scholarly journals Experimental Investigation of Dynamic Response and Deformation of Aluminium Honeycomb Sandwich Panels Subjected to Underwater Impulsive Loads

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Da-Lin Xiang ◽  
Ji-Li Rong ◽  
Xuan He
Keyword(s):  
High Speed ◽  
Sandwich Panel ◽  
Blast Resistance ◽  
Three Dimensional ◽  
Sandwich Panels ◽  
Core Structure ◽  
Image Correlation ◽  
High Speed Photography ◽  
Full Field ◽  
Deformation Modes

The response of aluminium sandwich panels with three thicknesses’ core subjected to different underwater loading levels has been studied in the fluid-structure interaction (FSI) experiments. The transient response of the panels is measured using a three-dimensional (3D) Digital Image Correlation (DIC) system, along with high-speed photography. The full-field shape and displacement profiles of dry face sheets were recorded in real time compared with those of monolithic plate. The out-of-plane deflection and in-plane strain were quantified and analyzed. Three typical deformation modes of sandwich panel were identified. The results show that the core structure is crushed resulting in an initial large circular shape of deformation in the center area of panels. From this moment on, the panel is starting to act as a free vibration beam with initial velocities. The deformation modes consisted of homogeneous large deformation for both face sheets, obvious deformation border on wet face sheet, core node imprinting, remarkable wrinkled skin of deformation border, and a partial delamination and partial tear failure of the dry face. The blast-resistance of sandwich panel can be highly efficiently improved by increasing the thickness of core structure.

Hydrostatic Implosion of GFRP Composite Tubes Studied by Digital Image Correlation

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Michael Pinto ◽  
Sachin Gupta ◽  
Arun Shukla
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
High Speed ◽  
Dynamic Pressure ◽  
Three Dimensional ◽  
Image Correlation ◽  
High Speed Photography ◽  
Damage Potential ◽  
Full Field ◽  
Pressure Transducers

The mechanisms and pressure fields associated with the hydrostatic implosion of glass fiber reinforced polymer (GFRP) tubes with varying reinforcement are investigated using high-speed photography. Experiments are conducted in a large pressure vessel, designed to provide constant hydrostatic pressure throughout collapse. Three-dimensional (3D) digital image correlation (DIC) is used to capture full-field displacements, and dynamic pressure transducers measure the pressure pulse generated by the collapse. Results show that braided GFRP tubes release pressure waves with significantly greater impulse upon collapse as compared to filament-wound tubes, increasing their damage potential.

scholarly journals Failure behavior of woven fiberglass composites under combined compressive and environmental loading

2019 ◽  
Vol 54 (4) ◽  
pp. 519-533
Author(s):  
Ariana Paradiso ◽  
Isabella Mendoza ◽  
Amanda Bellafato ◽  
Leslie Lamberson
Keyword(s):  
High Speed ◽  
Shear Failure ◽  
Resin Composite ◽  
Compressive Loading ◽  
Image Correlation ◽  
Failure Behavior ◽  
High Speed Photography ◽  
Environmental Loading ◽  
Full Field ◽  
Environmental Conditioning

The purpose of this study is to quantitatively characterize the compressive and damage behavior of a woven fiberglass composite under combined environmental loading. Cuboidal samples of a commercially available woven fiberglass epoxy resin composite, garolite G10, are examined under uniaxial compressive loading perpendicular to the plies at quasi-static (10−3 s−1) and dynamic (103 s−1) strain rates using a standard load frame and Kolsky (split-Hopkinson) bar. In order to simulate environmental conditions, a subset of samples were soaked in either distilled or ASTM standard seawater prior to loading. Two time periods of environmental conditioning were investigated: short term at two weeks and long term at four months. Results demonstrate that, on average, the dynamic compressive strength of the fiberglass increased 35% from the quasi-static. Moreover, environmentally treated samples generally experienced a decrease strain to failure, and composites exposed to water for only short periods exhibited signs of the absorbed water sustaining additional load under quasi-static rates. Ultra-high-speed photography combined with digital image correlation, a full-field surface kinematic measurement technique, is used to map 2D strains on the sample during loading. In all cases, a clear shear failure mechanism from local instabilities appears, and a Mohr–Coulomb failure criterion is used to extract a mesoscale cohesive shear stress and coefficient of internal friction.

scholarly journals Full Field Strain Measurement in Split Hopkinson Bar Experiments

2008 ◽  
Author(s):  
Amos Gilat ◽  
Tim Schmidt ◽  
John Tyson ◽  
Andrew Walker
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Hopkinson Bar ◽  
Image Correlation ◽  
Full Field ◽  
Split Hopkinson Bar ◽  
Strain And Strain Rate ◽  
Full Field Measurement ◽  
Split Hopkinson ◽  
Correlation System

A method for full field measurement of strain (and strain rate) in split Hopkinson bar experiments (compression, tensile, and shear) is introduced. The measurements are done by using the Aramis three-dimensional image correlation system. The system uses two digital high-speed cameras that provide a synchronized stereo view of the specimen. Depending on the number of pixels used, the system is capable or recording frames at a rate of up to about 110,000 per second. Before conducting a test, a random dot pattern is applied to the surface of the specimen. The image correlation algorithm uses the dot pattern to define a field of overlapping virtual gage boxes. The 3-D coordinates of the center of each gage box is determined at each frame, interpolated to better than 1/100 of a pixel. The coordinates are then used for calculating the deformations, strains, and strain rates throughout the surface of the specimen.

Validation of Impact Simulations of a Car Bonnet by Full-Field Optical Measurements

2011 ◽  
Vol 70 ◽  
pp. 57-62
Author(s):  
George Lampeas ◽  
Vasilis Pasialis ◽  
Thorsten Siebert ◽  
Mara Feligiotti ◽  
Andrea Pipino
Keyword(s):  
Displacement Field ◽  
High Speed ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Quantitative Information ◽  
Image Correlation ◽  
Optical Measurements ◽  
Optical Techniques ◽  
Full Field ◽  
Dynamic Events

Innovative designs of transport vehicles need to be validated in order to demonstrate reliability and provide confidence. The most common approaches to such designs involve simulations based on Finite Element (FE) analysis, used to study the mechanical response of the structural elements during critical events. These simulations need reliable validation techniques, especially if anisotropic materials, such as fibre reinforced polymers, or complex designs, such as automotive components are considered. It is normal practice to assess the accuracy of numerical results by comparing the predicted values to corresponding experimental data. In this frame, the use of whole field optical techniques has been proven successful in the validation of deformation, strain, or vibration modes [1]. The strength of full-field optical techniques is that the whole displacement field can be visualized and analyzed. By using High Speed cameras, the Digital Image Correlation (DIC) method can be applied to highly non-linear dynamic events and deliver quantitative information about the three-dimensional displacement field [2].

scholarly journals RGB Colour Encoding Improvement for Three-Dimensional Shapes and Displacement Measurement Using the Integration of Fringe Projection and Digital Image Correlation

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 3130 ◽  
Author(s):  
Luis Felipe-Sesé ◽  
Ángel Molina-Viedma ◽  
Elías López-Alba ◽  
Francisco Díaz
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
High Speed ◽  
Low Cost ◽  
Three Dimensional ◽  
Displacement Measurement ◽  
Image Correlation ◽  
Fringe Projection ◽  
Colour Pattern ◽  
Full Field

Three-dimensional digital image correlation (3D-DIC) has become the most popular full-field optical technique for measuring 3D shapes and displacements in experimental mechanics. The integration of fringe projection (FP) and two-dimensional digital image correlation (FP + DIC) has been recently established as an intelligent low-cost alternative to 3D-DIC, overcoming the drawbacks of a stereoscopic system. Its experimentation is based on the colour encoding of the characterized fringe and speckle patterns required for FP and DIC implementation, respectively. In the present work, innovations in experimentation using FP + DIC for more accurate results are presented. Specifically, they are based on the improvement of the colour pattern encoding. To achieve this, in this work, a multisensor camera and/or laser structural illumination were employed. Both alternatives are analysed and evaluated. Results show that improvements both in three-dimensional and in-plane displacement are obtained with the proposed alternatives. Nonetheless, multisensor high-speed cameras are uncommon, and laser structural illumination is established as an important improvement when low uncertainty is required for 2D-displacement measurement. Hence, the uncertainty has been demonstrated to be reduced by up to 50% compared with results obtained in previous experimental approaches of FP + DIC.

scholarly journals Full-Field Operational Modal Analysis of an Aircraft Composite Panel from the Dynamic Response in Multi-Impact Test

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1602
Author(s):  
Ángel Molina-Viedma ◽  
Elías López-Alba ◽  
Luis Felipe-Sesé ◽  
Francisco Díaz
Keyword(s):  
Modal Analysis ◽  
Energy Absorption ◽  
High Speed ◽  
Operational Modal Analysis ◽  
Modal Identification ◽  
Image Correlation ◽  
Composite Panel ◽  
Impact Excitation ◽  
Full Field ◽  
The Impact

Experimental characterization and validation of skin components in aircraft entails multiple evaluations (structural, aerodynamic, acoustic, etc.) and expensive campaigns. They require different rigs and equipment to perform the necessary tests. Two of the main dynamic characterizations include the energy absorption under impact forcing and the identification of modal parameters through the vibration response under any broadband excitation, which also includes impacts. This work exploits the response of a stiffened aircraft composite panel submitted to a multi-impact excitation, which is intended for impact and energy absorption analysis. Based on the high stiffness of composite materials, the study worked under the assumption that the global response to the multi-impact excitation is linear with small strains, neglecting the nonlinear behavior produced by local damage generation. Then, modal identification could be performed. The vibration after the impact was measured by high-speed 3D digital image correlation and employed for full-field operational modal analysis. Multiple modes were characterized in a wide spectrum, exploiting the advantages of the full-field noninvasive techniques. These results described a consistent modal behavior of the panel along with good indicators of mode separation given by the auto modal assurance criterion (Auto-MAC). Hence, it illustrates the possibility of performing these dynamic characterizations in a single test, offering additional information while reducing time and investment during the validation of these structures.

Age-Related Differences in Throwing Techniques Used by the Catcher in Baseball

1994 ◽  
Vol 6 (3) ◽  
pp. 225-235 ◽  
Author(s):  
Shinji Sakurai ◽  
Bruce Elliott ◽  
J. Robert Grove
Keyword(s):  
High Speed ◽  
High Performance ◽  
Age Groups ◽  
Three Dimensional ◽  
Transformation Method ◽  
High Speed Photography ◽  
Two Phase ◽  
Ball Speed ◽  
Age Related ◽  
Release Speed

Three-dimensional (3-D) high speed photography was used to record the overarm throwing actions of five open-age, four 18-year-old, six 16-year- old, and six 14-year-old high-performance baseball catchers. The direct linear transformation method was used for 3-D space reconstruction from 2-D images of the catchers throwing from home plate to second base recorded using two phase-locked cameras operating at a nominal rate of 200 Hz. Selected physical capacity measures were also recorded and correlated with ball release speed. In general, anthropometric and strength measures significantly increased through the 14-year-old to open-age classifications, while a range of correlation coefficients from .50 to .84 was recorded between these physical capacities and ball speed at release. While many aspects of the kinematic data at release were similar, the key factors of release angle and release speed varied for the different age groups.

scholarly journals Compression, Tension and Shear Testing of Fibrous Composite with the Split Hopkinson Bar Technique

2018 ◽  
Vol 183 ◽  
pp. 02006 ◽  
Author(s):  
Amos Gilat ◽  
Jeremy D. Seidt
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
Fibrous Composite ◽  
Hopkinson Bar ◽  
Image Correlation ◽  
Compression Tests ◽  
Strain Rate Effects ◽  
Full Field ◽  
Split Hopkinson Bar ◽  
Split Hopkinson

The Split Hopkinson Bar (SHB) technique is used for high strain rate testing of T800/F3900 composite in compression, tension and shear. Digital Image Correlation (DIC) is used for measuring the full-field deformation on the surface of the specimen by using Shimadzu HPV-X2 high-speed video camera. Compression tests have been done on specimens machined from a unidirectional laminate in the 0°and 90° directions. Tensile tests were done in the 90° direction. Shear tests were done by using a notched specimen in a compression SHB apparatus. To study the effect of strain rate, quasi-static testing was also done using DIC and specimens with the same geometry as in the SHB tests. The results show that the DIC technique provides accurate strain measurements even at strains that are smaller than 1%. No strain rate effect is observed in compression in the 0° direction and significant strain rate effects are observed in compression and tension in the 90° direction, and in shear.

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