Abstract：The potential advantage of using nonlinear guided waves to track early damage is that they are sensitive to micro-cracks or degradation that manifest in the form of micro-structural changes. The capable of propagating long distance makes the cumulative nonlinear second-harmonic longitudinal guided wave an ideal candidate to interrogate pipes. A scheme to generating axisymmetric second-harmonic longitudinal guided waves that is mono-frequency zero order longitudinal waves in a homogeneous, isotropic, stress-free elastic solid pipe is presented in this paper. The possible pairs corresponding to the scheme are obtained according to the condition of phase matching. Then they are validated numerically based on the other condition, i.e., non-zero power flux. At last the operating points to generate second-harmonic longitudinal guided waves in pipes are determined.
2011, Vol. 32 
