scholarly journals Underwater Acoustic Measurements on Polyvinylidene Fluoride Transducers

1978 ◽  
Vol 5 (3) ◽  
pp. 149-157 ◽  
Author(s):  
B. Woodward ◽  
R. C. Chandra
Keyword(s):  
Polyvinylidene Fluoride ◽  
Characteristic Impedance ◽  
Thin Sheet ◽  
Piezoelectric Transducers ◽  
Thin Sheets ◽  
Acoustic Measurements ◽  
Underwater Acoustic ◽  
Source Level ◽  
Operation Parameters

Methods of making piezoelectric transducers from very thin sheets of polyvinylidene fluoride (PVDF) are discussed, together with techniques for calibrating these devices, particularly for underwater operation. Parameters measured include receiving response, source level, beamwidth, characteristic impedance and variation of impedance with frequency. Consideration is also given to the dependence of receiving response on the poling fields and temperatures used in making PVDF transducers. Because of their broadband response thin sheet PVDF transducers have been shown to be ideal for monitoring the true form of acoustic pulses underwater.

Characterization of Tensile and Compressive Behavior of Microscale Sheet Metals Using a Transparent Micro-Wedge Device

2011 ◽  
Author(s):  
James Magargee ◽  
Jian Cao ◽  
Rui Zhou ◽  
Morgan McHugh ◽  
Damon Brink ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Thin Sheet ◽  
Thin Sheets ◽  
Stainless Steel Sheet ◽  
Sheet Metals ◽  
Compressive Behavior ◽  
Buckling Modes ◽  
Full Field ◽  
Compressive Loads

The cyclic and compressive mechanical behavior of ultra-thin sheet metals was experimentally investigated. A novel transparent wedge device was designed and fabricated to prevent the buckling of thin sheets under compressive loads, while also allowing full field strain measurements of the specimen using digital imaging methods. Thin brass and stainless steel sheet metal specimens were tested using the micro-wedge device. Experimental results show that the device can be used to delay the onset of early buckling modes of a thin sheet under compression, which is critical in examining the compressive and cyclic mechanical behavior of sheet metals.

scholarly journals Wrapping Liquids, Solids, and Gases in Thin Sheets

2019 ◽  
Vol 10 (1) ◽  
pp. 431-450 ◽  
Author(s):  
Joseph D. Paulsen
Keyword(s):  
Recent Progress ◽  
Geometric Model ◽  
Thin Sheet ◽  
Nonlinear Problems ◽  
Small Scale ◽  
Thin Sheets ◽  
Interfacial Film ◽  
Metal Foils ◽  
High Flexibility ◽  
Significant Attention

Many objects in nature and industry are wrapped in a thin sheet to enhance their chemical, mechanical, or optical properties. Similarly, there are a variety of methods for wrapping, from pressing a film onto a hard substrate to inflating a closed membrane, to spontaneously wrapping droplets using capillary forces. Each of these settings raises challenging nonlinear problems involving the geometry and mechanics of a thin sheet, often in the context of resolving a geometric incompatibility between two surfaces. Here, we review recent progress in this area, focusing on highly bendable films that are nonetheless hard to stretch, a class of materials that includes polymer films, metal foils, textiles, and graphene, as well as some biological materials. Significant attention is paid to two recent advances: a novel isometry that arises in the doubly-asymptotic limit of high flexibility and weak tensile forcing, and a simple geometric model for predicting the overall shape of an interfacial film while ignoring small-scale wrinkles, crumples, and folds.

The Influence of Shielding Gas on Strength of the Laser Welded Thin Sheet Lap Welds

2018 ◽  
Vol 786 ◽  
pp. 98-103 ◽  
Author(s):  
Markku Keskitalo ◽  
Aappo Mustakangas ◽  
Mikko Hietala ◽  
Kari Mäntyjärvi
Keyword(s):  
Energy Input ◽  
Thin Sheet ◽  
Thin Plates ◽  
Thin Sheets ◽  
Laser Weld ◽  
Shielding Gas ◽  
Corrosion Properties ◽  
Weld Joints ◽  
Gas Nozzle ◽  
Better Than

The laser welding is usable method for joining thin plates with low energy input and precise penetration control. When joining of very thin sheets such as 0.5 mm the shape of the weld must be complete in order to achieve a good strength of the joint. The part of the test welds were welded without shielding gas and other part of the test welds by using 65 mm shielding gas nozzle behind the key hole. The strength of the laser weld of 0.5 mm Austenitic stainless steel (ASS) plate was measured in welds without shielding gas and Ar shielded weld. The strength of the shielded weld joints was significantly better than the joint weld without shielding gas due to convex shielded welds. In addition the shielded welds were bright which improves the corrosion properties of the joint.

A Model for Analyzing Multi-Asperity Contact of Thin Sheets With Real Surfaces on Both Sides

2005 ◽  
Author(s):  
John J. Jagodnik ◽  
Sinan Mu¨ftu¨
Keyword(s):  
Thin Sheet ◽  
Beam Theory ◽  
Contact Problems ◽  
Elastic Half Space ◽  
Asperity Contact ◽  
Thin Sheets ◽  
Bending Rigidity ◽  
Bernoulli Beam ◽  
Substrate Rigidity ◽  
Euler Bernoulli Beam

A model for two-sided contact of a thin sheet of material, with real surfaces on both sides is presented. The model combines cylindrical-contact equations, with Euler-Bernoulli beam theory to examine the importance of substrate rigidity in two-sided contact problems. A finite difference program for solving this model is developed. Results for two-sided contact of numerically generated surfaces on thin tapes are presented. The effects of tape thickness and tension are explored. It is shown that substrate’s bending rigidity contributes significantly to the overall equilibrium, for typical tape thicknesses and tension values used by the industry. However, large thickness values exists for which substrate bending is negligible and elastic half-space solutions applied to both sides of the tape are adequate.

scholarly journals A New Compression Test for Determining Free Surface Roughness Evolution in Thin Sheet Metals

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 451 ◽  
Author(s):  
Tsuyoshi Furushima ◽  
Kohei Aoto ◽  
Sergei Alexandrov
Keyword(s):  
Surface Roughness ◽  
Free Surface ◽  
Compression Test ◽  
Thin Sheet ◽  
Principal Strain ◽  
Strain Rates ◽  
Thin Sheets ◽  
Strain Paths ◽  
Effect Of The Support ◽  
Metallic Sheet

In sheet microforming processes, in-surface principal strain rates may be compressive such that the thickness of the sheet increases in the process of deformation. In general, the evolution of free surface roughness depends on the sense of the principal strain normal to the free surface. Therefore, in order to predict the evolution of free surface roughness in processes in which this normal principal strain is positive by means of empirical equations, it is necessary to carry out experiments in which the thickness of the sheet increases. Conventional experiments, such as the Marciniak test, do not provide such strain paths. In general, it is rather difficult to induce a sufficiently uniform state of strain in thin sheets of increasing thickness throughout the process of deformation because instability occurs at the very beginning of the process. The present paper proposes a compression test for thin sheets. Teflon sheets are placed between support jigs and the metallic sheet tested to prevent the occurrence of instability and significantly reduce the effect of the support jigs on the evolution of surface roughness. The test is used to determine the evolution of surface roughness in thin sheets made of C1220-O under three strain paths.

To: “The electromagnetic response of thin sheets buried in a uniformly conducting half‐space,” by R. Clark Robertson in January 1987 GEOPHYSICS, p. 108–117

Geophysics ◽  
1987 ◽  
Vol 52 (4) ◽  
pp. 583-583
Keyword(s):  
Electric Field ◽  
Half Space ◽  
Thin Sheet ◽  
Skin Depth ◽  
Modeling Technique ◽  
Electromagnetic Response ◽  
Thin Sheets ◽  
Incident Electric Field

On p. 112, the caption of Figure 4 should read “The (a) magnitude and (b) phase in radians of the x component of the horizontal electric field obtained for a square thin sheet of integrated conductivity 1 S, 8 skin depths on a side, buried at a depth of 0.1 skin depth when the incident electric field is x polarized. Each segment is 1 skin depth on a side.” On p. 114, the last sentence of the first paragraph in the Discussion should read “It is easy to see why the surface thin sheet is a popular modeling technique for magnetotelluric applications.”

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