Use of a digital image correlation method for full-field shrinkage measurement in injection molding

2021 ◽  
pp. 030932472110602
Author(s):  
Antoine Dupuis ◽  
Jean-Jacques Pesce ◽  
Jean-Baptiste Marijon ◽  
Stéphane Roux ◽  
Gilles Régnier
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Correlation Method ◽  
Image Correlation ◽  
Reference Image ◽  
Discharge Process ◽  
Full Field ◽  
Molded Parts ◽  
Geometrical Constraints ◽  
Injection Molded

An original methodology using Digital Image Correlation (DIC) has been designed to precisely measure full-field shrinkages of injection molded polymer plates and then to give the opportunity to compare quantitatively extensive numerical simulations to experiments. The principle of the methodology is based on the full-field strain determination between a reference image of the mold and that of injection-molded parts, which are 275 × 100 × 2.2 mm3 plates. To allow for DIC calculation, 50 µm-depth engravings were machined by electro-discharge process at the surface of the mold. The result of the analysis is a 2D full-field shrinkage map over the whole plate surface (i.e. flow and transverse), with a standard deviation of 0.03%. The marking density has been shown to have a roughly linear influence on the precision of shrinkage measurement. This methodology allows the quantification of the effect of several injection parameters on in-plane shrinkage fields: holding pressure, injection flow rate and direction, geometry of injection gates, or geometrical constraints. Once the best set of parameters of material constitutive laws is identified for the simulation of polymer plates, the simulation procedure is ready to be applied on more complex 3D geometries.

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 DIC (Digital Image Correlation) method in the research of RC beams strengthened with PBO-FRCM materials

2019 ◽  
Vol 97 ◽  
pp. 03008 ◽  
Author(s):  
Dorota Marcinczak ◽  
Tomasz Trapko
Keyword(s):  
Composite Materials ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Strain Gauge ◽  
Concrete Beam ◽  
Correlation Method ◽  
Reinforced Concrete Beam ◽  
Image Correlation ◽  
Strain Gauges ◽  
Reference Image

The article presents tests of a reinforced concrete beam strengthened in a shear with PBO-FRCM composite materials. Measurement of the deformation of the composite was carried out using two methods - with strain gauges and the optical DIC method (Digital Image Correlation). The DIC method consists in taking a series of photographs of the tested object before and during loading. The surface of the tested element must have randomly spaced spots that are applied to the object before measurement. During the study, the cameras monitor the shifting of spots against each other, which in comparison to the reference image before loading gives information about strains and stresses of the tested element. Measurements of deformation of composite materials using strain gauges are difficult to clearly analyse, because the strain gauge is in a specific, limited place, which does not correspond to the work of the entire composite. In addition, the strain gauge tends to break at the place of crack. The article discusses this problem by presenting the results of deformation of PBO-FRCM composite meshes measured in two mentioned ways, their comparison and discussion of results.

Metoda DIC

BUILDER ◽  
2019 ◽  
Vol 259 (2) ◽  
pp. 66-68
Author(s):  
Dorota Marcińczak
Keyword(s):  
Composite Materials ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Strain Gauge ◽  
Concrete Beam ◽  
Correlation Method ◽  
Reinforced Concrete Beam ◽  
Image Correlation ◽  
Strain Gauges ◽  
Reference Image

DIC (DIGITAL IMAGE CORRELATION) METHOD IN THE RESEARCH OF RC BEAMS STRENGTHENED WITH PBOFRCM MATERIALS. The article presents tests of a reinforced concrete beam strengthened in a shear with PBO-FRCM composite materials. Measurement of the deformation of the composite was carried out using two methods - with strain gauges and the optical DIC method (Digital Image Correlation). The DIC method consists in taking a series of photographs of the tested object before and during loading. The surface of the tested element must have randomly spaced spots that are applied to the object before measurement. During the study, the cameras monitor the shifting of spots against each other, which in comparison to the reference image before loading gives information about strains and stresses of the tested element. Measurements of deformation of composite materials using strain gauges are difficult to clearly analyze, because the strain gauge is in a specific, limited place, which does not correspond to the work of the entire composite. In addition, the strain gauge tends to break at the place of crack. The article discusses this problem by presenting the results of deformation of PBO-FRCM composite meshes measured in two mentioned ways, their comparison and discussion of results.

scholarly journals Brief communication: Full-field deformation measurement for uniaxial compression of sea ice by using the digital image correlation method

2019 ◽  
Author(s):  
Anliang Wang ◽  
Zhijun Wei ◽  
Xiaodong Chen ◽  
Shunying Ji ◽  
Yu Liu ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Sea Ice ◽  
Uniaxial Compression ◽  
Digital Image ◽  
Correlation Method ◽  
Nonlinear Behavior ◽  
Image Correlation ◽  
Mechanical Behaviors ◽  
Full Field

Abstract. We took advantage of digital image correlation to measure the full-field deformation of sea ice in a uniaxial compression experiment in situ. The characteristics of failure mode, nonlinear behavior and crack propagation are all captured by the strain field of specimens. To our knowledge, this is the first attempt to experimentally capture sequential full-field deformations in the mechanical properties of sea ice. This achievement will extend the ability to further explore the complex mechanical behaviors of sea ice.

Buckling Measurement of Cylindrical Shells by Digital Image Correlation Method

2013 ◽  
Author(s):  
Tzu-Yu Kuo ◽  
Wei-Chung Wang ◽  
Chun-I Chu ◽  
Jia-He Chen ◽  
Te-Heng Hung ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Strain Measurement ◽  
Cylindrical Shells ◽  
Compressive Load ◽  
Correlation Method ◽  
Tensile Tests ◽  
Image Correlation ◽  
Strain Gages ◽  
Full Field

In this study, deformation of cylindrical shells under axial compressive load was studied and characterized by a noncontact detection technique, called digital image correlation (DIC). As opposed to commonly used strain gages for measuring structure strains at specific points, the DIC method can render not only 2D but also 3D full-field measurements for strain as well as structure deformation. The accuracy of strain measurement obtained using the DIC method was carefully validated by following ASTM standard E8 for strain measurement using strain gages in tensile tests. The DIC technique provided convenient measurements for characterizing the buckling behaviors of defective cylindrical shell samples. This study has engineering implications for providing 3D strain and deformation analyses to ensure structure reliability and safety.

Investigation of Shrinkage in Softwood Using Digital Image Correlation Method

2011 ◽  
Vol 83 ◽  
pp. 157-161 ◽  
Author(s):  
Ming Kai Peng ◽  
Ying Hei Chui ◽  
Yi Chiech Ho ◽  
Wei Chung Wang ◽  
Yao Tang Zhou
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Growth Ring ◽  
Correlation Method ◽  
Image Correlation ◽  
Eastern Canada ◽  
Full Field ◽  
Different Types ◽  
Differential Shrinkage ◽  
Tree Stem

Distortion in lumber, such as twist, cup, spring and bow, can cause serious problems for its use in service. Lumber distortion is largely a result of differential shrinkage in wood in different directions and the presence of different types of wood (i.e. juvenile and mature wood) in a single piece. Shrinkage varies within tree because of different types of wood. In this paper, the digital image correlation (DIC) method was used to investigate shrinkage variation within tree. The DIC method is an image-based, non-contact and full-field displacement and strain measurement method. Two softwood species grown in Eastern Canada, jack pine and white spruce, were used in this study. In this paper, average full-field shrinkage over each growth ring was measured, and the growth ring position in relation to pith of the tree was recorded. The shrinkage variations in the radial, tangential and longitudinal directions in a tree stem are presented. The work described in this paper is part of a larger study to develop a modeling technique to predict distortion of lumber based on its position in a tree stem.

Speckle Pattern Characterisation for High Resolution Digital Image Correlation

2011 ◽  
Vol 70 ◽  
pp. 261-266 ◽  
Author(s):  
G. Crammond ◽  
S.W. Boyd ◽  
Janice M. Dulieu-Barton
Keyword(s):  
High Resolution ◽  
Digital Image Correlation ◽  
Spatial Resolution ◽  
Digital Image ◽  
Speckle Pattern ◽  
Correlation Method ◽  
Image Correlation ◽  
Optical Technique ◽  
Full Field ◽  
Grey Scale

Digital image correlation (DIC) is an optical technique for full field deformation measurement. The spatial resolution and precision of the measurements are limited by the number of pixels within the image. The use of magnifying optics provides greater spatial resolution images, enabling smaller displacements to be observed with greater accuracy. Increasing the magnification of an image significantly changes the appearance of the non-periodic, stochastic speckle pattern which provides the grey scale contrast necessary for the image correlation method. In the paper a methodology is developed to evaluate the properties of different speckle pattern types under a range of resolutions up to 705 pixel / mm. Numerical deformation of the patterns is also undertaken to evaluate how the changes in the pattern properties affect the accuracy of the DIC measurements.

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