Crash Impact Research Articles

Study on the Numerical Analysis of Crash Impact Test for External Auxiliary Fuel Tank based on ALE

Study on the Numerical Analysis of Crash Impact Test for External Auxiliary Fuel Tank based on ALE

The vehicle frontal impact safety evaluation and design method based on the coupling effect between crash pulse and restraint system characteristic

This paper presents a new method to evaluate the design stiffness of vehicle structure and restraint system from the perspective of coupling effect, at the preliminary stage of safety design. The fast iteration algorithm is established to calculate occupant response database. Subsequently, the expressions about three indexes are derived to evaluate the crash pulse, the restraint system and the coupling effect between them. Based on the data from National Highway Traffic Safety Administration (NHTSA) frontal crash impact tests, the star-estimate map is established to estimate the star rating and design stiffness. Finally, a safety design example of M6 model is optimised to verify the validity of the proposed method, and the relative risk score (RRS) of design solution decreases by 43.6%. The proposed method can be used in the phase of conceptual design, greatly reduce the calculation amount of CAE analysis and shorten the product development cycle.

The vehicle frontal impact safety evaluation and design method based on the coupling effect between crash pulse and restraint system characteristic

This paper presents a new method to evaluate the design stiffness of vehicle structure and restraint system from the perspective of coupling effect, at the preliminary stage of safety design. The fast iteration algorithm is established to calculate occupant response database. Subsequently, the expressions about three indexes are derived to evaluate the crash pulse, the restraint system and the coupling effect between them. Based on the data from National Highway Traffic Safety Administration (NHTSA) frontal crash impact tests, the star-estimate map is established to estimate the star rating and design stiffness. Finally, a safety design example of M6 model is optimised to verify the validity of the proposed method, and the relative risk score (RRS) of design solution decreases by 43.6%. The proposed method can be used in the phase of conceptual design, greatly reduce the calculation amount of CAE analysis and shorten the product development cycle.

Crash reconstruction technique for cable barrier systems

ABSTRACTCable barrier systems consisting of steel cables mounted on widely spaced weak posts are one of the most commonly used guardrail systems to protect errant vehicles from roadside hazards. When a vehicle impacts cable barriers, the cables are stretched, producing tension forces that safely redirect the impacting vehicle. The estimation of the energy absorbed during a vehicle barrier crash can aid in accident reconstructions, as it relates to estimation of the initial impact velocity, crash severity, and other accident features such as the occupant injuries during the accident. This article details an accident reconstruction technique developed for estimating the energy absorbed during a cable barrier impact. This absorbed energy comprises several components: (1) plastic deformation and rotation of posts in soil or a rigid foundation, (2) tire-ground interaction, (3) internal cable energy, and (4) frictional losses during vehicle-barrier interaction. Charts were developed to estimate the energy absorbed by deforming S3 × 5.7 posts. Three full-scale crash tests, conducted on straight and curved, three-cable barrier systems were used to validate the proposed methods. For both systems, the vehicles' estimated initial velocities using the reconstruction technique were within 1% and 10% of the actual velocities of the vehicle, respectively.

Analysis of Crash Impact of Composites Stay-shaped Bumper using FEM Method

Analysis of Crash Impact of Composites Stay-shaped Bumper using FEM Method

Occupant thorax response variations due to arm position and restraint systems in side impact crash scenarios

Recent epidemiological studies have identified that thoracic side airbags may vary in efficacy to reduce injury severity in side impact crash scenarios, while previous experimental and epidemiological studies have presented contrasting results. This study aimed to quantify the variations in occupant response in side impact conditions using a human body computational model integrated with a full vehicle model. The model was analyzed for a Moving Deformable Barrier side impact at 61km/h to assess two pre-crash arm positions, the incorporation of a seatbelt, and a thorax air bag on thorax response. The occupant response was evaluated using chest compression, the viscous criterion and thoracic spinal curvature. The arm position accounted for largest changes in the thorax response (106%) compared to the presence of the airbag and seatbelt systems (75%). It was also noted that the results were dependant on the method and location of thorax response measurement and this should be investigated further. Assessment using lateral displacement of the thoracic spine correlated positively with chest compression and Viscous Criterion, with the benefit of evaluating whole thorax response and provides a useful metric to compare occupant response for different side impact safety systems. The thoracic side airbag was found to increase the chest compression for the driving arm position (+70%), and reduced the injury metrics for the vertical arm position (−17%). This study demonstrated the importance of occupant arm position on variability in thoracic response, and provides insight for future design and optimization of side impact safety systems.

Vulnerability Analysis of Pipelines and Equipment of the Existing NPP Power Units with VVER-1000 under Vibrations Caused by the Aircraft Crash

Low-frequency dynamic loads from earthquakes were taken into account in the design of the equipment and pipelines of the existing nuclear power plants. Therefore, in the case of an aircraft crash impact on a nuclear reactor containment, exciting intense high-frequency vibrations of the building, the reliability of the nuclear power plant cannot be guaranteed without the failure risk assessment of objects that are involved in the safe shutdown.
 The paper suggests a method of the failure risk assessment using the concept of the ultimate resistance of pipelines and equipment of nuclear power plants to vibrations typical for the “aircraft crash” emergency design situation. The ultimate resistance is defined by the value of the load impulse, the application of which results in the probability of failure of the considered pipeline or equipment of 0.01 taking into account that it performs functions to provide 0.50 safety.

Comparing Occupant Injury in Vehicles Equipped with and without Frontal Airbag

Most vehicle structures have been designed to withstand crash impact during an accident. The front area of the vehicle will crumple to absorb crash energy while the passenger compartment remains intact to protect the occupant inside. In addition, restraint system inclusive of airbag and seatbelts has been integrated in vehicles to further enhance the occupant's protection. However, in certain cases, the airbag is removed due to cost saving by car manufacturers. Although the frontal airbags have been removed, the structure remains the same. This can be observed from the crash tests conducted by ASEAN NCAP on two variants of the same car model which are fitted with and without airbags, where the cars obtained two different rating. This case study compares and presents occupant injuries for both variants.

Numerical Analysis of Crash Impact Test for External Auxiliary Fuel Tank of Rotorcraft

Numerical Analysis of Crash Impact Test for External Auxiliary Fuel Tank of Rotorcraft

Strength analysis of nuclear power plant structures in case of aircraft crash impact

In this article the results of the strength analysis of nuclear power plant structures in case of aircraft crash impact problem are presented.Finite element analysis was performed using ABAQUS CAE system. Nonlinear material models were used, such as “Concrete damaged plasticity” and “Drucker-Prager” for concrete and elastic-plastic model for steel.For the purpose of verification of the mathematical models and engineering methods used in reinforcement concrete buildings strength analysis under different loads (static and transient temperature, structural and other loads), the following computational simulations were carried out: uniaxial compression of the cylindrical concrete specimens; reinforced concrete beams analysis under the static loads;reinforced concrete slab analysis under dynamic loads; reinforced concrete slab analysis under the missile impact. Experimental data for the aforenamed verificatory tasks was found in periodicals.

Triaxial braiding 기술을 이용한 원형 튜브의 횡방향 저속충격파괴 거동분석

In comparison to metal alloys, braided composite features a high impact resistance and crash energy absorption potential, and also it still remained competitive stiffness and strength properties. Braiding angle is one of the most important parameters which affect the mechanical behaviors of braided composite. This paper presents transverse low velocity impact failure behavior analysis on the carbon 3D triaxial braided composite tube with the braiding angle of <TEX>$20^{\circ}$</TEX>, <TEX>$50^{\circ}$</TEX> and <TEX>$80^{\circ}$</TEX>. The flexural behaviour of 3D triaxial braided composite tube under bending loads was studied by conducting quasistatic three point bending test. Also, the low velocity impact responses of the braided composite tubes were also tested to obtain load-displacement curves and energy absorption. Consequently, the increase of the braided angle, the peak load also increases owing to the bigger bending stiffness.

Full-Scope Probabilistic Safety Assessment of Balakovo Unit 1 in Russia

The Balakovo Nuclear Power Plant operating in Russia has four operating units of a VVER-1000 type. The first unit was connected to the grid on Dec. 28, 1985, and put in commercial operation on May 23, 1986. According to modern requirements of the Russian Nuclear Regulatory Authority, the full-scope probabilistic safety assessment (PSA) must be performed to extend the license for operation beyond an initial 30-year lifetime of the unit. The paper presents the results of the Level 1 PSA covering internal initiating events for power and shutdown operational plant states, internal hazards (fires and floods), and external hazards, including natural and man-made events, in particular, seismic impact, and aircraft crash.

New mass optimization technique to achieve low mass BIW designs using optimal material layout methodology on the frontal vehicle crash

BIW is the car body made of sheet metals welded together. Numerous researches were performed across the world to optimize and save mass on the car body design. This paper describes the new methodology which can be used to reduce mass of the BIW in a full frontal rigid wall impact crash model. The new methodology of identifying materials for the BIW components has been presented. Frontal crash load case has been considered for the research. Since Frontal impact is an evaluation to predict only the frontal performance, parts in the front impact load path like dash, A-pillar, reinforcements and hinge pillar region has been considered as the design space for the material layout optimization. List of materials have been provided as a variable for a list of parts in the BIW and DOE sampling were generated. Response for the DOE designs results have been extracted to study the sensitivity of the parts for the frontal load case and design performance was analysed. Subsequent multi-objective optimization have been performed based on the DOE results, to achieve an optimal material selection for each of the parts in the design space. Further performance improving techniques considering the sensitivity chart have been explored and optimal design with low mass and improved frontal crash performance have been achieved and presented. The use of this methodology on a full vehicle crash model has achieved 15.4 % mass saving with the performance better than the baseline design.

Morphomics of the Talus.

Previous studies of frontal crash databases reported that ankle fractures are among the most common lower extremity fractures. While not generally life threatening, these injuries can be debilitating. Laboratory research into the mechanisms of ankle fractures has linked dorsiflexion with an increased risk of tibia and fibula malleolus fractures. However, talus fractures were not produced in the laboratory tests and appear to be caused by more complex loading of the joint. In this study, an analysis of the National Automotive Sampling System - Crashworthiness Data System (NASS-CDS) for the years 2004-2013 was conducted to investigate foot-ankle injury rates in front seat occupants involved in frontal impact crashes. A logistic regression model was developed indicating occupant weight, impact delta velocity and gender to be significant predictors of talus fracture (p<0.05). Separately, a specific set of Computed Tomography (CT) scans from the International Center for Automotive Medicine (ICAM) scan database was used to characterize the talar dome. This control population consisted of 207 adults aged 18 to 84, with no foot or ankle trauma, and scans that had suitable coverage of the talus. Size of the talus was determined using medial-to-lateral width and anterior-to-posterior depth measurements. Geometry was assessed by evaluating the radius of the articulating talus and strength was assessed using a combination of cross sectional area and density. Demographics were studied to investigate correlation with talus measurements from the CT scan database. A multi-variable linear regression model of the morphomics showed gender to be statistically significant (p<0.05) for talus depth, width, cross-sectional area, radius and strength. Body Mass Index (BMI) was significant for depth and radius. Weight was significant for depth, width, density and strength. Stature was significant for depth, cross-sectional area, radius and strength. Age was significant for radius and density.

Association of Impact Velocity with Risks of Serious Injuries and Fatalities to Pedestrians in Commercial Truck-Pedestrian Accidents.

This study aimed to clarify the relationship between truck-pedestrian crash impact velocity and the risks of serious injury and fatality to pedestrians. We used micro and macro truck-pedestrian accident data from the Japanese Institute for Traffic Accident Research and Data Analysis (ITARDA) database. We classified vehicle type into five categories: heavy-duty trucks (gross vehicle weight [GVW] ≥11 × 103 kg [11 tons (t)], medium-duty trucks (5 × 103 kg [5 t] ≤ GVW < 11 × 103 kg [11 t]), light-duty trucks (GVW <5 × 103 kg [5 t]), box vans, and sedans. The fatality risk was ≤5% for light-duty trucks, box vans, and sedans at impact velocities ≤ 30 km/h and for medium-duty trucks at impact velocities ≤20 km/h. The fatality risk was ≤10% for heavy-duty trucks at impact velocities ≤10 km/h. Thus, fatality risk appears strongly associated with vehicle class. The results also revealed that a 10 km/h reduction in impact velocities could mitigate the severity of pedestrian injuries at impact velocities ≥30 km/h for all five analyzed vehicle types. Therefore, serious injuries and fatalities to pedestrians could be decreased by the development and deployment of collision mitigation systems (CMSs) to all vehicles, including to commercial trucks, because CMSs can detect pedestrians in even severe conditions, such as when the drive's view is obstructed, and can reduce the impact velocity. The present results indicate that CMS design specifications should differ between vehicle types because of the strong dependence of seriousinjury and fatality risks on vehicle type.

Structure integrity of rack module for compressed natural gas (CNG) pressure vessel - under automotive collision and vibration

A rack module is used to load a tube trailer with Compressed natural gas (CNG) pressure vessels and transport them. While driving, vibration is inevitable due to rough road surface and engine torque. Furthermore an automotive collision could lead to the destruction of the rack module and pressure vessels, and cause gas leakage or the explosion of the pressure vessels. In this study, the structural integrity of a rack module, whose total weight is about 28.6 tons including 20 high pressure vessels, is evaluated by both crash test and impact analysis. The fatigue failure of the rack module is predicted under impact loading caused by collision and under repeated loading due to vibration.

Press-hardening of zinc coated steel - characterization of a new material for a new process

Press-hardening of zinc-coated PHS has been limited to the indirect process until a pre-cooling step was introduced before the hot forming to prevent liquid metal embrittlement. Even though that's only a minor change in the process itself it does not only eliminate LME, but increases also the demands on the base material especially in terms of hardenability or phase transformations at temperatures below 700 °C in general. This paper deals with the characterization of a modified zinc-coated material for press-hardening with pre-cooling that assures a robust process. The pre-cooling step itself and especially the transfer of the blank in the hot-forming die is more demanding than the standard 22MnB5 can stand to ensure full hardenability. Therefore the transformation behavior of the modified material is shown in CCT and TTT diagrams. Of the same importance are the changed hot forming temperature and flow curves for material at lower temperatures than typically used in direct hot forming. The resulting mechanical properties after hardening from tensile testing and bending tests are shown in detail. Finally some results from side impact crash tests and correlations of the findings with mechanical properties such as fracture elongation, tensile strength, VDA238 bending angle at maximum force as well as postuniform bending slope are given as well. Fracture elongation is shown to be of little help for damage prediction in side impact crash. Tensile strength and VDA bending properties enable however some accurate prediction of the PHS final damage behavior in bending dominated side impact load case.

Factor comparison of passenger-vehicle to vulnerable road user crashes in Beijing, China

ABSTRACTVehicle to vulnerable road user (VRU) crash is a large portion of traffic crashes in China Crash data from Beijing, China from the year 2009 to 2012 are used to identify the factors associated with the likelihood of vehicle to VRU crashes. 180 passenger-vehicles to VRU crashes are collected including 60 vehicle to pedestrian, 60 vehicle to bicycle and 60 vehicle to electric-bicycle cases. Then the statistics of the crash data are carried out, and the variables of human, vehicle, road, environment are investigated. Further, a logic regression model is established to analyse the significance of main contributing factors of these crashes. This paper describes the sample data, which includes time of incident, road user's age and gender, impact speed, crash pattern and VRU's head impact position. Also a comparative research among the three crash types is performed. According to the results, some characteristics of three crash types are different, such as the occurrence time, road position, impact speed and the impact position of VRU's head on the passenger-car. Moreover, chi-square test reveals that night-time travelling, crash type involving pedestrian and speeding of vehicle are significant related to non-fatal/fatal crashes. The logic regression model shows that night-time, intersection, older age of VRU and higher speed of vehicle increased the crash severity.

Serious injury prediction algorithm based on large-scale data and under-triage control

The present study was undertaken to construct an algorithm for an advanced automatic collision notification system based on national traffic accident data compiled by Japanese police. While US research into the development of a serious-injury prediction algorithm is based on a logistic regression algorithm using the National Automotive Sampling System/Crashworthiness Data System, the present injury prediction algorithm was based on comprehensive police data covering all accidents that occurred across Japan. The particular focus of this research is to improve the rescue of injured vehicle occupants in traffic accidents, and the present algorithm assumes the use of an onboard event data recorder data from which risk factors such as pseudo delta-V, vehicle impact location, seatbelt wearing or non-wearing, involvement in a single impact or multiple impact crash and the occupant’s age can be derived. As a result, a simple and handy algorithm suited for onboard vehicle installation was constructed from a sample of half of the available police data. The other half of the police data was applied to the validation testing of this new algorithm using receiver operating characteristic analysis. An additional validation was conducted using in-depth investigation of accident injuries in collaboration with prospective host emergency care institutes. The validated algorithm, named the TOYOTA-Nihon University algorithm, proved to be as useful as the US URGENCY and other existing algorithms. Furthermore, an under-triage control analysis found that the present algorithm could achieve an under-triage rate of less than 10% by setting a threshold of 8.3%.

Side impact motor vehicle crashes: driver, passenger, vehicle and crash characteristics for fatally and nonfatally-injured rear-seated adults.

BackgroundMost studies of rear-seated occupants have focused on or included pediatric occupants which may not translate to adults. This study examines passenger, driver, vehicle and crash characteristics for rear-seated adult occupants involved in side crashes.MethodsThe National Automotive Sampling System General Estimates System (NASS/GES) for calendar years 2011–2014 was used with accompanying weights to examine the occupant, vehicle and crash characteristics associated with injury in rear-seated adults (n = 395,504) involved in a side crash. A weighted subpopulation analysis includes occupants travelling in a vehicle with an IIHS safety rating (n = 39,208), which was used to control for vehicle safety. Statistical analysis used Chi-square tests and multilevel multivariable logistic regression. Unadjusted and adjusted odds ratios (ORs) are reported with 95 % confidence intervals (95 % CIs).ResultsRear-seated occupants on the same side as the crash impact were more likely to be severely/fatally injured than occupants seated on the opposite side (Multivariable adjusted OR: 2.54, 95 % CI: 2.31–2.79), as were those in angle crashes (Multivariable adjusted OR: 10.85, 95 % CI: 9.24–12.73). Rear-seated occupants of belted drivers were 3.28 times more likely to be belted compared to rear-seated occupants of an unbelted driver. In a subpopulation analysis of all same-side crashes, unrestrained occupants were 5.96 times more likely to be severely/fatally injured compared to restrained occupants.ConclusionRestraint use was protective for rear-seated adult occupants involved in side crashes, including those in same-side crashes. Angle and same-side crashes are associated with increased injury severity.