Effect of Tie-Down Geometry and Strap Angle on Personnel Restraint System Impact Dynamics

摘要

It has long been known that the proper use of safety restraining devices in aircraft can greatly reduce the risk of serious injury and even fatality in the event of a crash. The use of shoulder belts with lap belts could reduce major injuries by more than 85% and fatalities by 20% 3. Numerous studies have also linked the improper use of safety belts and shoulder harnesses to injuries in cases of rapid deceleration. Studies and investigations on fatal aircraft accidents led the Federal Aviation Administration (FAA) to require all new aircraft to have shoulder restraints installed in 1969. Head, neck, abdominal and chest trauma are the most critical to life. Even injury to the upper extremities can result in unnecessary loss of life if the individual is unable to evacuate the aircraft in an emergency, such as a post-crash fire or to avoid drowning. Roughly one third of the deaths in aviation accidents in the 1950's and 60's might have been avoided if shoulder restraints had been used 8. The question arises as to whether merely having restraints is good enough or if there is a best way to configure the restraints. It has been shown that using a double shoulder harness system with lap belts is preferred over a single diagonal shoulder belt and a 3-point belt system with a single shoulder belt and lap belts 6,7. The double harness prevents the torso from twisting out and around the single shoulder belt, significantly reducing the risk of injury. The distribution of applied loads to two belts is also greater than the same loads applied to a single belt, causing less stretching of the belt and greater restricted forward movement 9.