Crumple zone

As a crumple zone is referred to those areas of a vehicle that deform in the event of a collision and thus absorb energy. Admits became the first term in the automotive industry, then he has found in other areas, such as rail vehicles or aircraft entrance. The crumple zone goes back to a 1952 patented idea of the engineer Béla Barényi; the first vehicle model with crumple zone was the Mercedes -Benz W 111 ( " tail fin " ) of 1959.

In the early days of the automobile, the vehicles were designed as rigid as possible, so that in a collision with an obstacle or another vehicle often only small deformations on the car itself occurred ( frame construction ). Consequently, the inmates were subjected to enormous delays. The idea of the crumple zone is designed to reduce the force acting on the occupant, and the acceleration can be derived from the equation for the work.

In the event of a crash the kinetic energy stored in the vehicle is converted into deformation energy. The case of work done ( energy change ) is the integral of the force over the distance traveled:

Substituting now the force F by the product of mass (m) and acceleration (a ) concerns

Or

The work to be done (W ) and the mass (m ) depend on the vehicle and its impact velocity is constant. If the distance s increases the energy conversion, must necessarily be the acceleration a little, to maintain equality.

Deformation zones ( crumple zones )

The deformation zones of an automobile can be divided into the areas of vehicle front, side and rear.

• Front: In frontal collisions usually occur on the highest relative velocities to the obstacle, which is why the design of the front end of the greatest significance. In most automobiles, the engine is in this range, which is practically non- deformable despite the large forces occurring and thus receives no power. The majority of the energy absorbing cross member which are usually constructed as hollow sections made ​​of sheet steel. Among other things, by

Longitudinal beam is achieved with uneven force application ( offset crash, vehicle meets only a portion of the front end on an obstacle ) a uniform distribution of forces on structures of the shock side facing away.

• Page: Upon impact of the site is only a very small deformation available, and at the same time the structure is mainly subjected to bending stress, both of which are unfavorable for the energy absorption. The side impact is therefore the most critical impact form. In the door there are parts such as speakers, power window and door lock mechanisms. To prevent the penetration of these parts in the passenger compartment of a corresponding door lining is used. Side air bags act as internal deformation zone between passenger and side wall.

• Rear: The rear-end collision is quite a problem, because the relative speeds of the obstacle are usually rather small and a large deformation exists free of interfering elements such as an engine block. Only the fuel tank usually is located in the rear. In order to achieve the legally required tightness of the fuel system, the tank is positioned as far forward and down, often under the rear seat.

In modern automobiles, the body is designed specifically to crash behavior. The front of the vehicle can be roughly divided into three zones:

• The first area is designed to prevent collisions at low speeds, for example when parking accidents, permanent damage to the vehicle. This is achieved by means of elastic elements, such as, inter alia, the front apron. In some vehicles, the bumper is to filled with foam or similar resilient materials.

• The second area is in less severe collisions (up to 20 km / h) ensure that the supporting structure of the vehicle will not be damaged and a repair can be carried out as inexpensively as possible. These are used, among other so-called crash Tubes. These consist of a hollow steel profile, which convert the incident energy by rolling of the profile. In the picture is shown on the left undeformed, right the rolled Crashtube.

• The third area is the so-called survival space, which is designed maximum rigid to ensure the survival of the occupants.

Compatibility

Under compatibility refers to the attempt, even in unequal accident opponents (eg severe sedan against small cars, but also car against pedestrian / cyclists etc. ) the risk of injury to all involved to keep as low as possible. Put simply, it works on the principle that the bigger and heavier the vehicle, the softer the deformation zones. This means that, for example, in the collision of a small car with a heavier, larger vehicle, the latter absorbs the greater part of the kinetic energy of both vehicles, as it is a much greater deformation is usually available. So the risk of injury against the occupants of the heavier car is not significantly increased for the occupants of the smaller vehicle. However, this development is still relatively new.

Greater public attention regarding the unequal mass ratios of vehicles of various classes in an accident produced a crash test mid-1990s, in which a sedan in the Mercedes -Benz S- Class (W 140) collided with an Opel Corsa. After the head-on crash with 50/50 coverage of the vehicles appeared on the S-Class only marginal deformations, while the crumple zone of the Corsas completely collapsed and pulled damage to the passenger cell by itself. In response to these test results Mercedes fit its occupant protection to the compatibility and requirements of collisions with smaller vehicles at comprehensively.

• Vehicle Safety