To reduce the risk of fatigue problems and flutter phenomena, the structural damping of turbomachinery components is increased by integrating constrained viscoelastic patches into rotating composite blades. However, the temperature, the frequency (of the vibration mode to be damped) and the rotation speed are all parameters which may affect significantly the efficiency of the viscoelastic damping treatment. In the presented work, a numerical tool is developed to predict the structural damping of a dynamic rotating composite fan blade while varying the temperature and the rotation speed. This study is based on a finite element model of a fan disk sector equipped with constrained viscoelastic patches. This work will allow quantifying the influence of temperature and rotation speed on the efficiency of the passive damping treatment and contribute to the design of higher performing blades.