If mechanical random vibrations caused by variable loads continue for a period of time, they can cause damage to a working machine part or a vehicle body. Whether this damage will occur or in which part of the structure can be determined by vibration analysis. For damage determination, first of all, the natural frequencies of the structure are examined by modal analysis. Then, by performing modal based PSD analysis, high stress levels and regions are determined as a result of the coinciding of the driving frequencies with the resonance frequencies. With the subsequent vibration-based fatigue analysis, the damage and life that may occur in the structure that will be exposed to this vibration for a certain period of time can be determined. In this way, design improvements can be made on the structure before it is produced until the analysis results become appropriate.