Offset Crash Research Articles

A basic design for automotive crash boxes using an efficient corrugated conical tube

Frontal vehicle structure is of high importance through crash energy managements and crash boxes are the fundamental structural component for vehicle safety as well as after sales issues. Similar to many other vehicle components, the detail design of crash box is usually part of manufacture knowhow. However, some guide lines are always available. In this article a general procedure is introduced for designing of crash box with the aid of novel thin walled structures and according to conventional crash scenarios. The problem is followed through some basic steps. Firstly, the crash box idea is selected through a wide range of previous investigated elements and is packaged in a real bench vehicle. Then thanks to the protection provided by the new crash box on the other more expensive components (e.g. headlamp, cooling pack, etc.), the effectiveness of this element are acknowledged through the low speed offset crash. Further on the robustness of new proposed crash box is approved by high speed crash simulations. The quasi-static simulations implemented during the analyses are carried out by finite element explicit code (Abaqus) and the FE modeling and dynamic simulation through the next steps are also performed in ANSA and PAM CRASH respectively. Finally in addition to the general crash box design proposed procedure, the achieved results demonstrated that the corrugated conical thin walled tubes deforms in regular and rather stable shape under both axial and oblique loadings. They also produced a reasonable reaction force versus deformations which leads to stiff and crashworthy energy absorber in comparison to traditional rectangular and even some special models like as origami shapes, and so they could be a valuable selection for crash box implementations in passenger cars.

A proposed quasi-static test for improving the crash performance of trailer rear underride guards

Current U.S. and Canadian regulations for rear underride guards on large truck trailers do not promote designs with adequate protection in offset crashes. The objective of the current study was to determine whether a quasi-static evaluation could distinguish between underride guards with different performance in offset crash tests. Five different underride guard designs were evaluated in quasi-static testing. These designs were previously tested in 56 km/h impacts with a midsize passenger car with 30 or 50% overlap. Three of the guards exhibited marginally passing performance in the crash test, with car excursion under the rear of the trailer reaching the base of the windshield but stopping prior to trailer-to-dummy contact. The other two designs failed to prevent trailer-to-dummy contact. Two quasi-static test configurations were assessed for their potential to distinguish between the marginally passing and the failing designs: the outboard P1 test in the existing regulation and a new 20-degree-angled test developed using crash test acceleration measurements. In both configurations, the guard designs with marginally passing crash test results demonstrated higher force and energy levels than the designs with failing crash test results. However, the 20-degree-angled test showed greater differentiation between levels of crash test performance while also producing more representative damage patterns. Underride guards that prevented trailer-to-dummy contact in the crash tests sustained quasi-static force levels of a least 100 kN prior to 75 mm of displacement in the 20-degree test. Rear underride regulations could be improved by replacing the outboard P1 test with a 20-degree-angled load applied to the end of the underride guard. This evaluation also could supplement or replace underride guard crash tests conducted by the Insurance Institute for Highway Safety (IIHS).

Driver head kinematic analysis under frontal offset collision during the rebound phase

Frontal offset crash test, either regulator or NCAP, only focus on evaluating the primary impact during the collision phase. The rebound phase is not counted in the assessment. This study focused on the rebound phase. In this phase, vehicle will rotate to the side, causing occupant's head move toward the window door glass. At an impact velocity from 6 m/s to 9 m/s against tempered glass windows, HIC values can stand over a limit of 1000. However, the severity of the head injury cannot be evaluated in the offset collision test because the window glass winded down for the high speed camera recording purpose. The analysis from the video shows head are moving towards the b pillar and side windows glass during frontal offset crash test. The resultant head rebound velocities varies in the range of 4.63 to 10.18 metre per second.

Multi-objective optimization of crashworthiness for mini-bus body structures

In order to improve crash safety, the body structure of a mini-bus is optimized in this study. One type of multi-objective optimization method is proposed in this article. The peak acceleration amax at the B pillar lower end and total mass m of the body in white were set as two objective functions. First, the sample points were generated by Latin hypercube sampling design. Second, based on the evaluation index of 40% frontal offset crash, an approximation model was established by the Kriging method. Then, particle swarm optimization was performed on the approximate models. Finally, the simulation calculation by LS-DYNA proved that the peak acceleration amax at the B pillar lower end was reduced by 18.6%, and the total mass m of body in white was reduced by 0.87%. Therefore, the crashworthiness of the mini-bus was improved greatly without increasing the total mass of the body in white, which means that the optimization results were meaningful.

Evaluation of the crash mitigation effect of low-speed automated emergency braking systems based on insurance claims data

ABSTRACTObjective: The aim of the present study was to evaluate the crash mitigation performance of low-speed automated emergency braking collision avoidance technologies by examining crash rates, car damage, and personal injuries.Method: Insurance claims data were used to identify rear-end frontal collisions, the specific situations where the low-speed automated emergency braking system intervenes. We compared cars of the same model (Volvo V70) with and without the low-speed automated emergency braking system (AEB and no AEB, respectively). Distributions of spare parts required for car repair were analyzed to identify car damage, and crash severity was estimated by comparing the results with laboratory crash tests. Repair costs and occupant injuries were investigated for both the striking and the struck vehicle.Results: Rear-end frontal collisions were reduced by 27% for cars with low-speed AEB compared to cars without the system. Those of low severity were reduced by 37%, though more severe crashes were not reduced. Accordingly, the number of injured occupants in vehicles struck by low-speed AEB cars was reduced in low-severity crashes. In offset crash configurations, the system was found to be less effective.Conclusions: This study adds important information about the safety performance of collision avoidance technologies, beyond the number of crashes avoided. By combining insurance claims data and information from spare parts used, the study demonstrates a mitigating effect of low-speed AEB in real-world traffic.

Analysis of crash parameters and driver characteristics associated with lower limb injury

This study aims to investigate changes in frequency, risk, and patterns of lower limb injuries due to vehicle and occupant parameters as a function of vehicle model year. From the National Automotive Sampling System-Crashworthiness Data System, 10,988 observations were sampled and analyzed, representing 4.7 million belted drivers involved in frontal crashes for the years 1998–2010.A logistic regression model was developed to understand the association of sustaining knee and below knee lower limb injuries of moderate or greater severity with motor vehicle crash characteristics such as vehicle type and model years, toepan and instrument panel intrusions in addition to the occupant’s age, gender, height and weight. Toepan intrusion greater than 2cm was significantly associated with an increased likelihood of injury (odds ratio: 9.10, 95% confidence interval 1.82–45.42). Females sustained a higher likelihood of distal lower limb injuries (OR: 6.83, 1.56–29.93) as compared to males. Increased mass of the driver was also found to have a positive association with injury (OR: 1.04, 1.02–1.06), while age and height were not associated with injury likelihood. Relative to passenger cars, vans exhibited a protective effect against sustaining lower limb injury (OR: 0.24, 0.07–0.78), whereas no association was shown for light trucks (OR: 1.31, 0.69–2.49) or SUVs (OR: 0.76, 0.28–2.02).To examine whether current crash testing results are representative of real-world NASS-CDS findings, data from frontal offset crash tests performed by the Insurance Institute for Highway Safety (IIHS) were examined. IIHS data indicated a decreasing trend in vehicle foot well and toepan intrusion, foot accelerations, tibia axial forces and tibia index in relation to increasing vehicle model year between the year 1995 and 2013. Over 90% of vehicles received the highest IIHS rating, with steady improvement from the upper and lower tibia index, tibia axial force and the resultant foot acceleration considering both left and right extremities. Passenger cars received the highest rating followed by SUVs and light trucks, while vans attained the lowest rating.These results demonstrate that while there has been steady improvement in vehicle crash test performance, below-knee lower extremity injuries remain the most common AIS 2+ injury in real-world frontal crashes.

Assessment of Child Occupant Protection in ASEAN NCAP

Statistics show that child traffic injuries are a public health problem globally, including Southeast Asia (SEA) region. With an overall value of road traffic death rate among children of 7.4 per 100,000 populations has put SEA as the second region to have the highest death rate after Africa. Due to this alarming figure, many safety interventions and inventions have been introduced and implemented to mitigate child injuries resulted from road traffic accidents. One of them is the establishment of crashworthiness rating programme for new passenger cars to evaluate the resulted child injuries via destructive tests. The New Car Assessment Programme for Southeast Asia region (ASEAN NCAP) established to elevate vehicle safety standards, raise consumer awareness and encourage market for saver vehicles in the dedicated region. Currently the programme assessed and rated passenger cars based on performance of adult and child occupant protection in frontal offset crash tests. Since its introduction, ASEAN NCAP has crash tested 28 popular passenger cars throughout its development phases. During these phases, there has been improvement on the rating of child occupant protection (COP) with the increase of number of cars getting 4-star. This paper presents the results of ASEAN NCAP tests for the development phases in term of COP rating as well as provides explanation on the related assessment.

New Car Assessment Program for Southeast Asian Countries: Current Status and Future Developments

In line with the Vehicle Pillar of the United Nations Decade of Action for Global Road Safety 2011 2020 in elevating motor vehicle safety standards and encouraging a market for safer vehicles in the region, a new car assessment program for Southeast Asian countries (ASEAN NCAP) was recently established. During the first phase of the program, seven popular car models were selected and tested according to European New Car Assessment Program (Euro NCAP) protocol on offset frontal crash test. Thus, this paper reports the results for the completed phase along with the ratings for adult and child occupant protections. Future developments of this program as well as manufacturer responses are also discussed.

New Car Assessment Program for Southeast Asian Countries (ASEAN NCAP): Vehicle Selection and Results of Phase II

New Car Assessment Program for Southeast Asian countries (ASEAN NCAP) is established with specific objective to elevate motor vehicle safety in the region. In line with United Nations Decade of Action for Global Road Safety 2011-2020 decree, the program is anticipated to influence consumer perception towards opting safer cars. This paper presents the results of ASEAN NCAP Phase II test on eleven popular models via offset frontal crash test, as well as the Adult Occupant Protection (AOP) results. This paper also includes explanation on the criteria for vehicle selection, as well as the direction for ASEAN NCAP to encompass the whole spectrum of occupant protection and vehicle crashworthiness.

Analysis of Car Deformation Effect on AIS3+ Head Injury in Frontal Crash Using Logistic Regression Modeling

The influence of vehicle deformation on the risks of head injury for the drivers involved in frontal crashes is studied using real world crash data. There are three types of vehicle damage distribution considered in this paper, namely, wide distribution, moderate offset, and small offset. The adjusted odds ratios (OR) along with 95% confidence intervals (CI) for the head injuries are estimated by logistic regression, controlling for a wide variety of confounders. Results show that occupants' head injuries are highly related to damage distribution. Small offset crash has greatest threat to head injury. Seat belt is effective in all the crash types of concern. This study provides evidences to upgrade existing frontal crash test program and clue to countermeasure development for occupant protection in different crash modes.

승합 및 경트럭의 탑승자 보호성능 평가

The fatalities rate for passenger vehicles, vans, and commercial vehicles is 1.23, 1.90 and 2.46 deaths per 10,000 registered vehicles, respectively. This shows that vans and commercial vehicles are vulnerable compare to passenger vehicles. To evaluate the crashworthiness of van and Light Truck Vehicle(LTV), we carried out frontal offset crash test at 64km/h, 40% overlap as per IIHS(Insurance Institute for Highway Safety). The test result show that LTV is very poor to protect occupant at frontal crash cause there is no safety system such as airbag and pretensioner and front end length(distance from front bumper to steering wheel) is short. One of the van rated as the lowest rating even it is equipped with airbag, cause its safety cage was collapsed during the test. This result shows that the structural integrity is very important in terms of occupant protection.

Improved car occupant safety by expandable A-pillars

There are contradictory requirements on the A-pillar of a modern passenger vehicle. The A-pillar needs to be strong to help withstand the forces, as in a rollover situation, and maintain the occupant cell integrity in rollover and high-speed offset frontal crashes. The A-pillar needs to be slim to ensure good visibility for the driver and should be light to contribute to lower fuel consumption. An ideal A-pillar, which is folded during normal operation but is expanded by high-pressure gas in a crash, resulting in a signficant increase in cross-section and strength, should combine these contradictory requirements. Such an A-pillar was developed in this project. The A-pillar was initially folded and sealed. The goal was to develop an A-pillar that was lighter, had a smaller obscuration angle and had the same level of safety for the occupant as a state-of-the-art A-pillar. Expansion and pressurisation of the folded sealed A-pillar was accomplished by generating a high internal pressure using pyrotechnics, which is a cost- and weight-efficient way to generate high pressures. The development was carried out by combining full-vehicle crash simulations with mechanical tests. The load cases used in the development of the expandable A-pillar were an offset deformable barrier crash at 64 km/h and a roof crush test according to FMVSS 216. The expandable A-pillar concept was subsequently built and mechanically tested. The A-pillar model was validated by means of mechanical testing. Generally, there was a clear correlation between the predicted A-pillar shape and the shape of the expanded mechanical A-pillar. The developed expandable A-pillar combined the goals of high strength, smaller cross-section and lower mass. The developed A-pillar reduced the obscuration angle by 25% and the mass by 8% (excluding brackets and gas generator) relative to a state-of-the-art A-pillar, while maintaining the level of safety for the occupant.

A computational investigation on the effect of vehicle rotation on driver injury metrics in frontal offset crash

The angular acceleration about the vehicular vertical axis is an important characteristic in vehicle frontal offset crash. This study developed/validated a full vehicle FE model using LS-DYNA and an ORS model using MADYMO. Deformations of interior components from experiment and theoretically derived angular acceleration were input into the ORS model. A parametric study was conducted to investigate the effect of the angular acceleration on dummy performance according to the China-NCAP frontal offset test. Results showed that major injury metrics of the dummy were significantly affected by the angular acceleration in assessing dummy driver’s potential injury when developing MADYMO ORS model.

Analysis of Lower Leg Injury of Occupant in Frontal Crash Tests Based on China NCAP Protocol

With the popularization of passenger vehicle safety devices such as safety belt, airbag and so on, the chance that occupant’s upper limbs were injured seriously was decreased significantly in frontal impact. However, the injury of occupant’s lower limbs became more and more severe, especially on lower leg injury. 37 groups of test data of China NCAP crash tests including full-frontal rigid crash and 40% offset deformable barrier crash were investigated in this paper, and lower leg injury distributing characteristic of drivers and passengers in these two kinds of crash configurations were obtained. Finally the effect rules of characteristic parameters on lower leg injury were summarized.

Seatbelt effectiveness for rear seat occupants in full and offset frontal crash tests

In Japan, it became mandatory for rear seat occupants to wear seatbelts as of 2008. This paper summarises the results of full car crash tests for rear seat occupants, and compares the kinematics and injury risk to belted and unbelted rear sear occupants in order to show the effectiveness of seatbelts. Full-width rigid barrier and offset frontal impact tests were conducted using Hybrid III fifth percentile female and 3-year-old dummies in belted or unbelted conditions in the rear seat. In both full and offset frontal tests, the injury measures of the belted fifth female and 3-year-old dummies in the rear seat were relatively low because contact with the car interior was prevented by the seatbelt, although the head injury criterion and the chest deflection of the fifth female dummy were relatively large. In the tests with the fifth female dummy not belted, its knees and head made contact with the front seatback and the head of the front seat dummy, respectively. Due to this impact by the fifth female dummy, the injury measures of the driver dummy became high. The unbelted 3-year-old dummy moved in the passenger compartment, making contact with several locations in the car. These test results were comparable with accident analyses that show high injury risks to the chest of belted rear seat occupants, and high injury risks to the head and lower extremities in unbelted rear seat occupants.

Structure Improvement of the S Beam Based on the Safety of SUV

The S beam of a production SUV appeared instable deformation in frontal crash test, which was not beneficial to occupant protection. So the deformation of S beam should be controlled to improve the crashworthiness. Inner improvement structures were proposed according to the prototype S beam. A frontal crash FE model and a multi-rigid body model were developed and validated to investigate the crash safety of frontal impact. The influences of the improvements to the deformation of S beam and the energy absorption of longitudinal beams were analyzed by the FE model, and the injury risks of head and thoraces were analyzed by the multi-rigid body model. The better improvement structure was adopted in the frame for the crash test to validate the effectiveness of improved scheme, and the result shows better crash performance of frontal impact for prototype vehicle. Meanwhile, simulation study on crash safety of 40% offset crash were also conducted, which indicated that improved scheme was also beneficial for crash safety of 40% offset crash.

Crash Test Ratings and Real-World Frontal Crash Outcomes: A CIREN Study

To establish whether the Insurance Institute for Highway Safety (IIHS) offset crash test ratings are linked to different mortality rates in real world frontal crashes. The study used Crash Injury Research Engineering Network drivers of age older than 15 years who were involved in frontal crashes. The Crash Injury Research Engineering Network is a convenience sample of persons injured in crashes with at least one Abbreviated Injury Scale score of 3+ injury or two Abbreviated Injury Scale score of 2+ injuries who were either treated at a Level I trauma center or died. Cases were grouped by IIHS crash test ratings (i.e., good, acceptable, marginal, poor, and not rated). Those rated marginal were excluded because of their small numbers. Mortality rates experienced by these ratings-based groups were compared using the Mantel-Haenszel chi test. Multiple logistic regression models were built to adjust for confounders (i.e., occupant, vehicular, and crash factors). A total of 1,226 cases were distributed within not rated (59%), poor (12%), average (16%), and good (14%) categories. Those rated good and average experienced a lower unadjusted mortality rate. After adjustment by confounders, those in vehicles rated good experienced a lower risk of death (adjusted OR 0.38 [0.16-0.90]) than those in vehicles rated poor. There was no significant effect for "acceptable" rating. Other factors influencing the occurrence of death were age, DeltaV >or=70 km/h, high body mass index, and lack of restraint use. After adjusting for occupant, vehicular, and crash factors, drivers of vehicles rated good by the IIHS experienced a lower risk of death in frontal crashes.

범퍼체결구조 개선을 통한 손상성․수리성 향상방안에 관한 연구

본 연구의 목적은 저속충돌에서 승용차량의 범퍼체결구조를 분석하기 위한 것이다. 차량의 손상성?수리성 향상 연구를 위해 범퍼체결구조가 서로 상이한 3개 차종에 대해 RCAR(세계자동차 수리기술위원회)의 저속충돌시험(전,후면 40% 오프셋 충돌시험) 기준을 적용하였다. 시험결과 충격흡수능력은 직사각형 단면형상을 가지고 그 부분이 범퍼레일에 삽입되는 크래시박스식의 범퍼스테이가 대부분의 차량에 적용되고 있는 다른 두 유형의 범퍼체결구조에 비해 우수하게 나타났다. 우수하게 설계된 직사각형 단면형상을 가지는 범퍼체결구조가 저속충돌사고 시 차량의 손상성?수리성을 향상시킴으로써 승객의 안전성도 강화시킬뿐만 아니라 수리비 절감에도 기여할 수 있다는 것이 본 연구에서 입증되었다.

Preventing Passenger Vehicle Occupant Injuries by Vehicle Design—A Historical Perspective from IIHS

Motor vehicle crashes result in some 1.2 million deaths and many more injuries worldwide each year and is one of the biggest public health problems facing societies today. This article reviews the history of, and future potential for, one important countermeasure—designing vehicles that reduce occupant deaths and injuries. For many years, people had urged automakers to add design features to reduce crash injuries, but it was not until the mid-1960s that the idea of pursuing vehicle countermeasures gained any significant momentum. In 1966, the U.S. Congress passed the National Traffic and Motor Vehicle Safety Act, requiring the government to issue a comprehensive set of vehicle safety standards. This was the first broad set of requirements issued anywhere in the world, and within a few years similar standards were adopted in Europe and Australia. Early vehicle safety standards specified a variety of safety designs resulting in cars being equipped with lap/shoulder belts, energy-absorbing steering columns, crash-resistant door locks, high-penetration-resistant windshields, etc. Later, the standards moved away from specifying particular design approaches and instead used crash tests and instrumented dummies to set limits on the potential for serious occupant injuries by crash mode. These newer standards paved the way for an approach that used the marketplace, in addition to government regulation, to improve vehicle safety designs—using crash tests and instrumented dummies to provide consumers with comparative safety ratings for new vehicles. The approach began in the late 1970s, when NHTSA started publishing injury measures from belted dummies in new passenger vehicles subjected to frontal barrier crash tests at speeds somewhat higher than specified in the corresponding regulation. This program became the world's first New Car Assessment Program (NCAP) and rated frontal crashworthiness by awarding stars (five stars being the best and one the worst) derived from head and chest injury measures recorded on driver and front-seat test dummies. NHTSA later added side crash tests and rollover ratings to the U.S. NCAP. Consumer crash testing spread worldwide in the 1990s. In 1995, the Insurance Institute for Highway Safety (IIHS) began using frontal offset crash tests to rate and compare frontal crashworthiness and later added side and rear crash assessments. Shortly after, Europe launched EuroNCAP to assesses new car performance including front, side, and front-end pedestrian tests. The influence of these consumer-oriented crash test programs on vehicle designs has been major. From the beginning, U.S. NCAP results prompted manufacturers to improve seat belt performance. Frontal offset tests from IIHS and EuroNCAP resulted in greatly improved front-end crumple zones and occupant compartments. Side impact tests have similarly resulted in improved side structures and accelerated the introduction of side impact airbags, especially those designed to protect occupant's heads. Vehicle safety designs, initially driven by regulations and later by consumer demand because of crash testing, have proven to be very successful public health measures. Since they were first introduced in the late 1960s, vehicle safety designs have saved hundreds of thousands of lives and prevented countless injuries worldwide. The designs that improved vehicle crashworthiness have been particularly effective. Some newer crash avoidance designs also have the potential to be effective—e.g., electronic stability control is already saving many lives in single-vehicle crashes. However, determining the actual effectiveness of these new technologies is a slow process and needs real-world crash experience because there are no assessment equivalent of crash tests for crash avoidance designs.

Effectiveness and evaluation of SEAS of SUV in frontal impact

A sport utility vehicle (SUV) is inclined to have high-ground clearance of its longitudinal structural members from which a vertical mismatch can occur when colliding with cars. Some SUVs have a secondary energy absorbing structure (SEAS) to compensate for the mismatch by improving its structural interaction with cars during a crash. To examine the effectiveness of the SEAS of an SUV, vehicle-to-vehicle frontal offset crash tests of an SUV (with and without SEAS) were conducted against small cars. These tests demonstrated that the SEAS was effective, as the test of the SUV with the SEAS had improved engagement with the structures (and associated lower longitudinal deformations) of the small car, even though there was a lateral mismatch between the SUV's SEAS and the car's longitudinal structural member. A method to evaluate the SEAS of an SUV also was examined on the basis of the barrier force distribution in full-width rigid and deformable barrier tests. In the rigid barrier test, the SEAS could not be detected in the barrier force. In the full-width deformable barrier test a force was observed in the row of the load cells where the SEAS made contact. On the basis of these tests, it was demonstrated that the SEAS of the SUV can be detected and evaluated in full-width deformable barrier tests.