Car-electricbicycle Accident Reconstruction And Cyclist Head Injury Protection

Car-electricbicycle accident has become one of the major type in our country traffic accident, and it is also the common accident type in combination of urban and rural areas. This study aims to reveal the inherent law of this kind of accident form, and the causes of cyclist’s head injuries, injury characteristics and distribution, thus providing some reference for the automotive passive safety technology development and design.For those reasons, this paper makes statistical analysis with 254 involving electricbicycle traffic accidents in Songjiang area Shanghai from year 2012 to 2015, and make summarize with such accidents in characteristic and the cyclist’s head injuries distribution characteristics in the region. Analysis shows: Sedan is the most common vehicle type of the accident type, and the front of the car impact with electricbicycle is the main impacting form; cyclist’s head injury is the important couse which lead cyclist death or serious injury; the head of the cyclist on the front windshield of the car impact point distribution is uneven, concentrated on the left compared to the right side of the windshield, and the closer to the A-pillar, the greater the head appears above AIS3+ injury risk.With the help of the computer simulation method, this paper reconstructs 25 car-electricbicycle accidents by using multi-body dynamics simulation software PC- CRASH, and uses mathematical regression model to analyse the correlation of car collision speed with cyclists head dynamics response parameters and damage parameters. On the basis of this, through designing orthogonal test to explore the significant influence degree for structural parameters of front car with the cyclist’s head injuries. The study shows: the head collision relative velocity and the car collision speed are positively correlated relationship, head collision time is just oppisite; The head injury parameters all have a certain correlation with car collision speed in degree; Windshield angle, front edge height of engine hood above the ground and the height of the center of front bumper are sensitive to cyclist’s head injury parameters.Head impacting with the front windshield is the important reason which leads head injury, so this paper takes cyclist’s head impacting with front windshield simulation test research though building Head-Windshield finite element model, combining multi-body with finite element research method. Relying on head mutibody simulation calculation result as intital conditions based on the accident case, this paper set the initial impact of the head position, angle, and apply loads and boundary constraints to study the influence of the windshield structure parameters to head injury, including windshield impact area, each layer thickness of windshield, strength of the toughened glass layer. Research shows: under the same condition, compared to the center of the collision, the collision of the head with the front edge of the windscreen leads a significant increase in peak contact force, thereby increasing the risk of skull fracture; PVB interlayer material showed significant viscoelastic material properties under dynamic impact, the front windshield whole load-displacement behavior appears unlinear, progressive destruction characteristic, therefore, the head peak contact force decreases as PVB interlayer thickness increases, but HIC15 shows trend in contrast, despite this, the increasing trend are not exceeding the safe upper limit HIC15 = 1000 under simulation conditions; what’s more toughened glass layer thickness and strength are all positively correlated with the head of each injury parameters. Based on this, this paper give several measures according to the windshield to lighten cyclist’s head injury, including designing asymmetric U type cyclist’s head protection airbag, increasing the thickness of the PVB interlayer and other measures.