Creep damage characterization using a low amplitude nonlinear ultrasonic technique

► The low amplitude nonlinear ultrasound methods were explored for characterizing creep in copper. ► The (a) static, (b) second, and (c) third harmonics were studied. ► Third harmonic is more sensitive. ► Low amplitude nonlinear parameter show a 200% to 1500% improved sensitivity. ► This is a new and high sensitivity method.