First, basic noise, vibration, and harshness (NVH) models of the automobile body and crashworthiness models of the vehicle are established and then validated by corresponding actual experiments; hence the lightweight controlling quotas are extracted. Next, the contribution analysis method determines the final parts for lightweight optimization, for which both continuous thickness variables and discrete material variables are simultaneously taken into account. Subsequently, design of experiment (DoE) using the optimal Latin hypercube sampling (OLHS) method is carried out, considering the total mass and the torsional stiffness of the automobile body, the maximum intrusion deformation on the firewall, the maximum impact acceleration at lower end of the B-pillar, and the total material cost of the selected optimization parts as five competing optimization objectives. After that, the optimal combination of thickness and material parameters of the optimization parts is determined using EGRA and confirmed by technique for order preference by similarity to ideal solution (TOPSIS). Finally, a comparison between the original design and the post-lightweight design, namely the optimized design, further confirms the effectiveness of the lightweight optimization. According to the outcomes, the automobile body is lightweight optimized with a mass decrease of 4.98 kg on the basis of well guaranteeing other relevant mechanical performance. Accordingly, the EGRA could be well employed to the multi-objective lightweight optimization of the automobile body.

Development of driver’s assistant system of additional visual information of blind areas for Gazelle Next

The article is devoted to the development of the Advanced Driver Assistance Systems (ADAS) for the GAZelle NEXT car. This project is aimed at developing a visual information system for the driver integrated into the windshield racks. The developed system implements the following functions: assistance in maneuvering and parking; Recognition of road signs; Warning the driver about the possibility of a frontal collision; Control of "blind" zones; "Transparent" vision in the windshield racks, widening the field of view, behind them; Visual and sound information about the traffic situation; Control and descent from the lane of the vehicle; Monitoring of the driver’s condition; navigation system; All-round review. The scheme of action of sensors of the developed system of visual information of the driver is provided. The moments of systems on a prototype of a vehicle are considered. Possible changes in the interior and dashboard of the car are given. The results of the implementation are aimed at the implementation of the system - improved informing of the driver about the environment and the development of an ergonomic interior for this system within the new Functional Salon of the Gazelle Next vehicle equipped with a visual information system for the driver.

Atlanto-axial posterolateral dislocation associated with a type II displaced odontoid fracture

Atlanto-axial posterolateral dislocations associated with an odontoid fracture are rare traumatic lesions of the upper cervical spine. Their therapeutic management is discussed. We report the case of a 28-year-old man with no significant medical history admitted to the emergency room with upper cervical spinal trauma following a frontal collision of two vehicles. We found a left arm monoparesis and a posterolateral atlanto-axial dislocation associated with a fracture of the displaced type II odontoid. The patient was treated by a retropharyngeal approach anteriorly after reduction by intraoperative traction by Gardner wells tongs maintained by a weight of 10 kg. The evolution was marked by a complete recovery of the left arm monoparesis at two months followed by physiotherapy.

Modeling and simulation of cars in frontal collision

Protection of cars, mainly drivers and passengers in a collision are very important issues worldwide. Statistics given by “World Health Organization” are alarming rate of increase in the number of road accidents, most claiming with serious injury, human and material loss. For these reasons has been a continuous development of protection systems, especially car causing three quarters of all accidents. Mathematical modeling and simulation of a car behavior during a frontal collision leads to new solutions in the development of protective systems. This paper presents several structural models of a vehicle during a frontal collision and its behavior is analyzed by numerical simulation using Simulink.

Study regarding the influence of airbag deployment time on the occupant injury level during a frontal vehicle collision

The aim of this paper was to analyse the influence of airbag deployment delay upon the head of the occupant in the case of frontal collision using simulations in PC Crash and MADYMO dummy as the occupant. The study will also take into account the pretension delay of the seat-belt which is activated along with the airbag. Frontal airbags on both the passenger and the driver were analysed including the occupant kinematics during the collision. Also, to validate the simulation, a comparison was done with a real crash test. We predict that by increasing the delay of deployment, the head acceleration will increase due to the fact the head travels close to the instrument panel/steering wheel, and the force of the airbag will generate a significant acceleration upon the head. To better assess the potential injury of the occupant, the head injury criteria (HIC) will be calculated and correlated with the Abbreviated injury scale (AIS) code.

Investigation of the Effect of Neck Muscle Active Force on Whiplash Injury of the Cervical Spine.

The objective of the present study is to investigate the influence of neck muscle activation on whiplash neck injury of the occupants of a passenger vehicle under different severities of frontal and rear-end impact collisions. The finite element (FE) model has been used as a versatile tool to simulate and understand the whiplash injury mechanism for occupant injury prevention. However, whiplash injuries and injury mechanisms have rarely been investigated in connection with neck active muscle forces, which restricts the complete reappearance and understanding of the injury mechanism. In this manuscript, a mixed FE human model in a sitting posture with an active head-neck was developed. The response of the cervical spine under frontal and rear-end collision conditions was then studied using the FE model with and without neck muscle activation. The effect of the neck muscle activation on the whiplash injury was studied based on the results of the FE simulations. The results indicated that the neck active force influenced the head-neck dynamic response and whiplash injury during a collision, especially in a low-speed collision.

Study regarding the influence of airbag deployment time on the occupant injury level during a frontal vehicle collision

Study regarding the influence of airbag deployment time on the occupant injury level during a frontal vehicle collision

Effects of booster seat sliding on responses and injuries of child occupant

Booster seat sliding on vehicle seat can influence kinematical and injury outcomes of child occupant in frontal collision accidents. This paper presents a study of the effects of booster seat sliding on submarining tendency and other injury risks of child occupant. A multi-body model of the Hybrid III 6-year-old dummy positioned in a booster seat was developed on MADYMO platform. Using the model, four load cases were simulated to study the sliding effects on submarining and injury outcomes of the child dummy. The study has revealed that the booster seat sliding can increase ride-down efficiency and in general exert positive effects on injury reduction. It also has some unfavourable effects in cases when booster sliding causes the child to impact the seatback of the front-row seat or if the child is in a more reclined posture that has higher risk of submarining. The unfavourable effects can be avoided by optimising design of child restraint system.

A Novel Hybrid Algorithm for Solving Multiobjective Optimization Problems with Engineering Applications

An effective hybrid algorithm is proposed for solving multiobjective optimization engineering problems with inequality constraints. The weighted sum technique and BFGS quasi-Newton’s method are combined to determine a descent search direction for solving multiobjective optimization problems. To improve the computational efficiency and maintain rapid convergence, a cautious BFGS iterative format is utilized to approximate the Hessian matrices of the objective functions instead of evaluating them exactly. The effectiveness of the proposed algorithm is demonstrated through a comparison study, which is based on numerical examples. Meanwhile, we propose an effective multiobjective optimization strategy based on the algorithm in conjunction with the surrogate model method. This proposed strategy has been applied to the crashworthiness design of the primary energy absorption device’s crash box structure and front rail under low-speed frontal collision. The optimal results demonstrate that the proposed methodology is promising in solving multiobjective optimization problems in engineering practice.

Frontal collision of internal solitary waves of first mode

The dynamics and energetics of a frontal collision of internal solitary waves (ISW) of first mode in a fluid with two homogeneous layers separated by a thin interfacial layer are studied numerically within the framework of the Navier–Stokes equations for stratified fluid. It was shown that the head-on collision of internal solitary waves of small and moderate amplitude results in a small phase shift and in the generation of dispersive wave train travelling behind the transmitted solitary wave. The phase shift grows as amplitudes of the interacting waves increase. The maximum run-up amplitude during the wave collision reaches a value larger than the sum of the amplitudes of the incident solitary waves. The excess of the maximum run-up amplitude over the sum of the amplitudes of the colliding waves grows with the increasing amplitude of interacting waves of small and moderate amplitudes whereas it decreases for colliding waves of large amplitude. Unlike the waves of small and moderate amplitudes collision of ISWs of large amplitude was accompanied by shear instability and the formation of Kelvin–Helmholtz (KH) vortices in the interface layer, however, subsequently waves again become stable. The loss of energy due to the KH instability does not exceed 5%–6%. An interaction of large amplitude ISW with even small amplitude ISW can trigger instability of larger wave and development of KH billows in larger wave. When smaller wave amplitude increases the wave interaction was accompanied by KH instability of both waves.

Frontal collision of a vehicle with a pedestrian and one оf the probable signs of a pedestrian being in motion at the time of an accident (case analysis from practice)

The article analyzes the pedestrian injuries in a frontal collision with a vehicle and establishes the possibility of finding a pedestrian at the moment of an accident in motion by evaluating the characteristics of injuries to the lower limbs of a pedestrian, taking into account the damage to the protruding parts of the vehicle.

Crushing analysis and crashworthiness optimization of tailor rolled tubes with variation of thickness and material properties

Novel method-VGR technology is adopted to successfully produce tailor rolled tubes with axially varied thickness. Through microstructure observation and mechanical tests, there are obvious differences of grain size and properties in different thickness locations. After quasi-static axial-crushing tests for these tailor rolled tubes, it shows that the first fold always starts at the end of thin zone and gradually extends to the thick zone. Meanwhile, the loading and energy absorption trends show obvious increases, which are closer to the ideal case for energy absorbing parts. The corresponding FE models considering both thickness and performance distributions are also established, which have been verified by experimental test. Moreover, dynamic tensile tests are performed at varied strain rates. The effect of strain rate on crashworthiness is quantitatively analyzed and it is taken into account in the FE model. Combined with the practical part, a typical vehicle front assembly is used in frontal collision. Among these, the car crash boxes with conventional uniform thickness and novel varied thickness are selected to compare their crashworthiness. In order to determine the optimized geometric distribution of this novel structure, a multi-objective optimization technique is applied to the crashworthiness problems. Based on the Response Surface Methodology (RSM) and Genetic Algorithm (NSGA-II), the energy absorption of the optimized design has increased by 16.2% and 6.71% in two frontal collision conditions, while the weight reduced by 12.9%. From the failure modes, the deformation stability of novel design under shearing action is even higher.

Occupant Kinematics in Simulated Autonomous Driving Vehicle Collisions: Influence of Seating Position, Direction and Angle.

This two-part study analyzed occupant kinematics in simulated collisions of future automated driving vehicles in terms of seating configuration. In part one, a frontal collision was simulated with four occupants with the front seats reversed. The left front seat occupant was unbelted while the others were belted. In part two of the study, occupant restraint was examined in various seating configurations using a single seat model with a three-point seatbelt. The seat direction with respect to impact was considered as forward, rearward, and lateral facing in 45 degree increments. The effect of seat recline was also studied in the forward-facing and rear-facing cases by assuming three positions: driving position, resting position and relaxed position. Occupants were represented by human body finite element models. The results of part one showed that the front seat (rear-facing) occupants were restrained by the seatback, resulting in T1 forward displacement less than 100 mm; the rear seat occupants were restrained by the seatbelt resulting larger T1 forward displacement more than 500 mm. The results of the part two showed the directional dependence of occupant restraint. Greater T1 displacements were observed when the occupant faced lateral or front oblique. However, the seatbelt provided some restraint in all directions considered. The seatback generated contact force to the occupant when it was in the impact direction, including the lateral directions. The relaxed position allowed increased excursion compared to the driving position when the occupant faced rearward, but the magnitude of this increase was lower with lower impact speed.

The effect of impact duration on the axial fracture tolerance of the isolated tibia during automotive and military impacts.

Axial impacts to the lower leg during debilitating events such as frontal automotive collisions and military underbody blasts can cause significant injuries to the tibia. Several studies have conducted axial impact tests to determine the injury limits of the lower leg, mostly focused on automotive intrusions, resulting in an established force criterion for injury assessments. Due to the viscoelastic properties of bone, it remains unclear whether results from automotive experiments can be applied to higher-rate military blasts. Twelve male isolated cadaveric tibias (from six pairs, mean age: 62 ± 8 years) were subjected to axial impact loads using a custom-built pneumatic impactor, with one specimen from each pair tested at velocity and impact durations representative of a military blast condition, and the contralateral under conditions representing an automotive collision. Impacts were applied in increasing levels of intensity (defined using energy levels) until fracture occurred. Fracture risk was influenced by projectile velocity, kinetic energy, impulse, and load rate, and there was a significant difference in peak force (p = 0.023), impulse (p = 0.09), and load rate (p = 0.025) between the automotive and military test conditions causing fracture. A 10% risk of fracture corresponded to an impact force of 9.0kN for the automotive condition and 12.2kN for the military condition. These results suggest that fracture tolerances developed in studies that simulate automotive impacts cannot be directly applied to military impacts of shorter duration. The number of factors identified to predict injury also suggests that fracture is not controlled by a single variable.

Structural adaptivity in frontal collisions: implications on crash pulse characteristics

Today's passenger cars protect occupants better than ever against most injury types in passenger car frontal collisions. There is, however, one notable exception: neck injuries. Studies have shown that high mean vehicle deceleration is likely to lead to a greater risk of sustaining neck injuries. In order to design future cars that minimize occupant injury risk, it is suggested that the response of the front structure should be adapted to impact severity. A finite element model was used to predict the implications on acceleration time history by yield-strength variation of the longitudinal rails. Results indicate that lower mean deceleration can be attained by lower-yield-stress material, but caution must be taken to avoid stiff engine-firewall contact as this can create high mean decelerations. Furthermore, results indicate that for an adaptable frontal structure to reduce mean acceleration and neck-injury risk, global load paths must be controlled in frontal impacts.

Analysis of car’s frontal collision against pole

Reducing the effects of traffic accidents over the occupants is a major objective of collision attempts. Impacts between the car and the pole are very dangerous for the physical integrity of the car’s occupants. To minimalize the effects of such events on the passengers of a vehicle, a whole series of efforts by both designers and experienced engineers led to increasingly the vehicles safety. The main aim of these paper is to quantify the influences over the car passengers of loads involved by car against pole collisions using the same car model at different speeds. Also, this kind on occupant influences were study using a small car model. Other goal of the paper was the study of the cars stiffness in frontal collision against the pole. The paper’s experimental results were obtained by support of DSD, Dr. Steffan Datentechnik GmbH - Linz, Austria. The described tests were performed in full test facility of DSD Linz, in “Easter 2016 PC-Crash Seminar”. Cars accelerations, velocities, rotations angles after pole impact were registered and discussed. The novelty of the paper consists in studies referred for the same car model involved in car against pole collisions at different impact speeds. Paper’s conclusions can be future used for car safety improvement.

High-Risk Prehospital Mechanisms in Tier II Trauma Codes: An Analysis of Under-Triage at a Level II Trauma Center

Under-triage is used as a surrogate for trauma quality. We sought to analyze factors that may impact under-triage at our institution by a detailed analysis of prehospital mechanisms and patient factors that were associated with the need for invasive intervention, intensive care unit monitoring, or death. Patients admitted to our Level II trauma center who met the criteria for under-triage using the Cribari method were studied, n = 160, and prominent mechanisms were motor vehicle collisions (MVCs). Patient demographics, detailed mechanism characteristics, ED vital signs, operative intervention, and outcomes were studied. The age of the study group and injury severity score were 42 ± 20 and 22 ± 6, respectively. Alcohol or drug use was common as were high-speed frontal collisions. Overall, 38 per cent of patients required surgery, and a monitored bed was required in 60 per cent of patients. Logistic regression identified drug use as predictive of mortality and MVC speeds ≥40 mph as predictive of intensive care unit admission. Patients requiring surgery had a high incidence of frontal collisions, 40 per cent. MVCs were predominant in under-triaged trauma patients. Operative intervention, intensive care unit monitoring, and deaths were associated with frontal impacts, high speeds, and drug use. Further study is warranted to assess the incorporation of high-risk injury patterns in triage algorithms aimed at enhancing trauma quality.