Strain Analysis Technique Research Articles

非平行断面上の歪楕円を用いた３次元歪解析法

非平行断面上の歪楕円を用いた３次元歪解析法

Strain analysis of a rotating plate with X-ray diffraction techniques

A new technique for strain analysis of a rotating component by using X-ray diffraction analysis is presented. Aluminum foil is bonded to a rotating plate of epoxy resin, and strain in the foil is measured by the X-ray diffraction technique to estimate the strain of the plate under rotation. The X-ray diffraction angle is determined with the cross correlation method, and stiffness of the foil is taken into account in the analysis of the strain under rotation. The strain of the rotating plate is in good agreement with calculation.

Three-dimensional finite strain from crinoid ossicles

Randomly oriented crinoid ossicles are useful markers for the determination of three-dimensional finite strain. Two techniques are presented. Both make use of established methods to measure the two-dimensional strain ellipses on three surfaces, which are then combined to calculate the shape and orientation of the strain ellipsoid. First, ossicles positioned such that a thin section cuts across the cylinder appear as randomly oriented ellipses prior to deformation, and can be analyzed using standard Rfφ methods. Second, ossicles positioned such that the section cuts lengthwise through the cylinder appear as rectangular or sub-rectangular shapes with orthogonal geometries in the undeformed state. Measurements of angular shear strain on two or more such markers are analyzed using a non-linear least-squares solution to the Breddin graph, allowing determination of the best-fit strain ellipse.Both methods are applied to an echinoderm grainstone from the central Helvetic nappes of Switzerland. The results are internally consistent, and compatible with those from other strain analysis techniques.

Application and Comparison of Techniques for Three-Dimensional Analysis of Craniofacial Anomalies

Traditionally, cephalometric analysis has been limited to data determined from two-dimensional (2-D) cephalograms. With imaging facilities such as CT and biplanar radiography now available, the natural extension has been towards the use of three-dimensional (3-D) coordinate positions of landmarks for comparative purposes. While these data have been potentially available for several years, the accurate and reproducible extraction of anatomic landmarks suitable for comparative purposes has been limited. This paper presents results of the application of traditional comparative techniques to well determined 3-D coordinate data acquired from biplanar radiography and CT for a patient with Treacher Collins syndrome and further provides a comparison with the technique of strain analysis, often referred to as finite element analysis, which has been applied recently to craniofacial data. Comparisons of distances and angles between landmarks, landmark coordinate positions, and strains of the patient relative to experimental reference standards reveal that the essential skeletal features of Treacher Collins syndrome have been identified and quantified by the analysis techniques. Further, a measure of the significance of the deviations has been determined by comparisons with the experimental reference standards.

An Interactive Program for Doing Fry Strain Analysis on the Macintosh Microcomputer

This paper describes a Macintosh application for performing Fry's (1979) technique of strain analysis either as a research tool or teaching exercise. To acquire data for the program, an oriented section is cut through a rock specimen and the centers of deformed objects are located. The x,y coordinates of these centers are fed into a Macintosh™ microcomputer using either a mouse, keyboard, digitizing tablet, or pre-existing data file. All center-to-center distances are calculated and plotted by the computer in a matter of seconds, and the user is then given the opportunity to fit a strain ellipse to the characteristic central hole in the Fry plot. The goodness-of-fit of the ellipse is checked by a novel technique. The center-to-center vectors are restored to their pre-strain condition, and their distribution is evaluated for compatibility with the assumptions of the Fry method. The program is compiled from source code using the Microsoft™ BASIC compiler and conforms to the standard Macintosh user interface...

Application of the [formula omitted] technique to ellipitical markers deformed by pressure-solution

The applicability of the R f φ technique of finite strain analysis to elliptical markers whose shape is modified by pressure-solution is investigated. Variably oriented elliptical markers shortened by removing material from one or both sides in open and closed systems are compared to markers shortened homogeneously by the same amount. For the models examined, it was found that the R f φ technique correctly predicts the principal directions, the initial marker axial ratio, and the axial ratio of a circle deformed in a like manner. Interpretation of strain ratios in terms of percent shortening requires knowing how much volume was lost. Equations relating the strain ratio to percent shortening are given for both constant-volume and volume-loss deformation.

A strain interpretation in the comparison of network coordinate differences due to datum change

Strain analysis techniques can be applied in network inconsistency studies when, e.g., two sets of coordinates of the same network referred to different datums are compared. The displacement field induced by the inconsistency is translated into scalar strain invariant fields which after a filtering treatment provide additional information on the inconsistency characteristics of the network under comparison. A complete strain analysis algorithm is presented and an actual example is given, studying from the strain point of view the inconsistencies of the EDOC-2 network versus the ED-50 network.

Sheet-metal strain-analysis system based on a square reference-grid

A strain-analysis technique is presented which is particularly suited to the measurement and display of small strains in large, shallow sheet-metal pressings. This new technique enables contour plots of the principal surface-strains, their ratio, and their orientation to be computed. In addition, frequency distributions of the principal surface-strains may be obtained. A square reference-grid is used, typically of 100 mm grid size, and the standard deviations of the computed results are estimated to be 0.2 % for the principal strains and 2° for the orientation of the principal axes. Examples of the use of the method for industrial components are presented, and comparisons with previous techniques are made.

A new technique of strain analysis using three-dimensional distributions of passively deformed linear markers

Finite homogeneous strain may be deduced from the spatial distribution of initially uniformly oriented lines or planes in a rock, as recorded in a pole figure or petrofabric diagram. This paper presents a new analytic technique which is simple and rapid in practical application.

Strain analysis using deformed line distributions

This paper describes a new technique of strain analysis using passively deformed linear markers which were initially uniformly or symmetrically distributed in a plane. The axial ratio of the strain ellipse is determined from the quartiles or other percentiles of the deformed distribution. The technique permits statistical testing of assumptions and rapid reconstruction of the undeformed state.

Some limitations of the Rf/ φ technique of strain analysis — Discussion

A recent note by De Paor (1980) suggests that finite strain cannot be decomposed into tectonic and compaction components on the basis of asymmetry of the R f φ data about the mean φ trace. This is true if only the shape of the R f φ data field is considered, but shown to be incorrect when the distribution of data within this field is considered.

Some limitations of the Rfφ technique of strain analysis — Reply

The analysis presented in the discussion is statistically invalid.

Some limitations of the [formula omitted] technique of strain analysis

Finite strain determined from R f/φ analysis of deformed ellipse distributions cannot be separated into compactional and tectonic parts on the basis of population asymmetry about the orientational mean, as was originally suggested. Furthermore, where there is a ductility contrast between objects and matrix, R f/φ analysis yields an invalid estimate of the strain suffered by the objects.

A Strain Analysis Technique by Scattered-light Speckle Photography

A method for determining the displacement vector of transparent materials using the double-exposure speckle pattern created by scattered light is suggested. The method has been used in an investigation of the motion of morphological units in a polypropylene film during uniaxial tensile deformation by means of the point-wise filtering of the double-exposure pattern of scattered light. Model experiments confirming the validity of the method have been performed.

Small specimen strain measurement by moiré fringes.

The moiré fringe technique of strain analysis was applied to small beams of resin restorative materials. The feasibility of using this technique on small dental materials specimens was established.

Strength of Pyrolytic SiC Coatings of Fuel Particles for High‐Temperature Gas‐Cooled Reactors

Methods for measuring the strength of a hemispherical shell were developed and applied to SiC coatings obtained from reactor fuel particles. These methods allow independent evaluation of the strengths of the inner and outer layers of the coatings. The applied loads are related to the maximum tensile stress using strain‐analysis techniques. Coatings from standard SiC fuel particles have a median outer‐surface strength of 620 MN m−2 and a median inner‐surface strength of 720 MN m−2. These strengths relate only to a small region of the tested hemisphere, and statistical analysis is used to obtain strengths for complete spherical shells under internal pressure, the condition relevant to reactor performance. This procedure reduces the median working strength to 105 MN m−2, with failure occurring preferentially from the outer surface. A second statistical analysis shows that the critical failure stress for 1 particle in 104 (the reactor design requirement) is 22 MN m−2. A fracture‐mechanics analysis of strength indicates that failure occurs by the extension of inherent flaws at the surface. These flaws are associated with surface roughness. Strength was substantially improved by reducing this roughness by controlling the conditions of deposition of the coating and the topography of the underlying pyrocarbon layer. Greatly superior coatings were thus prepared; their median failure stress under internal pressure was 560 MN m−2 and the 1‐in‐104 failure stress 195 MN m−2.

Experimental analysis of slow viscous flow using photoviscosity and bubbles

Photoelasticity in solids is a well-developed technique for stress and strain analysis. Less progress has been made in applying a similar effect, photoviscosity, to flow analysis. This paper has three objects: (1) to simplify photoviscous methods; (2) to compare velocity profiles obtained from photoviscosity with those obtained by the double-exposure bubble technique; (3) to determine the principal strain rates and the maximum shear stress from photoviscotity. The problem of slow viscous flow about a cylindrical obstacle in a rectangular channel was selected for the comparison. The fluid was a suspension of milling yellow dye in water. Strain rates and stresses averaged over the path of ligh can be obtained easily using photoviscosity. The bubble technique is shown to be a very powerful tool that permits the determination of the velocity field in three-dimensional problems.

Deformation of a Slaty, Lapillar Tuff in the English Lake District: Discussion

Strain analysis techniques, used to investigate finite strain states of “bird9s-eye tuffs” from the English Lake District, are discussed. Results have been obtained that differ from those recently described by G. Oertel. The writers dispute most of Oertel9s conclusions and present the implications of their results for slaty cleavage development and the geological history of the English Lake District.

A technique of finite strain analysis using elliptical particles

When initial elliptical objects are deformed homogeneously with their matrix they change both their ellipticity and axial orientation. Mathematical expressions are derived which relate the final elliptical ratio and orientation of particles to their initial form and the magnitude and orientation of the finite rotational or irrotational strain. Curves are constructed from these expressions and examples given of their use to determine finite strain and initial shape of deformed aggregates.

A reflex spectrographic technique for in-plane strain analysis

A reflex camera that incorporates a light source and spectroscope for recording in-plane displacement fringes formed by reflective diffraction gratings is described and illustrated.