Dynamic behavior of a zero-group velocity guided mode in rail structures

Area of Science:

• Solid Mechanics
• Acoustics
• Materials Science

Background:

• Zero-group velocity (ZGV) modes are crucial for understanding wave propagation in structures.
• Previous research has identified ZGV modes in various materials, including plates.
• The behavior of ZGV modes in rail structures requires further investigation.

Purpose of the Study:

• To investigate the characteristics of the first zero-group velocity (ZGV) mode in a standard rail.
• To analyze the formation and behavior of ZGV modes through numerical and experimental methods.
• To establish an analogy between ZGV modes in rails and Lamb modes in plates.

Main Methods:

• Semi-analytical finite element analysis to compute dispersion curves and identify ZGV points.
• Time-dependent finite element modeling to simulate the dynamic response of the rail.
• Experimental measurements to validate numerical findings.

Main Results:

• The first ZGV point in the rail structure was successfully identified.
• Backward waves were characterized by opposing group and phase velocities.
• Experimental results confirmed ZGV modes arise from the interference of two opposite-traveling waves.

Conclusions:

• ZGV modes in rail structures are a result of wave interference phenomena.
• The observed ZGV modes in rails share similarities with the S1-S2b ZGV Lamb mode in plate structures.
• This study provides valuable insights into the wave dynamics of rail systems.