Non-contact, single-sided access ultrasonic guided waves for the assessment of materials mechanical properties

Abstract: Research about material characterization without contact has been carried out by many authors using immersion or laser-based ultrasonic techniques. Immersion techniques however imply that the material is not water sensitive and that the sample fits within the immersion tank. Therefore, it is important to develop a characterization process that is suitable for all types of materials, and ideally not requiring access to both sides of the tested specimen, as this is often not possible in industrial context.Résumé de la communication présentée lors du congrès international tenu conjointement par Canadian Society for Mechanical Engineering (CSME) et Computational Fluid Dynamics Society of Canada (CFD Canada), à l’Université de Sherbrooke (Québec), du 28 au 31 mai 2023

A Virtual Acoustic Black Hole on a Cantilever Beam

An acoustic black hole (ABH) consists of a tapered structure whose thickness follows a power-law profile. When attached to a host structure, an ABH localizes and traps the vibrational energy, which can then be dissipated through, e.g., a damping layer. However, effective vibration mitigation is known to occur only above a cut-on frequency which is inversely proportional to the length of the tapered structure. In this context, the main thrust of this paper is to replace a mechanical ABH by a digital controller so as to create a so-called virtual acoustic black hole (VABH), thus, freeing the ABH from possible mechanical constraints (e.g., compactness, manufacturing and fatigue issues). The proposed VABH is first detailed theoretically. The salient features and performance of the VABH are then demonstrated both numerically and experimentally using a cantilever beam as a host structure. Eventually, it is shown that the VABH significantly enlarges the applicability of the concept of an ABH

Transcatheter occlusion of a persistent left superior vena cava to the left atrium using the transseptal approach

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/102167/1/ccd24884.pd