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This article was downloaded by: [University of California, San Francisco]On: 19 November 2014, At: 07:54Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registeredoffice: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Vehicle System Dynamics: InternationalJournal of Vehicle Mechanics andMobilityPublication details, including instructions for authors andsubscription information:http://www.tandfonline.com/loi/nvsd20
Development and validation of side-impact crash and sled testing finite-element modelsTso-Liang Teng a , Kuan-Chun Chang a & Chien-Hsun Wu ba Department of Mechanical and Automation Engineering , Da-YehUniversity , Changhua, Taiwan, ROCb Automotive Research and Testing Center , Changhua County ,Taiwan, ROCPublished online: 30 Aug 2007.
To cite this article: Tso-Liang Teng , Kuan-Chun Chang & Chien-Hsun Wu (2007) Developmentand validation of side-impact crash and sled testing finite-element models, Vehicle SystemDynamics: International Journal of Vehicle Mechanics and Mobility, 45:10, 925-937, DOI:10.1080/00423110701560068
To link to this article: http://dx.doi.org/10.1080/00423110701560068
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Vehicle System DynamicsVol. 45, No. 10, October 2007, 925–937
Development and validation of side-impact crash and sledtesting finite-element models
TSO-LIANG TENG*†, KUAN-CHUN CHANG† and CHIEN-HSUN WU‡
†Department of Mechanical and Automation Engineering, Da-Yeh University, Changhua, Taiwan, ROC‡Automotive Research and Testing Center, Changhua County, Taiwan, ROC
Side-impact collisions are the second leading cause of death and injury in the traffic accidents afterfrontal crashes. Side-impact airbags, side door bars and other protection techniques have been devel-oped to provide occupant protection. To confirm the effectiveness of protection equipment installed invehicles, studying the degree of impact is fundamental to understand the effect of automobile collisionson the human body. Therefore, the dynamic response of the human body to traffic accidents shouldbe analyzed to reduce the level of occupant injuries. Generally, the experimental method is complexand expensive. Recently, numerical crash simulations have provided a valuable tool for automotiveengineers. This work presents full-scale and sled side-impact test finite-element (FE) models – basedon the Federal Motor Vehicle Safety Standard No. 214 – that simulate a side-impact accident. Thecrash simulations utilized the LS-DYNA finite-element code. The human body’s dynamic response tocrashes is discussed herein. Additionally, occupant injuries were measured. To verify the accuracy ofthe proposed crash test and sled test FE models, simulation results are compared with those obtainedfrom experimental tests. The comparison results indicate that the proposed crash test and sled test FEmodels have considerable potential for assessing a vehicle’s crash safety performance and assistingfuture development of safety technologies.
Keywords: Side impact; Full-scale crash test; Sled test; Simulation; Injury
1. Introduction
Traffic accidents claim 10,000 lives annually. Vehicle safety became a common concern ofmanufacturers and consumers. Accident statistics [1] indicate that injury and fatality rates infrontal collisions exceed those from side collisions and rear-end impacts. Manufacturers havemade significant improvements in protecting occupants during head-on collisions. Notably,side-impact collisions are the second leading cause of death and injury in the traffic accidentsafter frontal crashes. Unlike a frontal collision, side-impact collisions are unique; that is,the space between an occupant and the side of the vehicle is minimal. Hence, the occupanthas very little protection when a vehicle is struck on its side. Side-impact airbags, side doorbars and other protection techniques have been developed to occupant protection. Assessingthe effectiveness of protective equipment is crucial during the design stage. Discussing theinteraction between vehicle occupants and passive safety devices is essential when developing
*Corresponding author. Email: [email protected]
Vehicle System DynamicsISSN 0042-3114 print/ISSN 1744-5159 online © 2007 Taylor & Francis
http://www.tandf.co.uk/journalsDOI: 10.1080/00423110701560068
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safe and effective protective equipment. Therefore, researching the degree of impact a bodyundergoes during an impact is fundamental to vehicle safety design.
Analyzing the dynamic response of an occupant during a vehicle collision and confirmingthe effectiveness of vehicle protection equipment requires developing an efficient evaluativeand analytical methodology that can assess the safety aspects of a vehicle. Generally, dynamicresponse of and injury to human bodies in crash tests can be analyzed in two ways: experimen-tal and numerical simulations. The experimental analysis can be further deconstructed intofull-scale crash tests [1–3] and sled experiments [4–6]. Crash testing is commonly employedfor examining occupant protection capability of a particular vehicle. Although full-scale crashtests can achieve results that closely resemble an actual accident, this method is complexand expensive. Sled testing is an effective means of evaluating crash safety of vehicle inte-riors. This technique can simulate real crash conditions without destroying vehicle structure.Therefore, the sled system is typically employed to assess the protective capability of safetyequipment during vehicle research and development stages. Recently, advances in computertechnology have allowed applied mathematicians, engineers and scientists to solve previ-ously intractable problems. The crash and sled tests can be performed exactly by computersimulations. As such, computer simulation is an economical and time efficient alternativeto physical testing. Simulation methods for predicting occupant kinematics and calculatinginjury criteria include MADYMO, Pam Crash and LS-DYNA [7–11]. Advances in numericalsimulation techniques and computer capabilities have made computer testing a powerful toolfor investigating crash safety. Moreover, computer simulation for crashworthiness evaluationhas contributed to shortening the time required to design vehicles.
To confirm vehicle occupant safety, most countries issue safety standards and regulations towhich vehicles must conform, such as the Federal Motor Vehicle Safety Standards (FMVSS)and the Economic Commission for Europe (ECE) regulations, etc. Safety standards and reg-ulations are typically minimum safety performance standards for motor vehicles and theirrelated equipment. A goal of these standards is to protect the public against unreasonablerisk of crashes that result from design, construction or performance of motor vehicles andagainst unreasonable risk of death or injury during a crash. To meet these regulations anddevelop equipment with enhanced safety, finite-element (FE) modeling in simulations can beused to investigate the dynamic behavior of occupants and injury analysis. This work presentsfull-scale and sled side-impact test FE models – based on the FMVSS-214 – that simulatea side-impact accident. The crash simulations utilized the LS-DYNA FE code. The humanbody’s dynamic response to crashes is discussed herein. Additionally, occupant injuries weremeasured. To verify the accuracy of the proposed crash test and sled test FE models, simula-tion results are compared with those obtained from experimental tests. The comparison resultsindicate that the proposed crash test and sled test FE models have considerable potential forassessing a vehicle’s crash safety performance and assisting future development of safetytechnologies.
2. Full-scale crash test
2.1 Regulation
Side-impact protection standards have been adopted in both the USA and the Europe. FMVSS-214 (USA) and ECE-R95 (European) dynamic side-impact regulations are quite different,especially with respect to their concerns about occupant injury. In this study, a side-impacttest was performed according to the FMVSS-214 specification.
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Figure 1. The test set-up of FMVSS-214.
FMVSS-214 specifies performance requirements for protection of occupants in side-impactcrashes. The aim of this standard is to reduce the risk of serious and fatal injury to occupants ofmotor vehicles in side-impact crashes by setting vehicle crashworthiness requirements in termsof accelerations measured on anthropomorphic dummies in test crashes. For the physical test,the procedure was simplified with the struck vehicle stationary and the moving deformablebarrier (MDB) striking the target vehicle. Wheels of the deformable barrier were crabbed atan angle of 27◦ from the longitudinal direction of the barrier. Figure 1 shows the test set-up. Dummies in vehicle must satisfy the requirements of FMVSS-214 when the stationaryvehicle is impacted by MDB at 54 km/h (33.5 mph). This test was intended to simulate anintersection crash involving two moving vehicles. Dummy injuries to the thorax and pelvicarea were assessed along with vehicle structural damage.
The thorax and the pelvis are mainly injured by side impact. The US-SID dummy responsemeasurements consisted of the thorax and pelvic accelerations. The FMVSS-214 specificationstipulates that the TTI shall not exceed 85 and 90 g for a passenger car with four side doorsand with two side doors, respectively. And the peak lateral acceleration of the pelvis shall notexceed 130 g for all vehicles.
2.2 FE models of full-scale crash test
The FE side-impact test model was conducted according to the FMVSS-214 specification andprocedure. The model is shown in figure 2. The model consisted of three systems combinedinto one FE model: (1) the side-impact vehicle model; (2) the MDB model and (3) the US-SIDmodel. Overall models of side-impact test are validated according to the FMVSS-214. Thevalidations are described in [12].
In this study, a Ford Taurus model was analyzed in a dynamic side-impact test. The full-vehicle FE model was developed by EASi Engineering for the National Highway Traffic SafetyAdministration (NHTSA). The FE model of the Ford Taurus has 171 parts, representing thevehicle components. The full-vehicle FE model for the side-impact simulation, consistingof 49,453 nodes and 5,327 elements, was used. The MDB, weighing 1,367 kg, is designed
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Figure 2. FE model of the full-scale side-impact test: a) front view, b) isometric view.
to represent an average mid-size vehicle in the US market. The FE model of the MDB wasoriginally developed by NHTSA. The model is composed of seven components, 8,908 nodesand 5,848 elements. The US-SID FE model used in the simulation is based on the Hybrid III50% dummy. The model includes the head, neck, upper spine, lumbar spine, pelvis, upper legs,lower legs, feet, jacket and ribcage. The geometry of the different components of the dummywas obtained from design drawings of the Hybrid III 50% dummy. The model is composedof 69 components, 43,874 nodes and 57,032 elements. The overall mass, and the mass andinertia of each component of the dummy, match those of the Hybrid III 50% dummy.
3. Side-impact sled test
3.1 Side-impact sled system
The proposed side-impact sled systems, such as the BASIS system of TNO automotive(figure 3a) and the M-SIS system of HYGE Inc., were developed to assess vehicle
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manufacturers in developing side-impact safety technology. The sled system simulates aninner door panel to occupant intrusion during a side impact. This test’s set-up is appropriatefor the development of airbags and trim panel stiffness. By utilizing a sled test facility and elim-inating the need for test vehicles, this system is a cost effective alternative to full-scale crashtesting. The side-impact sled system was developed to realistically simulate the kinematics ofa full-scale side-impact crash test. This system utilizes the sled’s computer-controlled brakingsystem to precisely trace the acceleration and deceleration of the crash vehicle. The BASISsystem is employed in this work as an example to illustrate the components of a sled system[13]. As figure 3b indicates, the test set-up is a frame (1) on which a door (2) is mounted;next to the door is a seat, in which a dummy sits, placed on a smaller sled (3) that runs onlinear rails (4). Both the frame and rails are attached to the inverse crash simulator (ICS) sled.An appropriate pulse for the ICS is based on a full-scale test or computer simulation. Whena pulse is applied, the seat with the instrumented dummy moves along the linear rails towardthe door due to inertia. Similar to its action during a full-scale impact, the dummy hits a side
Figure 3. BASIS system of TNO automotive [13].
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door that may or may not deform. The dummy is loaded due to the impact and injury criteriaof the dummy are measured.
3.2 FE models of sled testing
The FE side-impact sled model was based on the specifications and procedure used bythe BASIS system. Figure 4 presents the FE side-impact sled model. The FE model com-prises three systems: (1) the linear rails model; (2) the door sled model and (3) the seat sledmodel.
The door sled is attached to and runs on two rectangular, solid fixed rails. Each rail is 600 cmlong, 10 cm wide and 20 cm high. For the FE model of side-impact sled testing, the door ismounted on the door sled model. The lower carriage of door sled has two tracks that canrun on the rails, and the seat sled model runs on the upper carriage of the door sled model.The required velocity profile is applied to the door sled model during the test. The velocityresponse of door trim is based on that in a full-scale crash test. Furthermore, the seat anddummy are positioned to the seat sled model. The lower carriage of the seat sled model hastwo tracks that run on the door sled model. The required velocity profile is applied to the seat
Figure 4. FE model of side-impact sled system: a) front view, b) isometric view.
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sled model during the test. The velocity response of non-impact side is based on that from afull-scale crash test.
4. Numerical simulation of side-impact testing
The full-scale crash test and sled test are performed according to the FMVSS-214 specification.As figure 2 shows, the full-scale crash test is performed by running an MDB into the stationaryvehicle side at a 54 km/h velocity impact. The wheels of the MDB are at an angle of 27◦ relativeto its axis to represent the relative motion of the two vehicles. The side-impact dummy wasseated on the struck side of the vehicle. As figure 4 shows, the door sled and seat sled modelare given the required velocity profile during the side-impact test. The velocity profiles forthe door sled and seat sled model are obtained from a full-scale crash test, as shown infigures 5 and 6. For a 60 ms simulation of full-scale crash test and sled test, the CPU timeon the IBM SP2 parallel system and LS-DYNA 970 SMP version was about 8 and 2.5 h,respectively. The dummy response measurements consisted of thorax and pelvic accelerations.The severity of injury analysis in the side impact can also be determined from the dummyresponse. The analytical results were compared with experimental results taken from Hultmanet al. [2].
Figure 5. The velocity profile of door sled model.
Figure 6. The velocity profile of seat sled model.
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5. Results and discussions
Figure 7 presents a simulated impact sequence in a full-scale crash model. The door was bentdue to the impact force of the MDB in 0.016 s. Since the MDB barrier face was located atroughly dummy pelvis height, the armrest initially contacted the dummy pelvis. Hence, thedummy left the seat, and its head hit the side window at 0.046 s. Figures 8–11 present theupper rib, lower rib, lower spine and pelvic accelerations used to simulate the behavior ofthe dummy’s thorax during both the test and the simulation. Simulation results demonstratethat the pelvis and the TTI computed by the full-scale crash simulation are in good agreementwith experimental results (table 1). The TTI and pelvic acceleration calculated by numericalanalysis were 78 and 114.7 g, respectively. In accordance with the injury criterion specifiedby regulations for a human body during side impacts, numerical results for the acceleration
Figure 7. A simulated impact sequence of full-scale crash test.
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Figure 8. Upper rib acceleration of the dummy.
of the lower spine, upper rib, lower rib and pelvic areas confirm that the current vehicle willprevent an occupant from sustaining fatal injuries during a side-impact accident.
Figure 12 presents a simulated sequence from the sled-testing model, demonstrating that thedoor armrest initially contacted the dummy at 0.015 s. The armrest induced serious deformationof the dummy arm at 0.019 s. The lower portion of door contacted the dummy pelvis at 0.027 s,causing the dummy to leave its seat and hit its head on the side window at 0.043 s. Figures 8–11present the lower spine, the upper rib, lower rib and pelvic accelerations to represent the
Figure 9. Lower rib acceleration of the dummy.
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Figure 10. Lower spine acceleration of the dummy.
Figure 11. Pelvic acceleration of the dummy.
Table 1. Injury risk comparison between the test and the simulation.
Method
Areas of Experimental Full-scale crash Sled testoccupant results [2] (g) simulation (g) simulation (g)
Lower spine 83.5 (78–90) 75.9 75Upper rib 59.2 (57–81) 58.5 77.1Lower rib 70.5 (62–77) 80.1 76.14Pelvis 115.2 (101–126) 114.7 100TTI 78 (73–83) 78 76
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Figure 12. A simulated impact sequence of side-impact sled test.
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behavior of the dummy’s thorax during experiment, full-scale test and sled test simulations.Owing to the door being mounted on the door sled model, the rotation phenomenon due tothe impact of the MDB cannot be simulated during sled test simulations. This is the reasonfor the wrong timing. The TTI and pelvic acceleration calculated by sled test simulation were76 and 100 g, respectively (table 1). Simulation results demonstrate that this combinationyielded fewer injuries to both the pelvis and the TTI than the experimental and full-scale crashsimulation results. The FE sled simulation models differ slightly from those in Hultman’s crashtest. Pelvic and TTI acceleration in the sled test simulations and experimental test differedby 13 and 2.6%, respectively. As figures 8–11 indicate, the accelerations calculated by sledtest simulation even have some wrong timing. Clearly, the side-impact sled model accuratelyassesses resulting injuries to an occupant. Notably, CPU time associated with the full-scalecrash model is considerably more than that for the sled test model. The sled test model can beused to examine different design concepts and vehicle safety during early stages of researchand development.
6. Conclusion
This study has presented a proposed simulation method and demonstrated the feasibility ofits application. The proposed model conforms to side-impact design requirements. Numer-ically, measuring human response in the side-impact accidents is useful. The validity forcrashworthiness analysis of the FE full-scale side-impact test and sled test models was vali-dated. These numerical models predicted severity of driver injuries during impacts, reducedthe duration of research and design cycles, and cut experimental costs. The accuracy of thenumerical sled test model renders it a valuable approach for side-impact crashworthiness sim-ulations. The proposed methods can be applied to examine the dynamic behavior of occupantsand analyze injuries during side-impact accidents. Moreover, the simulated models serve asdesign guidelines for the vehicular structure and safety equipment required to protect vehicleoccupants.
Acknowledgements
The authors would like to thank the Automotive Research and Testing Center, Taiwan, forfinancially supporting this research.
References
[1] Yonezawa, H., Toyofuku, Y., Irie, Y. and Mizuno, K., 1996, Absorbed energy of structure of passenger cars by90-degree side impact test. JSAE Review, 17(1), 95.
[2] Hultman, R.W., Laske, T.G., Chou, C.C., Lim, G.G., Chrobak, E.I. and Vecchio, M.T., 1991, NHTSA passengercar side impact dynamic test procedure-test-to-test variability estimates. SAE Paper No. 910603.
[3] Versace, J. and Berton, R.J., 1975, Determination of restraint effectiveness, airbag crash test repeatability. SAEPaper No. 750395.
[4] Yoganandan, N, and Pintar, F.A., 2005 Responses of side impact dummies in sled tests. Accident Analysis andPrevention, 37(3), 495–503.
[5] Stein, D.J., 1997, Apparatus and method for side impact testing. SAE Paper No. 970572.[6] Miller, P.M. and Gu, H., 1997, Sled testing procedure for side impact airbag development, safety-testing
technology. SAE Paper No. 970568, SP-1264, pp. 17–24.[7] Ito, T., Masuda, I., Sakamoto, M., Moriyasu, I. and Tsukamoto, H., 1997, Optimization of the crush characteristic
of door inner material for occupant injury in side impact. JSAE Review, 18(2), 197.[8] Zaouk, A.K. and Marzougui, D., 2002, Development and Validation of a US Side-Impact Moveable Deformable
Barrier FE Model (Ashburn: FHWA/NHTSA National Crash Analysis Center, The George WashingtonUniversity).
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Development and Validation of Side-Impact Crash and Sled Testing FE Models 937
[9] Marzougui, D., Kan, C.D. and Bedewi, N.E., 1997, Development and Validation of an NCAP Simulation UsingLS-DYNA3D (Ashburn: FHWA/NHTSA National Crash Analysis Center, The George Washington University).
[10] Zhang, H., Raman, S., Gopal, M. and Han, T., 2004, Evaluation and comparison of CFD integrated airbagmodels in LS-DYNA, MADYMO and PAM-CRASH. SAE Paper No. 2004-01-1627.
[11] Teng, T.L., Chang, F.A., Peng, C.P. andYang, B.W., 2004, The study of head and neck injury in traffic accidents.Journal of Applied Sciences, 4(3), 449–455.
[12] Teng, T.L., Liang, C.C., Peng, C.P. and Wu, C.H., 2003, The study of SID finite-element model. The 27thConference on Theoretical and Applied Mechanics, Taiwan, ROC.
[13] http://www.automotive.tno.nl/smartsite.dws?id=1320.
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