Collision beam is actually not let the car “anti-collision”, its main role is to force. When the car is impacted by the front or rear, if the force is applied to the anti-collision steel beam, the steel beam can be impact force to its body connected to the site. Usually steel girder and stringer (rear tail is sometimes the body bottom), and in between the steel beam and stringer, usually there will be a small energy-absorbing box structure.
Low-speed collision (how to be considered low-speed and high-speed collision and there is no strict concept to the protection of the current performance of the car, the general 10km / h considered low-speed collision, 40km / h has been considered high-speed collision), such as parking hit Columns or walls, whether it is before the collision or after the collision, anti-collision steel beams can play a role. It itself bear the impact force, and then the energy transfer to the energy-absorbing box, so that the first energy-absorbing box damaged. If the impact capacity does not exceed a certain design value, the result may be damaged only energy-absorbing box, steel body itself and the body structure will not be damaged. So when the maintenance-for-energy-box on the line, lower maintenance costs. Crashing steel beams actually played a role in protecting the body structure of the main body. If there is no collision of steel beams, obstructions may directly invade the body, and the main body structure or water tanks and other parts of direct contact, resulting in relatively large maintenance costs.
In the forward direction of the high-speed collision, the main impact force is the body of the stringer, the longitudinal beam is responsible for the impact energy back evacuated to the whole body, played unloading force, the role of energy absorption. Can be said that the longitudinal beam is the main body of the main body of security protection. If a high-speed collision, the longitudinal beam can not work, the entire body structure will not achieve energy absorption effect, so that the extent of damage (body and occupant) may be very large. North America IIHS 25% of the small overlap rate crash test has just launched, a lot of poor performance products, because the stringer is not being hit (a lot of cars more on the side of the beam, a small overlap rate collision collision no longitudinal beams ).
In this case, the collision beam can play a role. It can not hit the stringer would have been on the force, a part of the transmission to the stringer; or a side string to bear the force, a part of the conduction to the other side of the stringer.
Can be seen, the former collision beam in the high-speed collision, allowing the stringer as much as possible to play a role in the collision safety is improved. But must see if the collision is positive large area, large overlap rate (not as direct wall), the stringer itself can play the biggest role, there is no collision beam on the difference is not. This is why there are no significant differences in crashworthiness between low crash tests (eg C-NCAP frontal and 40% offset).
Look at the back of the situation was high-speed rear-end. It is with the forward direction of the impact is different, because most of the current car body tail structure, basically no conduction impact, the absorption of energy design. In short, the current car bear the ability to rear-end collision is far less than the ability to bear. So the rear end of the vehicle by the high-speed rear-end, the body structure is certainly to be seriously damaged, then the collision beam in the collision, but the collision between objects and a rigid body objects, both squeezed Less impact.
The impact of low-speed front-rear collision can reduce maintenance costs; high-speed front-end collision helps to improve the protection, especially in the complex real environment collision; high-speed rear-end basically no effect.
(This article comes from 驱动之家 editor released)