scholarly journals Shock Reduction Technique on Thin Plate Structure by Wave Refraction Using an Elastic Patch

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Dae-Hyun Hwang ◽  
Jae-Hung Han
Keyword(s):  
Thin Plate ◽  
Reduction Method ◽  
Reduction Technique ◽  
Target Area ◽  
Structural Stiffness ◽  
Wave Refraction ◽  
Bending Waves ◽  
Shock Response ◽  
Different Shapes ◽  
The Waves

In general, bending waves transfer the largest portion of shock energy in a plate-like structure. This study proposes a new shock reduction method using an elastic patch designed to defocus the bending waves through the refraction of the waves so that it is possible to effectively reduce the propagating shock for a certain target area. Elastic patches of three different shapes were considered. The shock reduction performance of these patches was analytically, numerically, and experimentally investigated and compared. All results consistently showed that attached patches can effectively reduce passing waves for areas behind patches. Therefore, utilizing the proposed methods, we can reduce the transient shock response at certain target areas of various practical structures without degradation of structural stiffness or strength simply by bonding with an elastic patch.

Design of a Variable Thickness Plate to Focus Bending Waves

2012 ◽  
Author(s):  
Noah H. Schiller ◽  
Sz-Chin Steven Lin ◽  
Randolph H. Cabell ◽  
Tony Jun Huang
Keyword(s):  
Numerical Simulations ◽  
Thin Plate ◽  
Traveling Waves ◽  
Variable Thickness ◽  
Focal Point ◽  
Frequency Range ◽  
Additional Energy ◽  
Broad Frequency Range ◽  
Bending Waves ◽  
Energy Dissipated

This paper describes the design of a thin plate whose thickness is tailored in order to focus bending waves to a desired location on the plate. Focusing is achieved by smoothly varying the thickness of the plate to create a type of lens, which focuses structure-borne energy. Damping treatment can then be positioned at the focal point to efficiently dissipate energy with a minimum amount of treatment. Numerical simulations of both bounded and unbounded plates show that the design is effective over a broad frequency range, focusing traveling waves to the same region of the plate regardless of frequency. This paper also quantifies the additional energy dissipated by local damping treatment installed on a variable thickness plate relative to a uniform plate.

Incorporating Compressional and Shear Wave Types Into Fuzzy Structure Models for Plates

1995 ◽  
Author(s):  
Judith L. Rochat ◽  
Victor W. Sparrow
Keyword(s):  
Thin Plate ◽  
Shear Waves ◽  
Wave Theory ◽  
Structure Theory ◽  
Detailed Knowledge ◽  
Bending Waves ◽  
Incident Plane ◽  
Dependent Mass ◽  
Mass Spring ◽  
Bending Wave

Abstract Although realistic complex structures are usually difficult to model theoretically, fuzzy structure theory enables one to produce such a model without a detailed knowledge of the entire structure. Using the theory established by Pierce et al. [A. D. Pierce, V. W. Sparrow, and D. A. Russell, J. Vib. Acoust. (to be published), also ASME 93-WA/NCA-17.] regarding fundamental structural-acoustic idealizations for structures with imprecisely known or fuzzy internals, the effects that fuzzy attachments have on different wave types in a primary (or master) structure are examined in this paper. In the theory by Pierce et al., the primary structure that undergoes vibrations is a thin plate mounted in an infinite baffle. On one side of the plate are fuzzy attachments, represented as an array of attached mass-spring-dashpot systems, which are excited by an incident plane pulse. This known theory explains the effects of these attachments on bending waves in the plate. In this paper, the theory is extended to isolated compressional and shear waves in a plate. While studying this new problem, it is discovered that coupling effects occur when the plate and attachment properties are not uniform in the direction perpendicular to the wave propagation. Hence, unlike the bending wave theory which models a finite thin plate with point attached oscillators, the new wave type theory uses a thin plate infinite in one direction with line attached oscillators also infinite in the same direction. For both the compressional and shear waves, it is found that the fuzzy attachments add an apparent frequency dependent mass and damping to the plate. These results are similar to those for the bending wave theory.

scholarly journals Periodicity: Interpreting Waves of Information in Osundare’s Harvestcall

2017 ◽  
Vol 10 ◽  
pp. 42-70
Author(s):  
Taofeek Olaiwola Dalamu
Keyword(s):  
Time Frame ◽  
The Past ◽  
Systemic Analysis ◽  
Literary Device ◽  
Different Shapes ◽  
Analytical Tools ◽  
The Waves

The study investigated the waves of information of Osundara’s Harvestcall to show textual movements as layered by the poet. To achieve that objective, the poem of about 76 lines was collapsed into 44 clauses as a tradition that paves a way for systemic analysis of texts in different shapes, sizes and constructs. Halliday’s Theme and Rheme served as analytical tools that processed the text after which the investigation utilized tables and graphs as indicators of waves of information of Harvestcall. The analysis reveals three separate waves of the text, namely: (i) sectional organization – perceives Sections I, II and III are the Theme while Section IV is the Rheme; (ii) clause constructs – demonstrates multiple Themes that flow to rhematic structures; and (iii) time frame exposition – espouses the past farming commitment as Theme and its current neglect as Rheme. In addition, observation shows waves interference. That is, the switching of Theme 2 and Subject Theme in Sections I, II and III for Subject Theme and Theme 2 respectively in Section IV. As linguistic concepts can reveal so much meanings of a literary device, the study suggests their applications across the board of genres of literature.

Propagation of bending waves in a thin plate with an ensemble of randomly located holes of non-canonical form

2020 ◽  
Vol 18 (0) ◽  
Author(s):  
Ya. I. Kunets' ◽  
V. V. Matus ◽  
V. O. Mishchenko ◽  
V. V. Porokhovs'kyi
Keyword(s):  
Thin Plate ◽  
Canonical Form ◽  
Bending Waves

scholarly journals Lamb Wave Local Wavenumber Approach for Characterizing Flat Bottom Defects in an Isotropic Thin Plate

2018 ◽  
Vol 8 (9) ◽  
pp. 1600 ◽  
Author(s):  
Guopeng Fan ◽  
Haiyan Zhang ◽  
Hui Zhang ◽  
Wenfa Zhu ◽  
Xiaodong Chai
Keyword(s):  
Thin Plate ◽  
Lamb Wave ◽  
Spatial Information ◽  
Laser Doppler Vibrometer ◽  
Target Area ◽  
Flat Bottom ◽  
Wavenumber Domain ◽  
Time Space ◽  
Local Wavenumber ◽  
Rectangular Groove

This paper aims to use the Lamb wave local wavenumber approach to characterize flat bottom defects (including circular flat bottom holes and a rectangular groove) in an isotropic thin plate. An air-coupled transducer (ACT) with a special incidence angle is used to actuate the fundamental anti-symmetric mode (A0). A laser Doppler vibrometer (LDV) is employed to measure the out-of-plane velocity over a target area. These signals are processed by the wavenumber domain filtering technique in order to remove any modes other than the A0 mode. The filtered signals are transformed back into the time-space domain. The space-frequency-wavenumber spectrum is then obtained by using three-dimensional fast Fourier transform (3D FFT) and a short space transform, which can retain the spatial information and reduce the magnitude of side lobes in the wavenumber domain. The average wavenumber is calculated, as a real signal usually contains a certain bandwidth instead of the singular frequency component. Both simulation results and experimental results demonstrate that the average wavenumber can be used not only to identify shape, location, and size of the damage, but also quantify the depth of the damage. In addition, the direction of an inclined rectangular groove is obtained by calculating the image moments under grayscale. This hybrid and non-contact system based on the local wavenumber approach can be provided with a high resolution.

A Quantitative Analysis of Flagellar Movement in Echinoderm Spermatozoa

1978 ◽  
Vol 76 (1) ◽  
pp. 85-104 ◽  
Author(s):  
YUKIO HIRAMOTO ◽  
SHOJI A. BABA
Keyword(s):  
Quantitative Analysis ◽  
High Speed ◽  
Single Equation ◽  
Entire Length ◽  
High Speed Camera ◽  
Sine Function ◽  
Active Force ◽  
Bending Waves ◽  
The Waves ◽  
Flagellar Axoneme

Computerized analyses were performed on the movement of spermatozoa recorded with a high-speed camera. These provide evidence for active bending waves over the entire length of the flagellum and a single equation for waves in all cases examined. In the equation, the angular direction of the flagellum at any distance from the base is expressed by a sine function of time plus a constant, and thus flagellar waves are ‘sine-generated’. To explain the waves a model was proposed in which the active force required to generate sliding between peripheral microtubules is propagated along and around the flagellar axoneme.

Balancing Model Order Reduction Technique for Descriptor-Like Systems

1995 ◽  
Vol 1 (4) ◽  
pp. 481-491
Author(s):  
Omid Ansary
Keyword(s):  
Structural Properties ◽  
Model Order Reduction ◽  
Reduction Method ◽  
Order Reduction ◽  
Reduction Technique ◽  
Model Order ◽  
System Representation ◽  
Order Reduction Method

This paper presents the balancing model order reduction technique in the context of a descriptor- like system representation, which exhibits special structural properties. This is done by integration of these properties into the conventional balancing model order reduction method. An example is given to illustrate the tractability and the application of the proposed technique.

Wave Propagation along Flagella

1958 ◽  
Vol 35 (4) ◽  
pp. 796-806 ◽  
Author(s):  
K. E. MACHIN
Keyword(s):  
Wave Propagation ◽  
Viscous Medium ◽  
Bending Waves ◽  
Elastic Filament ◽  
Wave Forms ◽  
The Waves

1. The types of bending waves which can propagate along a thin elastic filament immersed in a viscous medium are derived. 2. It is not possible to account for the form of the waves observed on actual flagella if the flagellum is regarded merely as a passive elastic filament driven from its proximal end. 3. The observed wave forms can be explained by assuming active contractile elements distributed along the length of the flagellum. These elements could be activated by local bending.

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