Design of a Frontal Rail Structure With Thickness Variation That Performs Under Axial and Oblique Loading

Progressive crushing of the frontal part of the frame in any collision (frontal, offset and oblique) is one of the factors that determine the safety level that a car or a truck can provide to the occupant. A new approach in frontal rail design will be covered in this paper. The rail thickness will vary along the length of the rail in such away that the compressive strength of a rear section on the compression side of the rail will be greater than or equal to the section in front of it. This design will enable the front rail to collapse in a progressive manner such that the collapse will be transmitted from the front to the rear. Preventing early global bending in the rail will enhance the efficiency of energy absorbed during a crash. Starting with the section with the lowest compressive strength (most forward section of the rail), in a controlled way, the section strength is designed to increase with length. This will help meet the federal regulations such as FMVSS 208 by collapsing the least strong front sections at lower speeds and the strong rear sections at higher speeds. Also, collapsing of the weak frontal sections in a crash can help in compatibility between different vehicles on the road.