2013 Volume 79 Issue 801 Pages 1516-1525
The dispersion curve of an extensional wave of a curved beam has negative slope at a restricted frequency region. A wave packet which is synthesized by more than two extensional waves at the region of negative slope has negative group velocity. This paper addresses an issue of engineering application of the negative group velocity. Firstly, the horizontal axis of dispersion curve was normalized as a dimensionless frequency to specify the frequency region of negative slope. Then, a structure to allow negative group velocity was designed as a U-shaped beam based on the normalized dispersion curve, and waves on the beam was verified using transient response analysis of a finite element model. Validation was carried out from the standpoint of both negative group velocity and backward movement of structural intensity. The results show that wave energy in a curved beam does not propagate in the positive direction along the axial direction.
Transactions of the Society of Mechanical Engineers
Transactions of the Japan Society of Mechanical Engineers
Transactions of the Japan Society of Mechanical Engineers Series A
Transactions of the Japan Society of Mechanical Engineers Series B
Transactions of the Japan Society of Mechanical Engineers Series C
TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series A
TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B