Papers by Keyword: Strength

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Authors: Camilla Colla
Abstract: The 12th C. Modena Cathedral is a masterpiece testimony of early Romanesque architecture, artand civic values of the time. Following the inclusion in the UNESCO list in 1997, studies, surveysand maintenance works have started. The Emilia’s seismic events of May 2012 have happenedwhen the maintenance operations were already in an advanced phase. The quakes caused damageand re-opening of some historical cracks, in particular in the thin vaults of the naves, near thefaçade and at the junction between naves and choir and crypt. Fragments of brick, mortar from thejoints between bricks and even limited portions of a diagonal rib have fallen to the ground. In viewof seismic assessment and strengthening for improvement of the structural behaviour, detailedstudies of the vaults’ mortar became necessary. The investigation approach was minimal andpreservative, combining on-site close-up visual inspections and micro-destructive testing of themortar joints by mortar penetrometer. For this purpose, openings of 0.25x0.25 m2 in the renderlayer of the 23 vaults were created. The outcome has allowed differentiating between repair mortarsof different strength, used in different historic periods. The mortar resistance was very low butdifferent for lime mortar and gypsum. Values, divided in 3 classes of strength, were found tocorrelate well with the location and severity of the crack pattern and damage map in the vaults. Theresults were useful for a correct design (minimal and reversible) of the cathedral strengtheningintervention.
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Authors: Xiang Hong Zhang, Han Yang, Hao Zhang, Chun Yang Wang
Abstract: In this study, nylon PA6 resin was filled with carbon fibers by employing the technique of mechanical alloying and utilizing the special properties of carbon fiber. The effects of carbon fiber on the mechanical property of the nylon PA6 were also studied. From the results, filling nylon PA6 resin with carbon fiber could effectively enhance the tensile strength, the elastic modulus, the flexural strength and the flexural modulus for the material. In addition, the material shrinkage was also significantly reduced. The enhancing effects varied as CF content changed. Through comparative experiments, the optimal proportion of the addition was determined. Replacing the conventional irony back pad of military outdoor pot by this composite would not only largely reduce the load and improve the motility for the soldiers, but also ensure a better battlefield adaptability and comfort.
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Authors: J.-Ph. Verhelle, P. Descamps, Marc Poorteman, Fabrice Petit, F. Cambier, Richard Duclos
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Authors: Pius Bamidele Mogaji, Tamba Jamiru, Dawood Desai, Rotimi Sadiku
Abstract: Efforts at utilizing ceramic materials with their undeniably interesting range of properties in automobile manufacture, has persisted for many years. The corrosion resistance, the resistance to oxidation at high temperatures, the capacity of its resistance to wear and the low relative density of these materials make them especially attractive candidates for use in the automotive engine block production. The limitations of ceramics materials in the area of low fracture toughness can be assuaged by using various methods of grain and boundary size strengthening. This paper presents a critical survey of some of the existing materials used in the production of automotive engine block, the existing methods of toughening and strengthening of ceramic composite materials with emphasis on methodologies, strengths and weaknesses.
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Authors: Xiao Liang Chen, Shun Hong Lin, Zuan Tian
Abstract: Due to the relatively high surface-to-volume ratio, the surface effect can be significant for micro/nano-scale materials. This paper focuses on geometric size-dependent strength mechanisms of micro/nano-scale metal single crystals. A dimensional analysis model relating surface energy with the geometric size-dependent yield strength is presented and compared with results of microscale uniaxial compression tests on Ni and Au single crystals. The results indicate this model can predict the geometric size effects on the yield strength of micro/nano-scale metal single crystals.
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Authors: Y. Zhang, Nozomu Uchida, Kazuyoshi Uematsu, Tadashi Hotta, K. Nakahira, Masami Naito
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Authors: Patimat G. Rizvanova, Gasan M. Magomedov, George V. Kozlov
Abstract: The applicability of irreversible aggregation model for theoretical description of nanofiller particles aggregation processes in polymer nanocomposites has been shown. The correspondence of the indicated model and strength dispersive theory results was obtained. The main factors, influencing on nanoparticles aggregation process, were revealed.
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Authors: Leo Kestens, D. Vanderschueren, Paul van Houtte, E. Aernoudt, J. Dilewijns, C. Standaert
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Authors: Kai Zhong Xie, Le Qin Qin, Wen Gao Lv
Abstract: Based on strength and ductility, the seismic capabilities of the chords of arch ribs, web members, horizontal integrations, suspenders and beams of suspenders of concrete filled steel tube (CFST) arch bridges are studied, then the seismic capability of the bridge is obtained. Firstly, the internal forces of the members are calculated respectively by finite element under the actions of gravity representative value and small earthquakes (0.05g). Then the ultimate bearing capacities, the ratio of ductility and the reduction coefficients of earthquake are obtained according to the failure modes. Finally, yield accelerations of ground movement are multiplied by the reduction coefficients of earthquake, which the resistance seismic capabilities of the members Ac are obtained. The seismic capability of bridge is the minimum Ac. Taking Nanning Yonghe Bridge that is a 346m CFST arch bridge as example, the seismic capability is evaluated that the bridge can resisted the earthquake which the acceleration of ground movement is respectively 0.677g. The results show that the method of seismic capability evaluation is a feasible and efficient method for seismic capability evaluation of CFST arch bridge.
377
Authors: Werner Menk
Abstract: Years ago, especially in Sweden, a new family of ductile iron materials was propagated: Solid solution strengthened ferritic ductile iron. Since the 2011 edition, three grades are integrated into the European Standard EN 1563: EN-GJS-450-18, EN-GJS-500-14 and EN-GJS-600-10. The introduction of these materials into the European standard generated a large interest of many engineers, which came to a real hype meanwhile. The reason is clear: While GJS-450-18 is not very different from the standard GJS-400-15, especially the grade EN-GJS-500-14 promises to have big advantages compared to the standard grade EN-GJS-500-7. Same tensile strength, from 320 MPA to 400 MPa raised 0.2%- proof strength and from 7% to 14 % doubled elongation after fracture are very interesting properties of course and the pure ferritic structure promises a better machinability furthermore. With the higher strength grade EN-GJS-600-10 very early sceptic comments raised, because the Silicon content to reach the required strength is such high, that the risk of an embrittlement of the ferrite even at room temperature and on a tensile test bar is high. But up to now, the grade EN-GJS-500-14 has the reputation to be a high strength and very high ductile material. So, a customer of us also substituted a part from steel to EN-GJS-500-14. All calculations showed a very good performance of the parts, but as soon as in serial production field damages occurred in a manner that the parts completely broke without advance warning. The investigation of the damages showed, that the parts are not only statically and cyclically loaded, but also by strikes. Deeper investigations about strike loads confirmed, that EN-GJS-500-14 is not really ductile under these conditions. The reflection to the philosophy we had with our SiboDur-700 concept, namely to combine a moderate solid solution strengthening with a moderate strengthening by pearlite with Copper, brought us to a new high strength high ductile material we call SiboDur-500. Same strength as EN-GJS-500-14, 10 % lower in 0.2%- proof stress, slightly lower in elongation after fracture, but double to more than four times energy consumption at strike loads depending om temperature!
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