Side Crash Research Articles

Enhancements on strength of body structure due to bake hardening effect on hot stamping steel

Body structure projects are designed to develop lightweight structures, which result in low fuel consumption and emissions for internal combustion engines and longer battery life in the case of electric vehicles. The structures need to be lightweight but also strong in order to provide maximum safety to the occupants. These premises have led to the development of special materials such as the hot stamping steels. The most used steel in this process, quenched 22MnB5, also exhibits the bake hardening effect: its yield stress increases after being exposed at temperatures close to 200 °C (typical heat treatment of paint lines in the automotive industry). The aim of this study was to verify the improvement in the mechanical strength of a body structure due to the bake hardening effect to which the hot-stamped steel components were submitted. Samples of annealed 22MnB5 steel were submitted to tensile and chemical analysis. A second group of the same steel was subjected to an additional heat treatment in a laboratory furnace simulating the heating that occurs in the body paint line. Subsequently, the same tests were performed with the samples from the first group. Tensile tests evidenced the increase of 6.5% in the yield stress of the samples that suffered the bake hardening effect. The stress-strain diagram curves were used as the input to the side crash simulation program. The simulations demonstrated that the body structure whose hot-stamped parts were subjected the bake hardening effect had a 2% reduction in side crash intrusion compared to body structure where the parts did not suffer this effect. In the case of the lateral protection bar test, the bake hardening effect provided a 5% increase in the maximum bending load.

Poprawa sztywności belki wzmocnienia tylnych drzwi samochodu osobowego

To protect passengers against consequences of side crash side door beams are assembled to doors of passenger cars. Their stiffness is examined during stand tests. The FE model to simulate such a test is described. After verification the model has been applied to improve of rear door side beam stiffness.

Severe injury in multiple impacts: Analysis of 1997–2015 NASS-CDS

ABSTRACTPurpose: This is a descriptive study of the incidence and risk for severe injury in single-impact and multi-impact crashes by belt use and crash type using NASS-CDS.Methods: 1997–2015 NASS-CDS data were used to determine the distribution of crashes by the number of impacts and severe injury (Maximum Abbreviated Injury Score [MAIS] 4+F) to >15-year-old nonejected drivers by seat belt use in 1997+ MY vehicles. It compares the risk for severe injury in a single impact and in crashes involving 2, 3, or 4+ impacts in the collision with a focus on a frontal crash followed by other impacts.Results: Most vehicle crashes involve a single impact (75.4% of 44,889,518 vehicles), followed by 2-impact crashes (19.6%), 3-impact crashes (5.0%) and 4+ impacts (2.6%). For lap–shoulder-belted drivers, the distribution of severe injury was 42.1% in a single impact, 29.3% in 2 impacts, 13.4% in 3 impacts, and 15.1% in 4+ impact crashes. The risk for a belted driver was 0.256 ± 0.031% in a single impact, 0.564 ± 0.079% in 2 impacts, 0.880 ± 0.125% in 3 impacts, and 2.121 ± 0.646% in 4+ impact. The increase in risk from a single crash to multi-impact collisions was statistically significant (P < .001).In a single impact, 53.8% of belted drivers were in a frontal crashes, 22.4% in side crashes, 20% in rear crashes, and 1.7% in rollover crashes. The risk for severe injury was highest in a rollover at 0.677 ± 0.250%, followed by near-side impact at 0.467 ± 0.084% and far-side impact at 0.237 ± 0.071%. Seat belt use was 82.4% effective in preventing severe injury (MAIS 4+F) in a rollover, 47.9% in a near-side impact, and 74.8% in a far-side impact.In 2-impact crashes with a belted driver, the most common sequence was a rear impact followed by a frontal crash at 1,843,506 (21.5%) with a risk for severe injury of 0.100 ± 0.058%. The second most common was a frontal impact followed by another frontal crash at 1,257,264 (14.7%) with a risk of 0.401 ± 0.057%. The risk was 0.658 ± 0.271% in a frontal impact followed by a rear impact. A near-side impact followed by a rear crash had the highest risk for severe injury at 2.073 ± 1.322%.Conclusions: Restraint systems are generally developed for a single crash or sled test. The risk for severe injury was significantly higher in 2-, 3-, and 4+-impact crashes than a single impact. The majority (57.9%) of severe injuries occurred in multi-impact crashes with belted drivers. The evaluation of restraint performance warrants additional study in multi-impact crashes.

Accident analysis to support the development of strategies for the prevention of brain injuries in car crashes

This study estimated the frequency and risk of Moderate-to-Maximal traumatic brain injuries sustained by occupants in motor vehicle crashes in the US. National Automotive Sampling System - Crashworthiness Data System crashes that occurred in years 2001–2015 with light vehicles produced 2001 or later were incorporated in the study. Crash type, crash severity, car model year, belt usage and occupant age and sex were controlled for in the analysis. The results showed that Moderate concussions account for 79% of all MAISbrain2+ injuries. Belted occupants were at lower risks than unbelted occupants for most brain injury categories, including concussions. After controlling for the effects of age and crash severity, belted female occupants involved in frontal crashes were estimated to be 1.5 times more likely to sustain a concussion than male occupants in similar conditions. Belted elderly occupants were found to be at 10.5 and 8 times higher risks for sub-dural haemorrhages than non-elderly belted occupants in frontal and side crashes, respectively. Adopted occupant protection strategies appear to be insufficient to achieve significant decreases in risk of both life-threatening brain injuries and concussions for all car occupants. Further effort to develop occupant and injury specific strategies for the prevention of brain injuries are needed. This study suggests that these strategies may consider prioritization of life-threatening brain vasculature injuries, particularly in elderly occupants, and concussion injuries, particularly in female occupants.

Study and modelling of the passenger safety devices of an electric vehicle by finite elements

Electric mobility gets mainly involved quadricycles and cars. Between these two vehicle types there are differences in terms of stability, performance, cost, autonomy and safety. The authors studied the implementation of passenger safety devices on a prototype for an electric vehicle derived from a heavy quadricycle. A finite element analysis starting from experimental results was carried out in order to determine the effectiveness in case of frontal and side crashes.

A NUMERICAL STUDY ON CORRELATION OF RIB FRACTURES WITH THORACIC INJURY CRITERIA IN OBLIQUE IMPACT

Thoracic injury is one of the vital issues in vehicle side crashes. Experiments have been done widely to study thoracic injuries using biological subjects but less virtual tests were made by using Finite Element (FE) models. This study aimed at determining the correlation of the computationally calculated thoracic injury (Number of Rib Fractures NRF) with existing thoracic injury criteria under pure side and oblique impacts. For this purpose, a previously developed thorax FE model was validated by using Post Mortem Human Subject (PMHS) tests in pure side and oblique impacts in this study. The rib fractures were reconstructed and compared with the fractures observed in the PMHS tests. The model was then used to simulate rib fractures in human thorax impactor tests at Principal Direction of Force (PDOF) angles of 90[Formula: see text] to 35[Formula: see text] (total of 12 impacts). Furthermore, the normalized NRF were calculated and analyzed for comparing with normalized simulated injury parameters based on various human thoracic injury criteria, including contact force criterion, thorax deflection criterion, compression criterion, upper spine acceleration criterion and Thoracic Trauma Index (TTI). It is suggested that the TTI criterion has better correlation with the NRF than the other injury criteria.

Study of automotive side sill/rocker by using carbon fibre reinforced polymer tubes

ABSTRACTVehicle side crash is a critical crash event where the vehicle is crashed by a movable car or vehicle may hit a tree or pole. Minimising the intrusion into the occupant space is important to protect the occupant. In side pole crash, vehicle rocker (sill) plays an important role in resisting the load due to the crash. The objective is to study the functional performance and potential mass reduction in the vehicle sill/rocker area by use of carbon fibre reinforced polymer (CFRP) tubes. The study is divided into three parts. First part investigates the behaviour of CFRP square section tubes in a three-point quasi-static bending in comparison to conventional steel structure using finite element method. By keeping the resistance force offered by a steel section as the baseline resistance value, different combination of CFRP tubes and metal holding brackets are evaluated and compared with the baseline. In the second part, CFRP tube is simulated in dynamic three-point bending test and compared with quasi-static simulations in order to check the influence of inertial effects on the CFRP tube behaviour. In the third part, the best performing design variants from the three-point quasi-static bending simulations are used in the sill or rocker of a vehicle and evaluated in full vehicle US NCAP pole impact load case. The full vehicle crash simulations for side pole impact is compared between the baseline with the steel reinforcement and design variants with the CFRP tube. Resistance force levels, intrusion and structural integrity are the key parameters on which this comparison is made. It is concluded that using CFRP tubes does not reduce the performance in terms of structural integrity and intrusion levels in typical side crash scenario like a US NCAP side pole impact. It can also be concluded that there is potential for mass reduction. Further investigation into the assembly feasibility is suggested as future work.

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.

Structural crashworthiness analysis of a ladder frame chassis subjected to full frontal and pole side impacts

ABSTRACTAutomobile chassis is a major element of structural crashworthiness in road motor vehicles. Various chassis geometry and topology research studies have been conducted to improve crash energy absorption characteristics of the chassis. In side impacts, crashworthiness of an automobile body depends not only on the chassis geometry and topology, but also on the design and reliability of other structural members such as B-pillar and side panels. This study aims to contribute to the investigations on the effects of chassis geometry over crashworthiness, particularly focusing on the structure of a ladder frame chassis subjected to full frontal and pole side collisions. Preliminary work has been conducted to evaluate the behaviour of steel beam profiles under impact loading through finite element (FE) modelling, which helps understand the mechanics of the particular beams chosen as chassis elements. Another FE model is developed utilising a previously generated mesh of a pickup truck with a ladder frame chassis. The FE model is employed to simulate full frontal and pole side crash test scenarios on the isolated chassis as well as on the whole body of the vehicle. Crash energy absorption results and reaction forces are collected for different thicknesses and beam profile cross sections of the vehicle chassis to be utilised in several proposed design improvements aiming to enhance crashworthiness. Computational results exhibit good agreement with experimental findings.

Crash Tests and the Loads over Driver Head in Different Side Impact Cases

Car occupant protection in traffic accidents is a key target of today cars manufacturers. Known as active or passive safety, many technological solutions were developing over the time for an actual better car’s occupant safety. In the real world, in traffic accidents are often involved cars from different generations with various safety historical solutions. The aims of these papers are to quantify the influences over the car driver head loads in cases of different generation of cars involved in side crashes. For each case the experimental load results can be future used to calculate Head Injury Criterion (HIC) [1]

새로운 기둥측면충돌 시험방법에 관한 실험적 연구

In recent years, WorldSID has been continuously developed and investigated to be the representative biofidelic anthropomorphic test device (ATD) as well as the device for replacement of the current EuroSID-2. In Korea, the side impact accident is one of the major severe accidents in terms of the number of accidents and fatality. Since 2003, the side crash test with a speed of 50 kph in the perpendicular direction has been initiated as a safety standard with EuroSID-1 at the first stage. Simultaneously, a 55 kph impact test has been conducted as a part of Korean New Car Assessment (KNCAP). Currently, only EuroSIDE-2 is accepted as a regulatory tool for vehicle certification and KNCAP. The tests with WorldSID are conducted experimentally in order to use WorldSID of the KNCAP in near future.

Implications of Functional Capacity Loss and Fatality for Vehicle Safety Prioritization

Objective: We investigate the use of the Functional Capacity Index (FCI) as a tool for establishing vehicle safety priorities by comparing the life year burden of injuries to the burden of fatality in frontal and side automotive crashes. We demonstrate FCI’s utility by investigating in detail the resulting disabling injuries and their life year costs.Methods: We selected occupants in the 2000–2013 NASS-CDS database involved in frontal and side crashes, merged their injuries with FCI, and then used the merged data to estimate each occupant’s overall functional loss. Lifetime functional loss was assessed by combining this measure of impairment with the occupants’ expected future life spans, estimated from the Social Security Administration’s Actuarial Life Table.Results: Frontal crashes produce a large number of disabling injuries, particularly to the lower extremities. In our population, these crashes are estimated to account for approximately 400,000 life years lost to disability in comparison with 500,000 life years lost to fatality. Victims of side crashes experienced a higher rate of fatality but a significantly lower rate of disabling injury (0.3 vs. 1.0%), resulting in approximately 370,000 life years lost to fatality versus 50,000 life years lost to disability.Conclusions: The burden of disabling injuries to car crash survivors should be considered when setting vehicle safety design priorities. In frontal crashes this burden in life years is similar to the burden attributable to fatality.

Occurrence of Serious Injury in Real-World Side Impacts of Vehicles with Good Side-Impact Protection Ratings

Objective: The Insurance Institute for Highway Safety (IIHS) introduced its side impact consumer information test program in 2003. Since that time, side airbags and structural improvements have been implemented across the fleet and the proportion of good ratings has increased to 93% of 2012–2014 model year vehicles. Research has shown that drivers of good-rated vehicles are 70% less likely to die in a left-side crash than drivers of poor-rated vehicles. Despite these improvements, side impact fatalities accounted for about one quarter of passenger vehicle occupant fatalities in 2012. This study is a detailed analysis of real-world cases with serious injury resulting from side crashes of vehicles with good ratings in the IIHS side impact test.Methods: NASS-CDS and Crash Injury Research and Engineering Network (CIREN) were queried for occupants of good-rated vehicles who sustained an Abbreviated Injury Scale (AIS) ≥ 3 injury in a side-impact crash. The resulting 110 cases were categorized by impact configuration and other factors that contributed to injury. Patterns of impact configuration, restraint performance, and occupant injury were identified and discussed in the context of potential upgrades to the current IIHS side impact test.Results: Three quarters of the injured occupants were involved in near-side impacts. For these occupants, the most common factors contributing to injury were crash severities greater than the IIHS test, inadequate side-airbag performance, and lack of side-airbag coverage for the injured body region. In the cases where an airbag was present but did not prevent the injury, occupants were often exposed to loading centered farther forward on the vehicle than in the IIHS test. Around 40% of the far-side occupants were injured from contact with the struck-side interior structure, and almost all of these cases were more severe than the IIHS test. The remaining far-side occupants were mostly elderly and sustained injury from the center console, instrument panel, or seat belt. In addition, many far-side occupants were likely out of position due to events preceding the side impact and/or being unbelted.Conclusion: Individual changes to the IIHS side impact test have the potential to reduce the number of serious injuries in real-world crashes. These include impacting the vehicle farther forward (relevant to 28% of all cases studied), greater test severity (17%), the inclusion of far-side occupants (9%), and more restrictive injury criteria (9%). Combinations of these changes could be more effective.

Factors associated with mortality in rear-seated adult passengers involved in fatal motor vehicle crashes on US roadways.

BackgroundRecent efforts to pass rear seat belt laws for adults have been hampered by large gaps in the scientific literature. This study examines driver, vehicle, crash, and passenger characteristics associated with mortality in rear-seated adult passengers.MethodsThe Fatality Analysis Reporting System (FARS) 2010 to 2011 was used to examine motor vehicle occupant mortality in rear-seated adult passengers 18 years and older. Side crash vehicle safety ratings were assessed in a subset analysis of vehicles struck on the same side as the rear-seated passenger. Multilevel logistic regression models used SAS GLIMMIX.ResultsOf the 7,229 rear-seated adult passengers, 2,091 (28.9%) died. Multivariable predictors of increased mortality were advancing passenger age, younger driver age, excessive speed, ejection, being unbelted, rear impact, and same-side crash. Belt use was associated with a 67.0% reduction in total mortality. Despite this, belt wearing was low (48.1%) and differed by seating position, with less than one third of middle-seated passengers belted. Multivariable analysis showed mortality to be nearly three times higher in same-side crashes than other impact locations (odds ratio (OR) = 2.76, 2.22, 3.44). In a multivariable subpopulation analysis of same-side crashes, right-seated passengers had an increased mortality (52.7% vs. 43.2%, p < 0.01) compared to left-seated passengers (OR = 1.55, 1.02, 2.36). Vehicle side crash safety ratings, available for 27.7% (n = 172) of same-side crashes, were not predictive of mortality.ConclusionsExcept for same-side crashes, seat belts were associated with significantly lowered mortality. Despite this, seat belt wearing was low and represents one of several areas where further improvements in mortality might be realized.

Crash Patterns at Signalized Intersections

Traffic signals are often implemented to provide for efficient movement and to improve traffic safety. Nevertheless, severe crashes still occur at signalized intersections. This study aims to improve understanding of signalized intersection safety by identifying crash types, locations, and factors associated with signalized intersections. For this purpose, 1,295 police-reported crashes at 87 signalized intersections were analyzed on the basis of detailed crash descriptions, that is, crash data and collision diagrams. The information from the collision diagrams was used to distinguish six crash types and to create a crash location typology to divide the signalized intersection into 13 detailed typical segments. Logistic regression modeling techniques were used to identify relations between crash types, their crash location on certain signalized intersection segments, the crash severity, and the different features that affected crash occurrence. Four dominant crash types were identified: rear-end, side (i.e., left-turn plus right-angle), head-on, and vulnerable road user crashes. The results of the logistic regression models showed that the location of these crash types was related to specific signalized intersection segments. The results also revealed important signalized intersection features that affected the crash occurrence. As a result, connections between certain signalized intersection crash types, their crash location, and signalized intersection design characteristics were found. The combination of intersection features with detailed signalized intersection segments provided valuable insights into the nature of signalized intersection crashes and the safety impact of signalized intersection design.

Evaluation of Car Body Deformation by Image Analysis in Side Crash Test (Second Report)

Evaluation of Car Body Deformation by Image Analysis in Side Crash Test (Second Report)

Evaluation of Car Body Deformation by Image Analysis in Side Crash Test

Evaluation of Car Body Deformation by Image Analysis in Side Crash Test

Vehicle Side Crash Safety Research based on Dynamics Modeling and Analysis

The safety of vehicle side impact has become an important research content in the field of automotive passive safety. The nonlinear dynamic explicit finite element method is used to establish the side crashworthiness model of vehicle and side crash finite element model validation is also given. The finite element model is consistent with vehicle side stiffness, which can be used in the side crash simulation analysis. The simulation calculation and result analysis of side crash are carried out for a particular vehicle model to improve the side crash safety performance.

Integrated differential braking and electric power steering control for advanced lane-change assist systems

This paper describes the design and verification of a control algorithm for advanced lane-change assist systems with integrated control of the differential braking and the electric power steering system. The objective of the proposed control algorithm of the advanced lane-change assist system is to minimize the unexpected control input of electric power steering and to make maximum use of the differential brake effort. The advanced lane-change assist system can warn of potential rear and side crashes and prevent collisions in lane-change manoeuvres with active intervention when there is an upcoming vehicle with a potential risk to the rear in the next lane. An enhanced lane-change assist warning algorithm is developed with additional information on the estimated past trajectory of the subject vehicle. The upper controller of the advanced lane-change assist system determines the control on–off decision, the desired yaw rate for collision avoidance and the strategic control input distribution. The key strategy of this integrated control algorithm is to use the maximum tyre–road friction of the differential brake force and to operate with a smaller control effort of the electric power steering only when lacking in the level of yaw rate moment obtained by the electronic stability control, which is intended to minimize annoyance to a driver and control intervention. The lower controller decides the control input of the advanced electronic stability control and the electric power steering system. Finally the advanced lane-change assist system is implemented in a real vehicle and tested in both the steering-control-only case and the integrated-control case. It is shown that the proposed strategy can intervene appropriately and verifies the effectiveness of collision avoidance in a dangerous lane-change situation; a decrease in the electric power steering control input of about 20% can be achieved by the proposed algorithm.

Evaluation of NASS-CDS Side Crash Delta-V Estimates Using Event Data Recorders

Objective: Planar crash severity is most commonly defined by delta-V (ΔV), which is the change in a vehicle's velocity vector during a crash. All ΔV estimates contained in the NASS-CDS are generated using a damage-based program called WinSMASH. WinSMASH ΔV accuracy in side crashes has not previously been validated against real-world crash data. This study will investigate the accuracy of WinSMASH ΔV estimates in real-world side crashes.Methods: This study uses biaxial ΔV data from event data recorders (EDRs) to assess the accuracy of side crash ΔV estimates in NASS-CDS crash cases. Single-event side crashes were identified in the NASS-CDS for which (a) WinSMASH ΔV had been coded and (b) biaxial EDR data were available. For these crashes, the WinSMASH-estimated resultant ΔV was compared with the EDR-recorded resultant ΔV to assess the accuracy of the former. EDR ΔV values were adjusted for an assumed average restitution value of 10 percent, based on values reported in the literature. Principal direction of force (PDOF) is the orientation of the net crash impulse relative to the vehicle and is a key parameter in WinSMASH reconstructions. NASS-CDS PDOF estimates were compared to the PDOF computed from the EDR data to assess their accuracy as well.Results: WinSMASH systematically overestimates EDR ΔV by about 12.9 percent for cars struck by cars and by about 2.4 percent for cars struck by light trucks and vans (LTVs). ΔV error was significantly different (at 95% confidence) for crashes to different areas of the vehicle side. The mean discrepancy in NASS-CDS PDOF was −0.9° with a standard deviation of 12.6°.Discussion: WinSMASH systematically overestimates ΔV at common velocity by about 13 percent for cars struck by cars and about 2 percent for cars struck by LTVs. Since WinSMASH's assumption of zero restitution is accounted for in this analysis, this suggests that WinSMASH stiffness parameters represent LTV impacts better than car impacts in side crashes. ΔV error differs by impacted area, suggesting that side impact stiffness parameters used in damage-based ΔV reconstruction must closely represent the crash mode being reconstructed for best results. NASS-CDS estimates of PDOF do not appear to exhibit any systematic discrepancy. The amount of random PDOF discrepancy observed here is consistent with prior studies.