An Investigation of the Ring Hoop Tension Test for Anisotropic Tubes

2014 ◽  
Author(s):  
Christopher P. Dick ◽  
Yannis P. Korkolis
Keyword(s):  
Contact Pressure ◽  
Tension Test ◽  
Negligible Effect ◽  
Image Correlation ◽  
Element Analysis ◽  
Material Response ◽  
Full Field ◽  
Al 6061 ◽  
Full Field Measurement ◽  
Nominal Thickness

The ring hoop tension test (RHTT) is investigated experimentally and numerically to determine its validity and limitations in predicting the hoop response of materials in tubular form. Our experiments involved RHT-Testing of Al-6061-T4 tubes. Digital image correlation (DIC) was used to capture the strain evolution in the gage section of the specimens, giving a full-field measurement of the strains. The local hoop stress-strain response of the material was assessed in this way. Finite element analysis was used to further investigate the effects of friction, eccentricity and contact pressure on the recorded response. Friction was found to have a negligible effect on the recorded response for friction coefficient values of 0.01 and lower. However, it was found that larger values of friction may render the test meaningless. Tube eccentricity of the magnitude present in the tubes tested here (±4% of the nominal thickness) was determined to have no effect on the material response. It was also determined that tubes should not be turned to a uniform thickness as this may induce machining damage and release the existing residual stresses, thus causing error in determining the tube response in the hoop direction. The contact pressure was found to not significantly affect the state of uniaxial tension in the specimen and thus to have a negligible effect on the material response. By comparing the hoop with the axial response, the material anisotropy of the Al-6061-T4 tubes was established.

Shear Test on CFRP Full-Field Measurement and Finite Element Analysis

2010 ◽  
Vol 112 ◽  
pp. 49-62 ◽  
Author(s):  
Sébastien Mistou ◽  
Marina Fazzini ◽  
Moussa Karama
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Shear Modulus ◽  
Shear Test ◽  
Image Correlation ◽  
Optical Methods ◽  
Strain Gauges ◽  
Element Analysis ◽  
Full Field ◽  
Full Field Measurement

The purpose of this work is to study the Iosipescu shear test and more precisely its ability to characterize the shear modulus of a carbone/epoxy composite material. The parameters influencing this identification are the fibre orientation, the geometry of the notch and the boundary conditions. Initially these parameters were studied through the finite element analysis of the shear test. Then, the measurement of the shear strains was carried out by traditional methods of measurement (strain gauges) but also by optical methods. These optical methods: the digital image correlation and the electronic speckle pattern interferometry (ESPI); allow for various levels of loading, to reach a full-field measurement of the shear strain. This enabled us to study the strain distribution on the section between the two notches. The finite element model enabled us to study the parameters influencing the calculation of the shear modulus in comparison with strain gauges, image correlation and ESPI. This work makes it possible to conclude on optimal parameters for the Iosipescu test.

Full-field measurement of micro strain of printed circuit board assembly using digital image correlation

2017 ◽  
Vol 46 (11) ◽  
pp. 1103004
Author(s):  
杨靖 Yang Jing ◽  
吴思进 Wu Sijin ◽  
郑伟巍 Zheng Weiwei ◽  
李伟仙 Li Weixian ◽  
杨连祥 Yang Lianxiang
Keyword(s):  
Digital Image Correlation ◽  
Field Measurement ◽  
Printed Circuit Board ◽  
Image Correlation ◽  
Circuit Board ◽  
Printed Circuit Board Assembly ◽  
Full Field ◽  
Printed Circuit ◽  
Full Field Measurement ◽  
Circuit Board Assembly

scholarly journals Towards a Planar Cruciform Specimen for Biaxial Characterisation of Polymer Matrix Composites

2010 ◽  
Vol 24-25 ◽  
pp. 115-120 ◽  
Author(s):  
Michael R.L. Gower ◽  
Richard M. Shaw
Keyword(s):  
Strain Distribution ◽  
Stress Raiser ◽  
Test Method ◽  
Image Correlation ◽  
Strain Gauges ◽  
Test Machine ◽  
Element Analysis ◽  
Full Field ◽  
Cruciform Specimen ◽  
Gauge Section

This paper details work undertaken towards the development of a standard test method for the biaxial response of planar cruciform specimens manufactured from carbon fibre-reinforced plastic (CFRP) laminates and subject to tension-tension loading. Achieving true biaxial failure in a cruciform specimen without the need for the inclusion of a stress raiser, such as a hole, in the gauge-section, is a subject attracting much research globally and is by no means a trivial exercise. Coupon designs were modelled using finite element analysis (FEA) in order to predict the stress and strain distributions in the central region of the specimen. An Instron biaxial strong-floor test machine was used to test the specimens. Strain gauges were used to measure the strain in the specimen arms and to assess the degree of bending. Digital image correlation (DIC) was used to measure the full-field strain distribution in the central gauge-section of the specimen and this was compared to values measured using strain gauges. The strain readings obtained from strain gauges, DIC and FEA predictions were in good agreement and showed that the strain distribution was uniform in the central gauge-section, but that strain concentrations existed around the tapered thickness zone. These regions of strain concentration resulted in interlaminar failure and delamination of the laminate propagating into the specimen arms.

scholarly journals Comparing full-field data from structural components with complicated geometries

2021 ◽  
Vol 8 (9) ◽  
pp. 210916
Author(s):  
W. J. R. Christian ◽  
A. D. Dean ◽  
K. Dvurecenska ◽  
C. A. Middleton ◽  
E. A. Patterson
Keyword(s):  
Thermoelastic Stress ◽  
Image Correlation ◽  
Qr Factorization ◽  
Process Data ◽  
Element Analysis ◽  
Full Field ◽  
Measurement Systems ◽  
Stress And Deformation ◽  
Complicated Geometries ◽  
Comparison Technique

A new decomposition algorithm based on QR factorization is introduced for processing and comparing irregularly shaped stress and deformation datasets found in structural analysis. The algorithm improves the comparison of two-dimensional data fields from the surface of components where data is missing from the field of view due to obstructed measurement systems or component geometry that results in areas where no data is present. The technique enables the comparison of these irregularly shaped datasets without the need for interpolation or warping of the data necessary in some other decomposition techniques, for example, Chebyshev or Zernike decomposition. This ensures comparisons are only made between the available data in each dataset and thus similarity metrics are not biased by missing data. The decomposition and comparison technique has been applied during an impact experiment, a modal analysis, and a fatigue study, with the stress and displacement data obtained from finite-element analysis, digital image correlation and thermoelastic stress analysis. The results demonstrate that the technique can be used to process data from a range of sources and suggests the technique has the potential for use in a wide variety of applications.

Full-field Measurement of Deformation and Vibration using Digital Image Correlation

Smart Science ◽  
2015 ◽  
Vol 3 (2) ◽  
pp. 80-86 ◽  
Author(s):  
Liang-Chih Chen ◽  
Ching-Yuan Chang ◽  
Wei-Chen Lee ◽  
Chien-Ching Ma
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Field Measurement ◽  
Image Correlation ◽  
Full Field ◽  
Full Field Measurement

scholarly journals Full Field Strain Measurement in Split Hopkinson Bar Experiments

2008 ◽  
Author(s):  
Amos Gilat ◽  
Tim Schmidt ◽  
John Tyson ◽  
Andrew Walker
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Hopkinson Bar ◽  
Image Correlation ◽  
Full Field ◽  
Split Hopkinson Bar ◽  
Strain And Strain Rate ◽  
Full Field Measurement ◽  
Split Hopkinson ◽  
Correlation System

A method for full field measurement of strain (and strain rate) in split Hopkinson bar experiments (compression, tensile, and shear) is introduced. The measurements are done by using the Aramis three-dimensional image correlation system. The system uses two digital high-speed cameras that provide a synchronized stereo view of the specimen. Depending on the number of pixels used, the system is capable or recording frames at a rate of up to about 110,000 per second. Before conducting a test, a random dot pattern is applied to the surface of the specimen. The image correlation algorithm uses the dot pattern to define a field of overlapping virtual gage boxes. The 3-D coordinates of the center of each gage box is determined at each frame, interpolated to better than 1/100 of a pixel. The coordinates are then used for calculating the deformations, strains, and strain rates throughout the surface of the specimen.

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