Lamb modes with multiple zero-group velocity points in an orthotropic plate

In this paper the spectrum of Lamb modes in an orthotropic plate is studied. Infinitely many modes are found which undergo a change of sign in their slopes twice, thus leading to two zero-group velocity points. A few modes possessing three such points also exist. (C) 2012 Acoustical Society of America. [http://dx.doi.org/10.1121/1.4730891]