scholarly journals On the determination of first-mode stress intensity factors and T-stress in a continuous functionally graded beam using digital image correlation method

2021 ◽  
Vol 9 (1) ◽  
pp. 56-70
Author(s):  
Ahmed M. Abood ◽  
◽  
Haider Khazal ◽  
Abdulkareem F. Hassan
Keyword(s):  
Stress Intensity ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Volume Fraction ◽  
Functionally Graded ◽  
Image Correlation ◽  
Bending Test ◽  
Fe Model ◽  
Functionally Graded Beam ◽  
T Stress

<abstract> <p>In this study, fracture parameters of epoxy/glass functionally graded composite were determined experimentally using the digital image correlation (DIC) method. A functionally graded material (FGM) with continuous variation in elastic properties was manufactured by gravity casting in vertical template. A 30% volume fraction of glass spheres was dispersed in a low viscosity resin. A single edge crack specimen was examined in a three-point bending test under mode Ⅰ loading with cracks along the gradient tendency of the material properties. The mechanical properties of FGM were calculated according to ASTM D638. The DIC technique was adopted to obtain the deformation region around the crack tip. William's series was employed to calculate stress intensity factor and T-stress. The experimental results then verified by solving the FE model using ABAQUS program. The comparison between DIC and numerical results illustrated a largely acceptable achievement.</p> </abstract>

Methodology for in situ stress intensity factor determination on cracked structures by digital image correlation

2010 ◽  
Vol 1 (4) ◽  
pp. 344-357 ◽  
Author(s):  
V. Richter‐Trummer ◽  
P.M.G.P. Moreira ◽  
S.D. Pastrama ◽  
M.A.P. Vaz ◽  
P.M.S.T. de Castro
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Digital Image Correlation ◽  
Intensity Factor ◽  
Digital Image ◽  
Strain Field ◽  
Image Correlation ◽  
Content Type ◽  
Cracked Structures

PurposeThe purpose of this paper is to develop a methodology for in situ stress intensity factor (SIF) determination that can be used for the analysis of cracked structures. The technique is based on digital image correlation (DIC) combined with an overdetermined algorithm.Design/methodology/approachThe linear overdeterministic algorithm for calculating the SIF based on stress values around the crack tip is applied to a strain field obtained by DIC.FindingsAs long as the image quality is sufficiently high, a good accuracy can be obtained for the measured SIF. The crack tip can be automatically detected based on the same strain field. The use of the strain field instead of the displacement field, eliminates problems related to the rigid body motion of the analysed structure.Practical implicationsIn future works, based on the applied techniques, the SIF of complex cracked plane stress structures can be accurately determined in real engineering applications.Originality/valueThe paper demonstrates application of known techniques, refined for other applications, also the use of stress field for SIF overdeterministic calculations.

The Stress Intensity Factor of Opening Mode Determined by Digital Image Correlation

2011 ◽  
Vol 83 ◽  
pp. 54-59 ◽  
Author(s):  
Rui Zhang ◽  
Ling Feng He ◽  
Chang Rong Li
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Digital Image Correlation ◽  
Intensity Factor ◽  
Digital Image ◽  
Correlation Method ◽  
Compact Tension ◽  
Image Correlation ◽  
Full Field ◽  
Opening Mode

Applications of the digital image correlation method (DIC) for the determination of the opening mode stress intensity factor (SIF) is investigated using an edge cracked aluminum plate in this paper. Standard compact tension test specimen was tested under tensile loading and the full-field displacement fields of the test sample were recorded using DIC. The SIF associated with unavoidable rigid-body displacement translation were calculated simultaneously from the experimental data by fitting the theoretical displacement field using the method of least-squares. Selection of displacement and convergence values is discussed. For validation, the SIF thus determined is compared with theoretical results, confirming the effectiveness and accuracy of the proposed technique. Therefore it reveals that the DIC is a practical and effective tool for full-field deformation and SIF measurement.

scholarly journals Simulation of the Hybrid Carbon-Aramid Composite Materials Based on Mechanical Characterization by Digital Image Correlation Method

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4184
Author(s):  
Camelia Cerbu ◽  
Stefania Ursache ◽  
Marius Florin Botis ◽  
Anton Hadăr
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Flexural Modulus ◽  
Image Correlation ◽  
Woven Fabric ◽  
Bending Test ◽  
Orthotropic Materials ◽  
The Impact ◽  
Longitudinal Strains ◽  
Hybrid Carbon

As hybrid carbon-aramid composites become widely used in various industries, it has become imperative to mechanically characterize them using accurate methods of measuring the entire deformation field such as the digital image correlation (DIC) method. The accuracy of the numerical simulation of carbon-aramid composite structures depends on the accuracy of the elastic constants. Therefore, the goal of this research is to model and simulate the mechanical behaviour of the composite based on epoxy resin reinforced with carbon-aramid woven fabric by considering the mechanical properties investigated by tensile test combined with DIC and the bending test. The curves of the transverse strains related to the longitudinal strains were investigated using DIC in order to determine the Poisson’s ratios in the case of tensile tests applied in warp or weft directions of the reinforcement fabric. The impact strength determined by Charpy tests is also reported. The other main objective is to use the analytical models to compute the tensile and flexural moduli of elasticity for the fictitious orthotropic materials which behave similarly to the carbon-aramid composite investigated. The simulations regarding the behaviour of the carbon-aramid composite in tensile and bending tests were validated by the experimental results, since the maximum errors recorded between experimental and theoretical results were 0.19% and 0.15% for the equivalent tensile modulus and for the equivalent flexural modulus, respectively.

Tension and compression moduli characterization of a bimodular ceramic-fiber reinforced SiO2 aerogel composite

2020 ◽  
Vol 62 (10) ◽  
pp. 1003-1009
Author(s):  
Yantao Sun ◽  
Jia Huang ◽  
Duoqi Shi ◽  
Shengliang Zhang ◽  
Zhizhong Fu ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Image Correlation ◽  
Bending Test ◽  
Ceramic Fiber ◽  
Fiber Reinforced ◽  
Compression Tests ◽  
Tension Tests ◽  
Aerogel Composite ◽  
Tension And Compression

Abstract Comprehensive characterization mechanical properties of aerogels and their composites are important for engineering design. In particular, some aerogel composites were reported to have varied tension and compression moduli. But conducting tension tests is difficult for the reason that low strength and brittleness will lead to unexpected failure in the non-test area. A method is presented for measuring both the tension and compression moduli of a ceramic-fiber reinforced SiO2 aerogel composite by bending via digital image correlation. First, the relationship between bending behavior and the tension/compression moduli was introduced for bimodular materials. Then a bending test was conducted to predict tension and the compression moduli of the ceramicfiber- reinforced SiO2 aerogel composite via digital image correlation. In addition, uniaxial tension and compression tests of the aerogel composites were carried out, respectively for measuring tension and compression moduli. The tension and compression moduli measured were numerically similar to results obtained from uniaxial tests with a difference of less than 14 %.

Use of Digital Image Correlation for the Evaluation of Flexural Fatigue Behavior of Asphalt Beams with Geosynthetic Interlayers

2017 ◽  
Vol 2631 (1) ◽  
pp. 55-64 ◽  
Author(s):  
Vinay Kumar V ◽  
Sireesh Saride
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Digital Images ◽  
Fatigue Behavior ◽  
Bottom Layer ◽  
Fatigue Performance ◽  
Image Correlation ◽  
Bending Test ◽  
Flexural Fatigue ◽  
Tensile Strains

In this study, the flexural fatigue performance of two-layer asphalt beams with and without geosynthetic interlayers was evaluated with a digital image correlation (DIC) technique. A field scenario was simulated by considering an old, destressed pavement as the bottom layer with a compacted bituminous mix as an overlay. An appropriate tack coat and geosynthetic interlayer were at the interface. The digital images were recorded at a specific interval of load cycles during a repeated load four-point bending test. The displacement fields obtained from the digital images were analyzed so that the crack width, crack height, and tensile strains could be obtained and the crack initiation and propagation phenomena studied. The deformation data obtained from the DIC analysis were validated with the vertical deformations measured through linear variable differential transformers. The DIC results correlated very well with the measured data. The DIC data indicated that the tensile strains were as high as 4.75% at the crack tip in the control specimen compared with 1.42% in a polyester grid interlayered specimen at the failure of the corresponding specimens. With the inclusion of interlayers, the fatigue performance of the two-layer asphalt beam specimens improved by about 39, 12, and 1.7 times for Specimens I1, I2, and I3, respectively.

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