Excitation of dominant flexural guided waves in elastic hollow cylinders using time delay circular array transducers

• The NME is adopted to analyze the excitation of dominant flexural waves in pipes.
• A time delay circular array transducer is proposed to excite dominant flexural mode.
• Expression to calculate time delay for exciting a specific flexural mode is given.
• Numerical evaluations indicate that dominant flexural waves are efficiently excited.

A time delay circular array transducer (TDCAT) is proposed to selectively excite a dominant flexural guided wave mode in an elastic hollow cylinder. The classical Normal Mode Expansion method (NME) is adopted to disseminate the forced response and perturbation analysis of a hollow cylinder with respect to a time delay circular array loading. A single dominant flexural mode is effectively excited in a hollow cylinder by a TDCAT with appropriate time delay parameters. The expression for calculation of time delay parameters to excite a specific flexural mode is given. Numerical evaluations that demonstrate the generation of dominant flexural modes in elastic hollow cylinders are carried out for both torsional and longitudinal flexural modes. A TDCAT with eight elements is recommended for practical flexural guided wave utilizations after studying the influence of element number on flexural wave excitation.