| 1. |
- Al-Khan, A., et al.
(författare)
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IFPA Meeting 2010 Workshops Report II: Placental pathology; Trophoblast invasion; Fetal sex; Parasites and the placenta; Decidua and embryonic or fetal loss; Trophoblast differentiation and syncytialisation
- 2011
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Ingår i: Placenta. - : Elsevier BV. - 1532-3102 .- 0143-4004. ; 32:Suppl. 2, s. 90-99
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Workshops are an important part of the IFPA annual meeting. At IFPA Meeting 2010 diverse topics were discussed in twelve themed workshops, six of which are summarized in this report. 1. The placental pathology workshop focused on clinical correlates of placenta accreta/percreta. 2. Mechanisms of regulation of trophoblast invasion and spiral artery remodeling were discussed in the trophoblast invasion workshop. 3. The fetal sex and intrauterine stress workshop explored recent work on placental sex differences and discussed them in the context of whether boys live dangerously in the womb.4. The workshop on parasites addressed inflammatory responses as a sign of interaction between placental tissue and parasites. 5. The decidua and embryonic/fetal loss workshop focused on key regulatory mediators in the decidua, embryo and fetus and how alterations in expression may contribute to different diseases and adverse conditions of pregnancy. 6. The trophoblast differentiation and syncytialisation workshop addressed the regulation of villous cytotrophoblast differentiation and how variations may lead to placental dysfunction and pregnancy complications. (C) 2011 Published by IFPA and Elsevier Ltd.
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| 2. |
- Barsoum, I., et al.
(författare)
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Analysis of the torsional strength of hardened splined shafts
- 2014
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Ingår i: Materials and Design. - : Elsevier BV. - 0261-3069. ; 54, s. 130-136
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Tidskriftsartikel (refereegranskat)abstract
- The current study presents a finite element modeling framework to determine the torsion strength of hardened splined shafts by taking into account the detailed geometry of the involute spline and the material gradation due to the hardness profile. The aim is to select a spline geometry and hardness depth that optimizes the static torsion strength. Six different spline geometries and seven different hardness profiles including non-hardened and through-hardened shafts have been considered. The results reveal that the torque causing yielding of induction hardened splined shafts is strongly dependent on the hardness depth and the geometry of the spline teeth. The results from the model agree well with experimental results found in the literature and reveal that an optimum hardness depth maximizing the torsional strength can be achieved if shafts are hardened to half their radius.
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| 3. |
- Barsoum, Zuheir, et al.
(författare)
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Fatigue strength evaluation of friction stir welded aluminium joints using the nominal and notch stress concepts
- 2012
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Ingår i: Materials & Design. - : Elsevier BV. - 0261-3069. ; 41, s. 231-238
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Tidskriftsartikel (refereegranskat)abstract
- In this study the fatigue strength is investigated for Friction Stir Welded (FSW) overlap and butt welded joints in different thicknesses based on nominal and effective notch stress concepts. The fatigue test results are compared with fatigue strength recommendations according to EN 1999-1-3 and International Institute of Welding (IIW). The results are also compared with available published data and Finite Element Analysis (FEA) is carried out to investigate the effect of plate thickness and nugget size on the fatigue strength of overlap joints. 3-3 mm butt welded joints shows the highest fatigue strength in comparison with 3-5 mm butt welded and overlap joints. Slopes of the SN-curves for two different joint types differ from the slope recommended by IIW. A specific failure trend is observed in overlap FSW joints. However, the slopes of the SN-curves are in close agreement with slopes found in EN 1999-1-3. The slopes of various published results and test results presented in this study are in good agreement with each other. The suggested fatigue design curves for the nominal and effective notch stress concept have a higher slope than given for fusion welds by IIW.
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| 4. |
- Barsoum, I., et al.
(författare)
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The effect of stress state on ductility in the moderate stress triaxiality regime of medium and high strength steels
- 2012
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Ingår i: International Journal of Mechanical Sciences. - : Elsevier BV. - 0020-7403 .- 1879-2162. ; 65:1, s. 203-212
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Tidskriftsartikel (refereegranskat)abstract
- Experiments on double notched tube specimens subjected to tension and torsion were conducted by Barsoum and Faleskog (2007) [8,9]. In this study a complementary experimental investigation was conducted on tensile round circumferentially notched bar specimens. The results from the current study were compared with the results from the double circumferentially notched tube specimens with stress triaxiality larger than 0.7 in order to asses the influence of the Lode parameter on ductility in the moderate stress triaxiality regime. The effective plastic strain, the stress triaxiality T and the Lode parameter L were determined at the center of the notch up to the point of onset of failure by means of finite element. The influence of the Lode parameter on the failure strain was significant for the high strength and low hardening material, whereas for the medium strength and high hardening material the influence of the Lode parameter was less distinguished. The experimental results were then analyzed with the micromechanical model proposed by Barsoum and Faleskog (2011) [15], which is based on the assumption that ductile failure is a consequence of that plastic deformation localizes into a band. The band consists of a square array of equally sized cells, with a spherical void located in the center of each cell, which allows for studying a single 3D unit cell with fully periodic boundary conditions. The unit cell is subjected to a proportional loading such that it resembles the stress state, in terms of T and L, from the experiments. The micromechanical model captures the experimental trend and the influence of L on ductility very well. It is found that the Lode parameter sensitivity increases by the combination of increase in the yield strength and decrease in strain hardening. The fractographical analysis reveals that this Lode parameter sensitivity is associated with the failure characteristics of the material.
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| 5. |
- Barsoum, I., et al.
(författare)
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The influence of the lode parameter on ductile failure strain in steel
- 2011
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Ingår i: ICM11. - : Elsevier BV. ; , s. 69-75
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Konferensbidrag (refereegranskat)abstract
- In this study an experimental investigation was conducted on tensile round circumferentially notched bar specimens. The results were compared to the experimental result on double notched tube specimens subjected to tension and torsion conducted in [5]. The comparison was done for moderate stress triaxiality levels larger than 0.7 with the objective to assess the influence of the Lode parameter on the ductile failure strain. The effective plastic strain, the stress triaxiality T and the Lode parameter L were determined at the center of the notch up to the point of failure by means of finite element based on J2-plasticity. The influence of the Lode parameter on the failure strain was remarkable for the high strength and low hardening material, whereas for the medium strength and high hardening material the influence of the Lode parameter was less prominent. The experimental results were then analyzed with the micromechanical model proposed in [6-7] which is based on the assumption that ductile failure is a consequence of that plastic deformation localizing into a band of imperfections. It is found that the micromechanical model captures the experimental trend and thus the influence of L on the ductility very well. It is found that the Lode parameter sensitivity increases with increase in the yield strength. The fractographical analysis reveals that Lode parameter sensitivity is associated with the failure characteristics of the material.
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| 6. |
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