The application of holographic multiplexing to record separate isopachic- and isochromatic-fringe patterns

1974 ◽  
Vol 14 (12) ◽  
pp. 502-504 ◽  
Author(s):  
A. Assa ◽  
A. A. Betser
Keyword(s):  
Isochromatic Fringe ◽  
Fringe Patterns

scholarly journals Experimental determination and finite element analysis of coefficients of the multi-parameter Williams series expansion in the vicinity of the crack tip in linear elastic materials. Part I

2020 ◽  
pp. 237-249
Author(s):  
L. V Stepanova
Keyword(s):  
Series Expansion ◽  
Digital Image ◽  
Power Series Expansion ◽  
Crack Tip ◽  
Higher Order ◽  
Accurate Estimation ◽  
Principal Stresses ◽  
Isochromatic Fringe ◽  
Higher Order Terms ◽  
Fringe Patterns

This study aims at obtaining coefficients of the multi-parameter Williams series expansion for the stress field in the vicinity of the central crack in the rectangular plate and in the semi-circular notched disk under bending by the use of the digital photoelasticity method. The higher-order terms in the Williams asymptotic expansion are retained. It allows us to give a more accurate estimation of the near-crack-tip stress, strain and displacement fields and extend the domain of validity for the Williams power series expansion. The program is specially developed for the interpretation and processing of experimental data from the phototelasticity experiments. By means of the developed tool, the fringe patterns that contain the whole field stress information in terms of the difference in principal stresses (isochromatics) are captured as a digital image, which is processed for quantitative evaluations. The developed tool allows us to find points that belong to isochromatic fringes with the minimal light intensity. The digital image processing with the aid of the developed tool is performed. The points determined with the adopted tool are used further for the calculations of the stress intensity factor, T-stresses and coefficients of higher-order terms in the Williams series expansion. The iterative procedure of the over-deterministic method is utilized to find the higher order terms of the Williams series expansion. The procedure is based on the consistent correction of the coefficients of the Williams series expansion. The first fifteen coefficients are obtained. The experimentally obtained coefficients are used for the reconstruction of the isochromatic fringe pattern in the vicinity of the crack tip. The comparison of the theoretically reconstructed and experimental isochromatic fringe patterns shows that the coefficients of the Williams series expansion have a good match.

Investigation of Fracture in Transparent Glass Fiber Reinforced Polymer Composites Using Photoelasticity

2004 ◽  
Vol 126 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Sanjeev K. Khanna ◽  
Marius D. Ellingsen ◽  
Robb M. Winter
Keyword(s):  
Mode I ◽  
Fiber Reinforced ◽  
Field Equations ◽  
Static Mode ◽  
Transparent Glass ◽  
Isochromatic Fringe ◽  
Fiber Reinforced Plastic ◽  
Plastic Composite ◽  
Reinforced Plastic ◽  
Fringe Patterns

Fiber-reinforced plastic composite materials are being widely used in a variety of load bearing and high-performance structures. Reliable use and optimum design requires accurate methods for predicting their fracture behavior, among other things. Fiber reinforced plastic composites are generally opaque and hence experimental fracture mechanics studies utilize surface measurements or post-fracture analysis. Hence quality transparent glass cloth reinforced polyester composites have been fabricated and transmission photoelasticity used to investigate quasi-static Mode-I fracture. The isochromatic fringe patterns obtained were analyzed using orthotropic photoelasticity to determine Mode-I stress intensity factors. Opening mode stress field equations in conjunction with an orthotropic stress-optic law were utilized to regenerate the isochromatic fringe patterns. Good agreement was found between the regenerated fringe patterns and the experimentally obtained patterns

WAVE PROPAGATION IN A LAYERED MODEL DUE TO POINT SOURCE LOADING IN A HIGH‐IMPEDANCE MEDIUM

Geophysics ◽  
1971 ◽  
Vol 36 (3) ◽  
pp. 517-532 ◽  
Author(s):  
I. M. Daniel ◽  
R. L. Marino
Keyword(s):  
Wave Propagation ◽  
Point Source ◽  
Explosive Loading ◽  
Isochromatic Fringe ◽  
Layered Model ◽  
High Impedance ◽  
Impedance Ratio ◽  
Fringe Patterns ◽  
Refracted Waves ◽  
Attenuation Characteristics

Dynamic photoelastic techniques were used to study the incident, reflected, and refracted waves in a layered model. The model, consisting of two birefringent layers with an impedance ratio of 2.2:1, was subjected to point source explosive loading in the high‐impedance medium. The isochromatic fringe patterns were photographed with a Cranz‐Schardin multiple spark camera operating at a rate of 200,000 frames per second. Propagation and attenuation characteristics of waves in both layers were studied.

Pulse Propagation in Straight and Curved Beams—Theory and Experiment

1974 ◽  
Vol 41 (1) ◽  
pp. 71-76 ◽  
Author(s):  
F. B. Crowley ◽  
J. W. Phillips ◽  
C. E. Taylor
Keyword(s):  
Method Of Characteristics ◽  
Pulse Propagation ◽  
Curved Beam ◽  
Curved Beams ◽  
Dimensional Theory ◽  
One Dimensional ◽  
Isochromatic Fringe ◽  
Fringe Patterns ◽  
Theory And Experiment ◽  
Good Agreement

The equations from Morley’s one-dimensional theory governing the motion of a curved beam subjected to an arbitrary pulse are solved numerically using the method of characteristics. Propagation of initially longitudinal pulses in beam assemblages with both straight and curved sections is investigated. Simulated isochromatic fringe patterns are constructed by a Calcomp plotter and are compared with actual photoelastic patterns. Remarkably good agreement is found between theory and experiment in all the cases investigated. It is concluded that Morley’s theory can be applied to pulse propagation problems of the type investigated.

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