Crashworthiness

A survey of accident statistics and harm to the head and neck from side impact and rollover, suggest that vehicle upper structure should be the next high priority goal in reducing severe casualties. Contrary to contentions that roof strength has little influence on these injuries, these results from a multiplicity of studies, indicate that roof collapse should be eliminated, passive interior padding improved, laminated and retained glazing be installed and restraints improved by pretensioning retractors. A statistical analysis of the 982 and 1983 NASS files of rollover accidents, indicates a greatly increased risk of severe injury to occupants under a collapsing roof section. The increased risk was also demonstrated by detailed investigation and analysis of 15 rollover accidents using the protocol of SAE #890382 (Live Subject Safety Research). The instrumented data from sixteen nearly identical, rollover tests conducted by General Motors with conventional and rollcaged roofs
and unrestrained and belted Hybrid III dummies were analyzed and confirmed the increased risk. Limiting the deformation extent of vehicle roofs by lightweight structural changes and simple and inexpensive force limiting, energy absorbing interior surface modifications, were demonstrated to reduce the rick of severe injuries by a factor of at least four. Further reductions stability by Anti-Lock Braking Systems, limiting an occupant's contact velocity by emergency tensioning retractors on restraints and by minimizing partial ejection potential by laminated and retained glazing.

Bus rollover is one of the most serious types of accident as compared to other modes of bus accidents. Strengthening bus frames to maintain residual space (occupant space) and minimizing occupant injury are necessary.

This paper deals with the study of bus roll over case as per AIS 031/ECE R66 regulation conditions. The AIS 031 is equivalent to ECE R66 regulation but excluding for driver and co-driver. The ultimate aim of this study was to investigate the impact on passenger residual space as per AIS 031 regulation. As a first step, before we go for complete rollover simulation, the critical bus body joints are physically tested same is repeated by simulation approach once we have the correlating results approval is taken from ARAI. As a second step, the complete vehicle rolls over simulation was performed.

FE model of the full vehicle was comprised of first order shell elements, spring elements, mass elements (ADMAS) and Rigid
Elements. An average Element edge length of 10 mm is maintained in the critical regions and 30 mm in the noncritical regions. The engine, power transmission, suspension and axles were modeled by 1D element. Mass balancing was done using balancing tool in HyperCrash V11 402.

Computer simulation of the joint test was showing low load carrying capacity of joints as compare to test results which means computer simulation was showing higher deformation (lower distance b/w superstructure & residual space) as compare to physical testing. Hence simulation results are conservative compared to test, if bus passes in simulation then we have confidence that it will pass in test with more margin. During roll-over simulation, the minimum distance between superstructure & residual space was found to be 38.0 mm on driver side as per AIS-031.

The Volvo Bus was found to meet the Rollover requirement as per AIS-031.

FE modeling & model setup of the entire bus structure was carried out using HyperMesh and HyperCrash respectively. Finally, simulation was carried out using RADIOSS explicit solver.

Unit system followed: KN, mm, ms, kg

A study of an existing B-pillar was conducted to examine the changes required to increase the lateral load carrying capability by a factor of ten. A finite element optimization package was used to adjust the geometric and material characteristics simultaneously while minimizing weight. The results show that the weight and cost necessary for the ten-fold improvement in lateral load carrying capability were very low. Further, the results illustrate how structural design optimization with finite element modeling can be effectively utilized to create cost effective elements for use in an integrated occupant protection system.

This paper presents the results of numerical studies performed to evaluate the performance of four commonly used traffic barriers on roadside and median slopes. The selected guardrail/barrier systems are the modified G4(1S) W-beam guardrail, modified thrie-beam guardrail, Midwest guardrail system and modified weak-post W-beam guardrail. For barriers placed on slopes, vehicle impact height varies depending on the trajectory of the vehicle along the ditch section and lateral offset of the barrier. Multi-rigid-body dynamic analysis code, CARSIM, is used to identify trajectories of the vehicles traversing various roadside and median cross-slopes. Performance limits of each barrier in terms of acceptable vehicle impact heights are superimposed on the trajectory data to identify safe lateral offset locations for each barrier. The resulting placement guidelines are then refined using the responses obtained from LS-DYNA simulations that capture the full encroachment event from departure of ...

Automobiles crashes are becoming a source of increasing social concern, which instigates government bodies to impose stringent requirements on vehicle safety. The development of the embedded intelligent safety system (ISS) platform is a difficult task and involves many factors such as generation and interconnection of the hardware that support the execution of software. This paper deals with high-performance computing to detect and monitor frontal vehicle crash using a sensing algorithm which has been embedded in the proposed ...

Background context-Motor vehicle collisions (MVC) are a leading cause of thoracic and lumbar (T and L) spine injuries. Mechanisms of injury in vehicular crashes that result in thoracic and lumbar fractures and the spectrum of injury in these occupants have not been extensively studied in the literature.
Purpose-The objective was to investigate the patterns of T and L spine injury following MVC; correlate these patterns with restraint use, crash characteristics and demographic variables; and study the associations of these injuries with general injury morbidity and fatality.
Study design/Setting-Retrospective study of a prospectively gathered database.
Patient sample-Six hundred and thirty-one occupants with T and L (T1-L5) spine injuries from 4572 occupants included in the Crash Injury Research and Engineering Network (CIREN) database between 1996 and 2011.
Outcome measures-No clinical outcome measures were evaluated in this study.
Methods-The CIREN database includes moderate to severely injured occupants from MVC involving vehicles manufactured recently. Demographic, injury and crash data from each patient was analyzed for correlations between pattern of T and L spine injury, associated extra-spinal injuries and overall injury severity score (ISS), type and use of seat belts, and other crash characteristics. T and L spine injury pattern was categorized using a modified Denis classification, to include extension injuries as a separate entity.
Results-T and L spine injuries were identified in 631 of 4572 vehicle occupants, of whom 299 sustained major injuries (including 21 extension injuries) and 332 sustained minor injuries. Flexion-distraction injuries were more prevalent in children and young adults, and extension injuries in older adults (mean age 65.7 years). Occupants with extension injuries had a mean BMI of 36.0 and a fatality rate of 23.8%, much higher than the fatality rate for the entire cohort (10.9%). The most frequent extra-spinal injuries (Abbreviated Injury Scale grade 2 or more) associated with T and L spine injuries involved the chest (seen in 65.6% of 631 occupants). In contrast to occupants with major T and L spine injuries, those with minor T and L spine injuries showed a strikingly greater association with pelvic and abdominal injuries. Occupants with minor T and L spine injuries had a higher mean ISS (27.1) than those with major T and L spine injuries (25.6). Among occupants wearing a three-point seat belt, 35.3% sustained T and L spine injuries, while only 11.6% of the unbelted occupants sustained T and L spine injuries. Three-point belted individuals were more likely to sustain burst fractures, while two-point belted occupants sustained flexion-distraction injuries most often, and unbelted occupants had a predilection for fracture-dislocations of the T and L spine. Three-point seat belts were protective against neurologic injury, higher ISS and fatality.
Conclusions—T and L spine fracture patterns are influenced by age of occupant and type and use of seat belts. Despite a reduction in overall injury severity and mortality, seat belt use is associated with an increased incidence of T and L spine fractures. Minor T and L spine fractures were associated with an increased likelihood of pelvic and abdominal injuries and higher ISS scores, demonstrating their importance in predicting overall injury severity. Extension injuries occurred in older, obese individuals, and were associated with a high fatality rate. Future advancements in automobile safety engineering should address the need to reduce T and L spine injuries in belted occupants.

This paper describes a study carried out to develop and apply computer analysis tools to simulate real-world accidents between vehicles and pedestrians. The main focus has been the incorporation of realistic pedestrian pre-impact gait motion and to investigate the outcome of real-world impacts. A combination of multi-body, FACET and finite element based vehicle models in conjunction with validated human body models developed by MADYMO were used to simulate and analyse vehicle–pedestrian accident scenarios. European regulations and consumer tests for passenger cars now address vehicle front aggressiveness, and vehicle manufactures have effectively developed design solutions for meeting these requirements. Vehicle frontal geometry and pedestrian pre-impact characteristics play a major role in determining the post-impact kinematics and severity of injury sustained during pedestrian–vehicle contact stage. A unique aspect of this study has been the application of the Injury Severity Index method developed for automotive occupant injury assessment to pedestrians. The injury results from the simulations were measured and the severity assessed by applying a quantitative rating method.

According to real-life crash data, one of the most harmful events among all side impacts is when the driver-head hits the far-side door when the car is hit from the far side. There is currently no established test method to simulate a crash where such an event is at risk of occurring. In order to assess real life injuries and develop countermeasures for far side crashes, standardized cost-effective test methods are needed. This paper presents a bending bar sled-test set-up simulating a full-scale 9 o'clock far side crash. In the full scale ...