Parametric　signal　representation　techniques　with　Chirplet　models　have　attracted　much　attention　in　ultrasonic　guided　waves-based　research　of　material　property　identification　and　structural　integrity　evaluation.　The　known　Chirplet　models　are　established　using　either　the　Gaussian　windows　or　the　linear　chirp　function.　This　is　inconsistent　with　practical　situations　where　the　excitation　is　a　Hanning-windowed　sinusoidal　signal,　and　the　received　signals　have　a　nonlinear　phase　and　asymmetric　envelope　due　to　the　dispersive　nature　of　the　waves.　A　nonlinear　Hanning-windowed　Chirplet　(NHWC)　model　was　proposed　to　eliminate　the　above　inconsistencies　in　which　a　nonlinear　phase　modulation　term　was　designed　to　modulate　the　classical　Hanning-window　and　the　sine　function.　The　phase　modulation　term　was　established　with　the　hyperbolic　tangent　function.　The　mathematical　properties　of　the　nonlinear　phase　modulation　term　and　the　NHWC　model　were　analyzed　mathematically,　including　the　time　variability,　parity,　concavity,　and　convexity　of　the　phase.　These　were　used　to　guide　the　parameter　setting　in　parametric　signal　representation　techniques.　The　NHWC　model　can　characterize　various　characteristics　of　guided　waves　signals,　including　the　symmetric　or　asymmetric　Hanning　envelopes　and　the　phase　nonlinearity.　Finally,　an　adaptive　genetic　algorithm　was　adopted　to　verify　the　effectiveness　of　the　NHWC　model　in　the　parameter　representation　of　experimentally　measured　ultrasonic　signals.