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Title: Design
of the occupant protection system for frontal impact using the axiomatic
approach
Author(s): S-K Jeon, M-K Shin, G-J Park
Source: Proceedings of the I Mech E Part D Journal
of Automobile Engineering
Volume: 222 part 3, pages 313-324, Mar 2008
DOI: 10.1243/09544070JAUTO658
Publisher: Professional Engineering Publishing
Abstract:
The functional requirements (FRs) and design equation of a flexible
system change in a continuous manner with respect to a variable
such as time. An event-driven flexible system is defined as a subcategory
of the flexible system in that it changes in a discrete space. A
design scenario is developed for the event-driven systems. The design
equation for each event should be defined by using the axiomatic
approach and the design equations are assembled to form a full design
equation. The design equation for each event can be established
by sensitivity analysis. In conceptual design, the design order
is determined on the basis of the full design equation. Design parameters
(DPs) are found to satisfy FRs in sequence. A DP may consist of
multiple design variables. In a detailed design, the design variables
are determined. The occupant protection system is an event-driven
flexible system because the design matrix and its elements change
according to the impact speed. The involved devices are designed
on the basis of the developed method. FRs at different impact speeds
and corresponding DPs are defined. In a detailed design, the full
factorial design of experiments is employed for the design variables
of the DPs to reduce the injury levels of the occupant. Computer
simulation is utilized for evaluation of the injuries. The results
are discussed.
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Title: Improvement
in numerical reconstruction for vehicle-pedestrian accidents
Author(s): J. Shen, X.-L. Jin
Source: Proceedings of the I Mech E Part D Journal
of Automobile Engineering
Volume: 222 part 1, pages 25-39, Jan 2008
DOI: 10.1243/09544070JAUTO660
Publisher: Professional Engineering Publishing
Abstract:
A full-scale vehicle–pedestrian crash simulation has been
applied to pedestrian accident reconstruction worldwide in the past
decade. Considering that the optimization method and pedestrian
human model play an important role in this simulation, this study
makes some improvements in them according to the characteristics
of real-world pedestrian accidents. On the one hand, the sequential
linear programming method replaces classical manual optimization
for pedestrian accident reconstruction which can automatically vary
pre-impact parameters to minimize the error between simulation and
real data. On the other hand, new anthropometry results and coupled
finite element (FE)–multi-body (MB) modelling technology are
applied to pedestrian human modelling. A Chinese pedestrian model
generator is developed in order to avoid using the Western human
population in China, and an FE leg model is combined into the MB
pedestrian model to perform a more detailed analysis of long bone
fracture.
The purpose of this paper is to evaluate the capability of and
necessity for the above improvements. The evaluation is conducted
by the reconstruction of three fatal pedestrian accidents. The first
two cases are mathematically reconstructed on the basis of the rest
position and pedestrian injury respectively. The influence of the
anthropometry parameters is illustrated by the reconstruction of
the last case.
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Title: A
study of the simulation of a front-crash-induced rollover crash
Author(s): C. Jiang, C.E. Neal-Sturgess
Source: Proceedings of the I Mech E Part D Journal
of Automobile Engineering
Volume: 221 part 12, pages 1487-1497, Dec 2007
DOI: 10.1243/09544070JAUTO628
Publisher: Professional Engineering Publishing
Abstract: Computer-based simulation of rollover
using MADYMO can assist in understanding the occupant and vehicle
kinematics of these complex long-duration events, and the resulting
occupant injuries. This study focused on the simulation of a front-crash-induced
rollover event. A hybrid finite element (FE)-rigid body model of
the vehicle was created to simulate the deformation during the impact
and its influence on the following rollover event. This was used,
together with a multi-body MADYMO model of a Hybrid III dummy, to
evaluate the probability of head injury in the crash. Special attention
was paid to the modelling of the suspension and tyres. Simulation
results from both the FE model and the rigid body model were validated
and evaluated. The results indicate that rollover simulations using
MADYMO proved to be an efficient computer aided engineering (CAE)
methodology. It is necessary to have a deformable FE front end for
the vehicle to simulate this type of event accurately. The injury
parameters from the simulation correlate well with the injury results
from the crash report.
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Title: A
driver-distraction-based lane-keeping assistance system
Author(s): J Pohl, W Birk, L Westervall of Volvo
Car
Source: Proceedings of the I MECH E Part I Journal
of Systems & Control Engineering
Volume: 221 part 4, pages 541-554, June 2007
DOI: 10.1243/09596518JSCE218
Publisher: Professional Engineering Publishing
Abstract: Single-vehicle roadway departure (SVRD)
accidents occur in many cases owing to driver distraction or drowsiness
constituting a substantial share of today's road vehicle accidents
and casualties. This paper describes a distraction-based lane-keeping
support system, which intervenes only when the driver is positively
detected as being distracted. Distraction here is understood as
cognitive and visual distraction, and the focus of this system is
on the latter one. In order to estimate the driver's visual distraction
level, a video-based driver monitoring system is used. Lane-keeping
support is provided by an additional torque applied on the steering
shaft in order to regain an appropriate lane position. In this manner
the system only intervenes when the vehicle has drifted out of its
lane and while the driver is distracted. Test track investigations
indicate large opportunities for such a system from a driver perspective,
provided that sufficient reliability of the employed vision sensor
for lane and face tracking can be obtained.
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Title: Effects
of ribs on S-frame crashworthiness
Author(s): P Hosseini-Tehrani, M Nikahd
Source: Proceedings of the I MECH E Part D Journal
of Automobile Engineering
Volume: 220 part 12, pages 1679-1689, December
2006
DOI: 10.1243/09544070JAUTO285
Publisher: Professional Engineering Publishing
Abstract: Safety and weight reduction continue
to be the main drivers of structural developments. Better control
of frontal collapse and avoidance of bending are the most important
aspects of the design of front longitudinal members. Such members
usually involve a curved section to provide clearance from mechanical
systems, so it is difficult to prevent the onset of bending collapse,
under end load, prior to the desired controlled longitudinal collapse
of the box sections. While vertical ribs are formed into the walls
of the box members to induce longitudinal buckling, it is found
that inclining these at an angle is successful in cancelling the
bending moment induced by the front end load. In this paper various
configurations of incorporating formed ribs into the walls of the
S-frame are considered and their effects on energy absorption and
force response of the S-frame are studied. It is shown that, by
using a proper arrangement of ribs in the walls of the S-frame,
better crashworthiness characteristics may be achieved.
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Title: Pedestrian
Risk from Cars and Sport Utility Vehicles - A Comparative Analytical
Study
Author(s): C K Simms, D P Wood
Source: Proceedings of the I MECH E Part D Journal
of Automobile Engineering
Volume: 220 part 8, pages 1085-1100, August 2006
DOI: 10.1243/09544070JAUTO319
Publisher: Professional Engineering Publishing
Abstract: Analysis of real-world crash data from
the USA shows that 11.5 per cent of pedestrians struck by large
sport utility vehicles (SUVs) are killed, compared with 4.5 per
cent of pedestrians struck by passenger cars. The design of the
vehicle front-end structure has a substantial influence on injury
outcome when pedestrians are struck by vehicles. In the context
of the rising population of SUVs, it is important to determine the
causes of their increased hazard to pedestrians. In this paper,
validated multi-body models are used to show that the shape of SUVs
results in higher pedestrian injuries to the mid-body regions compared
to passenger cars. Analysis shows that the mass difference between
cars and SUVs is not significant for pedestrian injury causation
and it is shown that an important effect of the higher front profile
of SUVs is that the pedestrian is struck more centrally with respect
to the body's centre of gravity, increasing the momentum transfer
in the primary impact. A further important effect of the higher
bonnet leading edge is that there is a direct impact to the mid-body
region, which explains the significant abdomen and other internal
injuries reported from real-world SUV/pedestrian impacts. By comparison,
head injuries sustained from primary vehicle contact are shown to
be similar or slightly lower for SUV/pedestrian impacts compared
to car/pedestrian impacts. However, real-world evidence and the
current models suggest that the secondary impact with the ground
is more severe in SUV/pedestrian impacts compared to car/pedestrian
impacts. Overall, these results show that the empirical finding
that SUVs are more hazardous for pedestrians than passenger cars
is primarily a function of the high bumper and bonnet for such vehicles.
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Title: A
Materials and Structure Perspective on the Feasibility of Automotive
Frontal Protection Systems Meeting the Proposed Pedestrian Safety
Test Criteria
Author(s): R Brooks
Source: Proceedings of the I MECH E Part L Journal
of Materials: Design and Applications
Volume: 220 Page: 67-78. 2006
DOI: 10.1243/14644207JMDA52
Publisher: Professional Engineering Publishing
Abstract: This article describes an investigation
into the material and structural requirements of an automotive frontal
protection system (FPS), i.e. 'bull bar', for an off-road sports
utility vehicle, to meet the proposed pedestrian safety test criteria.
An analytical impact model has been developed to investigate the
feasibility of an FPS meeting the 2006 requirements of upper legform
to leading edge and possible child headform to FPS tests. The results
show that a 520 mm high and 760 mm wide FPS should be designed to
have an effective cantilever flexural rigidity (EIeff)
in the range 800-1200 Nm2 or less, depending on the local contact
stiffness. These levels of flexural rigidity are only likely to
be achievable with a deformable hollow or foam-filled plastic-type
construction. Metallic and structural composite structures are too
stiff or, if thin-walled, are likely to fail prematurely. The operation
of the FPS relies both on cantilever bending and local crush of
the structure at the impact point to absorb the required energy.
Limiting EIeff values for higher or shorter FPSs are obtained by
scaling the above figures in the ratio of the height cubed. Whereas
for the child headform test, the FPS can absorb the energy within
the currently proposed 80 mm FPS to vehicle gap, and still pass
the test requirements, this is not the case for the upper legform
test. In the latter, some of the energy will need to be absorbed
by the vehicle leading edge on the FPS contact. The article concludes
that the analytical model is a useful tool for preliminary design
to meet pedestrian safety legislation requirements.
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Title: A
new methodology for investigating airbag-induced skin abrasions
Author(s): W J Hurst; J M Cormier; J D Stitzel;
M V Jernigan; D M Moorcroft; I P Herring; S M Duma
Source: Proceedings of the I MECH E Part D Journal
of Automobile Engineering
Volume: 219 Page: 599 - 605. May 2005
DOI: 10.1243/095440705X11158
Publisher: Professional Engineering Publishing
Abstract: Although airbags have been shown to reduce
the incidence of life-threatening injuries, they have increased
the risk of minor injuries such as those to the skin. Based on the
distribution of injuries that can be directly attributed to the
airbag itself, it is believed that shear loading exists as a mechanism
for these skin injuries. The purpose of this study was to develop
a new methodology designed to assess the injury potential from different
types of airbag with respect to shear loading. This new methodology
utilized a high-speed impactor to accelerate the airbag fabric past
a sample of skin. Contact normal forces were monitored by the use
of pressure sensors, and fabric velocity was determined from a high-speed
video. The abraded skin samples were analysed using light microscopic
analysis and ultraviolet light source photography. A new abrasion
rating method was developed called the total abrasion score, which
allows for quantifiable differentiation between the abrasions caused
by different airbag fabric and seam types.
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Title: Vehicle-pedestrian collisions: validated models for pedestrian impact and projection
Author(s): D P Wood; C K Simms; D G Walsh
Source: Proceedings of the I MECH E Part D Journal of Automobile Engineering
Volume: 219 Page: 183 - 195. Feb 2005
DOI: 10.1243/095440705X6703
Publisher: Professional Engineering Publishing
Abstract: The most important factor in pedestrian injuries from vehicle collisions is the impact velocity. In cases where the impact configuration can be ascertained, the most common method now used to determine vehicle speed involves the pedestrian projection distance. The more traditional method of using tyre brake marks is losing applicability as ABS braking systems become more common. The two most common impact configurations are wrap projection and forward projection, these being determined by the vehicle/pedestrian geometry and the initial conditions of the impact. In this paper, two models are presented for pedestrian forward and wrap projection impacts. These models are predicated on separating the total projection distance into the individual projection distances occurring during three principal phases of the collision. The models are novel as they use a rigid single-segment body representation of the pedestrian, include explicit modelling of the impact phase, and also allow for uncertainty in the input parameters. Published data are used to provide distributions for the input variables such as pedestrian and vehicle masses, etc. The model predictions of impact speed from overall projection distance are validated by comparison with real-world accident data.
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Title: Structural and biomechanical crashworthiness using multi-body dynamics
Author(s): J.A.C. Ambrósio; M.P.T. Silva
Source: Proceedings of the I MECH E Part D Journal of Automobile Engineering
Volume: 218 Page: 629 - 645. March 2004
DOI: 10.1243/0954407041166076
Publisher: Professional Engineering Publishing
Abstract: Multi-body dynamics methodologies are the prime tools used for the design and analysis of structural and biomechanical systems that undergo multiple-impact conditions during relatively long simulation times and for which the large rigid body motion of the components is of major importance. A computational methodology based on the use of Cartesian coordinates is presented to represent the general multi-body system. In order to represent the contact between the system components a continuous force model is introduced in the framework of the chosen multi-body formulation. The structural crashworthiness requires that some of the system components are allowed to undergo deformations. A methodology that uses the non-linear finite element method integrated with the classical multi-body dynamics equations is proposed here. The formulations are demonstrated by an application to a complex crash scenario represented by a rollover of an all-terrain vehicle with several occupants inside. Special emphasis is put on the determination of the occupants' initial positions using video cameras and spatial position reconstruction techniques in order to allow for the study of out-of-position occupant dynamics. It is shown that the methodology proposed here allows not only for the description of the major structural deformations of the vehicle but also for the evaluation of the occupants' kinematics.
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