Crash Simulation Research Articles

Study on the Crashworthiness of a Battery Frame Design for an Electric Vehicle Using FEM

This paper presents an optimized method for evaluating and enhancing the crashworthiness of an electric vehicle (EV) battery frame, leveraging finite element model (FEM) simulations with minimal computational effort. The study begins by utilizing a publicly available LS-DYNA model of a conventional Toyota Camry, simplifying it to include only the structures relevant to a side pole crash scenario. The crash simulations adhere to FMVSS214 and UNR135 standards, while also extending to higher speeds of 45 km/h to evaluate performance under more severe conditions. A dummy frame with virtual mass is integrated into the model to approximate the realistic center of gravity (COG) of an EV and to facilitate visualization. Based on the side pole crash results, critical parameters are extracted to inform the development of load cases for the EV battery. The proposed battery frame, constructed from aluminum, houses a representative volume of battery cells. These cells are defined through a homogenization process derived from individual and pack of cell crash tests. The crashworthiness of the battery frame is assessed by measuring the overall intrusion along the Y-axis and the specific intrusion into the representative volume. This method not only highlights the challenges of adapting conventional vehicle platforms for EVs or for dual compatibility with both conventional and electric powertrains but also provides a framework for developing and testing battery frames independently. By creating relevant load cases derived from full vehicle crash data, this approach enables battery frames to be optimized and evaluated as standalone components, offering a method for efficient and adaptable battery frame development. This approach provides a streamlined yet effective process for optimizing the crash performance of EV battery systems within existing vehicle platforms.

Effects of rear seat design on occupant injury risk during frontal crashes: A parametric study using finite element analysis

Rear seat occupants in newer vehicles might face a higher injury risk during traffic collisions compared to front seat occupants, whose seats have significantly improved over the last few decades. In addition, the rise in ridesharing and automation could increase exposure of rear seat occupants. Therefore, this study aims to evaluate the effects of various characteristics of rear seat design on occupant safety during frontal collisions. A simplified seat model was developed and validated against sled test data (ΔV of 32 km/h). Ten seat characteristics of the simplified seat were then investigated using two Design of Experiments techniques. Occupant injury risks were derived from crash simulations, and the correlation between the seat design and injury probabilities was evaluated. The results indicated that a more vertical seat back angle, specific D-ring location (a more rearward, inboard, a higher), and seatbelt anchorage location (wider and higher) would improve rear seat safety performance. Optimal seat models were developed based on the DOE results, and their superior performance was confirmed in finite element (FE) crash simulations. Overall, the whole-body injuries in optimized seats were significantly lower than the average injury risk in the DOE cases for both 50th percentile male Hybrid III (38.5% vs. 70.5%) and THOR (52.8% vs. 78.1%) dummies. These findings suggest substantial potential for improving rear seat designs to enhance occupant safety.

Effect Analysis of Different Use Ways of a Q10 Child Seat

In this paper, the injury situation of Q10 child dummy was optimized and analyzed by analyzing the impact of different ways of using a certain child seat ,and analyzing the crash test data of a real car based on LS-DYNA crash simulation analysis software after the vehicle benchmarking, by elaborating on the protection of child occupants in different ways of using this type of child seat, so as to provide a reference for the development of child restraint system of new cars. The results show that: Regardless of whether this type of child seat has an optional seat back, adding seat belt Secure Guard and not using ISOFIX fixing, the dummies' injuries show a decreasing trend. This study provides reference for the selection and use of this type of child seat in dynamic test.

Research and application of rapid reconstruction technology to existing bridge guardrails based on UHPC connection

A novel prefabricated segmental guardrail is proposed to facilitate connections between guardrails and between guardrails and bridge decks by casting ultrahigh-performance concrete (UHPC) joints in situ. Through finite element crash simulation analysis of three types of vehicles and crash tests of real vehicles, the prefabricated segmental guardrail with a UHPC connection was systematically evaluated in terms of its energy-absorbing capacity, vehicular acceleration, post-impact trajectory of the impacting vehicle, and behaviour of the guardrail upon impact. During the evaluation process, performance comparisons of the prefabricated segmental guardrails are made with the monolithic concrete guardrails. The results indicate that the performance of the prefabricated segmental guardrail with a UHPC connection was superior to that of the conventional concrete monolithic guardrails: it exhibited a higher level of crash performance, the occupants of the impacting vehicle were better protected, and the impacting vehicle exhibited better post-collision stability. Finally, the convenience of the prefabricated segmental guardrails with UHPC connections was proven in practical engineering applications.

Thermal–Electrical–Mechanical Coupled Finite Element Models for Battery Electric Vehicle

The safety of lithium-ion batteries is critical to the safety of battery electric vehicles (BEVs). The purpose of this work is to develop a method to predict battery thermal runaway in full electric vehicle crash simulation. The thermal–electrical–mechanical-coupled finite element analysis is used to model an individual lithium-ion battery cell, a battery module, a battery pack, and a battery electric vehicle with 24 battery modules in a live circuit connection. The lithium-ion battery is modeled using a representative approach, with each internal battery component individually modeled to represent its geometric shape and realistic thermal, mechanical, and electrical properties. A resistance heating solver and Randles circuit model built with a generalized voltage source are used to simulate the electrical behavior of the battery. The thermal simulation of the battery considers the heat capacity and thermal conductivity of different cell components, as well as heat conduction, radiation, and convection at their interfaces. The mechanical property of battery cell and battery module models is validated using spherical punch tests. The electrical property of the battery cell and battery module models is verified against CircuitLab simulation in an external short-circuit test. The simulation results for the battery module’s internal resistance are consistent with both experimental data and literature values. The multi-physics coupling phenomenon is demonstrated with a cylindrical compression simulation on the battery module. The multi-physics BEV model with 24 live battery modules is used to simulate the external short-circuit test and the side pole impact test. The simulation run time is less than 24 h. The results demonstrated the feasibility of using a representative battery model and multi-physics analysis to predict battery thermal runaway in full electric vehicle crash analysis.

Numerical Modeling and Simulation of Vehicular Crashes into Three-Bar Metal Bridge Rail

Advanced finite element (FE) modeling and simulations were performed on vehicular crashes into a three-bar metal bridge rail (TMBR). The FE models of a sedan, a pickup truck, and a TMBR section were adopted in the crash simulations subject to Manual for Assessing Safety Hardware (MASH) Test Level 2 (TL-2) and Test Level 3 (TL-3) requirements. The test vehicle models were first validated using full-scale physical crash tests conducted on a two-bar metal bridge using a sedan and a pickup truck with similar overall physical properties and sizes to their respective vehicles used in the simulations. The validated vehicular models were then used to evaluate the crash performance of the TMBR using MASH evaluation criteria for structural adequacy, occupant risk, and post-impact trajectory. The TMBR met all MASH TL-2 requirements but failed to meet the MASH TL-3 Criteria H and N requirements when impacted by the sedan. The TMBR was also evaluated under in-service conditions (behind a 1.52 m wide sidewalk) and impacted by the sedan under MASH TL-3 conditions. The simulation results showed that the TMBR behind a sidewalk met all safety requirements except for the occupant impact velocity in the longitudinal direction, which exceeded the MASH limit by 3.93%.

Research on finite element simulation and full-scale-vehicle crash test of B750HL bridge barrier

How to raise the bridge barrier with a concrete base height of only 51 cm to SS level of protection is not yet studied. In order to effectively retrofit an existing concrete barrier design to meet new crash testing criteria, the structural dimensions and concrete strength of the existing bridge barrier were investigated, and finite element simulation analysis was carried out, and simulation suggested the existing barrier was insufficient. Based on the structural dimension design principles of bridge barriers, the existing structure of bridge barrier was designed after adding lightweight and high-strength B750HL material crossbeams and posts on top of the concrete base, and the bearing capacity of the bridge barrier was calculated based on the yield line theory. Then, a finite element simulation analysis model was established to study and analyze the blocking, guiding, and cushioning functions of the improved design of bridge barrier. Finally, full-scale-vehicle crash tests were conducted with the SS-level small car, bus, and tractor-van trailer for this bridge barrier design scheme. This paper is the world’s first to use B750HL steel as the material for the crossbeam and post of a bridge barrier with a concrete base height of only 51 cm. According to the research results, the B750HL bridge barrier, which was designed based on the calculation of structural dimension design and yield line theory, effectively reduces the increased constant load on the bridge deck caused by the extra crossbeams and posts. At the same time, it can reduce material costs and save engineering costs. After being verified by finite element simulation crash tests and full-scale-vehicle crash tests, the protective capacity of the B750HL bridge barrier was proven to meet the SS-level evaluation requirements of the Standard for Safety Performance Evaluation of Highway Barriers (JTG B05-01-2013). The research findings of this paper is that the finite element simulation crash tests can effectively simulate full-scale-vehicle crash test, and the finite element simulation crash tests is reliable. If the safety performance of the barrier in the finite element simulation crash tests meets the requirements, the probability of passing the full-scale-vehicle crash test is higher. Therefore, a design scheme is proposed for the B750HL bridge barrier to improve hybrid bridge barriers at a height of 51 cm or more based on various design methods.

Multi-objective optimization design of NPR protection shell for hydrogen storage tank

In order to improve the safety of on-board hydrogen storage tanks during collision, a protective shell based on a negative Poisson’s ratio (NPR) core is designed in this paper. After analyzing and comparing the crashworthiness of three typical honeycomb structures, the concave hexagonal negative Poisson’s ratio honeycomb is selected as the energy-absorbing inner core of the hydrogen storage tank protection structure. The sensitivity analysis of the structural parameters of the NPR shell is conducted through orthogonal tests to identify parameters with a significant impact on crash performance. These parameters are then used as experimental variables for subsequent optimization design. Subsequently, a response surface approximation model between the optimization objective and the structural parameters is established based on the response surface method. Finally, the adaptive simulated annealing algorithm (ASA), neighborhood cultivation genetic algorithm (NCGA), and non-dominated sorting genetic algorithm-II (NSGA-II) are used to optimize the structural parameters, and the optimization results are verified by the whole-vehicle crash simulation. The simulation results demonstrate that all three algorithms achieve better optimization results, among which NCGA is more advantageous in improving the overall performance of the protective shell. After NCGA optimization, the specific energy absorption of the protective shell increases by 19.75%, the maximum collision force of the rigid wall decreases by 23.63%, and the maximum stress of the hydrogen storage tank body decreases by 22.77%. These findings indicate that the designed protection shell effectively improves the crashworthiness of the hydrogen storage tank during collisions.

Identifying the influence of airbag structure on driver injury during a crash using a dummy model

This study undertakes the analysis of collision scenario using a car model with a dummy and airbags, in the event of a direct collision with a hard wall, one of the necessary studies of passive safety. To describe in detail, the input conditions, a simulation problem of the driver's seat displacements was performed and this displacements data was exported as boundary conditions for the collision simulation. The results simulation crash show that the calculated energy values and simulation results are approximately the same (7.381E+07 and 7.367E+07), energy is converted from kinetic energy into internal energy of the elements. The airbag deployment simulation results are similar to NHTSA's previous research, both in terms of graph shape and maximum value. The impact of the collision incident on the driver is not excessively large, as evidenced by surveys on head (HIC 300), thigh (F 2.8 kN), and neck (F3,098 kN; T 190 Nm) injuries. However, the study proceeds to further analyze and assess the airbag's structure, examining its influence on these metrics, concluding that changes in the exhaust valve size (increase from 1000 mm2 to 2000 mm2) lead to a reduction in the evaluated parameters. These results suggest changes to the airbag structure to enhance driver safety, as well as a simpler simulation model to save analysis time

Efficient injury risk predictions for a diverse population using parametric human modeling and inducing points in Gaussian processes

Objective The objective of this study is to use parametric human modeling and machine learning methods to identify representative occupants that can account for injury variations among a more diverse population with a limited simulation budget. Method A maximal projection method was used to sample 100 occupants, considering the variations in stature, weight, and sitting height. An automated mesh morphing method was used to morph the THUMS v4.1 midsize male model into the target geometries. US-NCAP frontal crash simulations were conducted with morphed human models and validated vehicle/restraint models. Surrogate models based on the Gaussian Process (GP) method were trained to find inducing points (IP), here defined as a small number of representative occupants whose outcomes could be used to accurately estimate the variations in the injury risks and patterns throughout the population. Statistical analysis was conducted to validate the IPs’ coverage of total variation by illustrating the IP distribution. Restraint optimization was performed at IPs to yield an enhanced restraint system. The method was validated through comparisons among the predicted injury risks under the optimal and baseline designs. Results Only 20 IPs were needed to sufficient to properly represent the variations in the injury risks and patterns in the whole population with acceptable accuracy. Compared to the surrogate model built from 100 crash simulations, the IP-based surrogate models incurred only 0.4% and 1.8% errors in head injury risks for males and females, respectively. Regarding the injury risks on the chest and lower extremities, the IP-based surrogate models resulted in less than 0.1% and 0.5% errors for males and females, respectively. The FE simulations indicated that the optimal restraint system design reduced the injury risk by relatively 16% and 13% for male and female respectively when delta-V = 25 (mph), and 47% and 27% for male and female when delta-V = 35 (mph). Significance of results The study proposed a method to generate more accurate injury risk predictions for a more diverse population under a limited simulation budget. Simulations using IPs may enable restraint system optimization to be conducted more efficiently while reducing injury risks across a more diverse population.

Comprehensive crashworthiness simulation analysis of a large aircraft fuselage barrel section in various crash scenarios

To utilize computational techniques in investigate and evaluate the crashworthiness of typical fuselage section of a large transport aircraft in various crash scenarios, the finite element model of fuselage section was modeled and validated based on the vertical drop test of fuselage section at 6.02 m/s. The crash simulation analysis in various crash scenarios (such as concrete ground, soft soil grounds and water) were further conducted based on the validated model of fuselage section, and the crash response characteristics (deformation and failure mode, acceleration response and occupant injury risk, energy-absorbing characteristics) were analyzed and compared. The results show that the finite element model can accurately simulate the unrolling failure mode (three plastic hinges failure mode) of fuselage section and the failure of the connections of cargo floor crossbeams and fuselage frames, and it is in good agreement with the test results in terms of impact velocity and acceleration response. In the case of various soft soil grounds impact scenarios, the partial impact energy is absorbed by the soft soil ground, resulting in slightly different failure modes of fuselage section and a reduction in the peak acceleration. The water-entry impact failure mode of fuselage section is consistent with the rigid ground impact failure mode, the overall deformation degree of fuselage section decreases, but the degree of bending and upturning of fuselage frames increases with the increasing of the water-entry impact velocities The safety of occupants can be effectively protected in the soft soil ground and water-entry impact scenarios. The unrolling failure mode of fuselage section can be changed to the flattening failure mode (multiple plastic hinges failure mode) through the reasonable design to avoid the rupture of cargo floor crossbeams, and the more crash energy can be absorbed due to the production of more plastic hinges for the flattening failure mode, and the crashworthiness of fuselage section can be significantly improved.

Optimization Study of Fire Prevention Structure of Electric Vehicle Based on Bottom Crash Protection

As the market share of electric vehicles continues to expand, fire accidents due to impacts from the power battery located at the bottom of the electric vehicles are receiving increasing attention. Lithium-ion batteries, as the mainstream choice of power battery for electric vehicles solving the problem that they are prone to thermal runaway due to damage when impacted, are the key to preventing and controlling fire accidents in electric vehicles. To address the protective problem of the bottom power battery of electric vehicles when it is impacted by road debris, two new types of sandwich structures with an enhanced regular hexagonal structure and semicircular arch structure as the core layer, respectively, are innovatively proposed in this article. They are used to protect the bottom power battery of electric vehicles and are compared with the traditional homogeneous protective structure in terms of protective performance. A local finite element simulation (FEM) of an electric vehicle containing the necessary components was established for simulation. Stress distribution, deformation, and energy absorption data for each component of an electric vehicle assembled with a protective structure when subjected to a bottom impact were obtained safely and cost-effectively. Three evaluation coefficients, namely, the cell shape variable (Bcmax), the protective effect parameter (ƒPE), and the total energy absorption of the structure (Ea), are proposed to compare and analyze the simulation results of different protective structures under equal mass conditions. The maximum values of the battery deformation of arched sandwich construction and reinforced honeycomb sandwich construction were 0.35 mm and 0.40 mm, respectively, which are much smaller than that of the maximum deformation of the battery under the protection of a homogeneous protective structure, which is 0.62 mm. Their protective effect parameters are 43.55 and 35.48, respectively, which proves that the optimization degree of the protective structure of the bottom of the electric vehicle after the application of the new structure is 35% or more. The total energy absorptions of the two structures are 91.77 J and 87.19 J, respectively, accounting for more than 70% of the kinetic energy in the system, which proves that the deformation of the sandwich structure can effectively absorb the kinetic energy of the collision between the road obstacle and the bottom of the car. The final results show that the arched sandwich structure showed the best impact resistance in the simulation, which can be used for the power battery’s protective structure on the electric vehicle’s bottom. This study fills a gap in local finite element modeling in electric vehicle crash simulations and provides ideas for fire prevention designs of electric vehicle structures.

Simulation of Automobile Structural Member Deformation and Crash via Isogeometric Analysis

We conducted an isogeometric analysis (IGA) to evaluate the performance of automobile structural member deformation and crash. In automobile crash analysis, ensuring the accuracy of the acceleration, velocity, and load in time series, as well as the structural deformation behavior, is important. To maintain the aforementioned consistency, accurately reproducing the bending and buckling of structural members is indispensable. In this study, we firstly computed the bending and buckling of structural members using IGA and validated its performance by comparing the results with those of a conventional finite element analysis and experiments. In addition, we utilized IGA for the crash analysis of an automobile body.

The importance of first-principles tools for safety enhancement in the design of passenger ships in the case of flooding events

The design of a passenger ship is a complex process covering multiple aspects of naval architecture and marine engineering to address performance, functionality safety, and cost as primary objectives. Between them, safety is a key element focusing on the people on board. In this sense, ship safety in the case of flooding events needs proper estimation from the first stages of the design process employing an appropriate metric. To this end, safety can be evaluated as a risk by calculating the Potential Loss of Life. Thanks to a multi-level framework developed during project FLARE, it is possible to calculate the risk associated with an accident, increasing the level of reliability as the design process advances. The framework aims at employing first-principles tools from the early stages of the design process, abandoning static calculations and empirical formulae as soon as data is available to set up advanced calculation techniques. Then, the framework adopts rigid-body time-domain calculations for the flooding simulations, advanced evacuation analysis tools, and direct crash simulation to evaluate collision damages. The process allows for testing alternative design solutions for the ship to enhance safety. Investigating risk control options is also possible, considering active or passive systems such as fixed foam installations, deployable barriers, or crashworthiness. Such an approach allows for evaluating safer solutions, respecting other design constraints and cost-related aspects. The present work describes the risk assessment framework for the case of flooding events, together with the different levels of accuracy that can be achieved, showing the improvements that could be reached by employing alternative risk control options.

Applicability of the Madymo Pedestrian Model for forensic fall analysis

Forensic reconstruction and scenario evaluation are crucial in investigations of suspicious deaths related to falls from a height. In such cases, distinguishing between accidental falls, being pushed or jumping is an important but difficult task, since objective methods to do so are currently lacking. This paper explores the possibility of repurposing a passive rigid body model of a human from commercially available crash simulation software for forensic reconstruction and scenario evaluation of humans dropping from heights. To use this approach, a prerequisite is that the human body model can produce realistic movements compared to those of a real human, given similar environmental conditions. Therefore, this study assessed the validity of the commercially available Simcenter Madymo Pedestrian Model (MPM) for simulating human fall movements. Experimental kinematic and kinetic data was collected from nine participants, who dropped from a height in three different ways: passively tilting over, getting pushed, and jumping. Next, the performance of the MPM in reproducing the kinematics of the experimental falls was assessed by comparing the orientation of the body 0.3 s after platform release. The results show that the MPM currently does not consistently reproduce the experimentally recorded falling movements across multiple falling conditions and outcome measures. The MPM must therefore be adapted if to be used for forensic reconstruction and scenario evaluation, for example by implementing active movement.

MODELING AND 3D PRINTING OF TWO WHEELER CRASH GUARDS

The crash guard is a protective device installed on vehicles to minimize damage in case of accidents. It helps to protect the front or rear of the vehicle from collisions.3D printing is designing crash guards for two-wheelers, aiming to enhance safety and customization. By employing solid works software and simulations, complex geometries are optimized for impact resistance. Advanced materials with high strength-to-weight ratios are selected to ensure performance and lightweight characteristics. This delves into novel materials and ergonomic considerations for rider comfort. The optimizing crash guard structures for impact resistance but also on ensuring economic feasibility and scalability for mass production. It explores the potential for widespread adoption within the automotive industry. Additionally, it emphasizes the importance of comprehensive real-world crash simulations to validate the effectiveness of the proposed approach. By considering a holistic approach that blends advanced numerical analyses, sophisticated 3D printing methodologies, and user experience factors, the research aims to pave the way for a new era in two-wheeler crash guard design and manufacturing. Keywords: Solidworks, Ansys, Flash Forge Pro

Influence of car front-end designs on motorcyclists’ trajectory in head-on and side-on-head crashes

Motorcyclists are highly vulnerable road users, and cars are one of their primary crash opponents. This study investigates the influence of car front-end designs on motorcyclist trajectory in head-on and side-on-head crashes. The analysis is based on a dataset of 120 multi-body crash simulations conducted using MADYMO and post-processed with MATLAB. An analysis of 1412 real-world Powered Two-Wheeler (PTW) to car accidents was conducted to determine the most common crash configurations and the associated ranges of the variables, such as vehicle speeds and contact points. Three PTW styles (sport-touring, scooter, and sport) and four car front-end designs (Sport utility vehicle (SUV), Family Car/Sedan (FCR), Roadster (RDS), and Multi-purpose vehicle (MPV)) were considered.The study examined the riders’ thrown distance in both collision types. It was observed that, regardless of the collision type, the head was identified overall as the primary body region coming into contact with the opposing vehicle, followed by the chest and neck. In frontal collisions, an augmented bonnet height corresponded to an increased incidence of head contact, whereas a lower bonnet height resulted in a higher frequency of chest contact. Moreover, the thrown distance depended also on PTW speed, particularly for sport and sport-touring motorcycles. Notably, contact with the car windscreen was only observed at velocities exceeding 60 km/h, whereas impact with the bonnet leading edge occurred exclusively below this threshold. Due to the shielding effect of their PTW’s fairing, scooter riders predominantly experienced no contact with the opposing vehicle. Sport-touring motorcycles exhibited a more vertical trajectory upon ejection, leading to a greater likelihood of overturning and subsequent rearward head impact with the vehicle. In contrast, sport motorcycles tended to forward projections with a high likelihood of chest contact. In the case of lateral impacts, it was observed that vehicles with a more prominent profile, such as SUVs and MPVs, equipped with protruding bumpers, effectively restrained riders. In this case, vehicle speed did not exert a significant influence on the thrown distance. Additionally, the presence of a conspicuous fuel tank and the initial posture of the rider on the PTW played a crucial role in determining the final thrown distance. Due to their upright postures and the absence of a pronounced fuel tank, scooter dummies were thrown further than others, thus causing head contact with the windscreen.These findings highlight the importance of car front-end design and PTW fairings in mitigating riders’ injuries and provide valuable insights to vehicle manufacturers for developing tailored safety measures for riders.

Advancements in Bicycle Safety: Integrating Control Sensors and Artificial Intelligence for Enhanced Airbag Innovation

Abstract: Motorcycle safety is a critical concern in traffic systems worldwide. This paper introduces a novel approach to enhancing rider safety through the integration of airless tires and advanced airbag systems, underpinned by artificial intelligence (AI) and control sensors. Airless tires contribute to vehicle stability by eliminating the risk of sudden deflation, while AI-driven airbag systems promise dynamic protection for riders during collisions. The study begins with an analysis of airless tire technology, emphasizing its impact on motorcycle stability and safety. It then transitions to the development of motorcyclespecific airbag systems, which utilize AI to process sensor data and make real-time decisions regarding airbag deployment. The effectiveness of these systems is validated through crash simulation tests and impact force measurements, demonstrating a substantial reduction in injury severity. Challenges such as cost, user acceptance, and technical constraints are thoroughly examined. The paper concludes with a discussion on future trends, including the potential for AI to predict and prevent accidents before they occur, thereby setting a new standard for motorcycle safety.

Optimisation design of child seat based on chaos mutation MOPSO

To improve the safety of the children in child seats when a vehicle collision occurs, a finite element model of a child safety seat is established, and LS-DYNA is used for crash simulation. Select backrest inclination, headrest inclination, and seat belt centre height as design variables to establish response surface models. The application of chaotic mutation theory in particle swarm optimisation (PSO) is proposed, and the optimal solution of child seat parameters is obtained by using the chaotic mutation based grouped multi-objective particle swarm optimisation (MOPSO). The optimal solution was used to carry out the simulation experiment again, and compared with the original performance. It turned out that the Head Performance Criterion (HPC) is 47.08% better than the original child seat. Besides, the rib deformation is reduced by 21.30%, the neck shear stress is reduced by 55.74%, and the thigh stress is reduced by 48.55%, which indicate significant improvements. The results suggest that a certain parameter combination of the child seat leads to the optimal overall performance in child injury prevention, which indicates significant improvement in the damage of all parts of the child.

Effect of vehicle speed on injury of child passenger in frontal crashes

Speed is major cause of death to vehicle occupants especially children. Studying effect of speed on child injury severity is crucial to establishing safety regulations. This work investigates the effect of vehicle speed on the severity of injury sustained by three-year-old (3YO) children. Restrained 3YO child dummy Finite Element (FE) model was used to conduct crash simulation at impact speed of 40km/h, 46 km/h and 48 km/h in Ford Taurus FE model using LS DYNA code. Vehicle deceleration was found to increase with increase in speed. Head Injury Criteria (HIC36), HIC15, chest acceleration (CA), chest severity index (CSI), chest deflection (CD) and neck moment (NM) were evaluated and compared with National Highway Traffic Safety Administration (NHTSA) threshold. It was found that the injury parameters sustained by 3YO child increased with increase in speed. HIC36 was found to be above threshold for 48km/h and 46km/h. Speed of 40 km/h had all the injury values below the threshold. Chest deflection was lower than the threshold for all the three speeds. Chest acceleration and neck moment were also presented and their values also increase with speed, though, NHTSA doesn’t capture their threshold. The study disseminates information on the effect of speeding on child injuries in frontal crashes for road safety agents and vehicle designers and users. Limiting vehicle speed is therefore crucial to child occupant protection.