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Gasser Abdelal

Bio: Gasser Abdelal is an academic researcher from Queen's University Belfast. The author has contributed to research in topics: Finite element method & Lightning strike. The author has an hindex of 16, co-authored 53 publications receiving 795 citations. Previous affiliations of Gasser Abdelal include Delft University of Technology & University of Liverpool.


Papers
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Journal ArticleDOI
TL;DR: In this paper, a physics-based modeling procedure is presented to predict the thermal damage of composite material when struck by lightning using the Finite Element Method with non-linear material models to represent the extreme thermal material behaviour of the composite material (carbon/epoxy) and an embedded copper mesh protection system.

178 citations

Journal ArticleDOI
TL;DR: In this article, a combination of tests and non-linear finite element analyses is used to investigate the effect of such holes on web crippling under end-one-flange (EOF) loading condition.
Abstract: Web openings could be used in cold-formed steel beam members, such as wall studs or floor joints, to facilitate ease of services in buildings. In this paper and its companion paper, a combination of tests and non-linear finite element analyses is used to investigate the effect of such holes on web crippling under end-one-flange (EOF) loading condition. The present paper includes a testing programme on web crippling of channel section and material tensile coupons, followed by a numerical study, where the models are firstly validated against the performed experiments. The results of 74 web crippling tests are presented, with 22 tests conducted on channel sections without web openings and 52 tests conducted on channel sections with web openings. In the case of the tests with web openings, the hole was either located centred above the bearing plates or having a horizontal clear distance to the near edge of the bearing plates. A non-linear finite element model is described, and the results compared against the laboratory test results; a good agreement between the tests and finite element analyses was obtained in term of both strength and failure modes.

73 citations

Journal ArticleDOI
TL;DR: In this article, the chemical interactions of iron and carbon were described through an analytical bond order interatomic potential (ABOP) energy function, and the indentations were performed at an indentation speed of 50 m/s and a repeat trial was performed at 5 m/m/s.
Abstract: Study of nanomechanical response of iron carbides is important because presence of iron carbides greatly influences the performance and longevity of steel components. This work contributes to the literature by exploring nanoindentation of Fe3C and tetrahedral-Fe4C using molecular dynamics simulation. The chemical interactions of iron and carbon were described through an analytical bond order inter-atomic potential (ABOP) energy function. The indentations were performed at an indentation speed of 50 m/s and a repeat trial was performed at 5 m/s. Load–displacement (P–h) curve for both these carbides showed residual indentation depth and maximum indentation depth (hf/hmax) ratio to be higher than 0.7 i.e. a circumstance where Oliver and Pharr method was not appropriate to be applied to evaluate the material properties. Alternate evaluation revealed Fe3C to be much harder than Fe4C. Gibbs free energy of formation and radial distribution function, coupled with state of the average local temperature and von Mises stresses indicate the formation of a new phase of iron-carbide. Formation of this newer phase was found to be due to deviatoric strain rather than the high temperature induced in the substrate during nanoindentation.

58 citations

Journal ArticleDOI
TL;DR: In this article, a combination of tests and non-linear finite element analyses is used to investigate the effect of such holes on web crippling under the interior-one-flange (IOF) loading condition; the cases of both flange fastened and flange unfastened to the bearing plate are considered.
Abstract: Web openings are increasingly used in cold-formed steel beam members of buildings to facilitate ease of services. In this paper, a combination of tests and non-linear finite element analyses is used to investigate the effect of such holes on web crippling under the interior-one-flange (IOF) loading condition; the cases of both flange fastened and flange unfastened to the bearing plate are considered. The results of 61 web crippling tests are presented, with 18 tests conducted on channel sections without web openings and 43 tests conducted on channel sections with web openings. In the case of the tests with web openings, the hole was either located centred beneath the bearing plate or having a horizontal clear distance to the near edge of the bearing plate. A good agreement between the tests and finite element analyses was obtained in term of both strength and failure modes.

56 citations

Journal ArticleDOI
TL;DR: In this article, the fiber orientation variation in the direction of the loading, and the other one perpendicular to the loading direction, were identified as possible contributors to the buckling load improvements.
Abstract: Analysis of non-traditional Variable Stiffness (VS) laminates, obtained by steering the fiber orientation as a spatial function of location, have shown to improve buckling load carrying capacity of flat rectangular panels under axial compressive loads. In some cases the buckling load of simply supported panels doubled compared to the best conventional laminate with straight fibers. Two distinct cases of stiffness variation, one due to fiber orientation variation in the direction of the loading, and the other one perpendicular to the loading direction, were identified as possible contributors to the buckling load improvements. In the first case, the increase was attributed to the favorable distribution of the transverse in-plane stresses over the panel platform. In the second case, a higher degree of improvement was obtained due to the re-distribution of the applied in-plane loads. Experimental results, however, showed substantially higher levels of buckling load improvements compared with theoretical pred...

55 citations


Cited by
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01 Jan 2007

1,932 citations

Journal ArticleDOI
TL;DR: In this paper, a composite laminate may be designed as a permutation of several straight-fiber layers or as a matrix embracing fibers positioned in curvilinear paths.

354 citations

Journal ArticleDOI
TL;DR: Molecular dynamics simulations have been used to understand the occurrence of brittle-ductile transition due to the high-pressure phase transformation (HPPT), which induces Herzfeld-Mott transition.
Abstract: Molecular dynamics (MD) simulation has enhanced our understanding about ductile-regime machining of brittle materials such as silicon and germanium. In particular, MD simulation has helped understand the occurrence of brittle–ductile transition due to the high-pressure phase transformation (HPPT), which induces Herzfeld–Mott transition. In this paper, relevant MD simulation studies in conjunction with experimental studies are reviewed with a focus on (i) the importance of machining variables: undeformed chip thickness, feed rate, depth of cut, geometry of the cutting tool in influencing the state of the deviatoric stresses to cause HPPT in silicon, (ii) the influence of material properties: role of fracture toughness and hardness, crystal structure and anisotropy of the material, and (iii) phenomenological understanding of the wear of diamond cutting tools, which are all non-trivial for cost-effective manufacturing of silicon. The ongoing developmental work on potential energy functions is reviewed to identify opportunities for overcoming the current limitations of MD simulations. Potential research areas relating to how MD simulation might help improve existing manufacturing technologies are identified which may be of particular interest to early stage researchers.

291 citations