Thin-Walled Rods with Semi-open Profiles

The semi-open cross sections are made from standard tubes by flattening them. Due to the possibility of significant variation of mechanical parameters along the length, the flattening could be easily adjusted for optimal design. From the design point of view, the semi-open cross sections fill the gap between the classic closed and open single-wall sections. Due to the high variability of the section geometry, the simple analytical model is essential for primary design purposes and estimation of numerous opposing static effects. The effective torsional stiffness \({r}_{t}\) , effective bending stiffness \({r}_{z}\) and effective bending spring \({r}_{c}\) of the twist beam in terms of section properties of the twist beam with semi-open cross section have been expressed with the analytical formulas. This chapter is the last section of the first part, which studies the elastic elements from the point of view of modeling and design.