The purpose of seat belt constraints in a crashing car is to keep the occupants securely in their seats during a collision. This helps to prevent them from being thrown out of the vehicle or hitting the interior structures, reducing the risk of serious injury or death.
Seat belt constraints work by using a combination of webbing, buckles, and retractors to secure the occupant's body to the seat. During a crash, the seat belt will stretch slightly to absorb some of the energy and then lock in place, preventing the occupant from being thrown forward.
Seat belt constraints are most effective for frontal and side-impact crashes. They are less effective for rear-end collisions, but can still help prevent the occupant from being thrown forward and hitting the steering wheel or dashboard.
While seat belt constraints are designed to prevent injuries, they can sometimes cause minor bruising or abrasions during a crash. However, these injuries are far less severe than those that would occur if the occupant was not wearing a seat belt.
Yes, there are other safety measures that can be used in addition to seat belt constraints. These include airbags, which can provide additional protection in a crash, and crumple zones in the car's structure, which help absorb some of the impact energy.