Frequency equation of axisymmetric guided waves in logs

摘要

According to the structure characteristics of logs, a log model with double layers (i.e. heartwood and sapwood) was constructed. Through the transmission characteristics of guided wave and the assumption of rigid connection at interface of heartwood and sapwood, the frequency equation of axisymmetric guided waves transmission in logs was deduced. In accordance with geometrical dispersion of guided wave in logs, Matlab was used to write the program, and the solution of frequency equation was gotten. Dispersion curve was calculated, the affect of different diameters to dispersion curve was analyzed, and the dispersion in decayed logs were compared to that in solid logs. This study provides the theoretical basis for guided wave using in internal decay detection of logs.