Experimental Study on Flow-Induced Full-Field Vibration of a Flexible Splitter Plate Behind a Cylinder Using Stereo-Digital Image Correlation

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Ruili Xie ◽  
Liping Yu ◽  
Weidong Zhu ◽  
Bing Pan
Keyword(s):  
Wind Tunnel ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Plane Deformation ◽  
Splitter Plate ◽  
Image Correlation ◽  
Full Field ◽  
Out Of Plane ◽  
Stereo Digital Image Correlation ◽  
Deformation Measurements

Abstract The flow-induced vibration of a flexible splitter plate behind a circular cylinder is investigated experimentally in this study. Unlike previous studies that mainly devoted to flow dynamics, the full-field three-dimensional (3D) dynamic deformation of a splitter plate behind a cylinder in the wind tunnel is measured with an easy-to-implement, compact but practical single-camera high-speed (SCHS) stereo-digital image correlation (DIC) system. The system parameters of the wind tunnel, the configuration of the SCHS-DIC system, and the measurement principles are introduced first. Then, the effectiveness, accuracy, and stability of the SCHS stereo-DIC system are verified by the deformation measurements of the high-stiffness fixed cylinder. Finally, the full-field dynamic 3D deformation measurements of different splitter plates are carried out under different wind speeds. Results of the polyvinyl chloride (PVC) splitter plate show that the out-of-plane deformation is much larger than in-plane deformation. The maximum deformation occurs at the tip region of the plate, the position of which can move non-periodically along the free-end edge. The full-field deformation of the plate presents the characteristics of complex vortex distribution with high and low fluctuations, and exhibits an asymmetric and non-periodic oscillation in the out-of-plane direction. The comparison results reveal how the wind load and material type of the plate affect the oscillation characteristics.

scholarly journals A Simple and Practical Single-Camera Stereo-Digital Image Correlation Using a Color Camera and X-Cube Prism

Sensors ◽  
2019 ◽  
Vol 19 (21) ◽  
pp. 4726 ◽  
Author(s):  
Bo Dong ◽  
Fancang Zeng ◽  
Bing Pan
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
High Speed ◽  
Image Correlation ◽  
Single Camera ◽  
Full Field ◽  
3D Shape ◽  
Stereo Digital Image Correlation ◽  
Deformation Measurements ◽  
Dic Technique

A simple and practical full-frame single-camera stereo-digital image correlation (stereo-DIC) technique for three-dimensional (3D) shape, displacement, and deformation measurements is proposed. The technique uses a compact X-cube prism-based color separation device and a color camera to capture images of blue and red colors from different optical paths, and then extracts the surface 3D shape and deformation information of a test sample by processing the captured two sub-channel color images using regular stereo-DIC algorithm. Compared with the existing full-frame single-camera stereo-DICs, the proposed one eliminates the need for a beam splitter and two bandpass filters to capture images, and offers more simple, compact, and easy-to-use optical arrangement. This novel single-camera stereo-DIC technique was validated by a series of baseline experiments involving 3D surface reconstructions, translation tests, and full-field deformation measurements, which provide a new flexible and practical avenue for measuring surface 3D shape and deformation, particularly in microscopic and high-speed applications.

Error Assessment of Blade Deformation Measurements on a Multi-Megawatt Wind Turbine Based on Digital Image Correlation

2015 ◽  
Author(s):  
Jan Winstroth ◽  
Joerg R. Seume
Keyword(s):  
Digital Image Correlation ◽  
Wind Turbine ◽  
Error Estimation ◽  
Digital Image ◽  
Rotor Blades ◽  
Image Correlation ◽  
Optical Measurements ◽  
Full Field ◽  
Out Of Plane ◽  
Plane Bending

Optical full-field measurement methods such as Digital Image Correlation (DIC) provide a new opportunity for measuring deformation and vibration in wind turbine rotor blades during operation, in high spatial and temporal resolution. Recent field tests on a multi-megawatt wind turbine have demonstrated the vast potential for full scale testing, however little is known about the overall accuracy of DIC measurements on wind turbines. The present work proposes using a virtual 3D wind turbine model for estimating the error associated with the optical measurements. The entire setup is simulated a priori and accurate error estimation becomes possible. The error estimation for a 3.2 MW wind turbine suggests that relative out-of-plane bending of the rotor blades can be measured with an accuracy of ±9.1 mm, relative in-plane bending of the rotor blades can be measured with an accuracy of ±10.2 mm, and relative blade torsion can be measured with an accuracy of ±0.07 deg. This corresponds to a relative error of 0.46% for out-of-plane bending, 1.11% for in-plane bending and 5.46% for blade torsion.

scholarly journals Full-Field Microscale Strain Measurements of a Nitinol Medical Device Using Digital Image Correlation

2020 ◽  
Author(s):  
Kenneth I. Aycock ◽  
Jason D. Weaver ◽  
Harshad M Paranjape ◽  
Karthikeyan Senthilnathan ◽  
Craig Bonsignore ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Computational Models ◽  
Optical Microscope ◽  
Image Correlation ◽  
Full Field ◽  
Physiological Loading ◽  
Out Of Plane ◽  
Computational Modeling And Simulation ◽  
Cantilever Bending

Computational modeling and simulation are commonly used during the development of cardiovascular implants to predict peak strains and strain amplitudes and to estimate the associated durability and fatigue life of these devices. However, simulation validation has historically relied on comparison with surrogate quantities like force and displacement due to barriers to direct strain measurement–most notably, the small spatial scale of these devices. We demonstrate the use of microscale two-dimensional digital image correlation (2D-DIC) to directly characterize full-field surface strains on a nitinol device coupon under emulated physiological loading. Experiments are performed using a digital optical microscope and a custom, temperature-controlled load frame. Following applicable recommendations from the International DIC Society, hardware and environmental heating studies, noise floor analyses, and in- and out-of-plane rigid body translation studies are first performed to characterize the microscale DIC setup. Uniaxial tension experiments are also performed using a polymeric test specimen up to nominal stains of 5%. Sub-millimeter fields of view and sub-micron displacement accuracies (9 nm mean error) are achieved, and systematic (mean) and random (standard deviation) errors in strain are each estimated to be approximately 1,000 μϵ. The system is then demonstrated by acquiring measurements at the root of a 300 μm-wide nitinol device strut undergoing fixed-free cantilever bending motion. Lüders-like transformation bands are observed originating from the tensile side of the strut that spread toward the neutral axis at an angle of approximately 55°. Optical microscale 2D-DIC setups like that demonstrated herein will be useful in future studies for characterizing cardiovascular implant micromechanics, validating computational models, and guiding the development of next-generation material models for simulating superelastic nitinol.

Sign in / Sign up

Export Citation Format

Share Document