title: Symmetric low-frequency feature-guided ultrasonic waves in thin plates with transverse bends.
abstract: Recent research by the authors shows that bends in plates can act as features that can concentrate and guide ultrasonic energy along their axis. At low frequencies, two 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 slower mode has properties similar to the A0 (fundamental antisymmetric) Lamb mode in flat plates. This paper focuses on the faster bend-guided mode that is similar to the S0 (fundamental symmetric) Lamb mode in flat plates. Using 3D finite element (FE) simulation validated with experiments, this mode is shown to be more strongly generated in smaller angle bends. Features of the mode including velocity, attenuation and modal structure are considered in detailed studies. Results are discussed in light of simple modal studies using the Semi Analytical Finite Element (SAFE) method, suggesting a relationship of bend-guided waves to modes of curved bars.
authors.affiliation: Centre for Nondestructive Evaluation, Department of Mechanical Engineering, Indian Institute of Technology-Madras, Chennai 600036, Tamil Nadu, India. Electronic address: abilasha.ramadhas@gmail.com.
authors.forename: Abilasha
authors.initials: A
authors.lastname: Ramdhas
authors.affiliation: Centre for Nondestructive Evaluation, Department of Mechanical Engineering, Indian Institute of Technology-Madras, Chennai 600036, Tamil Nadu, India. Electronic address: roson.pattanayak@gmail.com.
authors.forename: Roson Kumar
authors.initials: RK
authors.lastname: Pattanayak
authors.affiliation: Centre for Nondestructive Evaluation, Department of Mechanical Engineering, Indian Institute of Technology-Madras, Chennai 600036, Tamil Nadu, India. Electronic address: balas@iitm.ac.in.
authors.forename: Krishnan
authors.initials: K
authors.lastname: Balasubramaniam
authors.affiliation: Centre for Nondestructive Evaluation, Department of Mechanical Engineering, Indian Institute of Technology-Madras, Chennai 600036, Tamil Nadu, India. Electronic address: prajagopal@iitm.ac.in.
authors.forename: Prabhu
authors.initials: P
authors.lastname: Rajagopal
keywords: Feature-guided waves; Finite element (FE) simulation; Plate bends; Semi Analytical Finite Element (SAFE) method; Ultrasonic guided waves