The　pulse-echo　signal　receiving　model　can　effectively　determine　a　defect＇s　axial　position　through　the　time　flight　of　the　defect　echo.　However,　some　materials　or　buried　structures　may　significantly　attenuate　the　ultrasonic-guided　wave,　making　the　defect　echo　challenging　to　observe.　Compared　with　the　pulse-echo　mode,　the　guided　wave　in　the　pitch-catch　signal-receiving　model　only　needs　to　propagate　a　one-way　distance.　Its　transmitted　wave　is　more　straightforward　to　observe.　However,　the　pitch-catch　model　is　difficult　to　judge　if　a　defect　exists　in　the　pitch-catch　model　and　identify　the　position　of　a　defect　through　the　transmitted　wave.　The　paper　presents　a　defect-induced　non-axisymmetric　transmitted　wave　model.　It　can　balance　the　advantages　and　disadvantages　of　the　two　signal-receiving　models.　First,　the　periodic　energy　distribution　altering　rule　of　the　non-axisymmetric　torsional　guided　wave　within　a　circular　tube　was　theoretically　analyzed.　Second,　the　numerical　and　experimental　results　verified　the　theoretical　analysis.　Third,　the　defect-induced　non-axisymmetric　transmitted　wave　model　was　proposed　based　on　its　periodic　energy　distribution　changing　rule　analysis　to　evaluate　whether　a　defect　exists,　while　the　traditional　pitch-catch　models　cannot　achieve　it.　The　axial　and　circumferential　positions　of　a　circumferential　crack　within　a　circular　tube　encased　in　concrete　can　be　estimated　using　the　proposed　model,　which　is　challenging　to　realize　by　the　traditional　pulse-echo　models.　©　2025　Elsevier　Ltd