A Novel Speckle-Free Digital Image Correlation Method for In Situ Warpage Characterization

Niu, Yuling; Shao, Shuyan; Park, S. B.; Kao, C. R.

doi:10.1109/tcpmt.2016.2635581

Cited by 17 publications

(4 citation statements)

References 21 publications

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“…At the beginning, a tested specimen need to be prepared applying a unique pattern of random speckles/dots on its surface. The speckle pattern can be the natural texture of the specimen surface [ 31 , 32 , 41 ]. In this work, we have conducted many tests to obtain reliable DiC conditions.…”

Section: Experiments Setup and Resultsmentioning

confidence: 99%

Modeling and Experimental Analysis of Shear-Slitting of AA6111-T4 Aluminum Alloy Sheet

et al. 2020

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This work presents experimental studies with numerical modeling, aiming at the development of guidelines for shaping aluminum alloy AA6111-T4, t = 1.5 mm thick, with the use of a shear-slitting operation. During the experimental tests, parametric analyses were conducted for the selected material thickness. For the purposes of the material deformation’s analysis, a vision system based on the digital image correlation (DiC) method was used. Numerical models were developed with the use of finite element analysis (FEA) and the mesh-free method: smoothed particle hydrodynamics (SPH), which were used to analyze the residual stress and strain in the cutting zone at different process conditions. The results indicate a significant effect of the horizontal clearance between knives on the width of the deformation zone on sheet cut edge. Together with the clearance value increase, the deformation zone increases. The highest burrs on the cut edge were obtained, when the slitting speed was set to v = 17 m/min, and clearance to hc = 6%t. A strong influence was observed of the horizontal clearance value at high slitting speeds on burr unshapeliness. The most favorable conditions were obtained for v = 32 m/min, hc = 0.062 mm, and rake angle of upper knife for α = 30°. For this configuration, a smooth sheared edge with minimal burr height was obtained.

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Section: Experiments Setup and Resultsmentioning

confidence: 99%

Modeling and Experimental Analysis of Shear-Slitting of AA6111-T4 Aluminum Alloy Sheet

et al. 2020

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“…Other techniques can be applied as well [1]. The speckle-free DIC method was also developed and applied [14]. A special preparation of the specimen surface with the pattern containing the characteristic speckles enables the observation of the changes in the position of these dots during the deformation period [12,15,16,17].…”

Section: Fundamentals Of Dicmentioning

confidence: 99%

Application of Digital Image Correlation (DIC) Method for Road Material Testing

2019

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The theoretical part of the paper presents the framework of the digital image correlation (DIC) method as well as its advantages and limitations. The DIC technique that can be used in static and fatigue tests is a non-contact, non-interferometric optical method for measuring the surface deformation of structural elements, and material samples. In the experimental part of the paper, the implementation of the DIC method for the selected laboratory tests of building materials is described. The results of the tests on the samples of the materials used in road construction, i.e., asphalt mixtures (HMA), stone, soil stabilized with a hydraulic binder, and geosynthetics are discussed. The conducted research pointed out the possibilities of using the DIC method to evaluate the deformation of road materials in laboratory tests, taking into account their specificity. The variety of samples of tested material allowed to indicate the areas in which the DIC method and the algorithms used to evaluate the results give a significant advantage compared to tensometric measurement methods.

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“…There has been significant work in the field involving projected patterns for 3D shape measurement [7], [8]; however, exploration into using white-light projection for supplying the random speckle pattern needed for DIC is relatively new and sparse. A DIC-based method called virtual speckle pattern DIC (VSP-DIC) was introduced by Niu et al [9] in 2017, where a 3D DIC system was used to measure the static warpage of packaged electronic components by correlating a projected speckle pattern within the stereo images and between frames. 3D DIC uses two synchronized and calibrated cameras to obtain displacements in both in-plane and out-of-plane directions through triangulation; however the calibration process is tedious and sensitive, and the need for two cameras adds costs and complexity.…”

Section: Introductionmentioning

confidence: 99%

Off-axis digital image correlation using projected speckles for damage imaging with minimal surface preparation

Abbott,

Yuan

2024

Nondestructive Characterization and Monitoring of Advanced Materials, Aerospace, Civil Infrastructure, and Transportation XVIII

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This paper presents a feasibility study for the visualization of hidden damage in aluminum plates using the integration of a digital camera, projected speckles, and a baseline-free wavelet transform mode shape curvature (WT-MSC) damage index. To capture out-of-plane motion in the plates, off-axis 2D digital image correlation (DIC) is applied. With the camera at an angle with respect to the plate surface normal, a component of the higher-amplitude transverse displacements can be captured. Compared to 3D DIC, the system is less complex, there is no need for camera calibration, and the 2D DIC algorithm is more computationally efficient. A major limitation of DIC for practical applications is the need to apply a speckle pattern to the surface to introduce trackable features in the image for tracking displacement. Projected speckles replace the need for surface-applied speckle patterns. Thus, minimal surface preparation is required. Two geometrically identical 305-mm ´ 305-mm aluminum plates with thinning defects of different sizes and depths were used to demonstrate the system. Through the excitation of a 20 Hz to 1 kHz chirp signal in a single-edge-clamped plate, the first 12 transverse vibration modes of the plate were sensed. These mode shapes were recreated with the off-axis 2D DIC system, and a wavelet transform mode shape curvature (WT-MSC) damage index was applied for damage imaging. This index is sensitive to irregularities in the higher mode shapes caused by differences in geometry in the damaged regions. The system provided clear damage images with a clear correlation with actual damage geometry regardless of plate orientation. This system serves as a preliminary study for the eventual application of imaging barely visible impact damage in composite plates using projected speckles.

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A Novel Speckle-Free Digital Image Correlation Method for In Situ Warpage Characterization

Cited by 17 publications

References 21 publications

Modeling and Experimental Analysis of Shear-Slitting of AA6111-T4 Aluminum Alloy Sheet

Modeling and Experimental Analysis of Shear-Slitting of AA6111-T4 Aluminum Alloy Sheet

Application of Digital Image Correlation (DIC) Method for Road Material Testing

Off-axis digital image correlation using projected speckles for damage imaging with minimal surface preparation

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