Frontal Collision Research Articles

Crashworthiness Analysis to Evaluate the Performance of TDM-Shielded Street Poles Using FEA

The mitigation of the risks of passenger injuries when a vehicle is involved in a collision with a street pole shielded with a layer of tire-derived material (TDM) was assessed. This can effectively absorb a fraction of the total energy from a speeding vehicle. Since such tests are expensive to conduct experimentally, the study relies on using the Abaqus/Explicit FEA solver to accurately calculate the non-linear nature of this scenario. Two categories of this scenario were evaluated to understand the effect a shielded street pole has on the vehicle—and the total absorbed energies during frontal and corner collisions, which are typically the most common categories of such accidents to happen. Results show that at lower speeds, these reinforcements are least effective in absorbing some of the kinetic energy applied by the vehicle, with about 5% of the energy absorbed by the reinforcement. At higher speeds, however, the results show that the TDM reinforcement absorbs about 28% of kinetic energy, which can reduce injury of the vehicle occupants, as well as decrease the damage on poles. Results for this simulation also show that there is a critical thickness of TDM that can absorb these kinetic energies, after which further thicknesses results in energies being applied back to the vehicle, therefore negating any purpose to further increase TDM thicknesses.

Optimal design of continuously inflated airbag for 12-year-old child occupants with various sitting postures

Owing to the lively nature, children often use a variety of non-standard sitting postures when riding school buses. Current restraint systems in school buses and traditional airbags cannot effectively protect the child occupants with the non-standard sitting postures in frontal collisions. A prototype design of a new continuously inflated airbag is proposed to increase the safety of child occupants. The aim of this study is to determine the injury thresholds of 12-year-old children using the dimensional analysis method, and under the eight mixed conditions, to propose an optimal design of a continuously inflated airbag. First, a simulation model of the restraint system is developed and validated by the experimental test conducted according to ECE R80/GB24406. Then, a coupling model of the restraint system and continuously inflated airbag is built. Second, a standard and three non-standard sitting postures of 12-year-old child occupants and the two crash pulses of school buses are combined to form the eight mixed conditions. Finally, the main design parameters of the continuously inflated airbag are optimized using the non-dominated sorting genetic algorithm III and entropy weight method. A continuously inflated airbag with the optimal configuration can significantly reduce the injuries to the 12-year-old child occupants. Under the original crash pulse, the optimized airbag can provide the best protections for the occupant head under the forward-leaning sitting posture and the occupant femurs under the slouched sitting posture, respectively. Under the higher-speed crash pulse, the protective effect on the occupant head under the standard sitting posture is better than that under the right-leaning sitting posture.

Injury of the Spinothalamic Tract Following Whiplash Injury: A Diffusion Tensor Tractography Study

Using diffusion tensor tractography (DTT), we demonstrated the spinothalamic tract (STT) injury in patients with central pain following whiplash injury. Our primary hypothesis is that fractional anisotropy (FA) and tract volume (TV) of the STT in injured people differ from non-injured people. Our secondary hypothesis is that the direction of the collision results in a different type of injury. Nineteen central pain patients following whiplash injury and 19 normal control subjects were recruited. The STT was reconstructed by the DTT, the FA and TV of the STT were measured. In addition, different characteristics of the STT injury according to the collision direction were investigated. The FA value did not differ significantly between the patient and control groups (p > 0.05). However, the significantly lower value of the TV was observed in patient group than the control group (p < 0.05). The onset of central pain was significantly delayed (13.5 days) in patients who were involved in a frontal collision, compared to patients with rear-end collision (0.6 days) (p < 0.05). In contrast, the Visual Analogue Scale was higher in the patients with rear-end collision (p < 0.05). We found the STT injury mild traumatic brain injury (TBI) who suffered central pain after whiplash injury, using DTT. In addition, we demonstrated different characteristics of the STT injury according to the collision direction. We believe that injury of the STT would be usefully detected by DTT following whiplash injury.

Parameter Study for Child Booster Seats in Frontal Collisions

To improve the safety of middle-aged and older child occupants, this paper proposes a framework to effectively design the layout parameters of child booster seats. The layout parameters of the child booster seat include both the three-point seat belt restraint path parameters and the structural design parameters. First, based on a validated frontal collision simulation model with the sled test, a parametric study of child booster seats for different injury indices is performed based on ECE R129 regulations in terms of a Q6 child dummy. To evaluate the effects of each parameter on the overall injury for children, the modified Weighted Injury Criterion (WIC) is proposed. Then, a parameter sensitivity based on the modified WIC is conducted to screen out parameters that have a significant impact on the response of injury indices. The position of the shoulder belt guide and the stiffness of the backrest have dominant effects on the WIC. Finally, a full factorial experiment is conducted for the above selected design variables based on the newly proposed WIC. The identified design position of the shoulder belt guide is 48 mm and its value corresponds to 30 mm of the relevant headrest position, which is explicitly utilized in the design process. The identified stiffness of the backrest is 30,400 Nm/rad. The corresponding WIC is decreased significantly, and the value is reduced by 19.6% compared with the reference model.

The effect of a braking maneuver on the occupant’s kinematics of a highly reclined seating position in a frontal crash

Objective This study aims to make the comparison of the kinematics and possible injury values of the occupant in the highly reclined seating position in two cases: the first case is without the braking maneuver prior to the frontal crash, and the second case is considering the braking maneuver prior to the impact. Methods This study used the MADYMO human body model 50th percentile mid-size male seated on the front passenger seat model with the seatback reclined rearward 53° (fully reclined seatback) to simulate the occupant biomechanics and behavior during a frontal collision. To achieve the study aim, two simulation models were created. The first model is called the non-precrash model (VaAM-O). It was set to simulate the occupant kinematics in the fully reclined initial seating posture in the 200 ms of a crash without the braking maneuver before the crash. The second model, called the precrash model (VaAM-I), identified the occupant’s initial position after the car model performed a 1s deceleration of a braking maneuver. VaAM-I has then also simulated the occupant kinematics in 200 ms of a crash. Results This study showed a significant difference in the occupant’s posture at the beginning of the crash phase in the two cases. The upper torso of VaAM-I rotated up and moved forward earlier than VaAM-O prior to the crash phase due to the influence of the braking maneuver, and at the 50 ms, when the airbag deployed completely, the head had no contact with the airbag, and the head in VaAM-I forwarded to the airbag closer than VaAM-O about 24% of the distance to the airbag. Conclusions This study supplements the value data for the study of the out-of-position OOP of the occupant in the frontal crash. The contact force and position contact between the head and the airbag could attract the audience’s attention. On the other hand, a comparison of the seatbelt force and the seatbelt contacts the body between the conventional seatbelt as in this study, and the seat-integrated seatbelt system in the case wherein the occupant seats on the front seat with a highly reclined seatback should be performed.

Modelling, testing and validation of an innovative AEB control logic on a Hardware-in-the-loop test bench

AEB, autonomous emergency braking, is an active safety system designed to prevent vehicle frontal collision. The most diffused AEB systems are based on simple Bang Bang control logic, which could often avoid, or at least mitigate collision effects, but their effectiveness can still be improved by increasing system repeatability. The aim of this study is to model and test an innovative AEB control logic that will increase system reliability by compensating for the non-immediate response of the braking system to braking requests. Using a hardware-in-the-loop test bench with two different braking systems implemented, the new controller was tested simulating the CCRs and CCRm scenarios, used by Euro NCAP for AEB system assessment. By compensating for the delay introduced by the response of two different braking systems, the innovative control logic stops the VUT, Vehicle Under Test, at the desired safety distance from the GVT, Global Vehicle Target.

Production and Performance Evaluation of Sisal Fibre (Agave Sisalana) As Composite Material for Car Bumper

A bumper is one of the main automobile parts used as protection for the car and passengers against front and rear collision. The aim of this study is to carry out a research on sisal fibre as a suitable reinforcement material for production of a composite car bumper. The research also evaluated the properties of the composite bumper to ascertain its improvement on crash-worthiness during car collision. Sisal fibre is a material that has properties of low weight, high strength, and low density. Considering the fact that fuel economy and efficiency is necessary in modern automobiles, the best way to increase the vehicle efficiency without sacrificing safety is to employ the use of sisal-fibre reinforced composite in the production of less weight and high strength bumpers. The research was conducted through experiment, analysis and production processes. Hand lay-up technique method was employed in the production of the mould and the composite car bumper. The results obtained from the tests are; Tensile strength; 69.51 MPa, Impact strength; 32.79kJ/m2, Compression strength; 6.92MPa, and flexural strength: 86.81MPa. At the end of the research, better quality, light weight and high strength composite bumper was produced. The analysis of the produced car bumper showed that it conformed to National Highway Traffic Safety Administration (NHTSA), 1971 and Federal motor vehicles safety standards (FMVSS, No. 215), at 8km/hr collision speed.

Impact Attenuator Design for Improvement of Racing Car Drivers’ Safety

An essential element for driver safety is represented by the Impact Attenuator (especially for race cars). The effect of the Impact Attenuator can be seen in the behavior of a dummy, tied with a seat belt, in a frontal collision with a rigid wall. The loads that act on the dummy are determined and checked to see if they fall within the values recommended by existing standards. The car is considered a structure with a dummy fixed with a seat belt and equipped with an Impact Attenuator. Two types of Impact Attenuator having constructive similarity and symmetries are studied, made up of three different materials and different thicknesses of material. The behavior of the dummy was studied, considering a frontal collision of the car–dummy assembly, in accordance with existing standards. Using simulation software, the accelerations were determined at various points on the mannequin’s body and the force appearing on the seat belts was determined. The Gibbs–Appell equations are the method used to determine the dynamic response in this problem involving shocks.

Inversion study of vehicle frontal collision and front bumper collision

&lt;abstract&gt; &lt;p&gt;The collision of a vehicle is often a process of strong nonlinearity and large deformation, and the finite element method is time-consuming. For this reason, a method of collision inversion research is proposed. Through the definition of the forward and inverse problems, the forward problem is inversely solved from the perspective of the inverse problem, and the collision process can be predicted quickly while the accuracy is ensured. In this paper, the idea of inversion is introduced into the collision test of the front bumper of the vehicle. First, a finite element model is established based on the geometric model of the bumper. The accuracy of the finite element model is verified by comparing the results of the drop weight test with the simulation results of the finite element model. Then, using the built simulation model, spring mass model and drop weight test, the inversion research of vehicle collision and the front bumper of a vehicle is carried out. The inversion research of the bumper first inverts the collision course in the inversion algorithm derived from the vehicle collision, and then compares the collision course derived from the inversion algorithm formula with the simulation test results. The research results show that the change trends of the time-velocity curve and the time-deformation curve obtained by the collision inversion algorithm are basically consistent with the simulation test results, indicating that the collision inversion algorithm can realize the rapid prediction of the collision course and improve derivation efficiency significantly, and it provides a new idea. Finally, under the constant energy condition of the drop weight test E = mgh, through the relationship between energy and deformation, it is concluded that the depth deformation of low-speed collision of the front bumper is greater than that of high-speed collision.&lt;/p&gt; &lt;/abstract&gt;

Retrospective Window of Interest Annotation Provides New Insights Into Functional Channels in Ventricular Tachycardia Substrate

Accurate annotation of local activation time is crucial in the functional assessment of ventricular tachycardia (VT) substrate. A major limitation of modern mapping systems is the standard prospective window of interest (sWOI) is limited to 490 to 500 milliseconds, preventing annotation of very late potentials (LPs). A novel retrospective window of interest (rWOI), which allows annotation of all diastolic potentials, was used to assess the functional VT substrate. This study sought to investigate the utility of a novel rWOI, which allows accurate visualization and annotation of all LPs during VT substrate mapping. Patients with high-density VT substrate maps and a defined isthmus were included. All electrograms were manually annotated to latest activation using a novel rWOI. Reannotated substrate maps were correlated to critical sites, with areas of late activation examined. Propagation patterns were examined to assess the functional aspects of the VT substrate. Forty-eight cases were identified with 1,820 ± 826 points per map. Using the novel rWOI, 31 maps (65%) demonstrated LPs beyond the sWOI limit. Two distinct patterns of channel activation were seen during substrate mapping: 1) functional block with unidirectional conduction into the channel (76%); and 2) wave front collision within the channel (24%). In addition, a novel marker termed the zone of early and late crowding was studied in the rWOI substrate maps and found to have a higher positive predictive value (85%) than traditional deceleration zones (69%) for detecting critical sites of re-entry. The standard WOI of contemporary mapping systems is arbitrarily limited and results in important very late potentials being excluded from annotation. Future versions of electroanatomical mapping systems should provide longer WOIs for accurate local activation time annotation.

Improving the load distribution in the automobile front collision zone by adding 'S' shaped curved collision rail

Improving the load distribution in the automobile front collision zone by adding 'S' shaped curved collision rail

Modeling, Aerodynamic and Crash Simulation on Car Using Fluient

Aerodynamics plays a crucial role while designing any automobile components. Due to the aerodynamics the entire performance of the automotive will be changed. With an improvement in computer technology, manufacturers are looking toward computational fluid dynamics instead of wind tunnel testing to reduce the testing time and cost. In this paper a car model considered and it is modeled using solid works modeling software. The car material is stainless steel. The lift and drag of production vehicle are determined by the analysis of flow of air around it using Ansys. The aerodynamic analysis of the design parameter of car will be performed by using a suitable turbulence model and to compare the drag coefficient of design of car model by using CFD software result and experimentally result and the results will be validated by CFD analysis/experimental studies. The result of software analysis has agreed excellently with field experimentally results. The aerodynamic and crash analysis on car with of material Al 6061&amp;AISI 4130 with wall and vehicle is considered The given model is tested under frontal collision conditions and the resultant deformation and stresses are determined with respect to a time of 80 Mille sec for ramp loading using ANSYS software. The crash analysis simulation and results can be used to assess both the crashworthiness of current frame and to investigate ways to improve the design. This type of simulation is an integral part of the designcycle and can reduce the need for costly destructive testing program.

Research on Occupant Safety in Frontal Collision Based on Different Sitting Positions of Intelligent Vehicles

Abstract: To study the safety of drivers with different sitting positions in intelligent vehicle collision, the slide model of SUV was established and the precision of the model was verified by slide test. The simulation model of driver's attitude was established by THUMS. According to the results of post mortem human surrogate (PMHS), the sitting postures of THUMS at different seat backrest angles were adjusted and the drivers’ injuries of three sitting postures in frontal collision were analyzed. Simulation results show that when the driver was in semi-recumbent and reclining posture, the protective effect of the airbag on the head was obviously reduced in collisions, and the head and chest will be seriously damaged due to the large seat backrest angle, resulting in increased distance between the head and the wheel. Besides, the tilting sitting posture leads to the risk of sunken seat in the collision. Therefore, with the development of autonomous driving technology, not only should intelligent vehicles meet occupants’ comfort requirements, but the collision safety caused by the change of sitting postures should be considered.

Analysis of Crashworthiness of Bishoftu Pickup Vehicle Structure during Side Pole Crash

Now a day’s, vehicle accident is becoming a critical issue all over the world, especially in Ethiopia. These vehicles have not been checked for any crash safety test specifications and are not evaluated for crashworthiness. So, it is now time to consider the safety features of Bishoftu pickup vehicles (BPV) to reduce the grave consequences for their users. This paper aimed to improve the crashworthiness of the existing Bishoftu pickup vehicle through remodeling. The structural response to a frontal collision with an existing BPV is analyzed. Based on the results obtained from the existing model, modifications are made by means of energy-absorbing components, a stable frame structure, and better crash performance. For doing the analysis software like CATIA is used for 3D modeling, and LS-DYNA is used for FEM analysis. The results show that by applying the modification, 39 kN (7.82%) of impact force is reduced and 5 kJ (3.52%) of additional energy is absorbed during the frontal collision. Finally, it can be concluded that with the modified model, the safety and crashworthiness of the BPV were greatly improved without affecting the appearance and weight of the existing one.

Correlation study between the square-cone energy-absorbing structure and the frontal collision behaviour of leading vehicles

Abstract In order to study the influence of square-cone energy-absorbing structures on the mechanical behaviour of the collision performance of the leading vehicle, a parameterization method for rapidly changing the performance of energy-absorbing structures was proposed. Firstly, a finite element simulation model of the collision of the leading vehicle with a square-cone energy-absorbing structure was constructed. Then, the platform force, the slope of the platform force and the initial peak force of the force-displacement curve derived from the energy-absorbing structure were studied for the collision performance of the leading vehicle. Finally, the correlation model of the square-cone energy-absorbing structure and the mechanical behaviour of the collision performance of the leading vehicle was established by the response surface method. The results showed that the increase of the platform force of the energy-absorbing structure can effectively buffer the longitudinal impact of the train and reduce the nodding attitude of the train. The increase of the platform force slope can not only effectively buffer the longitudinal impact and vertical nodding of the train, but also reduce the lateral swing of the train. An increase in the initial peak force to a certain extent may lead to a change in the deformation mode, thereby reducing the energy-absorption efficiency. The correlation model can guide the design of the square-cone energy-absorbing structure and predict the deformation attitude of the leading vehicle.

Effect of seat direction on sitting occupant injury risk and improving strategy in the commuter train frontal crash

ABSTRACT This study aims to analyse the dynamic response of occupant posture during the frontal collision of commuter train. Six occupants with different postures seating in three types of seats were introduced to compare their injuries. The results show that the injury values of the occupant in the forward-facing seat and at the rear end of the side-facing seat were beyond the requirements of GM/RT2100. As a result, the forward-facing seat was recommended to be designed as rotated seat, rotatable seat with headrest, or install two-point and three-point seat belt. And then handrail and partition were recommended to be installed in the side-facing seat. It can be found that the proposed strategies such as rotatable seat without headrest, three-point seat belt, and handrail with suitable height were effective to improve occupant safety. The findings are expected to provide recommendations for seat direction in commuter train to improve occupant safety during frontal collision event.

3G-optimization of multi-cell crash box cross-section of autobody based on crashworthiness

The cross-section, thickness, and material of the autobody structure determine the crashworthiness and lightweight level. Different from the variables in traditional autobody design that are considered separately, the basic theory of 3G-optimization is to simultaneously consider geometric shape (Geometry), the thickness of structure (Gauge), and material grade (Grade) in structural optimization design, which is conducive to maximizing the lightweight potential of the structure. This paper presents a cross-section optimization method for multi-cell thin-walled structures based on 3G-optimization, which is used in the structural design of crash box. Based on full width frontal collision condition, the cross-section shape, thickness, and material variables of the multi-cell crash box are optimized simultaneously. Multiple sets of optimization schemes show obvious weight reduction effect while ensuring safety. Besides, the sub-system decoupling method and hybrid cellular automaton (HCA) method are applied to 3G-optimization process, which is beneficial to improve the calculation efficiency and provide a theoretical basis for the definition of the initial design space for 3G-optimization.

Crashworthiness analysis and design of a sandwich composite electric bus structure under full frontal impact

The transition toward sustainable transportation includes adopting ecofriendly electric vehicles in public transport, which reduces greenhouse gas emissions and increases energy efficiency. One of the critical features in fuel economy improvement of electric vehicles lies in lightweight structural design. Nevertheless, the crashworthiness of the structures of the vehicles and the safety of passengers must be guaranteed in the attempt of mass reduction because the crash of large vehicles such as buses usually costs many lives. This paper, therefore, aims to present an in-depth analysis of the impact behavior of a lightweight monocoque sandwich composite microbus body under full-frontal crash conditions. The bus structure, made of a high-density polyurethane foam core and woven glass fabric-epoxy face sheets, was modeled and simulated via LS-DYNA dynamic analysis using strength-based Chang-Chang criteria to characterize the failure mechanism of the structure and investigate intrusion into the passenger survival space. Under front collision, the front panel, A-pillars, and front sidewalls of the original bus were found to be extensively damaged in the compressive fiber mode. Based on the 50th percentile male dummy anthropometric parameters, injury indices of 0-5 intervals were proposed to evaluate occupant injury risks. The maximum front and side intrusion into the specified safety space under a maximum impact speed of 50 km/h is 208 mm at the front panel and 221 mm at the sidewall, indicating high injury indices of 3.59 and 4.81, respectively. The effects of stiffeners reinforced in the front panel and foam core thicknesses in the sidewalls, floor, and bottom parts on crashworthiness improvement were thoroughly discussed. The improved bus design can significantly enhance the safety of the occupants with a minimal increase in structural weight of merely 35.6 kg. An effective vehicle safety design under full frontal collision is presented.

Development and assessment of alternative designs for side impact beam

Side collisions are the second most important cause of death and injury in traffic accidents. Such collisions are riskier than frontal collisions as there are no unique bumpers to absorb the impacts and the space between the passenger and the door is very limited. Therefore, one of the most studied collision types in vehicle safety research is side collisions. Passenger safety is ensured by the A, B, C-Pillar and the side impact beam. This study aims to design and test a composite side door impact beam with a higher strength/weight ratio against impacts. For this purpose, side impact beam design alternatives were created from glass fiber reinforced polymer composite and carbon fiber polymer composite materials, and the samples were tested to obtain maximum force, maximum stress, force/weight ratio, stress/weight ratio, energy absorption ability, specific energy absorption, cost, and mass results. Then, the effectiveness of the designed side impact beams was discussed by comparing the results obtained from the quasi-static compression tests. The study results show that an optimum design can be suggested by evaluating such structural elements in terms of many parameters and establishing trade-off relations between the parameters.

The soliton solutions and combined solutions of a high-dimensional wave soliton equation

In this paper, a high-dimensional wave soliton equation is considered and the simple Hirota method and bilinear backlund transformation are applied to construct the new soliton solutions, lump soliton solutions, breather solutions and their combined solutions. Then, through long-wave limit method and appropriate parameter constraints, one-soliton, one-breather, combined soliton-lump and lump-breather and soliton-breather solutions to nonlinear wave equation are obtained. Moreover, the physical interaction and frontal collision phenomena to the solutions of this equation are explored. In addition, a kind of hyperbolic and trigonometric ansatz is employed to derive other solutions such as kink soliton solution, periodic solutions for the high-dimensional wave equation.The obtained results verify the proposed solutions.