مطالعه خستگی اتصال جوشکاری مخزن انبساط ترانسفورماتور توزیع به بدنه تحت ارتعاشات ناشی از حمل و نقل جاده‌ای

In this paper, the fatigue of a welded joint of the expansion tank of a 25 kVA distribution transformer is studied by modeling it as two single degree of freedom (SDOF) systems subjected to bending and tensile stresses due to base excitation during road transportation. The excitation caused by road transport is considered as a harmonic motion with a frequency corresponding to the first mode bending resonance. Its intensity is determined based on the recommendations of guidelines regarding transport class specifications for manufacturers. Considering some realistic assumptions to simplify the model, constant and cyclic stresses generated at the welding joint are obtained. Using the theory of distortional energy, the equivalent von Mises stress is calculated. Then, based on fatigue theories, the safety factor for the existing geometry is determined. It is demonstrated that the safety factor for an unlimited lifetime for two different transport classes, according to the recommendations of the guidelines, is equivalent to 6.2 for poor roads and vehicles, and 8.2 for good roads and vehicles.