title: Antisymmetric feature-guided ultrasonic waves in thin plates with small radius transverse bends from low-frequency symmetric axial excitation.
abstract: The influence of bends constituting annular polygonal structures on ultrasonic guided waves propagating along their axis is investigated. Considering a single bend as a bent plate connects this problem to the better-understood physics of guided waves in straight plates. Using a three-dimensional finite element simulation validated with experiments, bends in plates are shown to act as features that can concentrate and guide ultrasonic energy along their length. Two interesting feature-guided modes are identified when the bent plate is subjected to "in-plane" or axial excitation applied uniformly along a through-thickness line bisecting the bent edge. Of these, the faster traveling mode has properties similar to, but travels at group velocities lower than, the S0 (fundamental symmetric) Lamb mode in flat plates. This paper however focuses on the slower bend-guided mode that is similar to the A0 (fundamental anti-symmetric) Lamb mode in flat plates. This mode is shown to be more strongly generated in smaller angle bends where it has a low attenuation. The results are discussed in light of simple modal studies performed using the Semi-Analytical Finite Element method.
authors: Centre for Nondestructive Evaluation, Department of Mechanical Engineering, Indian Institute of Technology-Madras, Chennai 600036, Tamil Nadu, India.
authors: Abilasha
authors: A
authors: Ramdhas
authors: Roson Kumar
authors: RK
authors: Pattanayak
authors: Krishnan
authors: K
authors: Balasubramaniam
authors: Prabhu
authors: P
authors: Rajagopal
mesh_terms: D000535:Aluminum; D003198:Computer Simulation; D004548:Elasticity; D004867:Equipment Design; D020342:Finite Element Analysis; D008422:Materials Testing; D008962:Models, Theoretical; D009038:Motion; D009716:Numerical Analysis, Computer-Assisted; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D013016:Sound; D013997:Time Factors; D014159:Transducers; D014465:Ultrasonics / Q000295:instrumentation*
chemical_list: D000535:Aluminum