Browse Topic: Crashworthiness

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Towards Crash-Tolerant Rotorcraft Design via Topology OptimizationF-0081-2025-02325/20/2025
We present our ongoing efforts towards the development of crash-tolerant rotorcraft airframe structures through topology optimization, with the goal of enhancing energy absorption and occupant survival during vertical impact events. A high strain rate explicit dynamics solver has been developed, fully accelerated on GPUs, to enable rapid and accurate simulation of impact events critical to crashworthiness evaluation. In parallel, we have built a scalable three-dimensional topology optimization framework that enforces stiffness, weight, and frequency constraints simultaneously, driving structurally efficient and vibration-resistant designs. Benchmarking results demonstrate significant GPU-enabled speedups, facilitating high-fidelity crash simulations and large-scale optimization at practical turnaround times. This work establishes a computational foundation for future integration of crash-centric objectives and constraints into the optimization framework.
Das, Ghanendra, James, Kai, Kennedy, Graeme, Webb, Lonnie, Oluwalana, Daniel
Impact of Harness Integrated Crash RestraintsF-0081-2025-02705/20/2025
The Crashworthy and Escape Systems Branch at NAWCAD has been developing an integrated restraint harness concept for several years, with the intent of developing a novel method of providing improved occupant protection in a crash scenario. A series of tests was conducted on the Horizontal Accelerator at NAS Patuxent River to evaluate the performance of the prototype integrated-restraint system under MIL-STD-58095 conditions with the 50th percentile male Hybrid III Anthropomorphic Test Device (ATD). While occupant flail was the primary metric being analyzed in this effort, ATD instrumentation was also captured, showing that the integrated restraint system demonstrated a significant reduction in head flail compared to five-point restraints while maintaining injury criteria within acceptable levels.
Anderson, Eric, Minnich, Shannon
Test and Analysis Methodology for Validating Crashworthiness of AW609 TiltrotorF-0078-2022-175035/10/2022
ABSTRACT
Anghileri, Marco, Miller, Ryan, DiRenzo,  Andrea, Waterman,  Jim, Turconi,  Fabrizio
Crashworthiness of a Lift plus Cruise eVTOL Vehicle Design within Dynamic Loading EnvironmentsF-0076-2020-1625810/5/2020
To aid in the development of electric Vertical Take-off and Landing (eVTOL) technology, the National Aeronautics and Space Administration has undertaken research initiatives to evaluate and optimize design features of eVTOL aircraft. One such initiative has been to develop energy attenuating design mechanisms to improve eVTOL vehicle crashworthiness. In this study, crashworthiness design mechanisms, implemented within a six-passenger lift plus cruise (LPC) eVTOL concept vehicle, were evaluated under multi-axis dynamic loading conditions. This work builds upon crashworthiness design concepts previously optimized within a simplified vehicle-loading environment. The results of this study found the effectiveness of energy attenuating design mechanisms to be dependent on the complexity of load environment in which they were employed. An increase in off-axis loading resulted in a decrease in occupant protective capability. These results indicate the necessity for evaluating vehicle design across the range of possible dynamic impact conditions to characterize crashworthiness. This work provides preliminary methodology for implementing energy attenuating design mechanisms and evaluating crashworthiness for future UAM markets.
Putnam, Jacob, Littell, Justin
Likelihood of Spinal Disc Herniations in Occupants Involved in Real World Side Impacts2020-01-05264/14/2020
The prevalence of spinal disc herniations in people with no spinal symptoms have been reported to increase with age; from about 20% in those below 40 years to about 30% in those above 40 years. Spinal disc herniations are usually associated with degenerative changes. Though rare, spinal disc herniations can also be caused by trauma. With an increasing number of older people on U.S. roads with a concomitant increase in the probability of getting injured in a vehicle collision, it is reasonable to expect that some of these occupants can present with clinical findings of spinal disc herniations after a side impact, and attribute these findings to the impact. In this study, we looked at the relationship between real world side impacts and the occurrence of spinal injuries, in particular disc herniations, in occupants involved in such impacts. We examined the reported occurrence of all spine injuries in side impact crashes in the National Automotive Sampling System - Crashworthiness Data System (NASS-CDS) database from 1993 through 2014. There were over 8,400 adult raw case occupants, corresponding to a weighted number of approximately 4.7 million that fit the inclusion criteria. The results showed that the most common spine injury in side impact is acute muscle strain of the cervical spine, followed by acute muscle strain of the lumbar spine. The total number of occupants with reported spinal disc herniations was only three; all from near-side impacts. The low prevalence of reported spinal disc herniations stands in sharp contrast to a background prevalence of 20% to 30% in asymptomatic individuals. The findings from the real world data in this study, in light of known spinal responses in experiments conducted on post-mortem human subjects (PMHSs) and anthropomorphic test devices (ATDs) exposed to near- and far-side impacts, suggest that side impacts do not present a mechanism of traumatic disc herniation.
Lam, Tack, Ivarsson, B. Johan
The Effects of Front-Mounted Accessories on Air Bag Sensors and CrashworthinessJ2431_201910 (Current)10/9/2019
Almost all light trucks now are being manufactured with at least a driver side air bag and all will have dual air bags by 1998. The driving forces behind this feature are occupant safety, federal regulations, and competition in the industry. Along with the booming popularity of pickups and SUVs, they are commonly accessorized with a wide variety of products. Many accessories for four-wheel drives in particular are mounted on the front of the vehicle. These products include grille/brush guards, winches, snow plows, replacement bumpers, bicycle carriers, etc. Concerns have arisen over the compatibility of these accessories with the vehicle’s air bag system. The vehicle manufacturers are concerned because of their huge investment in design and crash test verification of the complete vehicle system and keen awareness of the federal regulations. The crushability of the front bumper and supporting structure are key elements in the system, so alterations to that area become logical concerns. The accessory manufacturers, dealers, and installers are concerned because the very core of their business could be at risk. The unknowns can range from fear of setting off an airbag while working on the vehicle to liability issues in an injury accident situation. In some cases, the installation of the product is contrary to recommendations from the vehicle manufacturer and may void the warranty. The ultimate customers (end users) are in a unique situation and are not being well served in some situations. Their dilemma stems from the conflict between what a manufacturer is willing to certify for sale and what the customer needs and expectations are. Their needs in vehicle equipment can vary widely from making a living to recreational lifestyle issues to simplify the desire to individualize. The precedent for front-mounted accessories is well established. The customers for both the vehicle and the equipment are there, so finding ways for them to coexist safely is beneficial to all.
Motor Vehicle Council
Safety Testing for AVs is Just Beginning19AVEP03_093/1/2019
There is much work to be done in creating accurate, reliable tests for occupant crashworthiness tailored to new AV designs and seating configurations. NHTSA's plan to eventually update its New Car Assessment Program (NCAP) with new crash-test protocols is good news for both consumers and the mobility safety-systems industry. A revised NCAP will likely feature enhanced occupant safety testing as well as testing of active-safety features such as adaptive cruise control and automatic braking. It's also a positive step for autonomous vehicle (AV) developers. Studies show U.S. consumers are still resistant to the idea of self-driving cars, and such testing will provide the public with assurances that these vehicles are safe. This should serve to “warm up” consumers to the idea of a world with AVs, boosting demand and paving the way for an increasingly safer mobility future.
O'Connor, Christopher
Evaluation of Lumbar-Load Criterion Based on Test Data and Field Performance Results of the UH-60 Black Hawk Crew SeatF-0074-2018-127395/14/2018
ABSTRACT The BAE Systems legacy UH-60A/L Black Hawk Crew Seat has been in serial production for almost 40 years, and has garnered a reputation for providing a high degree of crash safety to its occupants. The seat has been dynamically tested over 150 times, providing a wealth of test data that are summarized in this paper. This paper also presents a review of data from actual UH-60A/L crashes that verifies the seat's excellent performance with regards to minimizing occupant compressive spinal injuries. In addition, this paper presents a compilation of test data containing ATD lumbar-load readings. The dynamic test results are then compared to the lumbar-load limits specified in JSSG-2010-7 and the more recent Full Spectrum Crashworthiness (FSC) Criteria for Rotorcraft. This comparison shows that the seat most likely would not have passed the FSC criteria, which indicates that either the FSC lumbar-load limits are set too low, or that the dynamic test pulses do not replicate the actual crash environment. The JSSG criteria were found to be a better predictor of the seat's actual crash performance.
Richards, Marvin
Automotive Crashworthiness Design Optimization Based on Efficient Global Optimization Method2018-01-10294/3/2018
Finite element (FE) models are commonly used for automotive crashworthiness design. However, even with increasing speed of computers, the FE-based simulation is still too time-consuming when simulating the complex dynamic process such as vehicle crashworthiness. To improve the computational efficiency, the response surface model, as the surrogate of FE model, has been widely used for crashworthiness optimization design. Before introducing the surrogate model into the design optimization, the surrogate should satisfy the accuracy requirements. However, the bias of surrogate model is introduced inevitably. Meanwhile, it is also very difficult to decide how many samples are needed when building the high fidelity surrogate model for the system with strong nonlinearity. In order to solve the aforementioned problems, the application of a kind of surrogate optimization method called Efficient Global Optimization (EGO) is proposed to conduct the crashworthiness design optimization. Based on few samples, the initial Kriging models are constructed. Then the new sample found by the expected improvement criterion (EI) is employed to update the Kriging models in each subsequent loop iteration. Since the expected improvement criterion can balance the global search and local search, a global optimal design will be found after several iterations. Thus, EGO will reduce the number of computationally expensive evaluations while achieving the desired optimal design. The application of the EGO on vehicle crashworthiness design is demonstrated through a case of vehicle low speed crash design. And a comparison study between the EGO and traditional surrogate model based crashworthiness design optimization method indicates that the EGO method is more effective in crashworthiness design.
Fang, Yudong, Chen, Tao, Zhan, Zhenfei, Liu, Xu, Yu, Huili, Zhao, Hui
Investigation of the Samples Size Effects on Hybrid Surrogate Model Component Surrogates for Crashworthiness Design2018-01-10284/3/2018
Surrogate model based design optimization has been widely adopted in automotive industry. Hybrid surrogate model with multiple component surrogates is considered to be a better choice when simulating highly non-linear responses in vehicle crashworthiness analysis. Currently, the number of component surrogates has to be decided before-hand when constructing of a hybrid surrogate model. This paper conducts a comparative study on the performances of three popular hybrid modeling methods including heuristic computation strategy, and two kinds of optimal weighted surrogates. The effects of samples size on the number of individual surrogates that should be included into the final hybrid surrogate models for crashworthiness responses are investigated. Different hybrid modeling techniques and multiple validation criteria are evaluated. Some observations and conclusions on the selection of component surrogates in hybrid surrogate modeling are given in the end.
Chen, Chong, Zhan, Zhenfei, Dong, Wenxiang, YU, Huili, Zhao, Hui
Studies on Impact Performance of Gradient Lattice Structure Applied to Crash Box2018-01-01194/3/2018
The conventional crash box with thin-walled column conceals some limitations on pedestrian protection and lightweight. The metallic NPR metamaterials designed in this study are based on re-entrant lattice structures. Re-entrant structures are known to be one main class of axenic structures that display negative Poisson’s ratio (NPR), which can be manufactured by 3D printing technology. This kind of metamaterial has good designability and can be used as the filling structure of the crash box to improve the crashworthiness of the car. This paper starts from the relations between geometric parameters of the metamaterial. Considering the deformation characteristics of the crash box, the structure were designed into some gradient types. The mechanical properties of different gradient structures under the same impact conditions were compared to find the proper gradient structures. Based on the studies, the gradient lattice structure is applied to the automobile crash box. We made some simulation by the finite element software LS-DYNA of vehicle head-on collision. We compared the crashworthiness of the cars which have different crash boxes. The accelerations of some key points in the crew compartment were measured. Also, we compared the energy absorption efficiency of the boxes. We came to the conclusion that the gradient lattice structure can efficiently improve the structural crashworthiness criteria of the thin-walled column and also achieve better pedestrian protection of the vehicle structure. Because the lattice structure has good impact performance, some other vehicle structures which need to have a good impact behavior can also be replaced by it .
Wu, Xian, Zhang, Shuxian, Shao, Jianwang
Effects of AHSS Sheared Edge Conditions on Crash Energy Absorption in Component Bend Test2018-01-01134/3/2018
Edge fracture of advanced high strength steels (AHSS) can occur in both the stamping process and the crash event. Fracture due to poor sheared edge conditions in the stamping process was reduced with a recently developed optimal shearing process for AHSS. Currently, the improvement in the energy absorption due to the improved edge condition during crashes performed under different loading conditions had not been closely verified. The purpose of this study is to design and build a miniature component of AHSS and a three-point bending test for investigating the influence of various conditions of the sheared edge on the energy absorption in crashes. AHSS including DP600, TRIP780, DP980 and DP1180 were selected in the study. A small channel component was developed and fabricated using DP980 to simulate key features of the B-pillar. The exposed non-constrained, as-sheared edge was subject to stretch bending forces in three-dimensional space during the three-point bending test. Two bottom rollers equipped in the three-point bending test allowed the test specimen to bend freely without generating extra friction force between the test material and tooling. Previously developed shearing parameters were fine-tuned for generating the test specimen on the flexible shearing machine and then compared to the specimens made by water jet cutting and laser cutting. A life cycle analysis was also conducted by FEA to evaluate the new design of the shear blade. The experiment results indicate the improvement of the sheared edge conditions can also increase the material energy absorption in crashes. The laser cut sample has the best energy absorption capability, while the conventional cutting edge shows the worst. In addition to the three-point bending test, a wedge bend test was conducted on the flat sample and reached a similar energy absorption trend as in the component bend test. The wedge bend test on flat sample is recommended for baseline comparison in material bendability and crash energy absorption capability among different advanced high strength steels.
Shih, Hua-Chu, Chen, Guofei
Analyses on Mechanical Properties of the Cylindrical Double-V Micro-Structure2018-01-01184/3/2018
The double-V micro-structures (DVMS) are a type of auxetic materials showing the negative Poisson’s ratio which can contract under compression different from the conventional materials. Due to the unique properties, it can have higher stiffness and better impact resistance with lightweight. In this paper, a cylindrical honeycomb tube based on the double-V unit cell is proposed. Firstly, the nominal Poisson’s ration and Young’s modulus in the longitudinal and circumferential directions are derived analytically. The effect of the geometry parameters of the DVMS tube on the mechanical properties is studied thoroughly. Also, the effect of the width in the radial direction on these mechanical properties is analyzed. Secondly, the finite element (FE) method is utilized to obtain the numerical solutions and verify the accuracy of the analytical solutions. The results show that there is a good agreement between the results obtained by the two methods when the width is smaller enough. With the width in a radial direction increasing, the difference between two solutions begins to appear and grow. Therefore, an adjust function related to the inner and outer radius needs to be introduced to improve the accuracy of the analytical prediction.
Gao, Qiang, wang, Yuanlong, Ma, Zheng-Dong, Zhong, Hong
Next Generation Smart Crashworthy Crew SeatsF-0072-2016-114155/17/2016
The next generation smart crashworthy crew seats will need to include design features that provide an enhanced level of crash safety while reducing the crew discomfort during long military missions. This paper presents the results from the Active Crash Protection Systems Enhancements II Program jointly funded by the U.S. Army Aviation Development Directorate - Aviation Applied Technology Directorate (ADD-AATD) and The Boeing Company under a Technology Investment Agreement. During this program a prototype crew seat design concept with actively-controlled seat energy absorbers was developed and integrated with an aircraft active crash protection system. The actively-controlled seat energy absorber technology developed enables automatic adjustment of the stroking load of the energy absorbers based on the occupant weight, available seat stroke, and the predicted crash impact conditions in order to provide an increased level of crash safety to the crew. The paper also includes results and recommendations from a crew seat ergonomic design study conducted to reduce crew discomfort during long missions.
Bolukbasi, Akif
Optimal Design of Cellular Material Systems for Crashworthiness2016-01-13964/5/2016
This work proposes a new method to design crashworthiness structures that made of functionally graded cellular (porous) material. The proposed method consists of three stages: The first stage is to generate a conceptual design using a topology optimization algorithm so that a variable density is distributed within the structure minimizing its compliance. The second stage is to cluster the variable density using a machine-learning algorithm to reduce the dimension of the design space. The third stage is to maximize structural crashworthiness indicators (e.g., internal energy absorption) and minimize mass using a metamodel-based multi-objective genetic algorithm. The final structure is synthesized by optimally selecting cellular material phases from a predefined material library. In this work, the Hashin-Shtrikman bounds are derived for the two-phase cellular material, and the structure performances are compared to the optimized structures derived by our proposed framework. In comparison to traditional structures that made of a single cellular phase, the results demonstrate the improved performance when multiple cellular phases are used.
Liu, Kai, Xu, ZongYing, Detwiler, Duane, Tovar, Andres
Development of Beam Elements for Crashworthiness Analysis of Thin-Walled Beam Structures2016-01-04014/5/2016
In this paper, a new beam element is developed for the purpose of capturing thin-walled beam’s collapse mechanisms under dynamic load such as impact load and will be validated in the next phase. Such beam element can be used to create simplified finite element models for crashworthiness analysis and simulation and, therefore, will significantly reduce the modeling effort and computing time. The developed beam element will be implemented into LS-DYNA and validated through crashworthiness analysis and simulation. This paper introduces the approach of deriving the new element formulation.
Liu, Yucheng
Crushing Analysis and Lightweight Design of Tapered Tailor Welded Hybrid Material Tubes under Oblique Impact2016-01-04074/5/2016
The increasing demand for lightweight design of the whole vehicle has raised critical weight reduction targets for crash components such as front rails without deteriorating their crash performances. To this end the last few years have witnessed a huge growth in vehicle body structures featuring hybrid materials including steel and aluminum alloys. In this work, a type of tapered tailor-welded tube (TTWT) made of steel and aluminum alloy hybrid materials was proposed to maximize the specific energy absorption (SEA) and to minimize the peak crushing force (PCF) in an oblique crash scenario. The hybrid tube was found to be more robust than the single material tubes under oblique impacts using validated finite element (FE) models. Compared with the aluminum alloy tube and the steel tube, the hybrid tube can increase the SEA by 46.3% and 86.7%, respectively, under an impact angle of 30°. Parameter analyses were performed to reveal the influence of four geometrical variables on the crashworthiness of the TTWTs. In addition, the radial basis function (RBF) metamodels were built for the SEA and PCF of the TTWTs, while the non-dominated sorting genetic algorithm (NSGA-II) was used to achieve the optimal solutions of the tube under oblique impact loads. The results show that the optimal solutions are different under different load angles and the solutions considering multiple load angles show more robust crashworthiness performance against oblique impacts. The proposed tapered hybrid tube has a potential application on vehicle bodies with improved crash performances under oblique loads.
Wang, Da-Zhi, Cao, Guang-Jun, Qi, Chang, Sun, Yong, Yang, Shu, Du, Yu
Behavior of Adhesively Bonded Steel Double Hat-Section Components under Axial Quasi-Static and Impact Loading2016-01-03954/5/2016
An attractive strategy for joining metallic as well as non-metallic substrates through adhesive bonding. This technique of joining also offers the functionality for joining dissimilar materials. However, doubts are often expressed on the ability of such joints to perform on par with other mechanical fastening methodologies such as welding, riveting, etc. In the current study, adhesively-bonded single lap shear (SLS), double lap shear (DLS) and T-peel joints are studied initially under quasi-static loading using substrates made of a grade of mild steel and an epoxy-based adhesive of a renowned make (Huntsman). Additionally, single lap shear joints comprised of a single spot weld are tested under quasi-static loading. The shear strengths of adhesively-bonded SLS joints and spot-welded SLS joints are found to be similar. An important consideration in the deployment of adhesively bonded joints in automotive body structures would be the performance of such joints under impact loading. Due to the brittle nature of adhesively-bonded joints as compared to conventional joining techniques especially welding, the viability of such joints for meeting vehicle crashworthiness requirements has been suspect. In the current study, with the aid of the same steel sheet metal and adhesive used in the joint coupon tests, the performance of adhesively bonded double hat-sections components is compared with that of conventional spot-welded double hat-section components under axial quasi-static loading and impact loading in an instrumented drop-weight test set-up. It is noticed that although nearly complete separation of adhesively bonded flanges resulted in impact tests, these components never-the-less performed admirably well in terms of crash metrics such as mean load and energy-absorption capability. It is also shown that for a combination of discontinuous adhesive bonding and sparse spot-welds with double the pitch of conventional spot-welds, not only the crash performance in terms of the metrics mentioned is assured, but the fear of premature collapse due to complete separation of purely adhesively bonded flanges is avoided.
Deb, Anindya, Chou, Clifford C., Srinivas, Gunti R., Gowda, Sanketh, Kurnool, Goutham
Uncertainty Optimization of Thin-walled Beam Crashworthiness Based on Approximate Model with Step Encryption Technology2016-01-04044/5/2016
Crashworthiness is one of the most important performances of vehicles, and the front rails are the main crash energy absorption parts during the frontal crashing process. In this paper, the front rail was simplified to a thin-walled beam with a cross section of single-hat which was made of steel and aluminum. And the two boards of it were connected by riveting without rivets. In order to optimize its crashworthiness, the thickness (t), radius (R) and the rivet spacing (d) were selected as three design variables, and its specific energy absorption was the objective while the average impact force was the constraint. Considering the error of manufacturing and measurements, the parameters σs and Et of the steel were selected as the uncertainty variables to improve the design reliability. The algorithm IP-GA and the approximate model-RBF (Radial Basis Function) were applied in this nonlinear uncertainty optimization. In order to improve the accuracy of the RBF model, a new step-encryption technology was proposed, in which the encryption points will be added to the current sample points according to the results of each iteration. As a result, when the uncertainty level was 5%, the optimal design vector [t, R, d] was [1.75mm, 3.25mm, 29.48mm], and the possible interval of the specific energy absorption was [841J/kg, 1028J/kg] while the possible interval of constraint was [49.12KN, 71.39KN]. And the optimum was verified with the exact solver. Therefore, this study can provide important references for the crashworthiness design of the front rails.
Du, Qianqian
CFRP Crash Absorbers in Small UAV: Design and Optimization2015-01-24619/15/2015
The high number of hull losses is a main concern in the UAV field, mostly due to the high cost of on-board equipment. A crashworthiness design can be helpful to control the extent and position of crash impact damage, minimizing equipment losses. However, the wide use of composite materials has recently put the accent on the lack of data about the behavior of these structures under operative loads, such as the crash conditions. This paper presents the outcome of a set of tests carried out to achieve a controlled crush of UAV structures, and to maximize the Specific Energy Absorption. In this work, a small-scale experimental test able to characterize the energy absorption of a Carbon-fiber-reinforced polymer under compression was developed introducing self-supporting sinusoidal shape specimens, which avoid the need for complex anti-buckling devices. The specimens were produced with different auto-triggering configurations and fibers' continuity was interrupted in selected position and for different extent in order to investigate the Specific Energy Absorption of the weakened laminates. The auto-triggering configuration was able to control the position of the initial failure of the specimen without any decrease in safety performance. This new kind of very light crash absorber can be used in small UAV to reduce the crash loads in the avionic and payload bay. With reference to a small UAV designed and manufactured at University of Bologna, an optimization of the crash absorbers positions has been carried out in order to achieve the best results in terms of energy dissipation.
Troiani, Enrico, Falaschetti, Maria Pia, Taddia, Sara, Ceruti, Alessandro
Selectable Profile Energy Absorber System for Rotorcraft Troop SeatsF-0071-2015-101395/5/2015
ABSTRACT A selectable profile energy absorber (SPEA) system was developed for crashworthy helicopter troop seats. This system combines information from an on-seat sensor and the aircraft data bus to tailor the energy absorber force profile not only to the weight of the occupant, but also to the predicted crash severity. The development testing was conducted using a vertical seat orientation on a drop tower under the U.S. Army Aircrew Survivability Technologies Project. This second Transport Rotorcraft Airframe Crash Testbed (TRACT 2) presented the opportunity for Safe, Inc. to independently test the SPEA system on a troop seat in an airframe undergoing a combined vertical and forward crash impact. The SPEA system is designed to use the lowest possible EA force profile considering the available stroking distance. Despite a component failure, the SPEA delivered a peak lumbar force of 572 lbf in a 50th-percentile male ATD and stroked 10 of an available 12 inches.
Desjardins, Stanley, Labun, Lance, Woodhouse, Jin, Belden, Leda
Laboratory and Field Evaluations of Textile Energy Absorbers for Crashworthy Cargo RestraintsF-0071-2015-101405/5/2015
ABSTRACT Improvement of cargo tie-down systems is of utmost importance to help ensure rotorcraft crew safety in the event of a hard but survivable crash or hard landing. To this end, various load-limiting, energy-absorbing devices, placed in-line with conventional tie-down hardware such as straps and chains, have been evaluated for their ability to prevent the complete failure of a tie-down and the unconstrained movement of cargo in the vicinity of nearby personnel and structure during a high-acceleration event. The current investigation aims to further this line of exploration by evaluating the performance of textile-based energy absorbing devices in well-controlled laboratory experiments using a horizontal sled and in field experiments using crash-tests of CH-46 hulks. Textile-based energy absorbers of a capacity suitable for rotorcraft tie-down systems are shown to behave as designed in both types of experiments. The devices prevented the failure of a simulated tie-down point in accelerative environments that failed the tie down point in the absence of an energy absorber.
Little, Eric, Bakis, Charles, Bark, Lindley, Yukish, Michael, Miller, Simon, Smith, Edward, Willis, Robert
Multi-Criteria Optimization of Foam Reinforced Thin-walled Tube Shape under Crashworthiness Requirements2015-01-13644/14/2015
The design of aluminum foam reinforced thin-walled tubes has garnered much interest recently due to the high energy absorption capacity of these tubes. As a new kind of engineering composite material, aluminum foam can hugely increase the crashworthiness capacity without sacrificing too much weight. In this paper, axisymmetric thin-walled hollow tubes with four different kinds of cross-sections (circular, square, hexagonal and octagonal) are studied to assess their performance for crashworthiness problems. It is found that the tube with square cross-section has the best crashworthiness performance under axial impact. To seek optimal designs of square aluminum foam reinforced thin-walled tubes, a surrogate modeling technique coupled with a multi-criteria particle swarm optimization algorithm has been developed, to maximize specific energy absorption (SEA) and minimize peak crash force (PCF). To improve the accuracy of the optimization process, meta-models of SEA and PCF were constructed using the response surface method and radial basis function method, respectively. Crash simulations carried out using LS-DYNA demonstrate that the optimal design has better crashworthiness characteristics than the baseline design. These results suggest that the proposed method can be of benefit in design optimization for other crashworthiness problems.
Wang, Tao, Wang, LIangmo, Wang, Yuanlong, Zou, Xiaojun, Guo, Fuxiang
Fracture Prediction for Automotive Bodies Using a Ductile Fracture Criterion and a Strain-Dependent Anisotropy Model2015-01-05674/14/2015
In order to reduce automobile body weight and improve crashworthiness, the use of high-strength steels has increased greatly in recent years. An optimal combination of both crash safety performance and lightweight structure has been a major challenge in automobile body engineering. In this study, the Cockcroft-Latham fracture criterion was applied to predict the fracture of high-strength steels. Marciniak-type biaxial stretching tests for high-strength steels were performed to measure the material constant of the Cockcroft-Latham fracture criterion. Furthermore, in order to improve the simulation accuracy, local anisotropic parameters based on the plastic strain (strain dependent model of anisotropy) were measured using the digital image grid method and were incorporated into Hill's anisotropic yield condition by the authors. In order to confirm the validity of the Cockcroft-Latham fracture criterion, uniaxial tensile tests were performed. It was found that the accuracy of the predicted rupture strain was improved if the local anisotropic r-value was used. To predict failure and force-stroke curve in collision phenomena, the Cockcroft-Latham fracture criterion, considering the local anisotropic r-value, was applied to three-point bending tests. The simulated results showed that the fracture locus of hat-shaped section and force-stroke curves were accurately predicted.
Takada, Kenji, Sato, Kentaro, Ma, Ninshu
Simulation Fidelity Improvement of H350 Lower Tibia Indices2015-01-05784/14/2015
Finite element dummy models have been more and more widely applied in virtual development of occupant protection systems across the automotive industry due to their predictive capabilities. H350 dyna dummy model [1] is a finite element representation of the Hybrid III male dummy [2], which is designed to represent the average of the United States adult male population. Lower extremity injuries continue to occur in front crash accidents despite increasing improvement of vehicle crashworthiness and occupant restraint system. It is therefore desirable to predict lower tibia injury numbers in front occupant simulations. Though lower tibia loading/index predictions are not studied as much as the FMVSS 208 regulated injury numbers, the tibia indices are injury criteria that need to be assessed during IIHS and Euro NCAP frontal offset occupant simulations. However during front crash simulations, it is very difficult to achieve good correlations or predictions of lower tibia loadings. A common issue is that the simulations often over-predict lower tibia loading (forces and/or moments) and in turn generate unrealistically higher tibia indices. For this reason, safety CAE engineers are not yet confident in presenting correlations or predictions of the lower tibia loadings/indices. This paper employs Pugh Concept Selection to study the effects of dummy foot location and carpet to sled buck floor interaction on the lower tibia loading/index response. Based on the understanding gained, improvements in the simulation fidelity of lower tibia indices were achieved. Additionally, these findings demonstrate that overall dummy performance is affected by the lower tibia index differences.
Li, Wei, Cheng, Yi-Pen, Furton, Lisa
An Investigation into the Effects of Body-borne Equipment on Occupant Injury Under Simulated Vertical Impact with Seat 'Bottom-out'F-0070-2014-94745/20/2014
Over recent years, military personnel have been required to carry increasing amounts of equipment, raising the overall mass of the occupant. A crashworthy seat is designed to a specified mass range, including equipment; and only provides energy absorption protection to the occupant within its designed mass and velocity range. If the increased mass causes the impact energy to be excessive, a phenomenon called bottoming out will occur when the seat stroking mechansim is exhausted and the occupant is exposed to excessive and likely injurous loads. In this study, an 8-degree-of-freedom mass-spring-damper system was modelled to represent an occupant with body-borne equipment and simulated under a crash test. Equations to represent a fixed load energy absorption device on a seat and a spring stiffness to characterize bottoming out were developed. The model was solved using the fourth-order-Runge-Kutta method in Matlab and the results indicate that with increased equipment mass, bottoming out will occur and the accelerations experienced by the occupant will increase significantly. This model can be used to analyse the loading affects at a number of locations on the occupant when experiencing bottoming out.
Thomson, Rodney, Aggromito, Daniel, Chen, Bernard, Yan, Wenyi, Wang, John
Performance of CH-46 Pilot seats in NASA Full Scale Crash TestF-0070-2014-94805/20/2014
This paper analyzes the performance of two CH-46 crew seats that were included in the full-scale CH-46 airframe crash test conducted on 28 August 2013 at the NASA Langley Research Center. The CH-46 crashworthy armored crew seat is an adaption of the H-53 Sea Stallion crashworthy armored crew seat and was qualified by similarity. During the crash tests, the CH-46 crew seats met the required structural performance for the test; specifically, they remained attached to the floor of the aircraft (without failing the floor structure), maintained the seat's structural integrity, and restrained the occupants. This paper compares the full-scale test performance to the qualification test performance of the seat. For the co-pilot seat, the MA-16 inertia reel was augmented with a Pre-tensioning Aircrew Restraint System (PARS), which may have resulted in some differences in the test results compared to the pilot position, most notably an improvement in the measured lumbar load. The test results indicate that the crew seats' performance in the airframe crash test was satisfactory, despite significant differences in the full-scale crash test input pulse as compared to the historical qualification test pulse. It should be noted that this seat design is decades old and the airframe crash test has resulted in substantially better visibility of the seat's performance in a "real-world" situation. This, coupled with improved crashworthy seat design practices, could lead to seating systems that would not only provide good energy-absorption, but would also accommodate additional features to further improve crash injury mitigation.
Bark, Lindley, Harris, Alex
Impact Tests and Simulations of Crashworthy Composite Structures Using Variable Load ConceptF-0070-2014-94775/20/2014
Composite materials are used extensively in modern helicopter structures to reduce weight. Applications include energy absorption components necessary to meet crashworthiness requirements, where composite material can offer higher Specific Energy Absorption (SEA) than traditional metallic materials. However, the constant force energy absorbers that are currently used exhibit some limitations, such as under-utilisation of the crushing stroke leading to inefficient material usage and therefore higher than necessary decelerations to the occupants in some crash scenarios. This paper describes the results of a project to develop an improved system for crashworthiness. As part of this project, a novel Variable Load Concept (VLC) has been introduced to improve the performance of the energy absorption components. The crushing force can be controlled through the radius size of trigger mechanism and the use of pressurised composite tubes. The concept and the system were developed and further validated by crush testing at speeds of quasi-static, 2 m/s and 8 m/s. The results established that the VLC with pressurised composite tube system can be used in crashworthiness applications, and that the significant improvement in energy absorption characteristics is possible. Finally, an explicit finite element study was carried out using software PAM-CRASH, where very good agreement with experiment was demonstrated.
Thomson, Rodney, Hou, Tiansong, Prusty, Gangadhara., Pearce, Garth, Kelly, Don, David, Matthew
Influence of Welded Joints on the Crashworthiness Response of Hybrid Structural Elements2013-01-07554/8/2013
In this paper, the effect of welded joints on the crashworthiness response of a hybrid system is presented. This hybrid system consists of a steel enclosure filled with different core materials: carbon-fiber reinforced polymer, glass-fiber reinforced polyamide, polyethylene terephthalate foam and natural cork conglomerate. The metallic enclosure is a cold-formed tube which has to be spot-welded to assemble the final design. The focus is set on the assessment of the effect of the pattern and the number of spot welds on the crashworthiness results in terms of absorbed energy. Results show that variations in the number or the geometric distribution of the spot welds have a direct and noticeable effect on the final amount of energy that the part can dissipate. This is due to the crushing mechanism of the metallic column which is highly sensitive to the way that cold-formed sections are joined. From these results, several design recommendations can be proposed for the design of hybrid elements with welded joints, depending on the geometrical and material properties of the system.
Costas, Miguel, Diaz, Jacobo, Romera, Luis Esteban, Hernandez, Santiago, Ledo, Raquel
Front Rail Crashworthiness Design for Front Oblique Impact Using a Magic Cube Approach2013-01-06514/8/2013
The front rail, as one main energy absorption component of vehicle front structures, should present steady progressive collapse along its axis and avoid bending collapse during the front oblique impact, but when the angle of loading direction is larger than some critical angle, it will appear bending collapse causing reduced capability of crash energy absorption. This paper is concerned with crashworthiness design of the front rail on a vehicle chassis frame structure considering uncertain crash directions. The objective is to improve the crash direction adaptability of the front rail, without deteriorating the vehicle's crashworthiness performance. Magic Cube (MQ) approach, a systematic design approach, is conducted to analyze the design problem. By applying Space Decomposition of MQ, an equivalent model of the vehicle chassis frame is generated, which simplifies the design problem. Based on this model, a two-layered front rail is proposed using a multi-step multi-domain topology optimization method and a response surface method. Numerical simulations are carried out with Altair/Hypermesh and LS-DYNA to compare the crashworthiness performances of the original front rail and the proposed two-layered design. The result shows that the two-layered front rail, with a reduced weight by 17%, can absorb 46% more energy in the 30 degree front impact than the original design, meanwhile, the proposed design eliminates the bending collapse on its rear end when the angle of loading direction reaches the critical angle. The energy absorption capability and the direction uncertainty adaptability of the front rail are significantly improved.
Hu, Sibo, Ma, Zheng-Dong, Qi, Chang, Ding, Yi
Idealized Vehicle Crash Test Pulses for Advanced Batteries2013-01-07644/8/2013
This paper reports a study undertaken by the Crash Safety Working Group (CSWG) of the United States Council for Automotive Research (USCAR) to determine generic acceleration pulses for testing and evaluating advanced batteries subjected to inertial loading for application in electric passenger vehicles. These pulses were based on characterizing vehicle acceleration time histories from standard laboratory vehicle crash tests. Crash tested passenger vehicles in the United States vehicle fleet of the model years 2005-2009 were used in this study. Crash test data, in terms of acceleration time histories, were collected from various crash modes conducted by the National Highway Traffic Safety Administration (NHTSA) during their New Car Assessment Program (NCAP) and Federal Motor Vehicle Safety Standards (FMVSS) evaluations, and the Insurance Institute for Highway Safety (IIHS). These crash modes included: Frontal rigid flat barrier test at 35 mph (NHTSA NCAP), 40% offset frontal deformable barrier test at 40 mph (IIHS), Side moving deformable barrier test at 38 mph (NHTSA side NCAP), Side oblique pole test at 20 mph (US FMVSS 214/NHTSA side NCAP), and Rear 70% offset moving deformable barrier impact at 50 mph (US FMVSS 301). The accelerometers used were located in the vehicle where deformation is minimal or non-existent, so that the acceleration represents the “rigid-body” motion of the vehicle. The wide range of variability from vehicle platforms was evident for each of the test modes. The test data were summarized using idealized step-ramp pulses obtained through parametric fit. Two-step Longitudinal and one-step Transverse acceleration test pulses were created based on the raw test data. These idealized vehicle crash test pulses may be used for evaluating the crashworthiness of advanced batteries for passenger vehicle applications.
Barbat, Saeed, Mehall, Mark, Nayak, Raviraj, Nusholtz, Guy S., Olds, Natalie M., Shi, Yibing, Stanko, William, Wang, Jenne-Tai, Weerappuli, Para, Xu, Lan, Yalamanchili, Krishnarao Venkata
An Assessment of the Effects of Passenger Vehicle Weight and Size on Accident and Fatality Risk Based on Data for 1991 through 2007 Model Year Vehicles2013-01-07574/8/2013
Quantifying the independent effects of vehicle weight and size on overall vehicle safety is necessary in order to assess the risks and benefits of vehicle weight reduction. This paper describes the results of one-stage and two-stage logistic regression analyses of the effects of passenger vehicle weight, wheelbase, track, and footprint on fatalities per accident, accidents per exposure (e.g., vehicle-miles-traveled), and fatalities per exposure using national and multi-state traffic accident and exposure databases. The analyses were accomplished in two phases. The first phase used 1995 though 2000 calendar year data for 1991 through 1999 model year vehicles. The second phase used 2002 through 2008 calendar year data for 2000 through 2007 model year vehicles. The overall fatalities per exposure results tend to confirm the one-stage results previously reported by NHTSA, however the new two-stage results provide additional insight into the independent effects of weight reduction and size reduction on vehicle crash involvement, crashworthiness and crash compatibility. The sensitivity of the results to various databases, variables, and assumptions was also investigated. The results from both phases indicated that the estimated overall effects of passenger vehicle weight reduction (while holding vehicle size constant) on fatalities are small in comparison to other variables and may not be statistically significant depending on various key assumptions (e.g., controlling for changes in wheelbase and track versus changes in footprint, and the type of induced-exposure data that are used), and this is due to small or opposing effects of these variables on crash involvement, crashworthiness and crash compatibility.
Van Auken, R. Michael, Zellner, John W.
The Front Center Airbag2013-01-11564/8/2013
General Motors and the Takata Corporation have worked together to bring to production a new, industry first technology called the Front Center Airbag which is being implemented on General Motors' 2013 Midsize Crossover Vehicles. This paper reviews field data, describes the hardware, and presents occupant test data to demonstrate in-position performance in far side impacts. The Front Center Airbag is an airbag that mounts to the inboard side of the driver front seat. It has a tubular cushion structure, and it deploys between the front seating positions in far side impacts, near side impacts and rollovers, with the cushion positioning itself adjacent the driver occupant's head and torso. This paper includes pictures of the technology along with a basic description of the design. In-position occupant performance is also described and illustrated with several examples. Single occupant and two front occupant far side impact test data are included, both with and without the airbag present. Resulting performance differences are discussed leading to the following test observations: a) In a far side impact with a single driver occupant present, the deployed airbag functions as a restraint to help keep the occupant away from the intruded passenger compartment structure. b) When two occupants are present, the deployed airbag functions as a cushion between the front occupants. In addition, field data from the Fatal Analysis Reporting System and National Automotive Sampling System - Crashworthiness Data System are initially presented to illustrate the challenges that this technology attempts to address.
Thomas, Scott D., Wiik, Richard A., Brown, Jacqueline E.
Selection of Optimal Design Parameters to Achieve Improved Occupant Performance in Frontal Impacts2013-01-07564/8/2013
Crashworthiness enhancement of vehicle structures is a very challenging task during the early design development process. Major factors influencing occupant injury in frontal impact are vehicle front crush space, crash pulse severity, restraint properties and occupant packaging space. This paper establishes a methodology to define suitable criterion that will guide the designers to select the optimal values of the above mentioned parameters during the early phase of the vehicle development. The usage of lumped mass models, pulse characterization techniques were explored to validate the results. Efficient crash energy management, the concepts of ride down and restraint efficiency parameters were also discussed in the paper.
Peddi, Sairama Narayana
Concepts for Mechanical Abuse Testing of High-Voltage Batteries2012-01-01244/16/2012
Currently lithium-batteries are the most promising electrical-energy storage technology in fully-electric and hybrid vehicles. A crashworthy battery-design is among the numerous challenges development of electric-vehicles has to face. Besides of safe normal operation, the battery-design shall provide marginal threat to human health and environment in case of mechanical damage. Numerous mechanical abuse-tests were performed to identify load limits and the battery's response to damage. Cost-efficient testing is provided by taking into account that the battery-system's response to abuse might already be observed at a lower integration-level, not requiring testing of the entire pack. The most feasible tests and configurations were compiled and discussed. Adaptions of and additions to existing requirements and test-procedures as defined in standards are pointed out. Critical conditions that can occur during and after testing set new requirements to labs and test-rigs. A ‘thermal runaway’ may emerge from a mechanical-induced short-cut, resulting in an extreme raise in temperatures, outgassing, smoke, fire and, under adverse conditions, explosions. Potentially critical situations and safety hazards were compiled, supporting labs in mitigating and averting hazardous situations. Existing safety concepts and evacuation strategies are outlined, reducing the hazards of battery testing.
Sinz, Wolfgang, Feist, Florian, Gstrein, Gregor, Gugler, Jürgen, Tomasch, Ernst, Breitfuss, Christoph, Luttenberger, Peter, Steffan, Hermann, Gollob, Peter, Hennige, Volker
An Application of Cluster Analysis to Dummy Injury Readings in a Frontal Crash2012-01-05564/16/2012
Public concern about the crashworthiness of vehicles has been continuously rising in recent years. Crashworthiness is evaluated under various crash configurations, including frontal collisions, in regulatory testing and in New Car Assessment Programs. Accordingly, vehicle manufacturers must deploy sophisticated product development strategies and redouble their engineering efforts in order to develop vehicles that satisfy the specified requirements for crashworthiness. Computer simulation is one effective approach to resolving this issue in that it provides a valuable tool for conducting multiple parameter studies and iterations in a short period of time. However, it is no easy task for CAE engineers to analyze the large volumes of calculation results obtained in frontal crash simulations and to understand the phenomena involved. One reason is that a great deal of time is needed to understand the many calculation results comprehensively, despite the fact that frontal crash phenomena are interrelated in complex ways. This paper presents an example of a parameter study in which cluster analysis was used effectively to examine front-seat passenger restraint systems in a frontal crash. In a cluster analysis, calculation results are grouped into clusters having the same response characteristics. Because the design variables are also similarly clustered, engineers can gain a deeper understanding of the phenomena of interest. Two types of simulation models were used in this study. First, a multibody system (MBS) model was used as a simple mass-spring model to conduct a parameter study. This simple model made it possible to perform many calculations in a broad design space in a short period of time. Cluster analysis was then applied to analyze the calculation results of the parameter study. Using this method to understand simulation results enables engineers to formulate hypotheses about design guidelines for satisfying safety performance requirements. As the next step, a detailed finite element model that facilitated highly accurate simulations was used to verify the validity of the hypotheses. This study made clear the influence of pelvis behavior on dummy chest injury readings, and the results also demonstrated the utility of cluster analysis in trying to understand the complex phenomena involved in a frontal crash.
Koizumi, Naoya, Ono, Masamoto, Natori, Sou, Araki, Toshihiro
Fuel System Crashworthiness for Recreational Off-Highway Vehicles2012-01-09884/16/2012
Recreational Off-Highway Vehicles (ROVs) are a distinct class of vehicles defined by an American National Standard (ANSI). The vehicles are intended primarily for recreational use and may have secondary general utility applications. The American National Standard (ANSI) for Recreational Off-Highway Vehicles addresses minimum requirements for aspects of ROV equipment and configuration, but includes no discussion regarding the design or performance of ROV fuel systems. The purpose of this study was to: survey pre- and post-ANSI Standard designs of ROV fuel systems; examine fuel system design recommendations and requirements for other types of fueled motive equipment, including diverse types of recreational equipment; and describe the environment in which the ROV was intended and the environment in which it was legal for use. SAE Standards, Recommended Practices and Information Reports for diverse human-operated fueled motive equipment from personal watercraft to motorcycles revealed numerous recommendations and requirements for fuel system design and performance. Observations of the sampled ROVs indicated that known and effective crashworthy concepts and features were not present on some fuel systems. Given the increasing popularity of ROVs, a combination of recommendations are proposed including that individual States discontinue the practice of registering ROVs for use on highways and that those that modify ROVs intended for on-road use adhere to the requirements of the Federal Motor Vehicle Safety Standards (FMVSSs). A new FMVSS is not proposed, but a minimum fuel system crashworthiness design and/or performance standard applicable to ROVs for their intended use should be considered.
Arndt, Mark William
Validation of Sled Tests for Far-Side Occupant Kinematics Using MADYMO2010-01-11604/12/2010
Far-side occupants are not addressed in current government regulations around the world even though they account for up to 40% of occupant HARM in side impact crashes. Consequently, there are very few crash tests with far-side dummies available to researchers. Sled tests are frequently used to replicate the dynamic conditions of a full-scale crash test in a controlled setting. However, in far-side crashes the complexity of the occupant kinematics is increased by the longer duration of the motion and by the increased rotation of the vehicle. The successful duplication of occupant motion in these crashes confirms that a sled test is an effective, cost-efficient means of testing and developing far-side occupant restraints or injury countermeasures. Previous work by these authors analyzed 9 crash modes that represent 44% of the total far-side occupant crash exposure and account for 56% of all MAIS3+ far-side injured occupants in the National Automotive Sampling System/Crashworthiness Data System (NASS/CDS). The study developed a methodology for using MADYMO to specify the sled test conditions that mimic a far-side occupant's kinematics for a wide range of crash environments, including cases with significant vehicle rotation. The approach used both crash tests and finite element models (FEM) to determine the crash pulse. The dummy motion was determined by MADYMO simulations [ 1 ]. Another technique was developed by Smyth and Smith in which they used a pulse from a full-scale crash test to develop a pulse shape, pulse magnitude, and Principle Direction of Force (PDOF) for a sled test [ 2 ]. The kinematics of the dummies in the resulting sled test was generally similar to the dummy kinematics in the crash test. Similarly, the study found that sled tests can be used to simulate highly complicated crashes in which the crash pulse was established by a crash test. The purpose of this study is to validate the previously developed MADYMO methodology using the crash pulse and dummy kinematics from the actual crash and sled tests presented by Smyth and Smith. Furthermore, a comparison of each technique is analyzed in MADYMO and the results are discussed to determine how each may be best applied for future research and testing of far-side countermeasures.
Cuadrado, Joseph, Smyth, Brian, Smith, James, Digges, Kennerly
Frontal Crash Protection in Pre-1998 Vehicles versus 1998 and Later Vehicles2010-01-01424/12/2010
This investigation addresses and evaluates: (1) belted drivers in frontal crashes; (2) crashes divided into low, medium, and high severity; (3) air-bag-equipped passenger vehicles separated into either model years 1985 - 1997 (with airbags) or model years 1998 - 2008; (4) rate of Harm as a function of crash severity and vehicle model year; and (5) injury patterns associated with injured body regions and the involved physical components, by vehicle model year. Comparisons are made between the injury patterns related to drivers seated in vehicles manufactured before 1998 and those manufactured 1998 or later. The purpose of this comparative analysis is to establish how driver injury patterns may have changed as a result of the introduction of more recent safety belt technology, advanced airbags, or structural changes. More recent years of NASS/CDS have meant that additional 1998+ model year vehicles were available for analysis, and there were almost equal number of frontal crashes involving pre-1998 and 1998+ model year vehicles. This investigation is based on the analysis of real-world crash data obtained from the National Automotive Sampling System / Crashworthiness Data System (NASS/CDS) between the years 1993-2008.
Scullion, Paul, Morgan, Richard M., Digges, Kennerly H., Kan, Cing-Dao
Ambulance Vehicle Crashworthiness and Passive Safety Design: A Comparative Evaluation2008-01-269510/7/2008
Ambulances are largely exempt from crashworthiness and occupant protection passive safety design standards in the USA, and have a poor road safety record. This comparative evaluation of USA ‘concept safety’ ambulances and a standard Australian ambulance is based on basic principles of crashworthiness and available crash test data. There are features of USA ambulance design that are not within known principles and technical aspects of crashworthiness and safety design, and include some predictable serious occupant protection hazards. The USA ambulance industry should recognize and apply crashworthiness and occupant protection principles to reduce current system failures for this fleet of essential service vehicles.
Levick, Nadine, Grzebieta, Raphael
A Frontal Impact Taxonomy for USA Field Data2008-01-05264/14/2008
An eight-group taxonomy was created to classify real-world frontal crashes from the Crashworthiness Data System (CDS) component of the National Automotive Sampling System (NASS). Three steps were taken to develop the taxonomy: (1) frontal-impact towaway crashes were identified by examining 1985-2005 model year light passenger vehicles with Collision Deformation Classification (CDC) data from the 1995-2005 calendar years of NASS; (2) case reviews, engineering judgments, and categorization assessments were conducted on these data to produce the eight-group taxonomy; and (3) two subsets of the NASS dataset were analyzed to assess the consistency of the resulting taxonomic-group frequencies. “Full-engagement” and “Offset” crashes were the most frequent crash types, each contributing approximately 33% to the total. The group identified as “D, Y, Z No-Rail” was the most over-represented crash type for vehicles with at least one seriously-injured occupant. However, that group represented only 2.6% of the crash-involved vehicles. The taxonomy provides a consistent way to categorize frontal impacts beyond that afforded by the CDC itself. Moreover, the taxonomy provides the basis for potential future studies (e.g., more comprehensive risk assessments and related countermeasure designs).
Sullivan, Kaye, Henry, Scott, Laituri, Tony R.
Rollover Dynamics: An Exploration of the Fundamentals2008-01-01724/14/2008
Research focusing on automotive rollovers has garnered a great deal of attention in recent years. Substantial effort has been directed toward the evaluation of rollover resistance. Issues related to crashworthiness, such as roof strength and restraint performance, have also received a great deal of attention. Much less research effort has been directed toward a more detailed study of the rollover dynamics from point-of-trip to point-of-rest. The reconstruction of rollover crashes often requires a thorough examination of the events taking place between point-of-trip and point-of-rest. Increasing demands are placed on reconstructionists to provide greater levels of detail regarding the roll sequence. Examples include, but are not limited to, roll rates at the quarter-roll level, CG trajectory (horizontal and vertical), roll angle at impact, and ground contact velocity. Often the detail that can be provided in a rollover reconstruction is limited by a lack of physical evidence. However, there are many cases where the physical evidence - both on the vehicle and the ground - allows for detailed re-positioning of the vehicle during the roll sequence. Using such a high level of detail would lead one to believe that the reconstruction of the rollover dynamics will be an accurate representation of the actual event. But, just how accurate will it be? This paper seeks to examine the commonly used constant deceleration method of rollover reconstruction in light of detailed analyses of actual rollover tests. By comparing methods used in the field to detailed experimental observations this paper will provide an understanding of the accuracy and limitations of those methods. The underlying data that provide the foundation for this article are derived from two high-speed soft-surface dolly rollover tests of sport utility vehicles.
Carter, Jarrod W., Luepke, Peter, Henry, Kevin C., Germane, Geoff J., Smith, James W.
Automotive Engineering International 2006-03-01AUTOMAR063/1/2006
Hybridization gathers momentum Gasoline-electric hybrid vehicles continue to grow in popularity, with many incremental advances coming from Japanese OEMs and suppliers. Broadening telematics' reach More infotainment options pose many challenges. Nano goes macro While nanotechnology deals with materials at the minutest of levels, the auto industry has grand plans for its use in a multitude of areas. The transformation of testing Software is helping physical tests produce more accurate results more efficiently. Advancing crashworthiness simulation BMW worked closely with software developers at ABAQUS to produce a customized solution for virtual product development. Low-cost latitude Contrary to popular belief, 'low cost' does not automatically mean 'Chinese.' SAE 2006 World Congress Preview Toyota and host company BMW join Ford, General Motors, and Chrysler for a record number of OEMs on the floor at the April 3-6 event.
Important Considerations in the Development of a Test to Promote Stable Bumper Engagement in Low-Speed Crashes2004-01-13193/8/2004
Nolan, Joseph M., Brumbelow, Matthew, Zuby, David S., Avery, Matthew
Structural Reinforcements for Automotive Applications2003-01-03303/3/2003
The use of adhesively bonded localized reinforcements is a relatively new concept in the automotive industry. Although use of this reinforcement method is in its early stages, these reinforcements are now used for a variety of applications in the automotive industry for improvements in crash worthiness, fatigue resistance, and NVH characteristics. This approach can provide relatively fast, easy, non-intrusive, and cost effective solutions for OEM's when compared to traditional reinforcement methods. Also, overall weight can be reduced simultaneously since the reinforcement is placed only where needed instead of filling an entire section with foam or changing the metal thickness along an entire body member. Materials and concepts have been developed that can be used to improve the structural stiffness and the resulting NVH performance of the vehicle. This paper will discuss the use of localized reinforcements including materials, applications, and potential uses and benefits.
Carlson, David, Czaplicki, Michael, Riley, Jon
Old car crash test program2001-06-01806/4/2001
Older vehicles do not have to meet the same safety standards that modern cars are required to meet. This paper presents some observations about the structural and safety performance of older vehicles in the frontal offset crash test conducted by the Australian New Car Assessment Program (ANCAP), the Insurance Institute for Highway Safety (IIHS) and EuroNCAP for consumer information. Some comparisons of the safety performance between new and old vehicles in offset crash tests are made. The test results were analyzed to determine the various factors that contribute making a vehicle crashworthy. The newer vehicles generally scored better than the older vehicles. The results inform consumers about differences in safety features between new and old vehicles.
Haley, Jack, Bonney, Vanessa
Improved safety for drivers and couriers of coaches2001-06-01386/4/2001
According to general accidents statistics a coach is the safest means of transportation with respect to fatalities per billion traveler kilometers. Reasons for this include the existing regulations related to coach safety and the self-regulation of the coach building industry. Most passive safety standards are, however, more related to the safety of the passengers and less to the safety of driver and courier. Their typical position at the front of the coach and the fact that most heavy structural parts of the coach are behind their position in the coach, make the driver and courier vulnerable in case of a frontal collision. The injury risk in specific frontal collisions can be reduced by applying crash technology within the front structure of the coach. By redesign and reorganizing the structure and the packaging underneath the driver and courier, the kinetic energy developed in a typical coach-to- trailerback collision can be absorbed whilst maintaining a survival space for driver and courier. This paper describes the development of a procedure for improvement in the frontal crashworthiness of coaches. Starting with analyses of related accident data and heavy vehicle crash experience from truck testing, numerical simulation, component and full-scale testing have been combined to create a new passive safety structural concept. The experience gained has since been used and is demonstrated in the design of a new coach.
de Coo, Peter, Hazelebach, Rene, van Oorschot, Eric, Wessels, Jaap
Evaluation of the effect of air bags in multi-year light truck NCAP tests2001-06-00956/4/2001
The New Car Assessment Program (NCAP) has evaluated the crashworthiness of numerous vehicles since 1979. Each year selected models were frontally crashed at 35 mph into a fixed barrier. Due to increased interest by the public in vehicle safety as part of their car-buying decisions, NHTSA has recently undertaken an expanded program of consumer information on vehicle safety issues. As part of this program, an analysis was performed to determine the effectiveness of light-truck driver air bags to reduce the risk of severe injury as measured by the head and chest injury responses of selected NCAP tests. The light trucks tested most frequently were analyzed to obtain reliable estimates of air bag effectiveness. The vehicles were tested with all the restraints available on that model, which in the case of the early years were safety belts, and in the latter years were a combination of safety belts and air bags. Analysis of NCAP data for multi-tested vehicle models for the period 1979 through 2000 indicated a significant reduction of 56% for light trucks in the risk of severe trauma for drivers in air-bag-equipped vehicles.
Berkowitz, Alan
PROGRESS OF PASSIVE SAFETY IN CAR-TO-CAR FRONTAL COLLISIONS: RESULTS FROM REAL-LIFE CRASH ANALYSES AND FROM CRASH TESTS2001-06-01986/4/2001
The progress of passive safety in car-to-car frontal collisions can be seen very clearly from the results of crash tests with old and new car models. The published federal accident statistics show an overall effort in passive safety, which is obvious by decreasing figures of killed and severely injured car occupants per year on German roads. But it is not possible to exclusively focus on car crashes with frontal collisions because the characteristics investigated in official statistics are not detailed enough. Therefore additional in-depth studies are necessary. The paper shows results of car-to-car and car-to-barrier frontal impacts for old and new car models. Some results of evaluations using the federal German statistics show historical trends in a more general view. Interdisciplinary real-life crash studies are focused on car-to-car frontal collisions. Results of connecting assessments using vehicle deformation index (VDI), energy equivalent speed (EES), velocity change (delta-v) and occupant injuries (injury severity, AIS) for old and new cars certify an effort of passive safety. Finally compatibility aspects “new car to old car” caused by different front-end stiffness and mass are discussed.
Berg, F. Alexander, Rücker, Peter, Niewöhner, Walter, Miltner, Erich, Stein, Kirsten Marion
Composite-Fuselage Concept for Greater CrashworthinessTBMG-3003111/1/1999
A continuing program of research is directed toward the development of crashworthy composite-material fuselages for small aircraft. These fuselages are required not only to withstand flight loads and exhibit the required aerodynamic characteristics, but also to protect occupants during crashes more effectively than do conventional fuselages. The design goal for protection against crashes is to limit loads applied to occupants to survivable levels in vertical impacts onto rigid surfaces at a speed of 31 ft/s (9.4 m/s). This vertical impact speed exceeds that specified in current regulatory criteria for small aircraft, but it is a realistic, potentially survivable, impact velocity that has been observed in crashes and in crash tests performed at Langley Research Center.
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