Collision Speed Research Articles

Lightweight Analysis of Automotive Anti-Collision Materials Based on Equal Energy Absorption Strategy

A new method is proposed to determine the maximum energy that absorbed by axial pressured thin wall tube. Three typical collision speeds are selected, which are low speed at 30km/h, medium speed at 60km/h and high speed at 90km/h. This paper also calculates the strain rates under different automotive collision conditions. Finite element software ABAQUS was used to investigate the effect of lightweight when circular thin wall tubes with different materials absorbing maximum and equal energy. The materials for thin wall tubes are high-strength steel, aluminum alloy and plain steel. The effect of lightweight of different material tubes in low strain rate, medium strain rate, and high strain rate can be obtained using the equal energy absorption strategy. The weight that reduced by high-strength steel tube and aluminum alloy tube is higher than that of plain steel tube, at all three strain rates.

Assessing the benefit of the brake assist system for pedestrian injury mitigation through real-world accident investigations

The compulsory fitting of the brake assist system (BAS) for new vehicles in the European Union has been recently established by Regulation (EC) 78/2009 to enhance the protection of pedestrians. This paper describes the main findings of a coordinated study performed by four Spanish Safety Research Centres aimed at assessing the potential influence of the BAS in vehicle–pedestrian collisions through the reconstruction of real-world accidents that occurred in three different cities of Spain. A total of 139 vehicle–pedestrian collisions were investigated in-depth following a common methodology, including on-the-spot data collection, analysis and reconstruction to estimate the collision speed and the pedestrian kinematics. A specific procedure was defined to emulate, through computer simulations, the performance of the BAS acting together with the antilock braking system (ABS). The benefit was assessed in terms of both collision speed and Injury Severity Probability (ISP) by comparing the reduction of their values from the real conditions to the virtual BAS+ABS simulations. The pedestrian ISP was estimated, depending on the collision speed and the head impact point, using a specific application that calculated its value based on the results of headform impact laboratory tests. The ISP values obtained in both conditions were compared. The findings show that while implementing the BAS+ABS would not have prevented the collision in most of the cases, it would have reduced their consequences in terms of the estimated ISP. It was also found that in few cases, a small reduction in the collision speed would increase the head injury severity.

From a theoretical model to a predictive simulation model of operator interaction with support systems: designing experiments to build the numerical simulation

In this paper, we will discuss a methodology developed and applied in the European ITERATE project with the objective of designing experiments that will provide data to seed the numerical model of operator behaviour in different surface transport modes: road vehicles, rail transport and ships. The experiments aim to investigate how new technologies support different types of operators in different contexts. A structured approach was adopted. Firstly, an initial selection of the systems to be investigated was made, describing the support they provide for operators. Hypotheses were formulated on the effects of operator parameters on the interaction with the systems. A final selection of systems for the experiments was made, focusing on systems providing support for collision avoidance and speed management. The operator parameters (culture, attitude and personality, experience, driver state (such as fatigue) and the demands of the task) were operationalised and piloted. The next step was the development of scenarios to be implemented in a driving simulator. In the last step, the final experiments were designed and detailed.

Complete trunk severance of a motorcyclist by a traffic sign post at a comparably low collision speed

Traumatic limb amputations and transections of the trunk generally indicate high impact velocities. Complete traumatic severances of the trunk in road accidents however are rarely reported in literature. We describe a case where the trunk of a motorcyclist was completely severed as he hit the post of a traffic sign. Based on the documented end position and damage of the motorcycle, an impact velocity range of 52–80km/h could be determined for the motorcyclist. To our knowledge, this is the first report on the type and mechanism of injury at this comparatively low collision speed range.

Turbulence-induced collisional velocities and density enhancements: large inertial range results from shell models

To understand the earliest stages of planet formation, it is crucial to be able to predict the rate and the outcome of dust grains collisions, be it sticking and growth, bouncing, or fragmentation. The outcome of such collisions depends on the collision speed, so we need a solid understanding of the rate and velocity distribution of turbulence-induced dust grain collisions. The rate of the collisions depends both on the speed of the collisions and the degree of clustering experienced by the dust grains, which is a known outcome of turbulence. We evolve the motion of dust grains in simulated turbulence, an approach that allows a large turbulent inertial range making it possible to investigate the effect of turbulence on meso-scale grains (millimeter and centimeter). We find three populations of dust grains: one highly clustered, cold and collisionless; one warm; and the third "hot". Our results can be fit by a simple formula, and predict both significantly slower typical collisional velocities for a given turbulent strength than previously considered, and modest effective clustering of the collisional populations, easing difficulties associated with bouncing and fragmentation barriers to dust grain growth. Nonetheless, the rate of high velocity collisions falls off merely exponentially with relative velocity so some mid- or high-velocity collisions will still occur, promising some fragmentation.

Alcohol intoxication in road traffic accidents leads to higher impact speed difference, higher ISS and MAIS, and higher preclinical mortality

Alcohol is one of the most important personal risk factors for serious and fatal injuries, contributing to approximately one third of all deaths from accidents. It is also described that alcohol intoxication leads to a higher mortality in the clinical course. In this study, we hypothesized that alcohol intoxication leads to different accident kinematics, a higher ISS (Injury Severity Score), and higher preclinical mortality compared to sober patients. A technical and medical investigation of alcohol intoxated road users was performed on the scene of the crash and at the primary admitting hospital. Alcohol testing was performed with either breath alcohol tests or measurement of blood alcohol concentration (BAC) in a standard laboratory test. Between 1999 and 2010, 37,635 road traffic accidents were evaluated by the Accident Research Unit. Overall 20,741 patients were injured, 2.3% of the patients were killed. Among the injured patients, 2.2% with negative BAC were killed, compared to 4.6% fatal injuries in patients with a positive BAC (p < 0.0001). Of the patients with a positive BAC, 8.0% were severely injured, compared to 3.6% in the BAC negative group (p < 0.0001). Regarding the relative speed at impact (Δv for motorized drivers, vehicle collision speed for pedestrians and bikers), there was a significant higher difference for BAC positive patients (30 ± 20) compared to the BAC negative patients (25 ± 19, p < 0.0001). Alcohol intoxication in trauma patients leads to higher preclinical mortality, higher impact speed difference, and higher injury severity. The subgroup analysis for different alcohol concentrations shows no difference in ISS, MAIS, and relative speed, but a correlation of increasing age of patients with higher alcohol concentrations.

Exploring the importance of quantum effects in nucleation: The archetypical Nen case

The effect of quantum mechanics (QM) on the details of the nucleation process is explored employing Ne clusters as test cases due to their semi-quantal nature. In particular, we investigate the impact of quantum mechanics on both condensation and dissociation rates in the framework of the microcanonical ensemble. Using both classical trajectories and two semi-quantal approaches (zero point averaged dynamics, ZPAD, and Gaussian-based time dependent Hartree, G-TDH) to model cluster and collision dynamics, we simulate the dissociation and monomer capture for Ne(8) as a function of the cluster internal energy, impact parameter and collision speed. The results for the capture probability P(s)(b) as a function of the impact parameter suggest that classical trajectories always underestimate capture probabilities with respect to ZPAD, albeit at most by 15%-20% in the cases we studied. They also do so in some important situations when using G-TDH. More interestingly, dissociation rates k(diss) are grossly overestimated by classical mechanics, at least by one order of magnitude. We interpret both behaviours as mainly due to the reduced amount of kinetic energy available to a quantum cluster for a chosen total internal energy. We also find that the decrease in monomer dissociation energy due to zero point energy effects plays a key role in defining dissociation rates. In fact, semi-quantal and classical results for k(diss) seem to follow a common "corresponding states" behaviour when the proper definition of internal and dissociation energies are used in a transition state model estimation of the evaporation rate constants.

Simulative Research on the Influence of Vehicle Brake Deceleration on the Throw Distance Property of Human-Vehicle Accidents

Braking deceleration of passenger-car has great influence on the pedestrian motion process after collision of human-vehicle accident, but it is considered not enough in current accident reconstruction and vehicle-speed analysis. In order to improve the accuracy of accident reconstruction, a computer simulation model of pedestrian-vehicle accidents based on finite element (FE) method and human parameters of Chinese adult human body is established. In this article, based on the FE model, human-vehicle crash is simulated through involving the influence of braking deceleration of passenger-car. For the application of the vehicle-speed analysis, the motion performance of pedestrian after collision were studied and the correlation between the pedestrian throw distance and vehicle impact speed are investigated. The influence of braking deceleration in same impact speed is analyzed. Research results show that the vehicle brake deceleration has a certain influence on the throw distance of pedestrian and it should be taken into account on the accident reconstruction. We can conclude that pedestrian throw distance can be used to estimate the vehicle collision speed accurately when drivers take full braking measure during the crash.

Multiobjective optimization design for vehicle occupant restraint system under frontal impact

Occupant Restraint System (ORS) can effectively protect passengers from severe injury in vehicle collision, thus its design signifies a key issue in automobile engineering. To ensure a high safety rating, e.g. five or at least four stars in the European New Car Assessment Program (Euro-NCAP) rating system, which has been widely used to rate the different vehicles from different manufacturers, design optimization becomes essential. Nevertheless, the effectiveness of conventional mathematical programming methods directly integrated with numerical simulation and sensitivity analysis for optimization is of limited practical value, due to high complexity of structures, nonlinearity of materials and deformation involved. To address the issue, this paper combines a Kriging (KRG) model with Non-dominated Sorting Genetic Algorithm II (NSGA-II) for vehicle ORS design. The ORS design of a 40% Offset Deformable Barrier (ODB) frontal impact test with the collision speed of 64 km/h is exemplified for the presented method. The results show that the KRG model can well predict the ORS responses for the design. Finally, the optimum result is verified by using sled physical tests. It is found that the ORS performance can be substantially improved for meeting product development requirements through the proposed approach.

Mechanically Assisted Deposition of Nikel Oxide–Ytttria Stabilized Zirconia Nanocomposite Film and its Microstructural Evolution for Solid Oxide Fuel Cells Anode Application

Nikel oxide–ytttria stabilized zirconia (NiO–YSZ) nanocomposite particles were synthesized and deposited on a dense YSZ substrate using an attrition‐type milling apparatus. The NiO–YSZ nanocomposite porous films were successfully fabricated from the nanocomposite particles with high specific surface areas (≫10 m2/g). In this deposition, the nanocomposite particles were mechanically dispersed in air, resulting in their fine aggregates (~100 nm in size). Then, they were mechanically impacted on the substrate (collision speed, ~30 m/s). By the subsequent sintering of the nanocomposite film, the finely constructed three dimensional NiO–YSZ network structure was formed, and its reduced Ni–YSZ porous film showed an excellent SOFC anode performance.

Cognitive Agent Based Critical Information Gathering and Dissemination in Vehicular Ad hoc Networks

Next generation vehicles will have capability of sensing, computing, and communicating capabilities. Different components in a vehicle have to constantly exchange available information with other vehicles on the road and cooperate for the purpose of ensuring safety and comfort using a Vehicular Ad hoc Network (VANET). Critical information like navigation, cooperative collision avoidance, lane-changing, speed limit, accident, obstacle or road condition warnings, etc. play a significant role for safety-related applications in VANET. Such kind of critical information gathering and dissemination is challenging, because of their delay-sensitive nature. This paper proposes an agent based model that consists of heavy-weight static cognitive (based on Belief Desire Intention : BDI) and light-weight mobile agents. Proposed model executes push (gather/store and disseminate) and pull (gather/store) operations on information gathered based on information relevance, criticalness and importance. The simulation results show that BDI based information gathering and dissemination scheme performs better than the reliable broadcast scheme in terms of bandwidth utilization, packet delivery ratio, push latency (information saturation time) and push/pull decision latency.

Polymeric Stabilized Emulsions: Steric Effects and Deformation in Soft Systems

Polymeric stabilizers are used in a broad range of processes and products, from pharmaceuticals and engine lubricants to formulated foods and shampoos. In rigid particulate systems, the stabilization mechanism is attributed to the repulsive force that arises from the compression of the polymer coating or "steric brush" on the interacting particles. This mechanism has dictated polymer design and selection for more than thirty years. Here we show, through direct measurement of the repulsive interactions between immobilized drops with adsorbed polymers layers in aqueous electrolyte solutions, that the interaction is a result of both steric stabilization and drop deformation. Drops driven together at slow collision speeds, where hydrodynamic drainage effects are negligible, show a strong dependence on drop deformation instead of brush compression. When drops are driven together at higher collision speeds where hydrodynamic drainage affects the interaction force, simple continuum modeling suggests that the film drainage is sensitive to flow through the polymer brush. These data suggest, for drop sizes where drop deformation is appreciable, that the stability of emulsion drops is less sensitive to the molecular weight or size of the adsorbed polymer layer than for rigid particulate systems.

A comparison between rubble-pile and monolithic targets in impact simulations: Application to asteroid satellites and family size distributions

Collisions are a fundamental process in the creation of asteroid families and in satellite formation. For this reason, understanding the outcome of impacts is fundamental to the accurate modeling of the formation and evolution of such systems. Smoothed-Particle Hydrodynamics/N-body codes have become the techniques of choice to study large-scale impact outcomes, including both the fragmentation of the parent body and the gravitational interactions between fragments. It is now possible to apply this technique to targets with either monolithic or rubble-pile internal structures. In this paper we apply these numerical techniques to rubble-pile targets, extending previous investigations by Durda et al. (Durda, D.D., Bottke, W.F., Enke, B.L., Merline, W.J., Asphaug, E., Richardson, D.C., Leinhardt, Z.M. [2004]. Icarus 170, 243–257; Durda, D.D., Bottke, W.F., Nesvorný, D., Enke, B.L., Merline, W.J., Asphaug, E., Richardson, D.C. [2007]. Icarus 186, 498–516). The goals are to study asteroid–satellite formation and the morphology of the size–frequency distributions (SFDs) from 175 impact simulations covering a range of collision speeds, impact angles, and impactor sizes. Our results show that low-energy impacts into rubble-pile and monolithic targets produce different features in the resulting SFDs and that these are potentially diagnostic of the initial conditions for the impact and the internal structure of the parent bodies of asteroid families. In contrast, super-catastrophic events (i.e., high-energy impacts with large specific impact energy) result in SFDs that are similar to each other. We also find that rubble-pile targets are less efficient in producing satellites than their monolithic counterparts. However, some features, such as the secondary-to-primary diameter ratio and the relative separation of components in binary systems, are similar for these two different internal structures of parent bodies.

Development of high-speed railway vehicle derailment simulation – Part II: Exploring the derailment mechanism

Based on the exactly solution for the wheel/rail contact point and the contact force, a vehicle/rail coupling model for analyzing dynamic derailment is developed in MATLAB as DDSHV (Dynamic Derailment Simulation for High-speed Vehicle). The calculation process of the simulation system is presented in detail, and the best solution conditions are also discussed to quickly obtain results. Two common types of dynamic derailment are studied in DDSHV. There exists a critical point in the process of wheel climb, and the dynamic weakening effect will promote the wheel-climbing rail. Meanwhile, some main factors, such as the speed, the rail condition and the wheel unload rate, have been studied on the dynamic weakening effect. The collision speed of the wheelset is the most important factor affecting impact derailment. As time becomes shorter, the collision can be investigated using LS-DYNA. The results confirm the equation for the critical impact speed used in this paper. DDSHV can also be used to find the vehicle running stability. Through the design of uplink and downlink algorithms, two critical running speeds, the critical speed and the nonlinear critical speed have been found. Yet, the changes in suspension parameters will directly influence these critical speeds. Therefore, an accurate configuration in vehicle will help to reduce the disturbances while an inaccurate configuration may lead to an incident. Although it is dangerous and difficult to make a derailment online test, the effectiveness of DDSHV has been verified by the known dynamic cases and lab tests. In conclusion, DDSHV has assisted in understanding the process of derailment, finding the important factors affecting derailment and exploring the mechanism of dynamic derailment.

An Investigation on Speedometer Pointer Residual-Value of Crashing Vehicle and its Application in Accident Reconstruction

According to the experience of traffic accident investigation over the years, the pointer of some crashed vehicles’ speedometer will stay in one place because of collision spread or heavily vibration, which may indicate the vehicle collision speed. However, the correlation between the residual speed value and actual vehicle collision speed still remains to be examined. For the practical needs of traffic accident reconstruction, this research work is carried out. Based on the principles of traditional speedometers, vehicle impact mechanics and failure mechanism, the damage and failure mode of speedometer in collision are studied. Through the statistics of 15 real traffic accident cases, the features and law about the pointer information of damaged speedometers are obtained initially. As an example, one of these cases is analyzed and calculated to verify the assumption. The availability of the mark information on the indicated place of speedometer after accidents (i.e. the correlation between the speed value of pointers and actual vehicle collision speed) is discussed, which can provide effective means and references for accident reconstruction and vehicle speed identification.

Finite Element Analysis of Woodball Mallet during Swing Stage

This study aims to analyze the relevant mechanical properties of woodball shafts by applying numerical methods. The structures of woodball were constructed in Solidworks 2007 to form the solid models, and the numerical model was analyzed in ABAQUS to acquire the simulation resluts. The collision speed between ball and mallet was from the experiment of motion analysis. As the maximal stress of mallet was concentrated in the proximal part of bottle, some enforcement design could be carried out in this part to reduce the fracture incidence. Another important finding is the contact area at the mallet head was really small, the rubber cover at head part may thicken at the centre part and thinner at the outside area. For further study, it is important to represent the higher fidelity of the input conditions for the finite element analysis (FEA).

Pengaruh Penggunaan Sabuk Pengaman Pada Pengemudi Dalam Kasus Tabrakan Frontal

A post-crash two-step analysis was performed on a fatal road accident involving a single-occupant pick-up truck that hit a concrete barrier in an almost perpendicular (frontal) direction. Firstly, the crash event was reconstructed to estimate the value of related parameters, such as collision speed, angle, speed of separation, and collision impulse time. Subsequently, models were developed to study the involved injury mechanism emphasizing on simulating the effects of using seatbelt to the occupant’s body during the collision. Accident reconstruction was carried out using VistaFX3 package software, while MADYMO package software was used in the study of injury mechanism. The results show that the acceleration rate suffered by occupant’s head and thorax (chest) could have been significantly reduced if the seatbelt were used properly. Keywords: traffic accident, safety belt, vehicle speed.

414 カーブ路正面衝突における衝突被害軽減ブレーキ(CMB)の衝突速度低減効果と事故件数低減予測～数値シミュレーションによる検討～(GS 交通システム)

414 カーブ路正面衝突における衝突被害軽減ブレーキ(CMB)の衝突速度低減効果と事故件数低減予測～数値シミュレーションによる検討～(GS 交通システム)

Adding particle collisions to the formation of asteroids and Kuiper belt objects via streaming instabilities

Modelling the formation of super-km-sized planetesimals by gravitational collapse of regions overdense in small particles requires numerical algorithms capable of handling simultaneously hydrodynamics, particle dynamics and particle collisions. While the initial phases of radial contraction are dictated by drag forces and gravity, particle collisions become gradually more significant as filaments contract beyond Roche density. Here we present a new numerical algorithm for treating momentum and energy exchange in collisions between numerical superparticles representing a high number of physical particles. We adopt a Monte Carlo approach where superparticle pairs in a grid cell collide statistically on the physical collision time-scale. Collisions occur by enlarging particles until they touch and solving for the collision outcome, accounting for energy dissipation in inelastic collisions. We demonstrate that superparticle collisions can be consistently implemented at a modest computational cost. In protoplanetary disc turbulence driven by the streaming instability, we argue that the relative Keplerian shear velocity should be subtracted during the collision calculation. If it is not subtracted, density inhomogeneities are too rapidly diffused away, as bloated particles exaggerate collision speeds. Local particle densities reach several thousand times the mid-plane gas density. We find efficient formation of gravitationally bound clumps, with a range of masses corresponding to contracted radii from 100 to 400 km when applied to the asteroid belt and 150 to 730 km when applied to the Kuiper belt, extrapolated using a constant self-gravity parameter. The smaller planetesimals are not observed at low resolution, but the masses of the largest planetesimals are relatively independent of resolution and treatment of collisions.

Comparison of rotationally inelastic rate constants for [formula omitted] + Ne measured using pulsed and cw lasers

We have measured rotationally inelastic rate constants for the processLi2∗A1Σu+(vi=5,ji=30)+Ne→Li2∗A1Σu+(vf=5,jf)+Ne using pulsed laser excitation and compared them to values previously measured using cw laser excitation, applying uniform analysis techniques to both sets of data. We compare the experimental results with rate constants calculated from quasiclassical trajectories on an ab initio potential energy surface, finding that the two experimental methods give consistent results when the different distributions of excited-state collision speeds are taken into account.