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M. Saad

Bio: M. Saad is an academic researcher from Henry Ford Hospital. The author has contributed to research in topics: Digital image correlation & Finite element method. The author has an hindex of 2, co-authored 2 publications receiving 717 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, a three-dimensional extension of two-dimensional digital image correlation is developed using digital image volumes generated through high-resolution X-ray tomography of samples with microarchitectural detail, such as the trabecular bone tissue found within the skeleton.
Abstract: A three-dimensional extension of two-dimensional digital image correlation has been developed. The technique uses digital image volumes generated through high-resolution X-ray tomography of samples with microarchitectural detail, such as the trabecular bone tissue found within the skeleton. Image texture within the material is used for displacement field measurement by subvolume tracking. Strain fields are calculated from the displacement fields by gradient estimation techniques. Estimates of measurement precision were developed through correlation of repeat unloaded data sets for a simple sum-of-squares displacement-only correlation formulation. Displacement vector component errors were normally distributed, with a standard deviation of 0.035 voxels (1.22 μm). Strain tensor component errors were also normally distributed, with a standard deviation of approximately 0.0003. The method was applied to two samples taken from the thigh bone near the knee. Strains were effectively measured in both the elastic and postyield regimes of material behavior, and the spatial patterns showed clear relationships to the sample microarchitectures.

723 citations

Journal ArticleDOI
TL;DR: This project demonstrates the feasibility of this approach by quantifying its best-case accuracy in determining the trabecular hard tissue modulus of analogues fabricated of a material with known material properties determined independently by direct testing.

74 citations

DOI
TL;DR: In this paper , the authors evaluated the resistance to the impact load of mortars incorporating natural fibers or polypropylene fibers at 28 days according to an experimental protocol developed in their laboratory, which consists in dropping a metallic ball on a square shaped specimen of 30x30x2 cm3.
Abstract: Given their specific properties, their natural and renewable sources and their low environmental impact in production, natural fibers offer an opportunity for the development of eco-friendly cement-based composites. The main objective of this experimental work is to evaluate the resistance to the impact load of mortars incorporating natural fibers or polypropylene fibers at 28 days. The assessment was carried out according to an experimental protocol developed in our laboratory. The method consists in dropping a metallic ball on a square shaped specimen of 30x30x2 cm3 to determine the energy supported by each sample. For each specimen, the number of blows required for the first crack initiation and for the total collapse of specimen are detected using a device allowing to measure the speed of ultrasonic waves. The device was fixed on the specimen itself. In order to fulfill the mechanical identity card of the composites, flexural and compression tests were also carried out at 28 days. In this experimental protocol, the pozzolanic binder was considered with different fiber percentages of polypropylene (0.25% and 0.5% by mass of binder) and of natural fibers (0.5% and 1% by mass of binder). All fibers have a length of 12 mm. Results show that natural fiber reinforcement could be considered as an ecological alternative to polypropylene fiber one to improve the resistance of mortars to impact loads.

Cited by
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Journal ArticleDOI
TL;DR: In this article, a review of the 2D digital image correlation (2D DIC) technique for displacement field measurement and strain field estimation is presented, and detailed analyses of the measurement accuracy considering the influences of both experimental conditions and algorithm details are provided.
Abstract: As a practical and effective tool for quantitative in-plane deformation measurement of a planar object surface, two-dimensional digital image correlation (2D DIC) is now widely accepted and commonly used in the field of experimental mechanics. It directly provides full-field displacements to sub-pixel accuracy and full-field strains by comparing the digital images of a test object surface acquired before and after deformation. In this review, methodologies of the 2D DIC technique for displacement field measurement and strain field estimation are systematically reviewed and discussed. Detailed analyses of the measurement accuracy considering the influences of both experimental conditions and algorithm details are provided. Measures for achieving high accuracy deformation measurement using the 2D DIC technique are also recommended. Since microscale and nanoscale deformation measurement can easily be realized by combining the 2D DIC technique with high-spatial-resolution microscopes, the 2D DIC technique should find more applications in broad areas.

2,530 citations

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TL;DR: A review of the principle, the advantages and limitations of X-ray CT itself are presented, together with an overview of some current applications of micro-CT in geosciences.

1,134 citations

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TL;DR: In this paper, the authors review the current state of the art as CT transforms from a qualitative diagnostic tool to a quantitative one, including the use of iterative reconstruction strategies suited to specific segmentation tasks and emerging methods that provide more insight than conventional attenuation based tomography.
Abstract: X-ray computer tomography (CT) is fast becoming an accepted tool within the materials science community for the acquisition of 3D images. Here the authors review the current state of the art as CT transforms from a qualitative diagnostic tool to a quantitative one. Our review considers first the image acquisition process, including the use of iterative reconstruction strategies suited to specific segmentation tasks and emerging methods that provide more insight (e.g. fast and high resolution imaging, crystallite (grain) imaging) than conventional attenuation based tomography. Methods and shortcomings of CT are examined for the quantification of 3D volumetric data to extract key topological parameters such as phase fractions, phase contiguity, and damage levels as well as density variations. As a non-destructive technique, CT is an ideal means of following structural development over time via time lapse sequences of 3D images (sometimes called 3D movies or 4D imaging). This includes information nee...

1,009 citations

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TL;DR: While the elastic modulus and yield strains for trabecular tissue are just slightly lower than those of cortical tissue, because of the cumulative effect of these differences, tissue strength is about 25% greater for cortical bone.

970 citations

Journal ArticleDOI
TL;DR: X-ray microtomographic imaging is a non-destructive technique for quantifying these processes in three dimensions within individual pores, and as reported here, with rapidly increasing spatial and temporal resolution.

968 citations