During a car accident, contact between two vehicles causes forces to be imparted on the cars themselves. Impact energy is directly proportional to the vehicles’ speeds at impact. But what about the driver and passengers of the vehicles? Does the force imparted to the car equal the force imparted to the occupants of the vehicles? The kinematics that the occupants are subjected to during an accident are an important part of accident reconstruction, and can have a direct correlation to the injuries caused to the occupants. For example, a front end impact will cause the occupants to move forward in the occupant compartment, away from the vehicle’s seatbacks and into the restraint system either by contact with the seatbelt or possibly airbag. If an occupant is not wearing seatbelts, a front end impact can result in the occupant contacting other areas of the compartment such as the inside surface of the windshield, A-pillar, dash, and so on. There are many factors to consider when analyzing occupant kinematics. For simplicity’s sake, let’s consider two common scenarios to describe how occupant kinematics can be useful during an accident reconstruction:
Driver position during low-speed rollover: We all know how important it is for us to wear seatbelts at all times when driving. However despite this knowledge, many drivers still do not wear them. Consider the importance of seatbelt usage during a vehicle rollover. In this scenario, a large SUV is rolling over onto its side at a very low speed. During a low speed rollover, if the driver is restrained, there is less of a chance that the driver will fall to the bottom of the inside of the occupant compartment as the vehicle rolls. There is also less of a chance that the driver will exit the vehicle through the window or sunroof during the rollover, reducing the chance that the driver will get pinned by the vehicle during the rollover event.
Cracked windshield. One piece of evidence commonly observed during a vehicle inspection is whether or not there is a circular cracked portion to the inner surface of a windshield. This type of crack can be indicative of a person’s head striking the inside of the windshield. In a frontal impact situation, a properly restrained driver will not be able to contact the inner surface of a windshield as a result of the crash. A seatbelt is designed to reduce the forward motion of a person’s torso during a front-end impact. Therefore, when used properly, a driver likely cannot contact the windshield during a crash. If this type of windshield crack is present, it may be worthwhile to investigate the occupant kinematics of the crash, as well as the injuries to the driver’s head.
Veritech is well-versed in examining the complex dynamics present to occupants during a crash. We have extensive experience with the computer simulation software Madymo, and can provide complex, multi-body physics based scenarios of a driver’s body movement within a vehicle. Contact us for more information on this specialized service to see how our simulations can help your case.
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