Acoustical wave propagator for time-domain flexural waves in thin plates

A relevant application of transformation elastodynamics has shown that flexural waves in a Kirchhoff-Love plate can be diverted and channeled to cloak a region of the ambient space. To achieve the goal, an orthotropic meta-structural plate should be employed. However, the corresponding mathematical transformation leads to the presence of an unwanted strong compressive prestress, likely beyond the buckling threshold of the structure, with a set of in-plane body forces to warrant equilibrium. In addition, the plate must possess, at the same time, high bending stiffnesses, but a null twisting rigidity. With the aim of estimating the performance of cloaks modelled with approximate parameters, an in-house finite element code, based on a subparametric technique, is implemented to deal with the cloaking of transient waves in orthotropic thin plates. The tool allows us to explore the sensitivity of specific stiffness parameters that may be difficult to match in a real cloak design. In addition, the finite element code is extended to investigate a meta-plate interacting with a Winkler foundation, to confirm how the subgrade modulus should transform in the cloak region.

Download Full-text

Poisson-like effect for flexural waves in periodically perforated thin plates

The Journal of the Acoustical Society of America ◽

10.1121/1.5051648 ◽

2018 ◽

Vol 144 (2) ◽

pp. 1053-1058 ◽

Cited By ~ 2

Author(s):

Penglin Gao ◽

José Sánchez-Dehesa ◽

Linzhi Wu

Keyword(s):

Thin Plates ◽

Flexural Waves

Download Full-text

Experiments on cloaking in optics, thermodynamics and mechanics

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2014.0357 ◽

2015 ◽

Vol 373 (2049) ◽

pp. 20140357 ◽

Cited By ~ 8

Author(s):

Muamer Kadic ◽

Tiemo Bückmann ◽

Robert Schittny ◽

Martin Wegener

Keyword(s):

Three Dimensional ◽

Thin Plates ◽

Visible Range ◽

Flexural Waves ◽

Discrete Lattices ◽

Mechanical Metamaterials ◽

Visible Frequency ◽

Transient Thermal ◽

Thermal Cloaking ◽

Static Core

Spatial coordinate transformations can be used to transform boundaries, material parameters or discrete lattices. We discuss fundamental constraints in regard to cloaking and review our corresponding experiments in optics, thermodynamics and mechanics. For example, we emphasize three-dimensional broadband visible-frequency carpet cloaking, transient thermal cloaking, three-dimensional omnidirectional macroscopic broadband cloaking for diffuse light throughout the entire visible range, cloaking for flexural waves in thin plates and three-dimensional elasto-static core–shell cloaking using pentamode mechanical metamaterials.

Download Full-text

CALCULATION OF THE POWER FLOW IN FLEXURAL WAVES ON THIN PLATES

Journal of Sound and Vibration ◽

10.1006/jsvi.1996.0347 ◽

1996 ◽

Vol 194 (1) ◽

pp. 103-106 ◽

Cited By ~ 8

Author(s):

Yu I. Bobrovnitskii

Keyword(s):

Power Flow ◽

Thin Plates ◽

Flexural Waves

Download Full-text

Linear transformation method to control flexural waves in thin plates

The Journal of the Acoustical Society of America ◽

10.1121/1.4961005 ◽

2016 ◽

Vol 140 (2) ◽

pp. 1154-1161 ◽

Cited By ~ 6

Author(s):

Yongquan Liu ◽

Zhaoyang Ma ◽

Xianyue Su

Keyword(s):

Linear Transformation ◽

Transformation Method ◽

Thin Plates ◽

Flexural Waves ◽

Linear Transformation Method

Download Full-text

Propagation of flexural waves in phononic crystal thin plates with linear defects

Journal of Zhejiang University SCIENCE A ◽

10.1631/jzus.a1000123 ◽

2010 ◽

Vol 11 (10) ◽

pp. 827-834 ◽

Cited By ~ 11

Author(s):

Zong-jian Yao ◽

Gui-lan Yu ◽

Yue-sheng Wang ◽

Zhi-fei Shi ◽

Jian-bao Li

Keyword(s):

Phononic Crystal ◽

Thin Plates ◽

Flexural Waves ◽

Linear Defects

Download Full-text

Field Validation of Effective Dispersion Analysis of Reflections, a New Method for Nondestructive Estimation of Pile Depth

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/03611981211008186 ◽

2021 ◽

pp. 036119812110081

Author(s):

Vivek Samu ◽

Murthy Guddati

Keyword(s):

Time Domain ◽

Depth Estimation ◽

Dispersion Analysis ◽

Side Impact ◽

New Method ◽

Flexural Waves ◽

Field Validation ◽

Length Estimation ◽

Effective Dispersion ◽

Pile Length

Several methods have been developed for nondestructive pile depth estimation over the past few decades, with impact-based methods remaining popular because of their ease of application. Sonic-echo techniques rely on generating nondispersive longitudinal waves by impacting the pile top and subsequently picking peaks that correspond to initial and reflected wave arrivals. Unfortunately, pile tops are often inaccessible for in-service foundations and alternate impacting techniques result in signals for which time domain peak picking can be difficult. Pile sides are often easily accessible, but side impact generates highly dispersive flexural waves resulting in complicated waveforms for which analysis is not straightforward. Existing methods to process dispersive flexural waves rely on signal processing based methods and do not explicitly incorporate the physical dispersion properties of the system, resulting in large errors. To address the current limitations, a new method called effective dispersion analysis of reflections (EDAR) was recently developed for pile length estimation. EDAR provides a simple and robust technique to analyze dispersive flexural waves generated from side impact for which time domain processing is not applicable. In this paper, length estimation through EDAR is explained for longitudinal and flexural waves using synthetic bar and Timoshenko beam models. Field validation for two types of pile, concrete filled steel tubes and prestressed concrete, with varying cross sections and embedment are presented. EDAR resulted in pile length estimates within 10% error.

Download Full-text