Search results for "image correlation"
showing 10 items of 36 documents
In Vitro Measurement of Strain Localization Preceding Dissection of the Aortic Wall Subjected to Radial Tension
2020
AbstractBackgroundAortic dissection (AD) is a common pathology and challenging clinical problem. A better understanding of the biomechanical effects preceding its initiation is essential for predicting adverse events on a patient-specific basis. Moreover, the predictability of patient-specific biomechanics-based computational models is hampered by uncertainty about boundary conditions and material properties.ObjectivePredisposition of thoracic aortic aneurysms (TAA) to ADs can be related to the degradation of biomechanically important constituents in the aortic wall of TAAs. The goal of the present study is to develop a new methodology to measure strain fields in aortic tissues subjected to…
Experimental application of digital image correlation for the tensile characterization of basalt FRCM composites
2021
Abstract Composites made with inorganic matrix, namely fabric reinforced cementitious mortar (FRCM) composites are becoming widespread as strengthening materials for existing masonry structures. These composites are made of a dry grid of fibres embedded in an inorganic matrix. FRCMs can be considered a valid alternative to traditional organic composites such as fibre reinforced polymers (FRPs) because of their better compatibility with the masonry support. This work presents an experimental study for the tensile characterization of a basalt fabric reinforced cementitious mortar (BFRCM) composite. Tensile tests were carried out on coupons reinforced with one, two or three layers of grid to i…
A DIC-based study of flexural behaviour of roving/mat/roving pultruded composites
2015
Abstract This paper reports a study of the flexural behaviour and resultant failure modes in E-glass/polyester pultruded composites. The digital image correlation (DIC) method is used to estimate the effect of fibre orientation on failure behaviour in thick beams, taking into account the presence of continuous filament mat layer (CFM) in the stacking sequence. In particular, the tests were carried out for specimens with off-axis angle of 0°, 7.5°, 15°, 30°, 45° and 90°. The crack initiation and the failure mechanisms depend on the mutual interaction between the stiffness properties of different areas in the stacking sequence. An influence index (I) was introduced to evaluate the magnitude o…
Experimental assessment of the shield-to-salt-fog properties of basalt and glass fiber reinforced composites in cork core sandwich panels applications
2018
Abstract In this paper, the effect of salt-fog exposition on the mechanical behavior of sandwich panels having cork agglomerate core was investigated. In particular, the aim of this research work is to assess the shield function of unidirectional basalt and E-glass reinforced polymer on the aging and failure mechanism of the core when such class of material are destined to operate in hostile environments (e.g., marine environment). To do this, the manufactured sandwich panels were exposed up to 60 days to salt-fog environment, according to ASTM B 117 standard. Unaged and aged specimens were analyzed through three point bending tests after aging time of 10, 25 and 60 days. Digital Image Corr…
Time-resolved X-ray microtomographic measurement of water transport in wood-fibre reinforced composite material
2016
Natural fibre composites are prone to absorb moisture from the environment which may lead to dimensional changes, mold growth, degradation of mechanical properties or other adverse effects. In this work we develop a method for direct non-intrusive measurement of local moisture content inside a material sample. The method is based on X-ray microtomography, digital image correlation and image analysis. As a first application of the method we study axial transport of water in a cylindrical polylactic acid/birch pulp composite material sample with one end exposed to water. Based on the results, the method seems to give plausible estimates of water content profiles inside the cylindrical sample.…
3D displacement field measurement with correlation based on the micro-geometrical surface texture
2011
Image correlation methods are widely used in experimental mechanics to obtain displacement field measurements. Currently, these methods are applied using digital images of the initial and deformed surfaces sprayed with black or white paint. Speckle patterns are then captured and the correlation is performed with a high degree of accuracy to an order of 0.01 pixels. In 3D, however, stereo-correlation leads to a lower degree of accuracy. Correlation techniques are based on the search for a sub-image (or pattern) displacement field. The work presented in this paper introduces a new correlation-based approach for 3D displacement field measurement that uses an additional 3D laser scanner and a C…
Object tracking in medical imaging using a 2D active mesh system
2003
International audience; Abstract: This article proposes a technique for tracking moving organs in medical imaging. It can be split into two stages. We first initialize a 2D-triangular mesh on the first image of the sequence. We distinguish different objects of interest by grouping together the triangles that make them up. Afterwards, we deform this mesh on the successive images in order to track each identified object. The tracking stage uses optical flow by adding a node relaxation step to avoid mesh deteriorations. The mesh deformations analysis provides access to motion information along the sequence. This technique is applied to a cine-MRI sequences of the heart and allows the analysis …
Digital image correlation analysis of interfacial debonding properties and fracture behavior in concrete
2007
The use of digital image correlation (DIC) as a fracture mechanics tool is described, for two projects currently underway. The goal of the first project is to examine the bond between carbon fiber reinforced polymers (CFRP) and concrete substrates. The second project involves the interfacial transition zone (ITZ) of plain concrete, and the softening and fracture behavior of this region. For both projects, DIC allows for precise measurement of the surface displacements of the deforming materials. The resulting strain data are higher in resolution than is possible with other experimental techniques. For both projects, the DIC results are being used to determine bond constitutive laws, which w…
Effects of Different Test Setups on the Experimental Tensile Behaviour of Basalt Fibre Bidirectional Grids for FRCM Composites
2020
Fibre-reinforced cementitious matrix (FRCM) composites have been effectively used during the last ten years for the strengthening of existing concrete and masonry structures. These composite materials are made of medium- and high-strength fibre meshes embedded in inorganic matrices. Synthetic fibres are the ones that are currently the most used
Unconventional application of Image Correlation techniques on Biomaterials and cardiovascular applications
2022
Image Correlation techniques are increasing in popularity and are now suitable to investigate complex structural and fluid-dynamics of cardiovascular systems. These approaches operate through a digital correlation of a pair of images to determine physical quantities of complex systems. In this thesis, their application to the mechanical characterisation of complex biomaterials (Nitinol and soft materials), and the characterisation of complex biofluid-dynamics was investigated, with the aim to analyse their reliability and enhance their accuracy and field of application. Digital Image Correlation, supported by Infrared Thermography, was used to achieve a more in depth understanding of the me…