Vehicle Biomechanics

Car collisions can occur in a million different ways and can happen at any time. A single glance to check the route on a cell phone can be enough to distract the driver and cause an accident. In spite of becoming aware of a potential accident, distinct factors are not under our control such as the wheels of the car locking or the brakes not functioning properly which can happen in each of the vehicles involved in an accident. Thus, vehicle motion in accidents can be extremely difficult to determine and consequently the motion of the occupants, thus testimony of the occupants becomes valuable when assessing potential of injuries in car collisions, however many times is difficult to remember or be aware of happen. Hence, biomechanics experts at NBI make use of accident reconstruction and 3D simulations to first have an idea of how the accident occurred. Based on this, the experts make use of scientific evidence, crash tests, physics laws and anatomical properties of the body to analyze the biomechanics of car occupants during collisions.

At the time of a crash, your body will move within milliseconds due to the interactive forces.  Now, how does the human body move after a collision? This is an extremely complicated question with not a single answer, given that each single collision is different, a slightly different factor can greatly change the aftermath of a collision. Consequently, different conditions have to be taken into account when trying to reproduce the movement – biomechanics – of vehicle occupants.  At NBI we consider each single collision as unique and thus utilize the specific conditions of collisions to perform our analyses.

When a collision occurs, the impacting car will transmit forces to the impacted one, consequently deforming the car structure but these forces will also be transmitted to the occupants.  Each occupant will experience these forces in a different manner depending on the characteristics of the collision;  location of the impact (front, side, rear), the principal direction of forces transmitted, the specific posture of the occupant at time of impact or if the occupant is near or far from the impacting location would influence on how the forces act upon the human body and as a consequence, cause the body to move in a distinct manner. Now, the internal dimensions of the car along with the occupants’ body dimensions helps us to determine if there was a potential for impact between a body segment and any internal car structure; a small sedan gets a lateral, T-Bone, impact on the driver’s side, the likelihood of a tall copilot hitting the window is extremely high.
Whereas a seatbelt was worn or not is another factor that plays an important role into how much an occupant’s motion is restricted for example when a rear collision occurs at a high speed it might prevent the occupant from ejecting their sit and impact the windshield. Notwithstanding, depending on the seatbelt’s configuration it can add strains to the body due to the restraining force of the seatbelt and enhance the potential of risk of injury.

Often times in a high-speed collision, airbags will be deployed to prevent subsequent hazardous impacts with structures within the car such as the windshield or a window. Nonetheless, airbag deployment can become a potential cause of an injury by altering the motion of the body in a sudden manner as well as adding another force that is acting upon the occupants. Moreover, potential injuries at the time of airbag deployment might occur due to an occupant’s posture being different to which airbags have been tested and designed for, thus putting the occupant at a heighten risk of injury. What is more, the height of the occupant’s upper body can highly influence the location of impact with the airbag, the face, neck or chest, each of which will move and absorb forces in a different manner, thus defining a different risk for potential injury.
NBI biomechanics experts incorporate these and many more variables into analyses to assess the biomechanics of occupants and thus determine the potential for injuries in car collisions.

Leading Expert