From: Application of Nonlinear Lamb Wave Mixing Method for Residual Stress Measurement in Metal Plate
Echo number | 1 | 2 | 3 | 4 | 5 | ||
Propagation path | \(d_{1}\) | \(d_{1}\) | \(d_{2}\) | \(d_{2} + d_{2}\) | \(d_{1} + d_{1}\) | ||
Time of arrival(μs) | t1 | t2 | t3 | tsum | t4 | t5 | |
48.65 | 78.08 | 134.4 | 126.7 | 178.8 | 199.6 | ||
Travel time | t1 | t2 | t3 | – | t1–t4 | t5–tsum | |
Mode( MHz) | S0 0.64 | A0 0.32 | A0 0.64 | A0 1.26 | S0 1.58 | S0 0.64 | S0 1.58 |
Calculating velocity(m/s) | 5139 | 2128 | – | 3163 | – | 5071 | 4664 |
Theoretical velocity(m/s) | 5300 | 2646 | – | 3159 | – | 5300 | 4406 |