Experimental,analytical,and numerical investigations on the flexural and fatigue behavior of steel thin-walled X-section beam

Thin-walled hollow shapes are of great interest in many industries with weight constraints, due to their availability, low price, and strength-to-weight ratio. This paper presents the development, calculation, and production of a thin-walled X-section beam design with a unique section geometry. This hollow X-section beam geometry is a beam that has been developed to use shape-connected jaws on the beam and to use less bolts and mounting elements, and to easily change the positions of the parts mounted on the beam. The bending strength of this unique beam section was investigated, and the fatigue damage of the beam was also handled with technological methods. Using both experimental stress measurements and finite element solution, the static and fatigue strength of the beam were calculated with computer-aided engineering software. The FEM solution was performed nonlinearly by defining the linear elastic and plasticity properties of the material. Validation studies were carried out in the laboratory using three-point and four-point bending tests. These traditional experiments were supported by strain gauge technology that measures strain with 0.05% accuracy. The weight and bending strength of the X-section beam were compared with the hollow section square beam. X-section beam (S355J0H) has 13% lower bending strength than 120 × 120 × 8 mm (S355J0H) beam; however, it is 37% lighter. ANSYS-analytical test results of difference are 3.95%, and ANSYS-experimental test results of difference are 0.85%. Experiments showed that a ∼22% increase in strength is found in these corners depending on the production method. The fatigue behavior of the X-section beam was determined with the nCode DesignLife software using validated FEM solutions and fatigue curves of the materials. X-section beam developed for shape–connected assembly systems can be used especially in the formation of chassis with its superior assembly ability and bending strength, increasing functionality, and production speed.