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A roof fairing is a commonly used add-on for trucks or tractor-trailers, where a significant difference in height exists between the cabin and the container. A roof fairing reduces the aerodynamic drag on the vehicle by directing the onward wind flow smoothly onto the container and thus reducing flow separation in front of the container. Since standard containers are available in two different heights and there are cases when vehicles ply without load i.e. without a container, it is necessary to adjust the height of the fairing accordingly to maintain an optimum aerodynamic configuration. While adjustable fairings have been in use in the commercial vehicle industry, these fairings are usually shaped as flat plates, often with open sides for ease of folding. A highly curved and bulbous fairing helps in reducing drag better, especially in presence of side winds, although it makes adjustability difficult.

Cold formed carbon steel C sections are often employed as load carrying structural members in heavy commercial trucks. The cold forming operations employed during the making of these members generate certain amount of residual stresses throughout the sections. As the residual stresses play a significant role in determining the structural behavior of truck frame rail members, a careful assessment of residual stresses resulting from cold forming operation is needed. In the present investigation, residual stresses in frame rail corner sections were numerically predicted with the help of non-linear Finite Element (FE) analysis in ABAQUS and compared with the experimentally measured residual stress values using X-ray diffraction technique. It has been observed that the numerically predicted residual stresses are in agreement with the experimentally measured residual stresses in forming direction.