Measurement of Intrinsic Residual Stresses in 3D Woven Composites Using Measurement of the Displacement Fields from Hole Drilling by Electronic Speckle Pattern Interferometry and Digital Image Correlation

2018 ◽  
Author(s):  
TODD GROSS ◽  
HILARY BUNTROCK ◽  
IGOR TSUKROV ◽  
BORYS DRACH ◽  
KOSTIANTYN VASYLEVSKYI ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Residual Stresses ◽  
Digital Image ◽  
Speckle Pattern ◽  
Image Correlation ◽  
Woven Composites ◽  
Electronic Speckle Pattern Interferometry ◽  
Hole Drilling ◽  
Displacement Fields ◽  
3D Woven Composites

Development of a New Method for Residual Stress Analysis on Fiber Reinforced Plastics with Use of Digital Image Correlation

2017 ◽  
Vol 742 ◽  
pp. 660-665 ◽  
Author(s):  
Thomas Rief ◽  
Joachim Hausmann ◽  
Nicole Motsch
Keyword(s):  
Residual Stress ◽  
Digital Image Correlation ◽  
Residual Stresses ◽  
Stress Analysis ◽  
Digital Image ◽  
Image Correlation ◽  
Strain Gauges ◽  
Hole Drilling ◽  
Drilling Process ◽  
Residual Stress Analysis

In scope of the investigation of residual stresses the hole drilling method is an accepted method. The method is though not applicable for materials with high anisotropic behavior. Therefore a new algorithm is derived which allows the calculation of residual stresses in laminates made of unidirectional layers. Also the strain gauges deliver only strains on the areas where the strain gauges are applied. With the use of a high resolution imaging system and digital image correlation this area and the informational output can be widely improved. First, the derivation of the residual stress analysis algorithm is presented. For this an adequate finite element model, which is modeling the cooldown process as well as the drilling process, is set up and the surface strains are extracted. Based on this information an algorithm is derived and presented. Within the derivation a change of the layup, a possible change of the cooldown process and a variation of the drilling steps can be investigated. In consequence the input parameters of the algorithm can vary dependent on these factors. Second, the new optical testing setup with refinements to be able to measure the small deformations within micro-strains on the specimen’s surface is prepared and the concept presented. To solve the problem of casting shadows of the drill a special camera setup is being used.

The Knowledge Acquired by Using of Optical Methods by Strain Fields Investigation

2013 ◽  
Vol 486 ◽  
pp. 141-146
Author(s):  
Martin Hagara ◽  
František Šimčák ◽  
Matúš Kalina
Keyword(s):  
Experimental Investigation ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Speckle Pattern ◽  
Image Correlation ◽  
Optical Methods ◽  
Optical Systems ◽  
Electronic Speckle Pattern Interferometry ◽  
Strain Fields ◽  
Pros And Cons

These days are preferably used contactless optical methods for experimental investigation of strains and displacements, which give some information on whole investigated surface. In this contribution the optical systems working on electronic speckle pattern interferometry (ESPI) principle and digital image correlation (DIC) method are described. By using of ESPI and DIC methods the displacements and strains fields on chosen types of specimens are determined. Pros and cons of particular methods and influence of various factors on reached results accuracy are compared. There are also mentioned the possibilities of using of optical methods in application of devices on authors department.

scholarly journals Design of a Unique Device for Residual Stresses Quantification by the Drilling Method Combining the PhotoStress and Digital Image Correlation

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 314
Author(s):  
Miroslav Pástor ◽  
Martin Hagara ◽  
Ivan Virgala ◽  
Adam Kaľavský ◽  
Alžbeta Sapietová ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Experimental Testing ◽  
Digital Processing ◽  
Image Correlation ◽  
Optical Systems ◽  
Hole Drilling ◽  
Element Analysis ◽  
Thin Specimen ◽  
Comparison Of The Results

This paper presents a uniquely designed device combining the hole-drilling technique with two optical systems based on the PhotoStress and digital image correlation (DIC) method, where the digital image correlation system moves with the cutting tool. The authors aimed to verify whether the accuracy of the drilled hole according to ASTM E837-13a standard and the positioning accuracy of the device were sufficient to achieve accurate results. The experimental testing was performed on a thin specimen made from strain sensitive coating PS-1D, which allowed comparison of the results obtained by both methods. Although application of the PhotoStress method allows analysis of the strains at the edge of the cut hole, it requires a lot of experimenter’s practical skills to assess the results correctly. On the other hand, the DIC method allows digital processing of the measured data. However, the problem is not only to determine the data at the edge of the hole, the results also significantly depend on the smoothing levels used. The quantitative comparison of the results obtained was performed using finite element analysis.

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