UDK 656.13.08; 656.13.13
RESEARCH OF MECHANISMS OF INJURY AT THE FRONT
COLLISION OF A CAR WITH A PEDESTRIAN
E. D. Kartashova, E. A. Eleskina
Annotation.
The features of the mechanisms of pedestrian injury in a frontal collision with a passenger car are investigated depending on the speed of the car and the position of the pedestrian in order to improve the methods of reconstruction of traffic accidents.
In the biomechanics of road traffic accidents (Traffic Accidents), the mechanism of injury to drivers, passengers and pedestrians is understood as the nature of the movement of parts of the human body, the sequence of damage they receive in a traffic accident. Despite all the variety of accidents, mechanisms injuries to drivers, passengers and pedestrians in the same types and types of accidents are similar. Therefore, knowledge of the mechanisms of injury to drivers, passengers and pedestrians in various types and types of accidents can help increase the reliability of automotive technical expertise.
The problem of increasing the reliability of automotive technical expertise is becoming particularly relevant in connection with a sharp increase in the number of cars, a change in their design features and an increasing number of accidents with human casualties.
There are several methods for studying the mechanisms of injury in road accidents, the experimental, calculation and calculation-experimental methods. In connection with the active introduction of computer technology in practice
automotive technical expertise, the calculation methods for studying the mechanisms of injury have acquired great significance at the present time.
Currently, a number of computer packages are widely used in the global market for accident reconstruction software: CarSim, TruckSim, PC-Crash, CARAT, VirtualCrash, etc. Software packages based on the use of the finite element method, such as Abaqus, LS-DYNA, etc., should also be included in this category. These packages allow you to simulate both the movement of a single vehicle or an individual stage in the “rapprochement - contact - expansion” phases, and the entire traffic situation considered by the expert.
They allow you to automate the research and reconstruction process as much as possible, increase the accuracy of the conclusions and make the expert’s conclusions more visual.
Currently, it is believed that there are three phases of a collision of a passenger car [1, 2].
The first phase of a collision is called the moment of contact of the body of the pedestrian with the surface of the car in a head-on collision, during which the victim receives a blow. As a result of the further movement of the car, possibly slowed down, the injured person, as though being coddled (hooked) by a car, falls on the hood, as a hit on a pedestrian falls below the center of gravity of a person located in the region of the fourth lumbar vertebra. This is the second phase of the collision.
The third phase of the collision is the victim’s fall on the road surface or curb from the height of the hood of the car.
A passenger car can stop at this time or, before it has time to brake,
keep moving.
The nature of the damage formed in the third phase, largely depends on the characteristics of the road surface. If the road is smooth and its surface is hard (asphalt, concrete), the nature of the damage is extremely severe and their number is maximum. If it falls on soft ground, it may not be damaged.
The mentioned three phases of pedestrian collision mentioned during traffic accidents involving other vehicles (trucks, buses, etc.) are not so clearly traced, and the collision itself has its own characteristics and various options. When a passenger car hits a pedestrian, the injured person is struck by the forward protruding part (part) of the car: the front bumper, the radiator lining, the front edge of the hood, the edge of the front wing or the front headlight. In this case, fractures of bones of the lower extremities, the so-called bumper fractures of the thigh or lower leg, fractures of the pelvic bones or ruptures of the pubic and sacroiliac joints, often in combination with damage to the urogenital organs, occur. Simultaneously with these injuries, damage arises from general concussion caused by a shock. Usually, shock phenomena are morphologically manifested by bruises of the abdominal cavity or chest in the form of parietal or intraorgan hemorrhages, tears or ruptures of parenchymal organs, etc.
If the initial contact of a person with the surface of a car occurred below the center of gravity of a person’s body located in the region of the fourth lumbar vertebra, the victim’s body is thrown onto the hood. When hitting a hood, a windshield or the front pillars of a car, the injured person receives additional bodily injuries in the form of a fracture of the ribs, and also, very importantly, an additional traumatic brain injury.
To study the pedestrian traming mechanism in a frontal collision with a car, the PC-Crash program was used [3]. With its help, the process of frontal collision of a car with a pedestrian was simulated. It was believed that a passenger car (VAZ-2110) performs a rectilinear movement with braking at a speed of 50, 40, 30, 20 and 10 km / h. The pedestrian was moving at a constant speed of 5 km / h. In modeling, a pedestrian was represented by a dummy of 50% representativeness. The simulation results are presented in Fig. 1-3. They made it possible to identify the mechanism of pedestrian injury in a collision with a car at the following speeds:
- at a speed of 10 km / h - a pedestrian’s knee knock on the protruding part of the car (bumper), the victim falls on the roadway, leaning on the hood, slides off the car, falls on his knees on the roadway, hits his head on the hood (Fig. 1, a );
- at a speed of 20 km / h - a pedestrian’s knee knock on the protruding part of the car (bumper), the pedestrian rests his hand on the hood, hits the hip joint, and then his chest and head on the hood. The body is thrown forward at a distance of 2.4 m from the original position of the pedestrian. When discarding, the lower limbs are injured, then the hip joint and chest, then the head (Fig. 1, b);
- at a speed of 30 km / h - a pedestrian’s knee knock on the protruding part of the car (bumper), the pedestrian rests his hand on the hood, hits the hip joint, and then the chest on the hood. The head touches the windshield, then the body is thrown forward 6.5 m from the original position of the pedestrian. When discarding, the hip joint and chest are injured, after which the head and legs are injured (Fig. 2, a);
- at a speed of 40 km / h - a pedestrian’s knee knock on the protruding part of the car (bumper), the pedestrian rests his hand on the hood, hits the hip joint, and then the chest on the hood. Then there is a blow to the head against the windshield, and the head slides down the hood. There is a roll of the pedestrian's body, after which the legs hit the roof of the car. In this case, the head is located below in front of the car. Then the body of the pedestrian is discarded at a distance of 10 m from the original position of the pedestrian. When discarding, the head and chest are injured, after which - the hip joint and legs (Fig. 2, b);
- at a speed of 50 km / h - a pedestrian’s knee knock on the protruding part of the car (bumper), the pedestrian rests his hand on the hood, hits the hip joint, and then the chest on the hood. There is a roll of the pedestrian's body, after which the legs hit the roof of the car, and the knees hit the windshield. There is a hit of the hip joint on the hood and a blow of the hand on the windshield, after which the head hits the hood of the car. Then the body of the pedestrian is discarded to a distance of 15.3 m from the original position of the pedestrian. The body glides along the road surface of 4.6 m, which lasts 0.85 s (Fig. 3).
Fig. 1. The mechanism of pedestrian injury at a vehicle speed of 10 km / h (a) and 20 km / h (b)
In frontal collisions, the severity of a person’s injury in a car is determined mainly by damage to the head, chest and hip joint.
Fig. 2. The mechanism of pedestrian injury at a vehicle speed of 30 km / h (a) and 40 km / h (b)
If, at the time of the collision of the car with a pedestrian, the speed of the car decreases to insignificant, namely to 10 km / h, or if the car is completely stops, then the victim most often does not remain on the hood, but falls off, as if moving off him on the road surface, receiving additional injury. In this case, as a rule, damage to the head and upper limbs occurs.
Fig. 3. Pedestrian injury mechanism at a vehicle speed of 50 km / h
However, if the car did not stop, the victim is thrown far to the side and forward in the direction of the car. In the event of a car impact in areas located close to the center of gravity of the human body, a part of the energy of the moving vehicle is transferred to the body of the victim. Having received primary damage in the area of contact with the car, the victim flies several meters through the air and falls on the road surface. Characteristically, damage resulting from impact on the road surface localized on the side opposite to the impact of the car.
Thus, it was found that the mechanism of pedestrian injury in a frontal collision with a car at speeds of 10, 20, 30, 40, 50 km / h is different, and this should be taken into account when conducting an automotive technical examination.
References
1. Examination of traffic accidents in examples and tasks
: textbook. manual for universities / Yu. Ya. Komarov, S.V. Ganzin, R.A. Zhirkov, etc. - M.: Hot line, Telecom, 2012. - 290 p.
2. Salokhin, А. А. Forensic medical examination in cases of car injury / А. А. Salokhin. – М. : Medicine, 1968. – 237 с.
3. Crash, P. C. A Simulation program for Vehicle Accidents. Operating Manual / P. C. Crash. – Linz : Dr. Steffan Datentechnik, 2001. – 291 p.
UDK 656.13.08; 656.13.13
Kartashova, E. D.
Study of injury mechanisms in a frontal collision of a car with a pedestrian E. D. Kartashova, E. A. Eleskina, 2013. No. 2 (6). S. 157–163
Kartashova Ekaterina Dmitrievna, engineer, department of transport vehicles, Penza State University, e-mail:katrina89@yandex.ru
