scholarly journals Full-Field Strain Measurement and Numerical Analysis of a Microalloyed Steel Subjected to Deformation with Strain Path Change

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5543
Author(s):  
Paulina Lisiecka-Graca ◽  
Janusz Majta ◽  
Krzysztof Muszka
Keyword(s):  
Strain Measurement ◽  
Strain Path ◽  
Surface Strain ◽  
Image Correlation ◽  
Bending Test ◽  
Model Parameters ◽  
Full Field ◽  
Advantages And Disadvantages ◽  
Chaboche Model ◽  
Strain Path Change

This study presents an effective technique for taking advantage of the full-field measurement method of Digital Image Correlation (DIC) for the assessment of the strain distribution during the metal forming process when the strain path change was performed. The applied methodology is based on the combination of a numerical simulation for the stress calculation and full-field surface strain measurement in a forward/reverse three-point bending test. In the numerical part, the Chaboche model and dislocation density-based model were selected and verified in terms of the prediction of a softening/hardening effect occurring during strain reversal. The Chaboche model parameters identification procedure, on the basis of a cyclic torsion test, combined with inverse analysis, was also described. The results of the study showed the advantages and disadvantages of both of the analyzed work hardening models. The obtained results were analyzed in the light of the deformation inhomogeneity and reorganization of the dislocation structure during the cyclic deformation test.

scholarly journals In-situ study of strain and texture evolution during continuous strain path change

2021 ◽  
Author(s):  
Sisir Dhara ◽  
Scott Taylor ◽  
Łukasz Figiel ◽  
Darren Hughes ◽  
Barbara Shollock ◽  
...  
Keyword(s):  
Strain Path ◽  
Texture Evolution ◽  
Test Method ◽  
Image Correlation ◽  
Field Strain ◽  
Correlation Technique ◽  
Full Field ◽  
Multi Stage ◽  
Experimental Apparatus ◽  
Strain Path Change

Automotive stamping is a multi-stage process where a sheet material is drawn in first stage and then redrawn, flanged and pierced in subsequent stages. In the first draw stage, continuous strain path change is induced in the material while a discontinuous strain path change occurs when the material is processed in the subsequent stages of a multi-stage stamping operation. The strain path transition can potentially alter the forming limit of the material. Previous research has investigated the effect of the discontinuous mode of strain path change by loading the sample in one strain path, unloading it, then reloading it in a second path. Thus, discontinuous strain path change was obtained. In this work, the effect of continuous strain path change was investigated with a novel experimental design that allowed cruciform samples to change strain path continuously without unloading. The work was carried out in two stages. In the first stage, the design of the cruciform sample was verified with finite element modelling to ensure the occurrence of continuous strain path change and this was validated experimentally using DX54 material by capturing full-field strain measurements data using digital image correlation technique. The size of the experimental apparatus permitted it to be placed inside a scanning electron microscope chamber. In the second stage, the validated test method was used to evaluate microstructural changes during the deformation including full-field strain and texture evolution. The micro-strain evolution showed rotation of strain bands while the texture evolution conveyed grain rotation during continuous strain path change.

scholarly journals A Review of Surface Deformation and Strain Measurement Using Two-Dimensional Digital Image Correlation

2016 ◽  
Vol 23 (3) ◽  
pp. 461-480 ◽  
Author(s):  
Sze-Wei Khoo ◽  
Saravanan Karuppanan ◽  
Ching-Seong Tan
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Strain Measurement ◽  
Surface Deformation ◽  
Optical Measurement ◽  
Image Correlation ◽  
Two Dimensional ◽  
Full Field ◽  
Computation Efficiency ◽  
Dimensional Measurements

Abstract Among the full-field optical measurement methods, the Digital Image Correlation (DIC) is one of the techniques which has been given particular attention. Technically, the DIC technique refers to a non-contact strain measurement method that mathematically compares the grey intensity changes of the images captured at two different states: before and after deformation. The measurement can be performed by numerically calculating the displacement of speckles which are deposited on the top of object’s surface. In this paper, the Two-Dimensional Digital Image Correlation (2D-DIC) is presented and its fundamental concepts are discussed. Next, the development of the 2D-DIC algorithms in the past 33 years is reviewed systematically. The improvement of 2DDIC algorithms is presented with respect to two distinct aspects: their computation efficiency and measurement accuracy. Furthermore, analysis of the 2D-DIC accuracy is included, followed by a review of the DIC applications for two-dimensional measurements.

Noise Reduction Technique for Digital Image Based Full Field Strain Measurement

2012 ◽  
Author(s):  
Yoshitaka Wada ◽  
Tomonari Furukawa
Keyword(s):  
Noise Reduction ◽  
Digital Image ◽  
Strain Measurement ◽  
Low Noise ◽  
Reduction Technique ◽  
Distortion Correction ◽  
Image Correlation ◽  
Full Field ◽  
Deformation Problem ◽  
Noise Reduction Technique

In recent years several techniques of full-field measurement have been studied by digital image correlation method, moiré interference method and holographic interferometry method and so on. Image based method can be easily applied to large deformation problem and moving specimen at slow speed. Because digital camera capabilities, which are high resolution, low noise and faster data transfer speed, have been improved, very small strain measurement can be achieved by those improvements. The improvement will widen those applications, for example, moving object at high speed and less 0.1% strain measurement which is almost the same accuracy with a precise strain gauge. In order to apply the advanced application, noise reduction for a digital image and lens distortion correction for an optical system should be developed. In this paper we propose noise reduction technique using statistical camera model to be applied to any kinds of digital cameras.

Non-Contact Technique for Characterizing Full-Field Surface Deformation of Shape Memory Polymers

2010 ◽  
Author(s):  
A. J. W. McClung ◽  
G. P. Tandon ◽  
K. E. Goecke ◽  
J. W. Baur
Keyword(s):  
Elastic Modulus ◽  
Shape Memory ◽  
Strain Measurement ◽  
Shape Memory Polymers ◽  
Material Behavior ◽  
Image Correlation ◽  
Optical Measurements ◽  
Transverse Strain ◽  
Strain Gages ◽  
Full Field

Thermally-actuated shape memory polymers (SMPs) typically display two phases separated by the glass transition temperature (Tg). At temperatures well below the Tg, the polymer exhibits a relatively high elastic modulus. Well above the Tg the elastic modulus drops by several orders of magnitude. In this high temperature region, SMP materials can achieve strain levels well above 100 %. The complex behavior of SMPs (stiffnesses dropping to the order of 1 GPa and extremely high strain levels) precludes the use of traditional strain gages and low-contact force extensometers. The present study presents a detailed expansion of state-of-the-art thermomechanical testing techniques used to characterize the material behavior of SMPs. An MTS environmental chamber with an observation window allows for non-contact optical measurements during testing. A laser extensometer is used for measurement and active control of axial strain. The upper limit on the strain rate capability of the laser extensometer is established. In addition, the photographic strain measurement method known as digital image correlation (DIC) is incorporated, allowing for full field measurement of axial and transverse strains of SMPs over a range of temperatures and strain rates. The strain measurements of the DIC and laser extensometer are compared to each other as well as to clip-on extensometers and strain gages. The comparisons provide insight into the limitations of the traditional strain measurement systems. A series of tensile tests are performed on a commercial SMP from 25 °C up to temperatures of 130 °C and strain levels above 100 %. The laser extensometer provides a robust method for controlling the strain in the gage section of the samples. In addition, results show that the full field measurements of both the axial and the transverse strain are essential for characterizing the constitutive response of SMPs at room and elevated temperatures.

Application of Image Based Methods for Monitoring and Measurements of Structures in Power Stations

2012 ◽  
Vol 518 ◽  
pp. 24-36 ◽  
Author(s):  
Małgorzata Kujawińska ◽  
Marcin Malesa ◽  
Krzysztof Malowany ◽  
Paweł M. Błaszczyk
Keyword(s):  
Power Plants ◽  
Optical Measurement ◽  
Image Correlation ◽  
Optical Methods ◽  
Future Application ◽  
Monitoring And Control ◽  
Full Field ◽  
Advantages And Disadvantages ◽  
Power Stations ◽  
Steam Pipes

The implementation of selected full-field optical methods for monitoring and measurements of displacements, strains and shape of structures in power plants are reported. Digital Image Correlation, Fringe Projection and integrated thermovision-DIC method have been utilized for monitoring and control of repair processes of selected elements during general overhauls in power plants, including control of welds annealing process in boiler drum and steam pipes and measurements of geometry changes of steam pipes in “hot” and “cold” states. The experience gathered during the measurement sessions in power plants has been used for enhancement and adaptation of typical architecture of measurement systems to demanding and difficult industrial environment conditions. The measurements had been carried out in different power plants located in Poland. The possible future application of full-field optical measurement methods as the alternative to standard techniques (ultrasound, X-ray, strain gauges) and their advantages and disadvantages are discussed.

scholarly journals A Probabilistic Approach with Built-in Uncertainty Quantification for the Calibration of a Superelastic Constitutive Model from Full-field Strain Data

2019 ◽  
Author(s):  
Harshad M Paranjape ◽  
Kenneth I. Aycock ◽  
Craig Bonsignore ◽  
Jason D. Weaver ◽  
Brent A. Craven ◽  
...  
Keyword(s):  
Machine Learning ◽  
Bayesian Inference ◽  
Constitutive Model ◽  
Probabilistic Approach ◽  
Surface Strain ◽  
Image Correlation ◽  
Full Field ◽  
Material Parameters ◽  
Superelastic Deformation ◽  
Calibration Approach

We implement an approach using Bayesian inference and machine learning to calibrate the material parameters of a constitutive model for the superelastic deformation of NiTi shape memory alloy. We use a diamond-shaped specimen geometry that is suited to calibrate both tensile and compressive material parameters from a single test. We adopt the Bayesian inference calibration scheme to take full-field surface strain measurements obtained using digital image correlation together with global load data as an input for calibration. The calibration is performed by comparing these two experimental quantities of interest with the corresponding results from a simulation library built with the superelastic forward finite element model. We present a machine learning based approach to enrich the simulation library using a surrogate model. This improves the calibration accuracy to the extent permitted by the accuracy of the underlying material model and also improves the computational efficiency. We demonstrate, verify, and partially validate the calibration results through various examples. We also demonstrate how the uncertainty in the calibrated superelastic material parameters can propagate to a subsequent simulation of fatigue loading. This approach is versatile and can be used to calibrate other models of superelastic deformation from data obtained using various modalities. This probabilistic calibration approach can become an integral part of a framework to assess and communicate the credibility of simulations performed in the design of superelastic NiTi articles such as medical devices. The knowledge obtained from this calibration approach is most effective when the limitations of the underlying model and the suitability of the training data used to calibrate the model are understood and communicated.

scholarly journals Bio-Inspired 3D Infill Patterns for Additive Manufacturing and Structural Applications

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 499 ◽  
Author(s):  
Jan Podroužek ◽  
Marco Marcon ◽  
Krešimir Ninčević ◽  
Roman Wan-Wendner
Keyword(s):  
Additive Manufacturing ◽  
Mechanical Performance ◽  
Peak Load ◽  
Fem Analysis ◽  
Material Model ◽  
Surface Strain ◽  
Image Correlation ◽  
Nonlinear Material ◽  
Full Field ◽  
Structural Applications

The aim of this paper is to introduce and characterize, both experimentally and numerically, three classes of non-traditional 3D infill patterns at three scales as an alternative to classical 2D infill patterns in the context of additive manufacturing and structural applications. The investigated 3D infill patterns are biologically inspired and include Gyroid, Schwarz D and Schwarz P. Their selection was based on their beneficial mechanical properties, such as double curvature. They are not only known from nature but also emerge from numerical topology optimization. A classical 2D hexagonal pattern has been used as a reference. The mechanical performance of 14 cylindrical specimens in compression is quantitatively related to stiffness, peak load and weight. Digital image correlation provides accurate full-field deformation measurements and insights into periodic features of the surface strain field. The associated variability, which is inherent to the production and testing process, has been evaluated for 3 identical Gyroid specimens. The nonlinear material model for the preliminary FEM analysis is based on tensile test specimens with 3 different slicing strategies. The 3D infill patterns are generally useful when the extrusion orientation cannot be aligned with the build orientation and the principal stress field, i.e., in case of generative design, such as the presented branching structure, or any complex shape and boundary condition.

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