An application of pattern mapping to plane motion

Fail, R. Wallace; Taylor, C. E.

doi:10.1007/bf02321512

Cited by 16 publications

(14 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this method, a photo-electronic camera, digitising (A/D) board and a computer based image-processing system are used to capture a digital image of the grid. This digital image is then analysed, using grey-level threshold techniques and centroid algorithms [27], in order to determine the positions of the centroids of the grid spots, and hence the grid deformations and strains. The main advantages of the automated grid method include: large strains (greater than 5%) and crack-widths can be measured; the analysis is fully automated; and the method provides a full-field analysis over a large area of the specimen.…”

Section: Grid Methodsmentioning

confidence: 99%

Flexural strain and crack width measurement of steel-fibre-reinforced concrete by optical grid and electrical gauge methods

Robins

Austin

Chandler

et al. 2001

Cement and Concrete Research

View full text Add to dashboard Cite

This item was submitted to Loughborough's Institutional Repository (https://dspace.lboro.ac.uk/) by the author and is made available under the following Creative Commons Licence conditions.For the full text of this licence, please go to: http://creativecommons.org/licenses/by-nc-nd/2.5/ FLEXURAL STRAIN AND CRACK WIDTH MEASUREMENT OF STEEL FIBRE REINFORCED CONCRETE BY OPTICAL GRID AND ELECTRICAL GAUGE METHODSPeter Robins, Simon Austin and Peter Jones, Department of Civil and Building Engineering Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK Keywords: crack detection (B), fibre reinforcement (E), fracture toughness (C), image analysis (B), modelling (E) Abstract: A research programme is discussed that has investigated the fracture of steel fibre reinforced sprayed concrete under flexural loading, with the aim of developing a stress-block model to predict flexural behaviour in the form of a load-deflection response. This paper reports the work associated with establishing the strain and crack-width profiles in relation to mid-span beam deflection. A strain analysis technique is described, which combines the use of electrical strain gauges with a semi-automated grid method (using digital image processing) for measuring and monitoring the strain and crack-width profile over the depth of a fibre reinforced beam during a flexural test.This novel strain analysis technique has established strain/crack-width data which forms a key part of a stress-block approach for predicting residual flexural strength, an essential requirement of a much needed design rationale for steel fibre reinforced concrete. Introduction Research ObjectivesThe work reported here formed part of a larger research project investigating the reinforcing mechanisms and fracture processes associated with steel fibre reinforced sprayed concrete under flexural load. A major aim of this project was to develop a model -based on conventional principles of mechanics -to predict flexural behaviour in the form of a load-deflection response, and thereby predict flexural toughness performance.The principal objective of this study was to test the following hypothesis: given the matrix compressive strength, fibre volume, fibre type, cross-section dimensions and loading geometry of a steel fibre reinforced sprayed concrete beam, the flexural loaddeflection curve can be predicted using a stress-block diagram approach, if the following principal parameter relationships are known: the uniaxial compressive stress-strain relationship; the uniaxial tensile stress-strain relationship; the single fibre pull-out load versus crack-width relationship; the number, distribution, embedment lengths and orientation of the fibres bridging the cracked section of the beam; and the strain profile and the crack-width profile in relation to mid-span beam deflection. This paper presents work carried out on the last principal parameter listed above, that is the strain and crack-width profiles, whilst that on fibre pullout and distribution are reported elsewhere [1, 2]. ...

show abstract

Section: Grid Methodsmentioning

confidence: 99%

Flexural strain and crack width measurement of steel-fibre-reinforced concrete by optical grid and electrical gauge methods

Robins

Austin

Chandler

et al. 2001

Cement and Concrete Research

View full text Add to dashboard Cite

show abstract

“…Any level below the threshold is considered black and any level above is considered white. The precise position of the spot is defined by the centroid of the spot, which is calculated using the following equations [5,7]: One drawback of using a threshold is that the centroid location is relatively insensitive to rigid body deformations. Therefore, using the actual intensity rather than a threshold to determine the centroid will increase the accuracy.…”

Section: Principle Of Grid Methodsmentioning

confidence: 99%

“…The grid method was implemented as described in Ref [5]. The image is rotated by 61°in order to align the spots along the x and y axes.…”

Section: Comparison Of Displacements From Grid Methods and Dic Techniquementioning

confidence: 99%

“…By comparing the grid of the deformed specimen to that of the undeformed reference state, the displacements and strains which are developed in the specimen during the loading can be quantified. There is a variety of approaches used to perform the image analysis, such as spot centroid tracking [5,6], cross-grid tracking [9], the spectral method [10,11] and Fourier transformation of the grid patterns [12]. The grid method has been successfully applied to obtain the displacement and strain mapping in various materials and structures, such as perforated aluminum strips [13], cracks in lamellar TiAl [14], three dimensional surface deformations of metals [15], necking zone of a tensile specimen [16] and small animal bones [17].…”

Section: Introductionmentioning

confidence: 99%

“…The grid method is one of the oldest methods for obtaining full-field deformation measurements [1][2][3][4][5][6][7][8][9]. A grid usually consists of lines, circles, dots or other shapes assembled in regular patterns.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Grid Method for Microscale Discontinuous Deformation Measurement

et al. 2011

View full text Add to dashboard Cite

The objective of this paper is to explore both grid method and Digital Image Correlation (DIC) technique for microscale and discontinuous displacement measurements, such as those associated with crack tips. First, the principle of the grid method is revisited. The grid method and DIC technique are then applied to computer generated images to calculate the displacement field around crack tips. Finally, the grid method is applied to actual experimental images of fracture tests which are conducted inside a Scanning Electron Microscope (SEM) chamber. A new technique is developed to generate microscale pattern that is suitable for both grid method and DIC technique. The displacement fields calculated from grid method are compared with those from DIC technique to identify the strengths and weaknesses of each technique for the microscale and discontinuous displacement measurements. It has been determined that grid method can obtain data closer to the discontinuity than DIC; however, DIC produces smoother displacement fields at the far field. Using this new pattern generation technique, both grid method and DIC technique can be applied to the fracture test at the microscale to complement with each other to achieve the best experiment results.

show abstract

Calculation of strain from an object grating on a reseau film

Andresen

Hübner

1992

Experimental Mechanics

View full text Add to dashboard Cite

An application of pattern mapping to plane motion

Cited by 16 publications

References 9 publications

Flexural strain and crack width measurement of steel-fibre-reinforced concrete by optical grid and electrical gauge methods

Flexural strain and crack width measurement of steel-fibre-reinforced concrete by optical grid and electrical gauge methods

Grid Method for Microscale Discontinuous Deformation Measurement

Calculation of strain from an object grating on a reseau film

Contact Info

Product

Resources

About