Study of injuries combining computer simulation in motorcycle–car collision accidents

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    right tibia of the back seat occupant was larger and more durative compared with the motorcycle driver; the back seat occupant suffered a bursting

    complicated motorcyclecar collision accidents in China, for

    example, there are two motorcycle victims that one is the

    the motorcycle. It is difficult to objectively judge by forensic

    collision course can be simulated by using computer

    simulation. The simulation results are helpful for forensic

    Available online at www.sciencedirect.com

    Forensic Science International* Corresponding author at: Room 225, Advanced Manufacture Building ofsituation involving motorcycles in China was more serious.

    In motorcyclecar collision accidents, motorcycle victims

    have no protective equipment other than helmets, and the

    impact injuries on their bodies vary [3]. The mechanisms and

    characteristics of injuries suffered by motorcycle victims are

    one of the research emphases for aiding judgment and

    prevention of traffic accidents. Forensic experts can offer

    some proposals to the police for judging accident responsibility

    by observing the characteristics of the injuries and the location

    conclusions which one of them is the motorcycle driver, and

    therefore the guilty party to be convicted in court, when this

    type of accident happens.

    Computer simulations of motorcyclecar collision accidents

    provide an effective approach [4,5] to reveal the mechanism of

    injuries of motorcycle victims and to solve the doubts faced by

    forensic experts. The collision course of accidents can be well

    reconstructed in three-dimensional space by establishing

    mathematical models of cars and human bodies, and the

    movement and the load of motorcycle victims bodies in theaccounted for approximately 21% of all traffic accident deaths

    in China. Compared with other countries in Europe, the accidentmotorcycle driver and the other one is the back seat occupant onIn 2005, according to the police statistics [2], the number of

    fatalities from motorcycle accidents was 20,774 whichfracture injury of his right tibia. These results might be useful for forensic experts in dealing with similar motorcyclecar collision accidents in the

    future.

    # 2007 Elsevier Ireland Ltd. All rights reserved.

    Keywords: Injury; Collision accident; Motorcycle; Computer simulation

    1. Introduction

    Collision accidents involving motorcycles are frequent in

    China, and motorcycle victims easily suffer serious injuries [1].

    of the motorcycle victims body or by analyzing the autopsy

    results. However, they sometimes cannot hypothesize and

    explain the cause of these various impact injuries of motorcycle

    victims in the collision course of real accidents. In someStudy of injuries combining comp

    collision

    Guo Lei a,*, Jin Xian-Long a, Zhang Xiao-Yua School of Mechanical Engineering, Shangha

    b Institute of Forensic Science, Minis

    Received 31 January 2007; received in revise

    Available online

    Abstract

    This paper presents the approach of computer simulation to clarify th

    characteristic of two motorcycle victims, including the motorcycle drive

    which one of them is the motorcycle driver. Two typical motorcyclecar

    both the motorcycle driver and the back seat occupant in the collision co

    he fell on the ground after being thrown higher than the motorcycle drivSchool of Mechanical Engineering, Shanghai Jiao Tong University, No. 800,

    Dongchuan Road, Shanghai 200240, China. Tel.: +86 21 34206099.

    E-mail address: glei@sjtu.edu.cn (G. Lei).

    0379-0738/$ see front matter # 2007 Elsevier Ireland Ltd. All rights reserved.doi:10.1016/j.forsciint.2007.10.011ter simulation in motorcyclecar

    ccidentsa, Shen Jie a, Chen Yi-Jiu b, Chen Jian-Guo b

    ao Tong University, Shanghai 200240, China

    of Justice, Shanghai 200063, China

    orm 9 July 2007; accepted 30 October 2007

    February 2008

    estions faced by forensic experts about what causes the various injuries

    d the back seat occupant on the motorcycle, and how to exactly confirm

    ident cases were reconstructed to analyze the movement and the load of

    e. In case one, the back seat occupant suffered fatal head injuries when

    ver the top of the car. In case two, the compressive force loaded by the

    www.elsevier.com/locate/forsciint

    177 (2008) 9096experts to analyze and discover the cause of various impact

    injuries, and assist the police in judging who should be held

    responsible for the accident.

  • This paper presents the approach of computer simulation to

    Euler or RungeKutta) to predict the motion of systems of bodies connected by

    kinematic joints, based on initial conditions and the inertial properties of the

    bodies. It is convenient to use the database of human body models developed by

    TNO (Netherlands Organisation for Applied Science Research) and EEVC

    (European Experimental Vehicles Committee), including the Hybrid III dummy

    and pedestrian models in this software. These human models are available to

    simulate occupants in various kinds of accidents.

    In this paper, the multi-body model of cars and motorcycles in both accident

    cases are set up according to their real shape and mass in MADYMO. The

    contact characteristics of the structure of the car and motorcycle in the collision

    course proposed by Motoaki [13] are used in the present study. The sitting

    Hybrid III dummy models in the database are used to simulate the motorcycle

    driver and the back seat occupant on the motorcycle, and the contact char-

    acteristics of the dummy model are examined by TNO. Some modifications of

    the dummy are performed on mass distribution and body posture according to

    the body characteristics of the motorcycle victims in each accident.

    In case one, the motorcycle suddenly crashed into the left rear of the car

    when the car was waiting for the traffic lamp to convert from red to green at the

    Fig. 1. The multi-body system of bodies connected by kinematic joints.

    G. Lei et al. / Forensic Science International 177 (2008) 9096 91reveal the cause of various impact injuries characteristic of

    motorcycle victims by reconstructing the collision course of

    two typical motorcyclecar accidents. Both accident cases

    concern two motorcycle victims, the motorcycle driver and the

    back seat occupant on the motorcycle, and the characteristic

    injuries are relevant to the different movements and load of

    their bodies in the collision course. It can be confirmed which

    one of them is the motorcycle driver who is responsible for the

    accident, by analyzing the injuries of their bodies under

    forensic study combining simulation results.

    2. Methods

    The multi-body dynamics method is presented using one of the most useful

    computer programming methodologies in the world, and it can simulate the

    dynamics response of complex multi-body systems. A multi-body system

    generally consists of rigid and flexible bodies joined together by kinematic

    joints (e.g., revolute or translational joints) or force elements (e.g., springs and

    dampers), and the presence of these kinematic joints is defined by means of

    global and local coordinate reference systems in such a model (Fig. 1(a)). It is

    sufficiently flexible to construct a multi-body model of a human body or vehicle

    with various kinematic joints and discrete bodies of particular size and shape

    (Fig. 1(b)).

    MADYMO [69] (mathematical dynamic model) is a software of the multi-

    body dynamics method which has been most widely applied in injury biomecha-

    nics and accident reconstruction [1012] involving many means of transport such

    as cars, motorcycles and bicycles. It uses numerical algorithms (e.g., modifiedFig. 2. Damage to the catown crossroad. The damage of the impacted car and motorcycle are shown in

    Fig. 2. The left rear taillight and bumper of the car were shattered, presumably

    by the motorcycle front cowl and front wheel. The left rear windshield of the car

    also was shattered, presumably by the motorcycle driver or the back seat

    occupant on the motorcycle when his head impacted the rear windshield. The

    front cowl of the motorcycle was smashed to pieces, and some green paint of the

    car body adhering to the front shock absorber of the motorcycle could be

    observed.

    The two motorcycle victims, the motorcycle driver and the back seat

    occupant on the motorcycle, did not wear helmets in this case. They both

    were thrown forwards from the motorcycle seat and fell to the ground at an

    unequal distance. The draft of the final accident scene drawn by the police is

    shown in Fig. 3, and the location of victim A and victim B were explicit when

    the collision happened. The distance between victim As head and the center of

    the motorcycle front wheel was 715 cm, and the distance between victim Bs

    head and the center of the motorcycle front wheel was 105 cm. Victim A mainly

    suffered fatal head and brain injuries, contusion and laceration of the right face,

    abrasion and bruising of limbs (Fig. 4(a)), and died at the location of the

    accident. Victim B suffered serious injuries, contusion and laceration of the

    calvarial scalp and left face, abrasion and bruising of the mandible, limbs and

    perineum (Fig. 4(b)), and survived in the hospital. By observing the damage of

    the left rear of the car, forensic experts thought that the motorcycle driver might

    easily suffer abrasion and contusion of the left face and mandible from the

    impact of the left rear windshield of the car, crush injury of the perineum from

    the impact of the gasoline tank of the motorcycle, and the back seat occupant on

    the motorcycle might be thrown farther away from the motorcycle than the

    motorcycle driver when the collision happened. Therefore, they could presume

    that victim B was the motorcycle driver who should be responsible for the

    accident by contrasting victim Bs injuries with victim As. However, victim B

    denied the charge of being the motorcycle driver himself and did not admit guiltr and the motorcycle.

  • in court. There was still some debate about which of the two victims was the

    motorcycle driver, and it could not be absolutely confirmed by the police.

    In case two, the motorcycle suddenly passed the crossroad when the traffic

    lamp was red, and then the car crashed into the right side of the motorcycle. The

    damage of the impacted car and motorcycle is shown in Fig. 5. Deformation of

    the front left bumper, hood edge and bonnet of the car could be observed,

    presumably caused by the motorcycle driver or the back seat occupant on the

    motorcycle when his right crus impacted the bumper, his thigh impacted the

    hood edge and his hip impacted the bonnet. The external plastic shell of the

    motorcycle body and the footplate on the right side, thought to be impacted by

    the car front structure, were smashed into pieces.

    Both motorcycle victims, the motorcycle driver and the back seat occupant,

    also did not wear helmets in this case. The final accident scene was not drawn by

    the police because one survival victim escaped from the location of the accident

    and another victim was immediately sent to the hospital. The motorcycle victim

    in the hospital died within several hours; he mainly had suffered fatal head and

    brain injuries, right tibia fracture and some body bruises. For the analysis of the

    right tibia fracture of the dead motorcycle victim, the anatomy of his right crus

    was performed by forensic experts in the Institute of Forensic Sciences,

    Ministry of Justice in Shanghai. The bursting fracture of the central section

    of his right tibia could be observed, and the length of the bone crack was more

    than 5 cm as shown in Fig. 6; it was thought to be severely impacted by the car

    bumper. By observing the deformation of the car bumper and the motorcycle

    steel body, forensic experts thought that the back seat occupant on the motor-

    cycle might easily suffer serious injury of his right crus from the crush between

    the car bumper and the motorcycle steel body in the collision course, and the

    motorcycle driver might not suffer such serious injury of his right crus.

    Therefore, they could presume that the escaping motorcycle victim, who did

    not suffer the fracture injury of right tibia, was the motorcycle driver. However,

    this supposition needed to be confirmed for a correct judgment of the accident.

    3. Results

    According to the investigation materials shown by the

    police, the situation where the impact velocity of the

    motorcycle was 52 km/h and the car instantaneously immobile

    was simulated in case one, and the situation where the impact

    velocity of the car and motorcycle were about 55 and 20 km/h,

    respectively was simulated in case two.

    For case one, the simulation result of the final accident

    scene is shown in Fig. 7, and the simulation result of the

    collision course is shown in Fig. 8. The distance between

    Fig. 3. The draft of the final accident scene.

    vic

    G. Lei et al. / Forensic Science International 177 (2008) 909692Fig. 4. Injuries to the two motorcycleFig. 5. Damage to the catims: (a) victim A and (b) victim B.r and the motorcycle.

  • t tib

    G. Lei et al. / Forensic Science Intvictim As head and the center of the motorcycle front wheel

    was 617 cm, and the distance between victim Bs head and

    the center of the motorcycle front wheel was 120 cm, as

    shown in Fig. 7. Compared with the draft of the final accident

    scene shown in Fig. 3, the simulation result in Fig. 7 was

    accordant and more visual. In Fig. 8, the front cowl and

    wheel of the motorcycle contacted with the left taillight and

    bumper of the car at 50 ms, and the motorcycle driver and the

    back seat occupant were thrown forwards from the

    motorcycle seat on the inertial velocity effect. The

    motorcycle drivers head smashed the left rear windshield

    of the car, bruised and contused his left face and mandible by

    the edge of windshield at 100 ms, and his shoulder and thorax

    contacted with the rear body of the car so that the forward

    movement of his body was blocked. The back seat occupants

    head did not directly impact the car body, but his right face

    was bruised by the side pillar nearby the rear windshield at

    200 ms, and then his body was thrown high over the car top at

    Fig. 6. Fracture injury of the righ300 ms, and his right hip and thigh contacted with the car top

    when he dropped from the air.

    Compared with the impact movement of the motorcycle

    driver, the back seat occupant was thrown higher in the air and

    fell to the ground at a farther distance so that he suffered more

    serious brain injuries when he hit his head on the ground. The

    fatal head injury was the cause of death of the back seat occupant.

    Fig. 7. Simulation result of the final accident scene of case one.That victim B was the motorcycle driver could be undoubtedly

    confirmed by analyzing the simulation result.

    For case two, the simulation result of the collision course is

    shown in Fig. 9. The bumper of the car contacted with the right

    side of the motorcycle body and the right crus of the motorcycle

    driver and the back seat occupant at 20 ms. The movement of the

    right crus of the back seat occupant was blocked by the

    motorcycle body, and his right crus was crushed between the

    bumper of the ca...

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