In immersion shear wave testing, waves are generated by angulating the transducer beyond the first critical angle. What is the direction of the material's particle motion?

• A. Perpendicular to the direction of wave propagation
• B. The same as the wave propagation
• C. Normal to the material surface
• D. Parallel to the direction of wave propagation

Answer: (A)

In immersion shear wave testing, angulating the transducer beyond the first critical angle generates a shear (S) wave in the material. Shear waves are transverse, meaning the particle displacement is perpendicular to the direction the wave is traveling. So the material’s particles move in a direction that is orthogonal to the wave's propagation path. This distinguishes them from compressional (P) waves, where particle motion is parallel to propagation.