scholarly journals Photoelastic Analysis of Three-Dimensional Stress Systems using Scattered Light

1940 ◽  
Vol 44 (349) ◽  
pp. 74-88 ◽  
Author(s):  
R. Weller ◽  
J. K. Bussey
Keyword(s):  
Elementary Theory ◽  
Scattered Light ◽  
Three Dimensional ◽  
Plane Section ◽  
Stress System ◽  
Principal Stresses ◽  
State Of Stress ◽  
Polarised Light ◽  
Photoelastic Analysis ◽  
Good Agreement

SummaryA method has been developed for making photoelastic analyses of threedimensional stress systems by utilising the polarisation phenomena associated with the scattering of light. By this method, the maximum shear and the directions of the three principal stresses at any point within a model can be determined, and the two principal stresses at a free-bounding surface can be separately evaluated. Polarised light is projected into the model through a slit so that it illuminates a plane section. The light is continuously analysed along its path by scattering and the state of stress in the illuminated section is obtained. By means of a series of such sections, the entire stress field may be explored. The method was used to analyse the stress system of a simple beam in bending. The results were found to be in good agreement with those expected from elementary theory.

The Measurement of Stresses in Composites

1986 ◽  
Vol 1 (2) ◽  
pp. 15-21 ◽  
Author(s):  
J. B. Cohen
Keyword(s):  
Three Dimensional ◽  
Stress System ◽  
Principal Stresses ◽  
Reasonable Time ◽  
Complete Measurement ◽  
Useful Life ◽  
Diffraction Peaks ◽  
The Difference ◽  
Full Investigation ◽  
Hydrostatic Component

AbstractAlthough there is mounting interest in the measurement of stresses in composite materials after fabrication and/or use, few measurements to date have not taken into account the three dimensional nature of the stress system in such materials. Most data give only the net stress, that is, the difference between principal stresses. A procedure for a more complete measurement (in a reasonable time) is developed here, including the separation of macrostresses and microstresses. If time does not permit a full investigation, measurements of the lattice parameters of the component phases provide a simple way to sample the hydrostatic component due to differential thermal contraction. The Barrett-Predecki method of adding filler is particularly promising for stress measurements in those composites whose component phases do not give appropriate diffraction peaks. This procedure could also be used for monitoring stresses during the useful life of such materials.

scholarly journals A Numerical Three-Dimensional Thermal Stress Analysis for Cooled Blades

1989 ◽  
Author(s):  
J. Srinivasan ◽  
R. M. S. Gowda ◽  
R. Padmanabhan
Keyword(s):  
Thermal Stress ◽  
Stress Analysis ◽  
Thermal Stresses ◽  
Three Dimensional ◽  
Numerical Procedure ◽  
Stress System ◽  
Blade Profile ◽  
Thermal Stress Analysis ◽  
State Of Stress ◽  
Second Degree

A modern gas turbine engine subjects the turbine rotor blade to severe thermal stress conditions. Thermal stresses constitute a major part of the state of stress in the blade. Improved blade design with optimum weight, long creep life and structural integrity necessitates more refined thermal stress analysis. In this work a plane blade profile is assumed to take the form of a second degree surface with constant curvatures. The general second degree polynomial allows all the six static equilibrium equations to be considered in evaluating the strained surface. The three dimensional state of stress is determined considering the lateral deformations of the blade profile. A numerical procedure is adopted to solve the non-linear simultaneous equations arising due to the self equilibrating thermal stress system. The results are close to that of original analysis. However, this procedure employs all the necessary equilibrium conditions and relaxes the constraints imposed due to the plane surface assumption to a lower level. The method of analysis is discussed in this paper.

On the Meaning of Isoclinic Parameters in the Plastic State in Cellulose Nitrate

1962 ◽  
Vol 29 (1) ◽  
pp. 1-6 ◽  
Author(s):  
M. M. Frocht ◽  
Y. F. Cheng
Keyword(s):  
Scattered Light ◽  
Three Dimensional ◽  
Plastic State ◽  
Basic Question ◽  
Stress Distributions ◽  
Principal Stresses ◽  
Special Equipment ◽  
Secondary Principal ◽  
Series Of Experiments ◽  
Stress Optic Law

In applying the shear-difference method to the determination of stress distributions in photo plasticity, a basic question arises whether, under plastic flow, the isoclinic parameters represent the directions of the secondary principal stresses. Special equipment, new techniques, and a series of experiments are described to study this problem. Tests were made with stress systems which varied in magnitude and direction at normal and oblique incidence, and at strains for which a one-to-one stress-optic relation exists as well as at strains for which it breaks down. Typical results are given. These findings together with the method of scattered light and an appropriate stress-optic law may provide a foundation for three-dimensional photoplasticity. The effects described are limited to loading. Cases of loading plus unloading are not considered in the present paper.

KINETICS OF SPINODAL DECOMPOSITION IN A CRITICAL POLYMER SOLUTION

1992 ◽  
Vol 06 (18) ◽  
pp. 1089-1097 ◽  
Author(s):  
K. KUBOTA ◽  
N. KUWAHARA
Keyword(s):  
Spinodal Decomposition ◽  
Scattered Light ◽  
Three Dimensional ◽  
Intermediate Stage ◽  
Wave Number ◽  
Time Resolved ◽  
Linearized Theory ◽  
Time Region ◽  
Kinetics Of ◽  
Good Agreement

Spinodal decomposition in a critical mixture of polydimethylsiloxane and diethyl carbonate was investigated by a time-resolved light-scattering technique in the time region of the early to the intermediate stage of phase separation. The exponential growth of the scattered light intensity without changing the wave number of its peak was observed, in good agreement with the linearized theory of Cahn-Hillard. The quench depth dependences of the interdiffusion coefficient and of the wave number corresponding to the most dominant fluctuation show the three-dimensional Ising-model behavior indicating the validity of the symmetric law of critical-point universality.

A Study of Shear-Spinnability of Metals

1961 ◽  
Vol 83 (4) ◽  
pp. 478-483 ◽  
Author(s):  
Serope Kalpakcioglu
Keyword(s):  
Experimental Data ◽  
Deformation Zone ◽  
Stress System ◽  
Two Dimensional ◽  
Maximum Reduction ◽  
State Of Stress ◽  
Analytical Work ◽  
Sine Law ◽  
Shear Spinning ◽  
Good Agreement

The deformation zone in shear-spinning is idealized for a two-dimensional process and maximum permissible thickness reduction without fracture is predicted in terms of the stress system in this zone. The effect of deviation from the sine law on the maximum reduction before fracture is shown analytically to be due to the influence of distortions of the unspun flange on the state of stress under the roller. The results of analytical work are compared with experimental data and good agreement has been obtained. The phenomenon of back extrusion in shear-spinning is shown to be the result of a compressive stress in the spun section parallel to the mandrel side and is greatly influenced by mandrel angle and deviation from the sine law.

Comparison of Conventional and Pontic Fixed Partial Dentures Over Implants Using the Finite Element Method: Three-Dimensional Analysis of Cortical and Medullary Bone Stress

2020 ◽  
Vol 46 (3) ◽  
pp. 175-181
Author(s):  
Marcelo Bighetti Toniollo ◽  
Mikaelly dos Santos Sá ◽  
Fernanda Pereira Silva ◽  
Giselle Rodrigues Reis ◽  
Ana Paula Macedo ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Three Dimensional ◽  
The Finite Element Method ◽  
Medullary Bone ◽  
Principal Stresses ◽  
Bone Stress ◽  
Bone Damage ◽  
Rehabilitation System ◽  
Minimum Requirements

Rehabilitation with implant prostheses in posterior areas requires the maximum number of possible implants due to the greater masticatory load of the region. However, the necessary minimum requirements are not always present in full. This project analyzed the minimum principal stresses (TMiP, representative of the compressive stress) to the friable structures, specifically the vestibular face of the cortical bone and the vestibular and internal/lingual face of the medullary bone. The experimental groups were as follows: the regular splinted group (GR), with a conventional infrastructure on 3 regular-length Morse taper implants (4 × 11 mm); and the regular pontic group (GP), with a pontic infrastructure on 2 regular-length Morse taper implants (4 × 11 mm). The results showed that the TMiP of the cortical and medullary bones were greater for the GP in regions surrounding the implants (especially in the cervical and apical areas of the same region) but they did not reach bone damage levels, at least under the loads applied in this study. It was concluded that greater stress observed in the GP demonstrates greater fragility with this modality of rehabilitation; this should draw the professional's attention to possible biomechanical implications. Whenever possible, professionals should give preference to use of a greater number of implants in the rehabilitation system, with a focus on preserving the supporting tissue with the generation of less intense stresses.

A Free Energy Perturbation Approach to Estimate the Intrinsic Solubilities of Drug-like Small Molecules

2019 ◽  
Author(s):  
Sayan Mondal ◽  
Gary Tresadern ◽  
Jeremy Greenwood ◽  
Byungchan Kim ◽  
Joe Kaus ◽  
...  
Keyword(s):  
Solid State ◽  
Small Molecules ◽  
Three Dimensional ◽  
Aqueous Solubility ◽  
Computational Approach ◽  
Free Energy Perturbation ◽  
Perturbation Approach ◽  
Energy Perturbation ◽  
State Form ◽  
Good Agreement

<p>Optimizing the solubility of small molecules is important in a wide variety of contexts, including in drug discovery where the optimization of aqueous solubility is often crucial to achieve oral bioavailability. In such a context, solubility optimization cannot be successfully pursued by indiscriminate increases in polarity, which would likely reduce permeability and potency. Moreover, increasing polarity may not even improve solubility itself in many cases, if it stabilizes the solid-state form. Here we present a novel physics-based approach to predict the solubility of small molecules, that takes into account three-dimensional solid-state characteristics in addition to polarity. The calculated solubilities are in good agreement with experimental solubilities taken both from the literature as well as from several active pharmaceutical discovery projects. This computational approach enables strategies to optimize solubility by disrupting the three-dimensional solid-state packing of novel chemical matter, illustrated here for an active medicinal chemistry campaign.</p>

scholarly journals Simulation of Thermal and Electric Field Distribution in Packaged Sausages Heated in a Stationary Versus a Rotating Microwave Oven

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1622
Author(s):  
Wipawee Tepnatim ◽  
Witchuda Daud ◽  
Pitiya Kamonpatana
Keyword(s):  
Temperature Distribution ◽  
Electric Field ◽  
Three Dimensional ◽  
Development Stage ◽  
Microwave Oven ◽  
Computational Time ◽  
Plastic Package ◽  
Heating Uniformity ◽  
The Cost ◽  
Good Agreement

The microwave oven has become a standard appliance to reheat or cook meals in households and convenience stores. However, the main problem of microwave heating is the non-uniform temperature distribution, which may affect food quality and health safety. A three-dimensional mathematical model was developed to simulate the temperature distribution of four ready-to-eat sausages in a plastic package in a stationary versus a rotating microwave oven, and the model was validated experimentally. COMSOL software was applied to predict sausage temperatures at different orientations for the stationary microwave model, whereas COMSOL and COMSOL in combination with MATLAB software were used for a rotating microwave model. A sausage orientation at 135° with the waveguide was similar to that using the rotating microwave model regarding uniform thermal and electric field distributions. Both rotating models provided good agreement between the predicted and actual values and had greater precision than the stationary model. In addition, the computational time using COMSOL in combination with MATLAB was reduced by 60% compared to COMSOL alone. Consequently, the models could assist food producers and associations in designing packaging materials to prevent leakage of the packaging compound, developing new products and applications to improve product heating uniformity, and reducing the cost and time of the research and development stage.

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