Federal Motor Vehicle Safety Research Articles

Correlation of Road Safety Criteria with Occupant Safety Criteria in Impacts on Crash Cushions

Road restraint systems are used to protect vehicle occupants if the vehicle runs off the road and potentially collides with a dangerous obstacle. These road restraint systems must successfully pass the tests defined in EN 1317, or the Manual for Assessing Safety Hardware (MASH) before they are allowed to be installed. The safety assessment is carried out according to the criteria of ASI (Acceleration Severity Index), THIV (Theoretical Head Impact Velocity), OIV (Occupant Impact Velocity), ORA (Occupant Ridedown Acceleration), and PHD (Post-Impact Head Deceleration). Usually very old vehicles are used for these tests, and there is no assessment of occupant criteria such as HIC (Head Injury Criteria), chest deflection, etc. The objective of the study was to compare the occupant safety of vehicles that are commonly used in EN 1317 with vehicles that have improved safety equipment. Test results from two different vehicles (a commonly used vehicle in EN 1317 and a vehicle with improved safety equipment) and two different impact conditions (full overlap and an overlap of 50%) were compared. Measurement data from a Hybrid HIII 50th percentile anthropomorphic test device (ATD) (Denton ATD, INC.) was recorded during the tests to assess occupant safety. The tests have shown that vehicles with improved safety equipment perform better than vehicles that are commonly used in EN 1317-3 tests. The values for the occupant safety criteria assessed were well below the Euro NCAP (New Car Assessment Programme) or Federal Motor Vehicle Safety Standard (FMVSS) limits. However, the limits of the road safety criteria were in some cases considerably exceeded regardless of the vehicle. This has been observed in particular for the offset impact condition. THIV and OIV were supposed to be able to assess the risk of head injuries. However, these two criteria correlated negatively with the head criteria, HIC or a3ms. However, a positive correlation was found for the ASI with the HIC and the a3ms head acceleration. Even if some of the criteria for road safety correlate with the criteria for occupant safety, it is doubtful whether the criteria for road safety are suitable for assessing the risk of injury to vehicle occupants.

Numerical Dolly Rollover Evaluation Using a Damping-Harmonic System with a Low Back Booster to Reduce Injuries in a Six-Year-Old Child

This study examined injuries sustained by a six-year-old child dummy in a numerical dolly rollover crash using a Toyota Yaris 2010. A harmonic dynamic system (HDS) composed of spring, dampers, and masses with a Low Back Booster (LBB) is denominated as HDS-LBB model. The HDS-LBB was designed to allow damping movements along three Cartesian axes (X, Y, Z) to reduce the energy transferred to the child by a motor vehicle accident and avoid a high injury risk. The HDS-LBB incorporates springs into the vertical axis to decrease the vertical movement during the rollover. The numerical analysis was conducted using LS-Dyna® R12.1 version during an interval of 1 s, and the boundary conditions were set by the Federal Motor Vehicle Safety Standard (FMVSS) 213 for child restraint recommendations and the FMVSS 208 for a dolly rollover procedure. Data on head and thorax decelerations, neck flexion-extension, and thoracic deflection were acquired at a rate of 1 ms. The injury values obtained by the HDS-LBB were compared with the injury values by another configuration denominated LBB-ISOFIX to assess the effectiveness of the model proposed. The results show a higher peak injury value in the neck and thorax because of seatbelt displacement across the child’s shoulder. Nevertheless, despite this seatbelt behavior, the injuries sustained remained below the Injury Assessment Reference Values (IARVS).

Flame Retardant Exposure in Vehicles Is Influenced by Use in Seat Foam and Temperature.

Flame retardants (FRs) are added to vehicles to meet flammability standards, such as US Federal Motor Vehicle Safety Standard FMVSS 302. However, an understanding of which FRs are being used, sources in the vehicle, and implications for human exposure is lacking. US participants (n = 101) owning a vehicle of model year 2015 or newer hung a silicone passive sampler on their rearview mirror for 7 days. Fifty-one of 101 participants collected a foam sample from a vehicle seat. Organophosphate esters (OPEs) were the most frequently detected FR class in the passive samplers. Among these, tris(1-chloro-isopropyl) phosphate (TCIPP) had a 99% detection frequency and was measured at levels ranging from 0.2 to 11,600 ng/g of sampler. TCIPP was also the dominant FR detected in the vehicle seat foam. Sampler FR concentrations were significantly correlated with average ambient temperature and were 2-5 times higher in the summer compared to winter. The presence of TCIPP in foam resulted in ∼4 times higher median air sampler concentrations in winter and ∼9 times higher in summer. These results suggest that FRs used in vehicle interiors, such as in seat foam, are a source of OPE exposure, which is increased in warmer temperatures.

Design of Multi-module LED Headlamp of Vehicle Under Federal Motor Vehicle Safety Standard

Design of Multi-module LED Headlamp of Vehicle Under Federal Motor Vehicle Safety Standard

Frontal-oblique impact sled tests of a rearward-facing child restraint system with and without a support leg

ObjectiveTo quantify the head and neck injury metrics of an anthropometric test device (ATD) in a rearward-facing child restraint system (CRS), with and without a support leg, in frontal-oblique impacts. MethodsSled tests using the Federal Motor Vehicle Safety Standards (FMVSS) 213 frontal crash pulse (48 km/h, 23 g) were performed with a simulated Consumer Reports test buck, which comprised a test bench that mimics the rear outboard vehicle seat of a sport utility vehicle (SUV). The test bench was rigidised to increase durability for repeated testing and the seat springs and cushion were replaced every five tests. A force plate was mounted to the floor of the test buck directly in front of the test bench to measure support leg peak reaction force. The test buck was rotated 30° and 60° relative to the longitudinal axis of the sled deck to represent frontal-oblique impacts. The door surrogate from the FMVSS 213a side impact test was rigidly attached to the sled deck adjacent to the test bench. The 18-month-old Q-Series (Q1.5) ATD was seated in a rearward-facing infant CRS, which was attached to the test bench with either rigid lower anchors or a three-point seatbelt. The rearward-facing infant CRS was tested with and without a support leg. Conductive foil was attached to the upper edge of the door panel and a strip of conductive foil was attached to the top of the ATD head so that a voltage signal quantified contact with the door panel. A new CRS was used for each test. A repeat test was performed for each condition for a total of 16 tests. Data sourcesResultant linear head acceleration 3 ms clip; head injury criterion 15 ms (HIC15); peak neck tensile force; peak neck flexion moment; potential difference between the ATD head and the door panel; support leg peak reaction force. ResultsThe presence of a support leg significantly reduced head injury metrics (p < 0.001) and peak neck tensile force (p = 0.004) compared to tests without a support leg. Rigid lower anchors were associated with significant reductions in head injury metrics and peak neck flexion moment (p < 0.001) compared to tests that attached the CRS with the seatbelt. The 60° frontal-oblique tests had significantly elevated head injury metrics (p < 0.01) compared to the 30° frontal-oblique tests. No ATD head contact with the door was observed for 30° frontal-oblique tests. The ATD head contacted the door panel in the 60° frontal-oblique tests when the CRS was tested without the support leg. Average support leg peak reaction forces ranged from 2167 to 4160 N. The 30° frontal-oblique sled tests had significantly higher support leg peak reaction forces (p < 0.001) compared to the 60° frontal-oblique sled tests. ConclusionsThe findings of the current study add to the growing body of evidence regarding the protective benefits of CRS models with a support leg and rigid lower anchors.

Crashworthiness Performance of Rear Underrun Protection Device under Simulated Car Collision

&lt;div&gt;A rear underrun protection device (RUPD) plays a fundamental role in reducing the risk of running a small car beneath the rear or the side of a heavy truck because of the difference in structure heights in the event of a vehicle collision. Even in cars with five-star safety ratings, crashing into a truck with poorly designed RUPD results in a passenger compartment intrusion (PCI) more than the maximum allowable limit as per the United States (US) American National Highway Traffic Safety Administration (NHTSA) standards Federal Motor Vehicle Safety Standard (FMVSS). In this article, mild steel was used to fabricate the new designs of RUPD. The design was analyzed using finite element (FE) analysis LS-DYNA software. Simulations of a Toyota Yaris 2010 and Ford Taurus 2001 were performed at a constant speed of 63 km/h at the time of impact. The ability to prevent severe injuries in a collision with the rear side of the truck was estimated to optimize the underrun design. The new design has achieved the goal of decreasing the head acceleration beyond the limit, which is less than 60 g. It has achieved a reduction in acceleration by 66.116% and zero PCIs even in collisions with different safety ratings cars.&lt;/div&gt;

Increasing seat belt use in the United States by promoting and requiring more effective seat belt reminder systems

Objective Federal Motor Vehicle Safety Standard (FMVSS) 208 requires every passenger vehicle to provide an auditory signal lasting 4 to 8 seconds and a visual display lasting 60 seconds when the driver is unbelted at ignition. This requirement does not increase seat belt use. This paper summarizes the latest research on using vehicle technology to increase seat belt use and existing safety standards worldwide to support the strengthening of FMVSS 208. Method Studies of seat belt reminders and interlocks published in peer-reviewed journals, conference proceedings, or as technical reports were identified in online databases and reviewed along with current requirements worldwide. Results from past research were used to estimate the front- and rear-seat daytime belt use rate and the annual number of lives that could be saved by a persistent audible reminder at each seating position. Results Most motor vehicle occupants routinely buckle up. Those that do not typically forget, are going a short distance, or find belts uncomfortable. Seat belt reminders can remind or motivate occupants to buckle up. Enhanced reminders that exceed FMVSS 208 increase belt use by 6 percentage points. Reminders also can increase rear belt use, and although required throughout the world, are not required by FMVSS 208. More persistent reminders, like those required around the world, with a continuous, long-lasting audible signal increase belt use by 30% among drivers who do not routinely buckle up. If every vehicle in the U.S. had such a reminder at each seating position, then it was estimated that the daytime belt use rate in the U.S. would increase about 3 percentage points from 90.3% to 93.2% in the front row and by about 6 percentage points from 80% to 85.9% in the rear row. It was estimated that the increase in belt use from a continuous, long-lasting audible reminder could potentially save about 1,600 lives each year. Seat belt interlocks can increase belt use, but acceptance is a stumbling block. Public outcry ensued after interlocks were required in 1973, and public sentiment remains negative. Opinions toward front and rear reminders are more favorable. Furthermore, past research suggests interlocks may be no more effective for increasing seat belt use than persistent audible reminders. The effect of interlocks on rear belt use have not been explored. Conclusion Persistent seat belt reminder systems that last at least 90 seconds can potentially save hundreds of U.S. motorists each year. Robust empirical evidence, successful exemplars from organizations throughout the world, and a clear public health benefit exists for strengthening FMVSS 208 to require more persistent audible reminders at every seating position.

Design of a Secure Automated Driving Systems Test Data Interface

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;Vehicles equipped with Level 4 and 5 autonomy will need to be tested according to regulatory standards (or future revisions thereof) that vehicles with lower levels of autonomy are currently subject to. Today, dynamic Federal Motor Vehicle Safety Standards (FMVSS) tests are performed with human drivers and driving robots controlling the test vehicle’s steering wheel, throttle pedal, and brake pedal. However, many Level 4 and 5 vehicles will lack these traditional driver controls, so it will be impossible to control these vehicles using human drivers or traditional driving robots. Therefore, there is a need for an electronic interface that will allow engineers to send dynamic steering, speed, and brake commands to a vehicle. This paper describes the design and implementation of a market-ready Automated Driving Systems (ADS) Test Data Interface (TDI), a secure electronic control interface which aims to solve the challenges outlined above. The interface consists of a communication port integrated into automobiles which lack traditional manual controls. Via this interface dynamic test scenarios can be executed by plugging in a Vehicle Control Unit (VCU), which is an element of the TDI hardware/firmware intended to be available only to authorized users. Physically, the VCU can interface with the On-board Diagnostics (OBD) OBD-II connector that is present on essentially all modern automobiles. This paper also describes a demonstration of the complete VCU with the secure TDI using a vehicle equipped with a Dataspeed drive-by-wire kit, with its steering, throttle, and brake control systems mimicking the behavior of an autonomous subject vehicle.&lt;/div&gt;&lt;/div&gt;

Low-speed finite element frontal impact analysis on aluminum alloy bumper made of 6063-T6

In this research, a low-speed impact numerical simulation has been performed on a 6063-T6 Aluminum alloy bumper welded by MIEA technique using ANSYS® LS-DYNA® Workbench™ 19.2, according to the requirements of the Federal Motor Vehicle Safety Standards and Regulations. For the numerical simulation, mechanical properties were obtained from quasi-static tensile tests in 6063-T6 aluminum alloy joints, these joints were manufactured using the MIEA (modified indirect electric arc) technique and a MIG welding process and post-weld heat treatment (PWHT). For the numerical impact simulation, the following parameters have been used: mass of the impactor of 1000 kg, speed of the impactor 4 km/hr and material of the impactor AISI 4130 steel. The simulation study showed that aluminum alloy joints used in bumper beam has excellent mechanical strength under low-speed impact conditions. Among the mechanical properties that have been recovered due to PWHT are the following: it was possible to harden the fusion zone, that is, there was an increase in hardness values from 80 HV0.1 to 98 HV0.1, the heat affected zone was eliminated, obtaining hardness values of approximately 110 HV0.1, a recovery in yield strength (59%) was observed, that is, in welding condition (170 MPa) and welding condition plus PWHT (270 MPa). In terms of tensile strength, a recovery (42%) was observed, going from welding condition (214 MPa) and welding condition plus PWHT (304 MPa). Tensile strength also had an increase ranging from 214 MPa to 304 MPa. This represents an increase of 42 pct. Finally, the simulation showed that the welding zone on the bumper has very good resistance to low speed impact since no permanent deformations were observed, that is, after the impact the bumper returns to its initial position.

Use of the FMVSS-214 static bending test to evaluate an automobile side door impact beam made of glass fiber-reinforced plastic

A side door impact beam absorbs energy and plays an important role in preventing intrusion of another vehicle into the occupant area. Impact beams are being actively researched to reduce vehicle weight while still meeting the strength requirements of environmental regulations and to improve fuel efficiency and enhance safety. No study has subjected a lightweight glass fiber-reinforced plastic (GFRP) impact beam to the Body in White (BIW) Federal Motor Vehicle Safety Standard (FMVSS)-214 quasi-static test. We compared three beams that differed in shape and stacking pattern. We performed three-point bending analyses, bending tests (including after bracket tightening), and static bending tests of door assemblies. The best GFRP beam (B) and a steel model were compared in terms of BIW static bending performance. The front-door GFRP beam exhibited an average reaction force 135% of that mandated by the FMVSS-214S test specification, an intermediate average reaction force 158% of that required, and a final force 154% of that required. In terms of bending performance, the initial average reaction force was 9.5% higher than that of the steel impact beam, and the rear door force was 6.6% lower. The reaction force of the GFRP beam decreased rapidly as breakage occurred after bending through 110.0–120.0 mm; however, the average reaction force was similar to that of the steel beam. Thus, the GFRP impact beam met the legal requirements but weighed 30% less than the steel beam.

Crash behaviour of unidirectional oil palm empty fruit bunch fibre-reinforced polypropylene composite car bumper fascias using finite element analysis

The number of road accidents has increased annually over the last 20 years, and this is a matter of considerable concern. Automobile safety systems must therefore be carefully evaluated to ensure they are able to serve their purpose in protecting passengers. One of these safety systems is the car bumper system. The bumper system plays a vital role, especially in protection against frontal impact. In this study, using finite element analysis employing LS-DYNA software, we analyse the crash behaviour of bumper fascias made of unidirectional oil palm empty fruit bunch (OPEFB) fibre-reinforced polypropylene (PP) composites. The incorporation of OPEFB fibres into the bumper part stems from the growth of environmental concerns and is in line with national sustainable development goals. In this analysis, the composite bumper was subjected to a frontal low impact speed of 4 km h−1 in accordance with Part 581 of the Federal Motor Vehicle Safety Standard regulations enforced by the National Highway Traffic Safety Administration for low-velocity impacts. Comparative study was made with existing bumper materials, namely steel, aluminium alloy and PP. The effect of fibre orientation and fibre content of the composite on the crash performance of the bumper was also investigated. The fibre orientation was varied between vertical, 45° and horizontal directions while fibre content varied between 25%, 35%, 45% and 55%. Our results show that the composite bumper fascia has comparable specific energy absorption to existing bumper materials. An increase in the fibre content of the composite results in an increase in the energy absorption ability, while fibre orientation made no significant difference to the impact performance.

Response Corridors for Blunt Impacts to the Back

Corridors for the biofidelity of blunt impact to the back are important for sled and crash testing with Anthropomorphic Test Devices (ATDs). The Hybrid III is used in rear sled tests as part of Federal Motor Vehicle Safety Standards (FMVSS) 202a. The only corridor for biofidelity is the neck extension. Eight Post Mortem Human Subjects (PMHS) were subjected to 20 blunt impacts with a 15.2 cm (6 in.) diameter pendulum weighing 23.4 kg. The impact was below T1 at 4.5 m/s and 6.7 m/s and below T6 at 4.5 m/s centered on the back. Head, neck, and chest responses were reported in 2001 [8]. In this study, the responses were scaled to the 50th male Hybrid III, and corridors were determined defining biofidelity for blunt impacts to the back. The scaled data gives an average peak force of 3.44 kN ± 0.74 kN at T1 and 4.5 m/s, 5.08 kN ± 1.35 kN at T1 and 6.7 ms, and 3.4 kN ± 1.2 kN at T6 and 4.5 m/s. The corresponding scaled deflection was 44.0 ± 19.7 mm, 60.2 ± 21.2 mm, and 53.1 ± 16.5 mm. The average stiffness of the back was 1.21 kN/cm at T1 and 4.5 m/s, 1.17 kN/cm at T1 and 6.7 m/s, and 1.14 kN/cm at T6 and 4.5 m/s. The corridors help to define biofidelity and can be used to assess the performance of the Hybrid III, Biofidelic Rear Impact Dummy (BioRID) II, and other ATDs.

Aluminum foam to improve crash safety performance: a numerical simulation approach for the automotive industry

Aluminum foams have recently received special attention due to their peculiar mechanical properties. For example, their energy absorption capacity in crash events and low density are very desirable characteristics for several applications. Actually, the energy absorption of aluminum foams is even magnified when they interact with aluminum tubes or when tubes are filled with aluminum foams. Since the automotive industry constantly demands light materials with high strain energy absorption capacity to reduce fuel consumption and fulfill safety requirements, aluminum foams are an excellent alternative to satisfy such demands. This work shows, by numerical simulations of reduced and full vehicle models, the usefulness of aluminum foams incorporated in a car structure when subjected to “35 mph Frontal Barrier Impact Test”, according to the Federal Motor Vehicle Safety Standard No 208 (FMVSS). Foam was used to dramatically improve load capacity and crush displacement. Thus, dash panel intrusions and acceleration gradient were reduced, increasing the vehicle safety performance. Finally, it is shown that foams can be beneficial in electric vehicle development by increasing load capacity.

Immune particle swarm optimization of SUV rollover crashworthiness and weight

When designing a sport utility vehicle (SUV), designers strive to improve the vehicle’s rollover crashworthiness while avoiding a significant increase in its weight. To aid in optimizing such a trade-off, this paper proposes a multi-disciplinary and multi-objective hybrid optimization algorithm that combines particle swarm optimization and the artificial immune method. First, the SUV structure’s influence on body mass and rollover crashworthiness is studied using contribution analysis, and structural improvements are discussed according to Federal Motor Vehicle Safety Standard 216. Building on the analysis results, the SUV’s rollover crashworthiness and weight optimization model are proposed. Radial basis function neural network and a genetic algorithm are used to build and optimize surrogate models of total weight, maximum contact force, and torsion frequency. The proposed algorithm then utilizes particle swarm and artificial immune to seek Pareto solutions that optimize SUV structure. Finally, the technique for order preference by similarity to ideal solution method determines a final solution from Pareto-optimal solutions. Compared to previous studies, the results show that the proposed hybrid optimization algorithm improves the Pareto solution sets’ diversity and distribution uniformity, enhances SUV rollover crashworthiness, and reduces SUV structure components’ weight.

Enhancing the properties of nylon 66 fabric coated with a combination of PVA and SiO2 nanoparticles composite for vehicle airbag application

Due to increase in fabric thickness and decrease compactness in packing, film bonding is unfavorable for airbag fabrics, furthermore, the uncoated fabric fabricated with a high density but it still has hot gas leakage problems. This study focuses on enhancement of vehicle airbag nylon 66 fabric properties by using a combination of different concentration of silica nanoparticles (SiO2 NPs) and low-density adhesion polyvinyl alcohol (PVA). The results illustrated that the nylon 66 fabric, which coated with PVA and SiO2 NPs presents an excellent property such as a thin layer reached at (0.009 mm), also thermal and mechanical properties have been enhanced to include better mechanical properties according to commercial guidelines airbag of Federal Motor Vehicle Safety Standards (FMVSS). Additionally, the weight per square meter of nylon 66 fabric coated with the PVA and high concentration of SiO2 NPs is 9.9 grams. Besides, the final dry weight of the coating (PVA/SiO2) material taken by the nylon 66 fabric is just 0.4 grams per square meter. The coated fabric demonstrated a hydrophobicity property in addition to the air-permeability has decreased by increasing the amount of SiO2 NPs in the composite material. The PVA and SiO2 NPs dispersed on the surface of the fabrics without any aggregation, as well, the coated fabric is gradually changed from flexible to hard which resulted in the better final performance in the proper and regular thickness along the whole fabric.

Enhanced Robust Design Optimization in Seat Belt Anchorage Strength for Front Crash Safety of Multi-Purpose Vehicle

This paper deals with an enhanced robust design optimization (RDO) method and its application to the strength design problem of seat belt anchorage, related to the front crash safety of multi-purpose vehicles. In order to determine the rational design safety of the newly developed automotive part, such as the seat, in which the reliability of the evaluation data is not sufficient at the design stage, it is necessary to implement a probabilistic design considering uncertainties. Thickness size variables of the seat frame structure’s members were considered random design variables, including uncertainties such as manufacturing tolerance, which are an inevitable hazard in the design of automotive parts. Probabilistic constraints were selected from the strength performances of the seat belt anchorage test, which are regulated in Economic Commission for Europe (ECE) and Federal Motor Vehicle Safety Standard (FMVSS), and the strength performances were evaluated by finite element analyses. The RDO problem was formulated such that the random design variables were determined by minimizing the seat frame weight subject to the probabilistic strength performance constraints evaluated from the reliability analyses. Three sigma level quality was considered for robustness in side constraints. The mean value reliability method (MVRM) and adaptive importance sampling method (AISM) were used for the reliability analyses in the RDO, and reliability probabilities from the MVRM and the AISM on the probabilistic optimum design were assessed by Monte Carlo simulation (MCS). The RDO results according to the reliability analysis methods were compared to determine the optimum design results. In the case of the RDO with the AISM, the structure reliability was fully satisfied for all the constraint functions, so the most reliable structural safety was guaranteed for the seat frame design.

Three-dimensional Numerical Model of Free Motion Headform Used in Impact Tests on Vehicle Interior

FMVSS (Federal Motor Vehicle Safety Standard) 201, Standard on Occupant Protection in Interior Impact, requires that the FMH (Free Motion Headform) impact tests result in HIC(d) less than 1000. Especially in the early stage of a vehicle development it is very difficult to conduct the impact tests, so it is necessary to develop a numerical model by which HIC(d) can be predicted. A finite element model for both the FMH and a vehicle can be a good solution, but it needs quite some time and effort to develop such a model. A two-dimensional simple numerical model was developed to predict HIC(d) in the impact tests, but the model does not take into account the impacts where the FMH translates and rotates in three directions. Thus, in this study a new numerical model based on three-dimensional governing equations for the FMH impacting against the interior trim was developed and successfully applied to simulations of the impact tests.

Numerical investigation of occupant injury risks in car-to-end terminal crashes using dummy-based injury criteria and vehicle-based crash severity metrics

Guardrails were designed to deter vehicle access to off-road areas and consequently prevent hitting rigid fixed objects alongside the road (e.g. trees, utility poles, traffic barriers, etc.). However, guardrails cause 10 % of deaths in vehicle-to-fixed-object crashes, which recently attracted attention in the highway safety community on the vehicle-based injury criteria used in regulations. The objectives of this study were to investigate both full-body and body-region driver injury probabilities using finite element (FE) simulations, to quantify the influence of pre-impact conditions on injury probabilities, and to analyze the relationship between the vehicle-based crash severity metrics currently used in regulations and the injury probabilities assessed using dummy-based injury criteria.A total of 20 FE impact simulations between a car (Toyota Yaris) with a Hybrid III M50 dummy model in the driver seat and an end terminal model (ET-Plus) were performed in various configurations (e.g. pre-impact velocities, offsets, and angles). The driver’s risk of serious injuries (AIS 3+) was estimated based on kinematic and kinetic responses of the dummy during the crashes. A non-linear regression approach was used to compare the injury probabilities assessed in this study to the vehicle-based crash severity metrics used in the testing regulations. In particular, the US Manual for Assessing Safety Hardware (MASH) guideline and European procedures (EN1317) were used for the study.All the recorded dummy-based injury criteria values pass the Federal Motor Vehicle Safety Standard (FMVSS) 208 limits which indicated a low driver risk of serious injury. Overall, the pre-impact vehicle velocity showed to have the highest influence in almost all injury probabilities (59 %, 79 %, 62 %, and 44 % in full-body, head, neck, and chest injuries, respectively). The offset between vehicle midline and the guardrail barrier was the most important variable for thigh injuries (56 %). The assessed injury probabilities were compared to vehicle-based severity metrics. The full-body and chest injuries showed the highest correlation with Occupant Impact Velocity (OIV), Acceleration Severity Index (ASI), and Theoretical Head Impact Velocity (THIV) (R2 > 0.6). Lower correlations of thigh injuries were recorded to OIV (R2 = 0.59) and THIV (R2 = 0.46). Meanwhile, weak correlations were observed between all the other regressions which indicated that no vehicle-based criteria could be used to predict head and neck injuries.Car-to-end terminal crash FE simulations involving a dummy model were performed for the first time in this study. The results pointed out the limitations of the standard vehicle-based injury methods in terms of head and neck injury prediction. The dummy-based injury assessment methodology presented in this study could supplement the crash tests for various impact conditions. In addition, the models could be used to design new advanced guardrail end terminals.

Analysing Flammability Characteristics of Green Biocomposites: An Overview

Stringent fire safety regulations have limited the use of green biocomposites in practical applications due to vulnerability of their constituents to heat and fire. To counter this weakness, several flame-retardant treatments and techniques have been introduced, such as halogenated and non-halogenated flame-retardants, nano fillers, layered silicates, copolymerization, grafting, and synergistic use of natural fibre and fire retardant. While the physical and chemical treatment of green biocomposites has improved their heat resistance to some extent, these materials still fail to comply with strict fire safety regulations such as the Federal Motor Vehicle Safety Standard No. 302 (FMVSS 302) and the code of Federal Aviation Regulation 25.853 applicable in the automotive and aerospace industry, respectively. Therefore, an in-depth study of thermal decomposition and fire behaviour of green biocomposites is inevitable to improve flame retardancy techniques, to discover flame-retardants that are more suitable and environment friendly, and to select appropriate natural fibres and biopolymers to develop fire safe biocomposite products. This article analyses the research done in the last decades for improving the thermal behaviour and fire resistance of green materials as well as the efficient synergistic techniques and fire retardant treatments to counter this vulnerability.

Increasing evacuation flow through school bus emergency roof hatches

Emergency escape roof hatches are used to evacuate school buses in rolled-over orientations. In the United States, the minimum opening size of a roof hatch is defined by Federal Motor Vehicle Safety Standard (FMVSS) no. 217. With the prevalence of rising obesity rates among children, the minimum roof hatch opening size may not be large enough to accommodate larger passengers. Post-accident conditions such as injuries, disorientation, and exit obstructions may also prevent unobstructed passage for egress within acceptable time limits. The purpose of this study was to redesign and fabricate a roof hatch with a larger opening and evaluate its egress characteristics for a range of typical school bus passengers. The larger roof hatch opening allows greater evacuation flow rates, and is almost functionally equivalent to the evacuation flow rate of the front door on an upright school bus.