Tension and compression moduli characterization of a bimodular ceramic-fiber reinforced SiO2 aerogel composite

2020 ◽  
Vol 62 (10) ◽  
pp. 1003-1009
Author(s):  
Yantao Sun ◽  
Jia Huang ◽  
Duoqi Shi ◽  
Shengliang Zhang ◽  
Zhizhong Fu ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Image Correlation ◽  
Bending Test ◽  
Ceramic Fiber ◽  
Fiber Reinforced ◽  
Compression Tests ◽  
Tension Tests ◽  
Aerogel Composite ◽  
Tension And Compression

Abstract Comprehensive characterization mechanical properties of aerogels and their composites are important for engineering design. In particular, some aerogel composites were reported to have varied tension and compression moduli. But conducting tension tests is difficult for the reason that low strength and brittleness will lead to unexpected failure in the non-test area. A method is presented for measuring both the tension and compression moduli of a ceramic-fiber reinforced SiO2 aerogel composite by bending via digital image correlation. First, the relationship between bending behavior and the tension/compression moduli was introduced for bimodular materials. Then a bending test was conducted to predict tension and the compression moduli of the ceramicfiber- reinforced SiO2 aerogel composite via digital image correlation. In addition, uniaxial tension and compression tests of the aerogel composites were carried out, respectively for measuring tension and compression moduli. The tension and compression moduli measured were numerically similar to results obtained from uniaxial tests with a difference of less than 14 %.

Microscopic Measurement of Strain Fields with Digital Image Correlation and Comparison to Finite Element Modelling

2019 ◽  
Vol 809 ◽  
pp. 575-580
Author(s):  
Marco Korkisch ◽  
Markus G.R. Sause
Keyword(s):  
Finite Element ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Mechanical Load ◽  
Speckle Pattern ◽  
Image Correlation ◽  
Bending Test ◽  
Fiber Reinforced ◽  
Full Field ◽  
Fiber Reinforced Materials

Digital Image Correlation (DIC) has become more and more important in the field of material characterization and research, especially for strongly anisotropic fiber reinforced materials. Its big advantage over the conventional methods like strain gauges or point based video-extensometers is the full field strain and displacement measurement and the ability to analyze three-dimensional displacements. Although theoretically, the concept of the DIC as a pure image-based method allows it to work on every imaginable scale, its main field of application is in the range, where the region of interest (ROI) has a size between 10 −2 m to 10 −1 m. In this case, imaging is accomplished with the use of high-resolution black and white digital cameras. This work is focused on a smaller scale with ROI sizes between 10 −4 m to 10 −3 m, where a digital microscope is used to create the images. The innovative idea behind this work is using the natural surface structure of a polished carbon fiber reinforced Polyamide-6 sample, produced by automated fiber placement, as a statistical pattern instead of the usual speckle pattern applied to the area to be investigated. This way the stress and strain distributionin different regions of the investigated sample area can be evaluated and displayed, while the sample is exposed to an increasing mechanical load in form of a three-point bending test. The resulting strain and displacement fields are compared to finite element modeling of the ROI. To provide an accurate model, the image of the sample is first segmented into fiber, matrix and voids using “Trainable Weka Segmentation” and the resulting phases mapped with the corresponding material properties. To compute the resulting strains in the sample, the measured displacements from the DIC on the edges of the ROI were used as boundary conditions for the simulation. Simulation and experimental results clearly point out the inhomogeneity of the strain field in these samples. Due to the presence of fiber rovings and the presence of voids, local strain values exceed the global average by up to 4 %.

scholarly journals Simulation of the Hybrid Carbon-Aramid Composite Materials Based on Mechanical Characterization by Digital Image Correlation Method

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4184
Author(s):  
Camelia Cerbu ◽  
Stefania Ursache ◽  
Marius Florin Botis ◽  
Anton Hadăr
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Flexural Modulus ◽  
Image Correlation ◽  
Woven Fabric ◽  
Bending Test ◽  
Orthotropic Materials ◽  
The Impact ◽  
Longitudinal Strains ◽  
Hybrid Carbon

As hybrid carbon-aramid composites become widely used in various industries, it has become imperative to mechanically characterize them using accurate methods of measuring the entire deformation field such as the digital image correlation (DIC) method. The accuracy of the numerical simulation of carbon-aramid composite structures depends on the accuracy of the elastic constants. Therefore, the goal of this research is to model and simulate the mechanical behaviour of the composite based on epoxy resin reinforced with carbon-aramid woven fabric by considering the mechanical properties investigated by tensile test combined with DIC and the bending test. The curves of the transverse strains related to the longitudinal strains were investigated using DIC in order to determine the Poisson’s ratios in the case of tensile tests applied in warp or weft directions of the reinforcement fabric. The impact strength determined by Charpy tests is also reported. The other main objective is to use the analytical models to compute the tensile and flexural moduli of elasticity for the fictitious orthotropic materials which behave similarly to the carbon-aramid composite investigated. The simulations regarding the behaviour of the carbon-aramid composite in tensile and bending tests were validated by the experimental results, since the maximum errors recorded between experimental and theoretical results were 0.19% and 0.15% for the equivalent tensile modulus and for the equivalent flexural modulus, respectively.

scholarly journals Application of digital image correlation system for analysis of local plastic instabilities of perforated thin-walled bars

2018 ◽  
Vol 196 ◽  
pp. 01032 ◽  
Author(s):  
Andrzej Piotrowski ◽  
Marcin Gajewski ◽  
Cezary Ajdukiewicz
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Plastic Material ◽  
Low Carbon Steel ◽  
Image Correlation ◽  
Theoretical Point ◽  
Low Carbon ◽  
Compression Tests ◽  
Correlation System ◽  
Thin Walled

In the presented paper the local instabilities occurring in compression test of perforated thin-walled bars of low slenderness are observed using digital image correlation system ARAMIS. The tested samples slenderness is so low, that from theoretical point of view we are dealing with compression tests of some perforated shells. The samples are made from typical low carbon steel, which has to be treated as elasto-plastic material. Because of that, the final geometry of the sample (after unloading) is also analysed giving a good data for calibration of the theory of elasto-plasticity for large deformations. In analysed cases the total strain values are not exceptionally large, while local rotation (and permanent deformations) have significant values.

Full-field strain measurements at the micro-scale in fiber-reinforced composites using digital image correlation

2016 ◽  
Vol 140 ◽  
pp. 192-201 ◽  
Author(s):  
Mahoor Mehdikhani ◽  
Mohammadali Aravand ◽  
Baris Sabuncuoglu ◽  
Michaël G. Callens ◽  
Stepan V. Lomov ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Image Correlation ◽  
Fiber Reinforced Composites ◽  
Field Strain ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Full Field ◽  
Strain Measurements ◽  
Micro Scale

Use of Digital Image Correlation for the Evaluation of Flexural Fatigue Behavior of Asphalt Beams with Geosynthetic Interlayers

2017 ◽  
Vol 2631 (1) ◽  
pp. 55-64 ◽  
Author(s):  
Vinay Kumar V ◽  
Sireesh Saride
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Digital Images ◽  
Fatigue Behavior ◽  
Bottom Layer ◽  
Fatigue Performance ◽  
Image Correlation ◽  
Bending Test ◽  
Flexural Fatigue ◽  
Tensile Strains

In this study, the flexural fatigue performance of two-layer asphalt beams with and without geosynthetic interlayers was evaluated with a digital image correlation (DIC) technique. A field scenario was simulated by considering an old, destressed pavement as the bottom layer with a compacted bituminous mix as an overlay. An appropriate tack coat and geosynthetic interlayer were at the interface. The digital images were recorded at a specific interval of load cycles during a repeated load four-point bending test. The displacement fields obtained from the digital images were analyzed so that the crack width, crack height, and tensile strains could be obtained and the crack initiation and propagation phenomena studied. The deformation data obtained from the DIC analysis were validated with the vertical deformations measured through linear variable differential transformers. The DIC results correlated very well with the measured data. The DIC data indicated that the tensile strains were as high as 4.75% at the crack tip in the control specimen compared with 1.42% in a polyester grid interlayered specimen at the failure of the corresponding specimens. With the inclusion of interlayers, the fatigue performance of the two-layer asphalt beam specimens improved by about 39, 12, and 1.7 times for Specimens I1, I2, and I3, respectively.

Characterization of Mechanical Behavior of Polyurethane Foams Using Digital Image Correlation

2005 ◽  
Author(s):  
Helena (Huiqing) Jin ◽  
Wei-Yang Lu ◽  
Simon Scheffel ◽  
Michael K. Neilsen ◽  
Terry D. Hinnerichs
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Polyurethane Foams ◽  
Image Correlation ◽  
Compression Tests ◽  
Steel Cylinder ◽  
Full Field ◽  
Strain Concentration ◽  
The Impact ◽  
Dic Technique

Polyurethane foams have good energy absorption properties and are effective in protecting sensitive components from damages due to impact. The foam absorbs impact energy by crushing cells and undergoing large deformation. The complex deformation of the foam needs to be modeled accurately to simulate the impact events. In this paper, the Digital Image Correlation (DIC) technique was implemented to obtain the deformation field of foam specimens under compression tests. Images of foam specimen were continuously acquired using high-speed cameras. The full field displacement and strain at each incremental step of loading were calculated from these images. The closed-cell polyurethane foam used in this investigation was nominal 0.32 kg/m^3 (20 pcf). In the first experiment, cubic specimens were compressed uniaxially up to 60%. The full-field displacements and strains obtained using the DIC technique provide detailed information about the inhomogeneous deformation over the area of interest during loading. In the second experiment, compression tests were conducted for a simple foam structure - cubic foam specimens with a steel cylinder inclusion. The strain concentration at the interface between steel cylinder and foam was studied to simulate the deformation of foam in a typical application. In the third experiment, the foam was loaded from the steel cylinder during the compression. The strain concentration at the interface and the displacement distribution over the surface were compared for cases with and without a confinement fixture to study the effects of confinement. These experimental results demonstrate that the DIC technique can be applied to polyurethane foams to study the heterogeneous deformation. The experimental data is briefly compared with the results from modeling and simulation using a viscoplastic model for the foam.

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