A New Method to “Lock-in” Elastic Effects for Experimental Stress Analysis

1958 ◽  
Vol 25 (2) ◽  
pp. 189-195
Author(s):  
J. W. Dally ◽  
A. J. Durelli ◽  
W. F. Riley
Keyword(s):  
Three Dimensional ◽  
New Method ◽  
Experimental Stress Analysis ◽  
Gravitational Loading ◽  
Distorted Grid ◽  
Gravitational Stress ◽  
Lock In ◽  
Modified Epoxy ◽  
Theoretical Results ◽  
Good Agreement

Abstract A new method is described for “locking-in” an optical interference pattern and a mechanical distortion. The transparent model is cast from a modified epoxy resin with an embedded rubber-thread grid. The model is permitted partially to cure before it is loaded, then held under load while the plastic continues to cure. Upon removal of the load an isochromatic fringe pattern remains which is proportional to the elastic distribution of the maximum shearing stress. In addition, the permanently distorted grid has deformations which are proportional to the elastic distribution of strains. The method is applied to a disk under diametrical compression and a disk under gravitational loading. A comparison of experimental and theoretical results for these two cases shows, in general, good agreement. Most of the discrepancies between experimental and theoretical results are due to the large deformations in the neighborhood of the points of load application. An application of the method to the solution of a three-dimensional problem, namely, the gravitational stress distribution in a buttress-type dam, is discussed briefly.

On the response of a poro-elastic bed to water waves

1978 ◽  
Vol 87 (1) ◽  
pp. 193-206 ◽  
Author(s):  
Tokuo Yamamoto ◽  
H. L. Koning ◽  
Hans Sellmeijer ◽  
Ep Van Hijum
Keyword(s):  
Porous Medium ◽  
Pore Water ◽  
Water Waves ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Three Dimensional ◽  
Fine Sand ◽  
Present Solution ◽  
Theoretical Results ◽  
Good Agreement

The problem of the response of a porous elastic bed to water waves is treated analytically on the basis of the three-dimensional consolidation theory of Biot (1941). Exact solutions for the pore-water pressure and the displacements of the porous medium are obtained in closed form for the case of waves propagating over the poro-elastic bed. The theoretical results indicate that the bed response to waves is strongly dependent on the permeabilitykand the stiffness ratioG/K’, whereGis the shear modulus of the porous medium andK’is the apparent bulk modulus of elasticity of the pore fluid. The earlier solutions for pore-water pressure by various authors are given as the limiting cases of the present solution. For the limitsG/K′→ 0 ork→ ∞, the present solution for pressure approaches the solution of the Laplace equation by Putnam (1949). For the limitG/K′→ ∞, the present solution approaches the solution of the heat conduction equation by Nakamuraet al.(1973) and Moshagen & Tørum (1975).The theoretical results are compared with wave tank experimental data on pore-water pressure in coarse and fine sand beds which contain small amounts of air. Good agreement between theory and experiment is obtained.

Torque and Cavitation Characteristics of Butterfly Valves

1961 ◽  
Vol 28 (4) ◽  
pp. 511-518 ◽  
Author(s):  
Turgut Sarpkaya
Keyword(s):  
Approximate Solution ◽  
Three Dimensional ◽  
Relaxation Technique ◽  
Dimensional Case ◽  
Practical Case ◽  
Two Dimensional ◽  
Actual Flow ◽  
Theoretical Results ◽  
Good Agreement

The present study deals with torque and cavitation characteristics of idealized two-dimensional and axially symmetrical butterfly valves. Theoretical results obtained for the two-dimensional case are compared with the ones obtained experimentally and by a relaxation technique. Based on the results of the two-dimensional case, an approximate solution is presented for the more general and practical case of three-dimensional butterfly valves. The results are in good agreement with the actual flow tests.

APPLICATION OF ELASTIC MATERIALS IN PROTECTION FROM STRONG IMPACTS

2004 ◽  
Vol 18 (14) ◽  
pp. 1977-1990
Author(s):  
MASKOVIC D. LJILJANA ◽  
MOHORA EMILIJAN ◽  
TOSIC S. BRATISLAV ◽  
VUJOVIC R. RATKO
Keyword(s):  
Elastic Material ◽  
Short Pulse ◽  
Three Dimensional ◽  
Polymer Materials ◽  
Elastic Materials ◽  
One Dimensional ◽  
Spherical Surfaces ◽  
The Impact ◽  
Theoretical Results ◽  
Good Agreement

The analysis of the behavior of elastic material subject to strong short pulse impact has shown that only one-dimensional structures support the impact without destruction. Compact two- and three-dimensional structures are destroyed during the impact along circular lines and spherical surfaces. For that reason, web-like shields are proposed for the protection of man and equipment. Polymer materials are most suitable for the production of web-like shields since they are made of fibers and highly stress resistant. Theoretical results are experimentally tested and the good agreement with theory was found.

scholarly journals The Experimental Registration of the Evanescent Acoustic Wave in YX LiNbO3 Plate

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 2238
Author(s):  
Andrey Smirnov ◽  
Boris Zaitsev ◽  
Andrey Teplykh ◽  
Ilya Nedospasov ◽  
Egor Golovanov ◽  
...  
Keyword(s):  
Acoustic Wave ◽  
Acoustic Waves ◽  
Three Dimensional ◽  
Evanescent Waves ◽  
Electrical Boundary Conditions ◽  
3D Finite Element Method ◽  
First Time ◽  
Theoretical Results ◽  
Good Agreement ◽  
Piezoelectric Plates

Evanescent acoustic waves are characterized by purely imaginary or complex wavenumbers. Earlier, in 2019 by using a three dimensional (3D) finite element method (FEM) the possibility of the excitation and registration of such waves in the piezoelectric plates was theoretically shown. In this paper the set of the acoustically isolated interdigital transducers (IDTs) with the different spatial periods for excitation and registration of the evanescent acoustic wave in Y-cut X-propagation direction of lithium niobate (LiNbO3) plate was specifically calculated and produced. As a result, the possibility to excite and register the evanescent acoustic wave in the piezoelectric plates was experimentally proved for the first time. The evanescent nature of the registered wave has been established. The theoretical results turned out to be in a good agreement with the experimental ones. The influence of an infinitely thin layer with arbitrary conductivity placed on a plate surface was also investigated. It has been shown that the frequency region of an evanescent acoustic wave existence is very sensitive to the changes of the electrical boundary conditions. The results obtained may be used for the development of the method of the analysis of thin films electric properties based on the study of evanescent waves.

Equivalent Elastic Modulus of the Open-Cell Cellular Solids

2010 ◽  
Vol 34-35 ◽  
pp. 1501-1505
Author(s):  
Ying An Kang ◽  
Jia Cai Tan
Keyword(s):  
Relative Density ◽  
Geometrical Structure ◽  
Three Dimensional ◽  
Cellular Structures ◽  
Cellular Solids ◽  
Aluminum Foams ◽  
Open Cell ◽  
Prism Model ◽  
Theoretical Results ◽  
Good Agreement

The useful properties of cellular solids depend on the material from which they are made, their relative density, and their internal geometrical structure. Based on two simple models (two-dimensional honeycomb and three-dimensional prism)of cellular structures, equivalent Young’s modulus related to the relative density is derived, and the theoretical results are found to be in good agreement with experimental data of open cell aluminum foams. And the results provide evidence that the three-dimensional prism model is reasonable, which two models are approximately true at low density.

scholarly journals Experimental tissue mimicking human head phantom for estimation of stroke using IC-CF-DMAS algorithm in microwave based imaging system

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mohammad Shahidul Islam ◽  
Mohammad Tariqul Islam ◽  
Ali F. Almutairi
Keyword(s):  
Electrical Properties ◽  
Imaging System ◽  
Three Dimensional ◽  
Reconstruction Algorithm ◽  
Human Head ◽  
Brain Stroke ◽  
Overall Performance ◽  
Coaxial Probe ◽  
Theoretical Results ◽  
Good Agreement

AbstractThis paper presents the preparation and measurement of tissue-mimicking head phantom and its validation with the iteratively corrected coherence factor delay-multiply-and-sum (IC-CF-DMAS) algorithm for brain stroke detection. The phantom elements are fabricated by using different chemical mixtures that imitate the electrical properties of real head tissues (CSF, dura, gray matter, white matter, and blood/stroke) over the frequency band of 1–4 GHz. The electrical properties are measured using the open-ended dielectric coaxial probe connected to a vector network analyzer. Individual phantom elements are placed step by step in a three-dimensional skull. The IC-CF-DMAS image reconstruction algorithm is later applied to the phantom to evaluate the effectiveness of detecting stroke. The phantom elements are preserved and measured multiple times in a week to validate the overall performance over time. The electrical properties of the developed phantom emulate the similar properties of real head tissue. Moreover, the system can also effectively detect the stroke from the developed phantom. The experimental results demonstrate that the developed tissue-mimicking head phantom is time-stable, and it shows a good agreement with the theoretical results in detecting and reconstructing the stroke images that could be used in investigating as a supplement to the real head tissue.

scholarly journals Resonant Steady-State Sloshing in Upright Tanks: Effect of Three-Dimensional Excitations and Viscosity

2018 ◽  
Author(s):  
Alexander N. Timokha ◽  
Ihor A. Raynovskyy
Keyword(s):  
Steady State ◽  
Order Approximation ◽  
Three Dimensional ◽  
Primary Resonance ◽  
Resonance Phenomenon ◽  
Phase Lag ◽  
Response Curves ◽  
Sloshing Frequency ◽  
Theoretical Results ◽  
Good Agreement

Bearing in mind recent experimental and theoretical results showing that viscous damping can qualitatively affect resonant sloshing in clean tanks, the Narimanov-Moiseev multimodal sloshing theory for an upright circular container is revised to analytically analyze steady-state surface waves when the container performs a small-amplitude sway/roll/pitch/surge prescribed periodic motion with the forcing frequency close to the lowest natural sloshing frequency. The revised theory is applicable for the radius-scaled mean liquid depths h > 1 providing the secondary resonance phenomenon does not occur at the primary resonance zone. A focus is on how the damping influences the phase lag as well as on the amplitude response curves versus the forcing type, which can in the lowest-order approximation be treated as if the container translatory moves along an elliptic orbit in the horizontal plane. The analytical results are compared with existing experiments for longitudinal and circular orbital tank excitations. Whereas a good agreement is found for longitudinal excitations, a discrepancy is detected for the circular orbital forcing. The discrepancy may, most probably, be explained by the wave breaking and mean angular mass-transport (Ludwig Prandtl, 1949) phenomena. Occurrence of the Prandtl phenomenon makes inapplicable the existing analytical inviscid sloshing theories, even if they are modified to account for damping.

Investigating the Nonlinear Optical Response of Pepper Oil under Low Power Irradiation with Continuous Wave Visible Laser Beam

2020 ◽  
pp. 131-138
Keyword(s):  
Refractive Index ◽  
Nonlinear Refractive Index ◽  
Nonlinear Optical ◽  
Continuous Wave ◽  
Diffraction Integral ◽  
Visible Laser ◽  
Limiting Property ◽  
Kirchhoff Diffraction Integral ◽  
Theoretical Results ◽  
Good Agreement

The nonlinear optical properties of pepper oil are studied by diffraction ring patterns and Z-scan techniques with continuous wave beam from solid state laser at 473 nm wavelength. The nonlinear refractive index of the sample is calculated by both techniques. The sample show high nonlinear refractive index. Based on Fresnel-Kirchhoff diffraction integral, the far-field intensity distributions of ring patterns have been calculated. It is found that the experimental results are in good agreement with the theoretical results. Also the optical limiting property of pepper oil is reported. The results obtained in this study prove that the pepper oil has applications in nonlinear optical devices.

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