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Viewing 1 to 30 of 57
2013-11-11
Technical Paper
2013-22-0017
Randa Radwan Samaha, Priya Prasad, Lilly Nix
An overview NASS study of US frontal crashes was performed to investigate crash involvement, driver injury distributions and rates in airbag equipped vehicles by vehicle class and structural engagement. Frontal crash bins were based on taxonomy of structural engagement, i.e., Full Engagement, Offset, Between Rails and Corner impact crashes. A new classification of Corner impacts included frontal small overlap impacts with side damage as coded by NASS CDS. Belted drivers of two age groups, between 16 and 50 and over 50 years old, were considered. Vehicles were grouped into light and heavy passenger cars and lights trucks, and vans. A method to identify and address overly influential NASS weights was developed based on considerations of weighting factor statistics. The new taxonomy, with an expanded definition of corner impacts, allowed a more comprehensive classification of frontal crash modes.
2010-11-03
Technical Paper
2010-22-0004
Priya Prasad, Harold J. Mertz, Dainius J. Dalmotas, Jeffrey S. Augenstein, Kennerly Digges
An evaluation of the four injury risk curves proposed in the NHTSA NCAP for estimating the risk of AIS≻=3 injuries to the head, neck, chest and AIS≻=2 injury to the Knee-Thigh-Hip (KTH) complex has been conducted. The predicted injury risk to the four body regions based on driver dummy responses in over 300 frontal NCAP tests were compared against those to drivers involved in real-world crashes of similar severity as represented in the NASS. The results of the study show that the predicted injury risks to the head and chest were slightly below those in NASS, and the predicted risk for the knee-thigh-hip complex was substantially below that observed in the NASS. The predicted risk for the neck by the Nij curve was greater than the observed risk in NASS by an order of magnitude due to the Nij risk curve predicting a non-zero risk when Nij = 0. An alternative and published Nte risk curve produced a risk estimate consistent with the NASS estimate of neck injury.
2011-11-07
Technical Paper
2011-22-0008
Srinivasan Sundararajan, Stephen W. Rouhana, Derek Board, Ed DeSmet, Priya Prasad, Jonathan D. Rupp, Carl S. Miller, Lawrence W. Schneider
This study evaluated the biomechanical performance of a rear-seat inflatable seatbelt system and compared it to that of a 3-point seatbelt system, which has a long history of good real-world performance. Frontal-impact sled tests were conducted with Hybrid III anthropomorphic test devices (ATDs) and with post mortem human subjects (PMHS) using both restraint systems and a generic rear-seat configuration. Results from these tests demonstrated: a) reduction in forward head excursion with the inflatable seatbelt system when compared to that of a 3-point seatbelt and; b) a reduction in ATD and PMHS peak chest deflections and the number of PMHS rib fractures with the inflatable seatbelt system and c) a reduction in PMHS cervical-spine injuries, due to the interaction of the chin with the inflated shoulder belt. These results suggest that an inflatable seatbelt system will offer additional benefits to some occupants in the rear seats.
2005-04-11
Technical Paper
2005-01-0297
Tony R. Laituri, Priya Prasad, Kaye Sullivan, Michael Frankstein, Robert S. Thomas
An age-dependent, serious-to-fatal (AIS3+), thoracic risk curve was derived and evaluated for frontal impacts. The study consisted of four parts. In Part 1, two datasets of post mortem human subjects (PMHS) were generated for statistical and sensitivity analyses. In Part 2, logistic regression analyses were conducted. For each dataset, two statistical methods were applied: (1) a conventional maximum likelihood method, and (2) a modified maximum likelihood method. Therefore, four statistical models were derived — one for each dataset/statistical method combination. For all of the resulting statistical models (risk curves), the linear combination of maximum normalized sternum deflection and age of the PMHS was identified as a feasible predictor of AIS3+ thoracic injury probability. In Part 3, the PMHS-based risk curves were transformed into test-dummy-based risk curves. In Part 4, validation studies were conducted for each risk curve.
2016-11-07
Technical Paper
2016-22-0001
Harold J. Mertz, Priya Prasad, Dainius J. Dalmotas, Annette L. Irwin
Injury Risk Curves are developed from cadaver data for sternal deflections produced by anterior, distributed chest loads for a 25, 45, 55, 65 and 75 year-old Small Female, Mid-Size Male and Large Male based on the variations of bone strengths with age. These curves show that the risk of AIS ≥ 3 thoracic injury increases with the age of the person. This observation is consistent with NASS data of frontal accidents which shows that older unbelted drivers have a higher risk of AIS ≥ 3 chest injury than younger drivers.
2008-04-14
Technical Paper
2008-01-0188
David C. Viano, Chantal S. Parenteau, Priya Prasad, Roger Burnett
The objective of this study was to analyze available anthropomorphic test device (ATD) responses from FMVSS 301-type rear impact tests. Rear impact test data was obtained from NHTSA and consisted of dummy responses, test observations, photos and videos. The data was organized in four test series: 1) NCAP series of 30 New Car Assessment Program tests carried out at 35 mph with 1979-1980 model year vehicles, 2) Mobility series of 14 FMVSS 301 tests carried out at 30 mph with 1993 model year vehicles, 3) 301 MY 95+ series of 79 FMVSS 301 tests carried out at 30 mph with 1995-2005 model year vehicles and 4) ODB series of 17 Offset Deformable Barrier tests carried out at 50 mph with a 70% overlap using 1996-1999 model year vehicles. The results indicate very good occupant performance in yielding seats in the NCAP, Mobility and 301 MY 95+ test series.
2007-04-16
Technical Paper
2007-01-0708
David C. Viano, Chantal S Parenteau, Priya Prasad, Roger Burnett
The objective of this study was to analyze available anthropomorphic test device (ATD) responses from KARCO rear impact tests and to evaluate an injury predictive model based on crash severity and occupant weight presented by Saczalski et al. (2004). The KARCO tests were carried out with various seat designs. Biomechanical responses were evaluated in speed ranges of 7-12, 13-17, 18-23 and 24-34 mph. For this analysis, all tests with matching yielding and stiff seats and matching occupant size and weight were analyzed for cases without 2nd row occupant interaction. Overall, the test data shows that conventional yielding seats provide a high degree of safety for small to large adult occupants in rear crashes; this data is also consistent with good field performance as found in NASS-CDS. Saczalski et al.'s (2004) predictive model of occupant injury is not correct as there are numerous cases from NASS-CDS that show no or minor injury in the region where serious injury is predicted.
2006-11-06
Technical Paper
2006-22-0009
Jason Forman, David Lessley, C. Greg Shaw, Jay Evans, Richard Kent, Stephen W. Rouhana, Priya Prasad
Injury to the thorax is the predominant cause of fatalities in crash-involved automobile occupants over the age of 65, and many elderly-occupant automobile fatalities occur in crashes below compliance or consumer information test speeds. As the average age of the automotive population increases, thoracic injury prevention in lower severity crashes will play an increasingly important role in automobile safety. This study presents the results of a series of sled tests to investigate the thoracic deformation, kinematic, and injury responses of belted post-mortem human surrogates (PMHS, average age 44 years) and frontal anthropomorphic test devices (ATDs) in low-speed frontal crashes. Nine 29 km/h (three PMHS, three Hybrid III 50th% male ATD, three THOR-NT ATD) and three 38 km/h (one PMHS, two Hybrid III) frontal sled tests were performed to simulate an occupant seated in the right front passenger seat of a mid-sized sedan restrained with a standard (not force-limited) 3-point seatbelt.
2006-11-06
Technical Paper
2006-22-0005
Tony R. Laituri, Scott Henry, Kaye Sullivan, Priya Prasad
A set of risk equations was derived to estimate the probability of sustaining a moderate-to-serious injury to the knee-thigh-hip complex (KTH) in a frontal crash. The study consisted of four parts. First, data pertaining to knee-loaded, whole-body, post-mortem human subjects (PMHS) were collected from the literature, and the attendant response data (e.g., axial compressive load applied to the knee) were normalized to those of a mid-sized male. Second, numerous statistical analyses and mathematical constructs were used to derive the set of risk equations for adults of various ages and genders. Third, field data from the National Automotive Sampling System (NASS) were analyzed for subsequent comparison purposes.
2006-11-06
Technical Paper
2006-22-0017
King H. Yang, Jingwen Hu, Nicholas A. White, Albert I. King, Clifford C. Chou, Priya Prasad
Numerical analyses frequently accompany experimental investigations that study injury biomechanics and improvements in automotive safety. Limited by computational speed, earlier mathematical models tended to simplify the system under study so that a set of differential equations could be written and solved. Advances in computing technology and analysis software have enabled the development of many sophisticated models that have the potential to provide a more comprehensive understanding of human impact response, injury mechanisms, and tolerance. In this article, 50 years of publications on numerical modeling published in the Stapp Car Crash Conference Proceedings and Journal were reviewed. These models were based on: (a) author-developed equations and software, (b) public and commercially available programs to solve rigid body dynamic models (such as MVMA2D, CAL3D or ATB, and MADYMO), and (c) finite element models.
2006-11-06
Technical Paper
2006-22-0018
Jesse S. Ruan, Raed El-Jawahri, Stephen W. Rouhana, Saeed Barbat, Priya Prasad
The biofidelity of the Ford Motor Company human body finite element (FE) model in side impact simulations was analyzed and evaluated following the procedures outlined in ISO technical report TR9790. This FE model, representing a 50th percentile adult male, was used to simulate the biomechanical impact tests described in ISO-TR9790. These laboratory tests were considered as suitable for assessing the lateral impact biofidelity of the head, neck, shoulder, thorax, abdomen, and pelvis of crash test dummies, subcomponent test devices, and math models that are used to represent a 50th percentile adult male. The simulated impact responses of the head, neck, shoulder, thorax, abdomen, and pelvis of the FE model were compared with the PMHS (Post Mortem Human Subject) data upon which the response requirements for side impact surrogates was based. An overall biofidelity rating of the human body FE model was determined using the ISO-TR9790 rating method.
2004-11-01
Technical Paper
2004-22-0020
Tony R. Laituri, Donald Sullivan, Kaye Sullivan, Priya Prasad
A theoretical math model was created to assess the net effect of aging populations versus evolving system designs from the standpoint of thoracic injury potential. The model was used to project the next twenty-five years of thoracic injuries in Canada. The choice of Canada was topical because rulemaking for CMVSS 208 has been proposed recently. The study was limited to properly-belted, front-outboard, adult occupants in 11-1 o'clock frontal crashes. Moreover, only AIS3+thoracic injury potential was considered. The research consisted of four steps. First, sub-models were developed and integrated. The sub-models were made for numerous real-world effects including population growth, crash involvement, fleet penetration of various systems (via system introduction, vehicle production, and vehicle attrition), and attendant injury risk estimation. Second, existing NASS data were used to estimate the number of AIS3+ chest-injured drivers in Canada in 2001.
2005-11-09
Technical Paper
2005-22-0017
Srini Sundararajan, Priya Prasad, Stephen W. Rouhana, Constantine K. Demetropoulos, King H. Yang, Albert I. King, Lutz -P. Nolte
The purpose of this study was to determine the characteristics of eighteen lumbar spine motion segments subjected to lateral shear forces under quasi-static (0.5 mm/s) and dynamic (500 mm/s) test conditions. The quasi-static test was also performed on the lumbar spine of a side impact anthropomorphic test device, the EuroSID-2 (ES-2). In the quasi-static tests, the maximum force before disc-endplate separation in the PMHS lumbar motion segments was 1850 ± 612 N, while the average linear stiffness of PMHS lumbar motion segments was 323 ± 126 N/mm. There was a statistically significant difference between the quasi-static (1850 ± 612 N) and dynamic (2616 ± 1151 N) maximum shear forces. The ES-2 lumbar spine (149 N/mm) was more compliant than the PMHS lumbar segments under the quasi-static test condition.
2005-11-09
Technical Paper
2005-22-0016
Jesse S. Ruan, Raed El-Jawahri, Saeed Barbat, Priya Prasad
Human abdominal response and injury in blunt impacts was investigated through finite element simulations of cadaver tests using a full human body model of an average-sized adult male. The model was validated at various impact speeds by comparing model responses with available experimental cadaver test data in pendulum side impacts and frontal rigid bar impacts from various sources. Results of various abdominal impact simulations are presented in this paper. Model-predicted abdominal dynamic responses such as force-time and force-deflection characteristics, and injury severities, measured by organ pressures, for the simulated impact conditions are presented. Quantitative results such as impact forces, abdominal deflections, internal organ stresses have shown that the abdomen responded differently to left and right side impacts, especially in low speed impact.
2006-04-03
Technical Paper
2006-01-1666
Tony R. Laituri, Scott Henry, Kaye Sullivan, Priya Prasad
Lower-body injury data for adults in real-world frontal impacts in the National Automotive Sampling System (NASS) were collected, analyzed, and modeled via statistical methods. Two levels of lower-body injury were considered: maximum serious-to-fatal (MAIS3+) and moderate-to-fatal (MAIS2+). In the analysis, we observed that a substantial fraction of all lower-body injured occupants had no recorded floor/toe pan intrusion: 47% of all MAIS3+ injured occupants; 69% of all MAIS2+ injured occupants. In the statistical modeling, we developed binary logistic regression models to fit the MAIS3+ and MAIS 2+ injury data. The statistically significant variables (p ≤ 0.05) were the speed change of the crash, postcrash floor/toe pan intrusion, level of restraint, occupant age, and occupant gender.
1990-10-01
Technical Paper
902308
Paul C. Begeman, Priya Prasad
Although various automobile accident surveys showed between 20 to 30% of lower extremity injuries involved the foot or ankle, there is little information in the existing literature on the the injury mechanisms of ankle injuries for automobile occupants involved in frontal impacts. This study addresses the injury to ankles involving dorsiflexion caused by impact loading to the bottom of the foot. Types of injuries include malleolus fractures and ligament avulsions and ruptures. Nine pair of cadaver and two Hybrid 3 lower limbs were impacted on the bottom of the foot with a 16 kg pneumatically propelled linear impactor. A horizontally oriented bar struck the foot 62 mm distally of the ankle joint with velocities between 3 and 8 m/s. The proximal end of the tibia/fibula was fixed to a rigid support through a triaxial load cell. Load cells on the foot and impactor along with high-speed photography provided the response data of the foot and ankle.
1990-10-01
Technical Paper
902318
Priya Prasad
Two 50th percentile anthropomorphic test devices are specified as alternate test devices for FMVSS 208 compliance testing. These test devices are commonly known as the Hybrid II and the Hybrid III dummies. The designs of the two dummies are different, representing the state-of-the-art in the time frame of their designs. The trajectory differences between the two dummies have been published in the literature, but response differences, e.g., HIC and chest acceleration are not available in the literature. To quantify response differences between the two dummies, a series of sled tests with open bucks and with bucks simulating vehicle interior were conducted with restrained dummies. Additional crash tests were also conducted with the two dummies. This paper reports on an analysis of the data from the above series of tests. The data indicate that in non-head contact simulations with belt restraint systems, Hybrid III HIC's are nearly 50% higher than Hybrid II HIC's.
1990-10-01
Technical Paper
902321
Tah Chuan Low, Priya Prasad
: A series of rigid wall tests have been conducted at three impact velocities to quantify the dynamic response of the Side Impact Dummy (SID) developed by US DOT. This paper reports the chest, pelvis and head responses of the dummy at various filter frequencies and describes the development and verification of the three-dimensional mathematical model of the Side Impact Dummy utilizing the rigid wall test results. The mathematical model uses the mass distribution and the linkage system of the current Part 572, Hybrid II dummy which forms the basic platform of the SID. The unique chest of the dummy is modeled by two systems of linkages simulating the rib cage and the jacket. Also included in the model is the internal hardware of the chest, e.g. a damper, rib stopper and a clavicle simulator at the upper spine. The material and linkage models are based on static and dynamic tests of the dummy components.
1994-11-01
Technical Paper
942212
Jesse S. Ruan, Priya Prasad
The potential of head injury in frontal barrier impact tests was investigated by a mathematical model which consisted of a finite element human head model, a four segments rigid dynamic neck model, a rigid body occupant model, and a lumped-mass vehicle structure model. The finite element human head model represents anatomically an average adult head. The rigid body occupant model simulates an average adult male. The structure model simulates the interior space and the dynamic characteristics of a vehicle. The neck model integrates the finite element human head to the occupant body to give a more realistic kinematic head motion in a barrier crash test. Model responses were compared with experimental cadaveric data and vehicle crash data for the purpose of model validation to ensure model accuracy. Model results show a good agreement with those of the tests.
1995-02-01
Technical Paper
950646
Priya Prasad, Leonid Smorgonsky
The result of two series of crash tests, 5 tests each series, are presented in this paper. Two car designs were subjected to various frontal impacts - full frontal, car-to-car 60% offset, 50% offset, and 50% offset with deformable barrier - at 56 km/h. Two tests were conducted at 60 km/h against the ECE deformable barrier with 40% overlap. Structural and occupant responses are compared between the various test conditions.
1995-02-01
Technical Paper
950885
Saeed D. Barbat, Priya Prasad
This paper first describes an experimental analytical approach and numerical procedures used to establish crushable foam material constants needed in finite element (FE) analysis. Dynamic compressive stress-strain data of a 2 pcf Dytherm foam, provided by ARCO Chemical, is used to determine the material parameters which appears in the foam constitutive equation. A finite element model simulating a 15 mph spherical headform impact with a foam sample 6 in. x 6 in. x 1 in. fixed against a rigid plate is developed. The predicted force-deflection characteristic is validated against test data to characterize the initial loading and final unloading stiffnesses of the foam during impact. Finite element modeling and analysis of 15 mph spherical headform impact with component sections of upper interior structures of a passenger compartment is presented.
1996-02-01
Technical Paper
960104
Saeed D. Barbat, Hyun-Yong Jeong, Priya Prasad
This paper describes the steps and procedures involved in the development, calibration, and validation of a finite element model of a deformable featureless headform (Hybrid III head without nose). Development efforts included: a headform scan to verify geometric accuracy, quantification of general-purpose construction of the finite element model from the scanned data, viscoelastic parameters for the constitutive model definition of the headform skin, and models of drop tests with impact speeds of 9.775, 14.484, 19.312, and 24.140 km/h (6.074, 9, 12, and 15 mph). The predictions of all pertinent headform responses during the calibration were in excellent agreement with related experiments. The validity of the headform model and the headform impact methodology were verified in both component and full vehicle environments. This was accomplished through comparisons of finite element simulations with tests of the headform responses at 24.140 km/h (15 mph) impact.
1995-11-01
Technical Paper
952710
Stanley H. Backaitis, Maurice E. Hicks, Priya Prasad, Tony Laituri, Jeffrey Nadeau
Locations of key body segments of Hybrid III dummies used in FMVSS 208 compliance tests and NCAP tests were measured and subjected to statistical analysis. Mean clearance dimensions and their standard deviations for selected body segments of driver and passenger occupants with respect to selected vehicle surfaces were determined for several classes of vehicles. These occupant locations were then investigated for correlation with impact responses measured in crash tests and by using a three dimensional human-dummy mathematical model in comparable settings. Based on these data, the importance of some of the clearance dimensions between the dummy and the vehicle surfaces was determined. The study also compares observed Hybrid III dummy positions within selected vehicles with real world occupant positions reported in published literature.
1991-02-01
Technical Paper
910601
Priya Prasad, Tah Chuan Low, Clifford C. Chou, George G. Lim, Srini Sundararajan
: This paper describes the development of a three-dimensional lumped-mass structure and dummy model to study barrier-to-car side impacts. The test procedures utilized to develop model input data are also described. The model results are compared to crash test results from a series of six barrier-to-car crash tests. Sensitivity analysis using the validated model show the necessity to account for dynamic structural rate effects when using quasi-statically measured vehicle crush data.
1997-02-24
Technical Paper
970128
Nripen Saha, Stephen Calso, Djamal Midoun, Priya Prasad
Global engineering is increasingly becoming a practice within the automotive industry. Due to added engineering and manufacturing benefits, more and more new vehicles are being developed with common structure to meet the consumer needs in many local regions. While vehicle development and manufacturing process is becoming global, automotive safety regulations in various parts of the world have not been as uniform. A good example is the differing requirements for dynamic side impact protection of new vehicles. United States National Highway Traffic Safety Administration (NHTSA) and European Union (EU) have each produced their own distinct test procedures such as, different barrier faces, impact configurations, and anthropomorphic test devices (dummies). Although both test procedures have the same final objective estimate occupant responses in side impacts, they differ greatly in execution and emphasis on occupant response requirements.
1996-11-01
Technical Paper
962426
Narayan Yoganandan, Frank A. Pintar, Melbourne Boynton, Paul Begeman, Priya Prasad, Shashi M. Kuppa, Richard M. Morgan, Rolf H. Eppinger
Axial loading of the calcaneus-talus-tibia complex is an important injury mechanism for moderate and severe vehicular foot-ankle trauma. To develop a more definitive and quantitative relationship between biomechanical parameters such as specimen age, axial force, and injury, dynamic axial impact tests to isolated lower legs were conducted at the Medical College of Wisconsin (MCW). Twenty-six intact adult lower legs excised from unembalmed human cadavers were tested under dynamic loading using a mini-sled pendulum device. The specimens were prepared, pretest radiographs were taken, and input impact and output forces together with the pathology were obtained using load cell data. Input impact forces always exceeded the forces recorded at the distal end of the preparation. The fracture forces ranged from 4.3 to 11.4 kN.
1999-03-01
Technical Paper
1999-01-0763
Tony R. Laituri, Priya Prasad
A new inflator specification, the “inflator thrust variable,” was developed to better explain measured mid-sized male, instrumented test dummy responses in the chest-on-module test condition. Specifically, controlled laboratory experiments were conducted with non-production, driver airbag modules with inflators of various outputs and gas constituents in an effort to assess their effects on a pertinent occupant response. Regression analyses showed that the inflator thrust variable is a better predictor of the observed variation in peak viscous criterion responses than either peak tank pressure or the related pressure rise rate when inflators of differing gas composition were compared.
2000-11-01
Technical Paper
2000-01-SC05
Harold J. Mertz, Priya Prasad
This paper describes improvements made to the injury risk curves for peak neck tension, peak neck extension moment and a linear combination of tension and extension moment that produce peak stress in the anterior-longitudinal ligament at the head-to-neck junction. Data from previously published experiments that correlated neck injuries to 10-week-old, anesthetized pigs and neck response measurements of a 3-year-old child dummy that were subjected to similar airbag deployments are updated and used to generate Normal probability curves for the risk of AIS ≥ 3 neck injury for the 3-year-old child. These curves are extended to other sizes and ages by normalizing for neck size. Factors for percent of muscle tone and ligamentous failure stress as a function of age are incorporated in the risk analysis. The most sensitive predictor of AIS ≥ 3 neck injury for this data set is peak neck tension.
2000-11-01
Technical Paper
2000-01-C086
Priya Prasad
The past, current and future role of electronics in reducing accidents, crash severity and crash notification is discussed. A holistic approach that ties pre-crash, crash and post-crash factors in enhancing automotive safety is examined and the growing role of electronics in affecting the three factors is discussed. Electronic technology has already entered the automotive safety arena, and its utilization in the future is expected to grow rapidly towards the goal of safer roadway environment.
2001-03-05
Technical Paper
2001-01-0165
Tony R. Laituri, N. Sriram, Brian P. Kachnowski, Brion R. Scheidel, Priya Prasad
In the 1999 Supplemental Notice for Proposed Rulemaking (SNPRM) for Advanced Airbags, the National Highway Traffic Safety Administration (NHTSA) sought comments on the maximum speed at which the high-speed, unbelted occupant test suite will be conducted, i.e., 48 kph vs. 40 kph. To help address this question, an analysis of constraints was performed via extensive mathematical modeling of a theoretical restraint system. First, math models (correlated with several existing physical tests) were used to predict the occupant responses associated with 336 different theoretical dual-stage driver airbag designs subjected to six specific Regulated and non-Regulated tests.
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