An experimental study on the behavior of Ao mode transduced using misaligned air-coupled transducers in composite laminates

• Three different misalignments were introduced in air-coupled probes.
• Experiments were performed on laminates employing air-coupled probes with the misalignments.
• Studied variation in normalized amplitude of Ao mode with the misalignment variable.
• Gaussian/quadratic curves represent amplitude variation with the misalignment variable.

Air-coupled transducers can be employed for generation and reception of Lamb waves in composite laminates. To generate and receive a particular Lamb mode, the transducers are oriented in a particular angle. The orientations of transducers also determine amplitude of a particular Lamb mode of interest. Any deviation (misalignment) from the right orientation results in a reduction in the amplitude. Therefore, an attempt has been made to establish variation in amplitude of the fundamental anti-symmetric Lamb mode (Ao) when misalignments were purposefully introduced in the air-coupled probes. In the present work, three different misalignments – linear, orientation and synchronized orientation were envisaged. Experiments were performed on two laminates – unidirectional ([03]s) and cross-ply ([0/902/0]s) of GFRP (Glass Fiber Reinforced Plastic) material. Curves were fitted on experimental data to characterize variation in amplitude of Ao mode in each misalignment. Moreover, wave splitting and merging was observed when the probe(s) was (were) rotated in a particular direction in orientation and synchronized orientation misalignments.