d displacement, t time, b damping factor or damping coefficient, m mass of the oscillating object. |a| is the displacement at t = 0, 2 pi /𝜔 is the period under simple harmonic motion (no damping).
Notice: that for b = 0 (zero damping), we have the formula for simple harmoinc motion ith amplitude |a| and period 2 pi / 𝜔