Abstract:Axisymmetric surface loading is an effective method for exciting axisymmetric guided waves in pipes. However, non-axisymmetric surface loading is usually produced due to various influence factors such as transducer installation deviation, and result in the complexity of the excited guided wave modes. Longitudinal guided waves excited by non-axisymmetric multielement surface loading are investigated extensively. Two typical non-axisymmetric loading conditions are considered and analyzed. Based on the normal mode expansion technology, the quantitative relationship between applied boundary loadings and acoustic field is advanced, and then the generation mechanism of individual guided waves is analyzed and the effects of non-axisymmetric loading array on the generation of longitudinal modes are also discussed. Theoretical predictions are validated by the finite element simulations. For the non-axisymmetric surface loading occurred in the actual pipe inspection, a new loading compensation strategy is proposed and implemented. The results show that the compensation strategy can suppress the flexural modes effectively, and contribute to improve the noise floor of the guided wave signals.