Min-Max Method

 
Dynamic stiffness
CDYN = (Fmax - Fmin)/(2*amplitude)
Strain energy
W = (Fmax - Fmin)*amplitude/4
Loss energy
dW = abs(Integral(F(t)*vel(t) dt)) in the interval [(i-1)*2pi , i*2pi]
Relative damping
PSI = dW / W
Loss angle
PHI = asin( PSI / (2*pi) )
Fmin and Fmax are measured at velocity = 0.