PSI - Issue 68

Emanuele Vincenzo Arcieri et al. / Procedia Structural Integrity 68 (2025) 969–973 E.V. Arcieri and S. Baragetti / Structural Integrity Procedia 00 (2025) 000–000

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Fig. 1. Description of the finite element model: (a) applied loading and boundary conditions (figure adapted from BS EN ISO 4210-6 standard, 2015); (b) assembly; (c) detail of multi-point constraints; (d) mesh detail.

To assess the structural integrity of the bicycle frame under the analyzed loading condition, the von Mises stresses (Fig. 2a) and the absolute maximum principal stresses (Fig. 2b) were evaluated. The absolute maximum principal stress represents the largest principal stress at a given point, considering its magnitude regardless of whether it is tensile or compressive. This stress was assessed because, in the areas far from where the various tubes of the frame are connected, it coincides with the axial or bending stress (in magnitude), when measured at points on the frame symmetry plane. This would enable the validation of the finite element model created using uniaxial strain gauges positioned in these areas. According to the finite element results, the most stressed areas of the bicycle frame are on the top and down tubes, near the head tube. The peak values are significantly higher than the ultimate tensile strength of the material from which these tubes are made since the ultimate tensile strength of titanium Grade 9 is UTS=620-910 MPa (matweb.com). It is important to note that the welds connecting the tubes are not simulated. The presence of welds could induce slightly different stress distributions in the areas close to them and should be investigated further. However, the results of the finite element analysis highlight that the top and down tubes should be thicker to ensure structural integrity under the investigated static loading condition. Much more thickness would be required to guarantee the durability of the frame under fatigue loading for the loading conditions prescribed by the standard.