67 research outputs found
Exploring Connotative Meanings and Metaphors of Saudi Animal Proverbs: A Semantic and Pragmatic Analysis
Proverbs tend to reflect a nation s social values attitudes and beliefs The connotative meanings underlying animal proverbial sayings can either be affectionate or abusive based on the cultural aspects of the language under investigation Although the semantic connotations of animal proverbs have been extensively studied little scholarly attention has been paid to the proverbial expressions pertaining to animals in Saudi Arabia The main aim of this study is to semantically and pragmatically investigate the connotations of animal proverbs in Hijazi Arabic in Saudi Arabia The paper also seeks to deduce the representation of human-animal relation and explore the cultural values of the Hijazi society as depicted in the proverbs The data is collected from different sources mainly from a book of Hijazi proverbs by Atique 2018 About 11 animal proverbs were selected classified and translated both literally and figuratively into Englis
Iron-Based shape memory alloy for strengthening of 113-Year bridge
This study focuses on the large-scale application of a Fe-Mn-Si shape memory alloy (Fe-SMA) for strengthening a historic roadway bridge in Petrov nad Desnou (113-years), Czech Republic. To the best of the authorsâ knowledge, this is the first application of an iron-based SMA (Fe-SMA) for prestressed strengthening of a bridge. In this study, the shape memory effect (SME) of the Fe-SMA was used for the prestressed strengthening of bridge girders. A mechanical anchorage system was developed to apply multiple Fe-SMA strips to the steel girders of the bridge subjected to daily passengers and heavy trucks. The SME of the Fe-SMA was activated by heating to approximately 260 âŠC using ceramic heating pads. The test results showed that the recovery stress of the Fe-SMA strips resulted in a compressive stress of approximately â33 MPa in the lower flange of the bridge girder. This compressive stress significantly increased the yield and fatigue capacity of the strengthened girder. Before and after the strengthening, the bridge was loaded with a 45-ton crane to assess the efficiency and performance of the system. Laboratory experiments were performed to optimize the mechanical anchors and examine the feasibility of the proposed strengthening method prior to application to the bridge. Finally, long-term monitoring of the prestressed Fe-SMA plates after installation on the bridge was conducted. The results showed that the main loss of the prestressing force caused by relaxation occurred within the first 30 days after activation and was approximately 20% of the original prestress.The authors are grateful to the Ministry of Culture of the Czech Republic for funding the research work within the framework of the Program of Applied Research and Development of the National and Cultural Identity (NAKI-II) project: Methods for achieving sustainability of industrial heritage steel bridges, ID: DG18P02OVV033. The authors also thank the re-fer AG Company for providing materials used for this study
Influence of thermomechanical treatment on the shape memory effect and pseudoelasticity behavior of conventional and additive manufactured FeâMnâSiâCrâNi-(V,C) shape memory alloys
This study evaluated the influence of heat treatment and thermomechanical training on the microstructural evolution and mechanical characteristics of conventional and additive-manufactured FeMnSi-based shape memory alloys. The conventional samples were produced by casting and rolling. The additive-manufactured samples were manufactured using the laser powder bed fusion (L-PBF) technique. Both specimens were subjected to the same heat treatment and thermomechanical training. The heat treatment involved solution annealing at 1050 °C for 2 h and aging at 750 °C for 6 h, and the thermomechanical training concluded with a 4% elongation at ambient temperature followed by annealing at 250 °C for 15 min. This training cycle was repeated four times for each sample after heat treatment. The heat treatment improved the pseudoelasticity and shape memory effect of the samples. Although training further enhanced the pseudoelasticity, it also reduced the shape memory effect. Thermomechanical training led to the formation of a large number of stacking faults, which facilitated the inverse phase transformation of martensite (Δ) to austenite (γ) during unloading, resulting in improved pseudoelasticity. The heat-treated additive-manufactured samples showed the highest total recovery strain owing to the pseudoelasticity and shape memory effect. This characteristic could be due to the smaller grain size and higher volume fraction of precipitates. The precipitates and grain refinement improved the conditions for partial dislocation motion by increasing the back stresses on the martensite tip
Effect of low-temperature precipitates on microstructure and pseudoelasticity of an FeâMnâSi-based shape memory alloy
FeâMnâSi-based shape memory alloys (Fe-SMAs) have attracted much research attention due to their potential applications for vibration mitigation, energy dissipation, and re-centering in the construction sector. Because of the crucial impact of precipitation on the pseudoelasticity (PE) behavior of Fe-SMAs, the equilibrium phase diagram of an Feâ17Mnâ5Siâ10Crâ4Niâ1(V-C) (wt%) SMA was used in this study to identify a low-temperature precipitate and study its effect on the microstructure and PE of the alloy after a low-temperature aging process. Transmission electron microscopy (TEM) studies revealed that aging at 485 °C for 6 h after aging at 750 °C for 6 h led to the precipitation of fresh, parallelogram-shaped, (CrâVâC)-rich precipitates along with elliptical-shaped, V-rich precipitates in the austenite grains of the recrystallized samples. Numerous parallel stacking faults (SFs) were formed due to the presence of the precipitates within the austenite grains. It is postulated that such an arrangement of SFs can further improve the PE by reducing the activation energy for the nucleation of É-martensite laths and inhibiting them from colliding with each other and consequent formation of α'-martensite, resulting in a residual strain reduction to 2.7% after 4.0% tensile straining
Fatigue strengthening of riveted girders in a historic railway metallic bridge in Switzerland using pre-stressed un-bonded CFRP laminates
Finite Element Analysis for Fatigue Damage Reduction in Metallic Riveted Bridges Using Pre-Stressed CFRP Plates
Many old riveted steel bridges remain operational and require retrofit to accommodate ever increasing demands. Complicating retrofit efforts, riveted steel bridges are often considered historical structures where structural modifications that affect the original construction are to be avoided. The presence of rivets along with preservation requirements often prevent the use of traditional retrofit methods, such as bonding of fiber reinforced composites, or the addition of supplementary steel elements. In this paper, an un-bonded post-tensioning retrofit method is numerically investigated using an existing railway riveted bridge geometry in Switzerland. The finite element (FE) model consists of a global dynamic model for the whole bridge and a more refined sub-model for a riveted joint. The FE model results include dynamic effects from axle loads and are compared with field measurements. Pre-stressed un-bonded carbon fiber reinforced plastic (CFRP) plates will be considered for the strengthening elements. Fatigue critical regions of the bridge are identified, and the effects of the un-bonded post-tensioning method with different prestress levels on fatigue susceptibility are explored. With an applied 40% CFRP pre-stress, fatigue damage reductions of more than 87% and 85% are achieved at the longitudinal-to-cross beam connections and cross-beam bottom flanges respectively
Metal 3D-printing for repair of steel structures
This work employs an innovative technique, wire arc additive manufacturing (WAAM) which is a type of directed energy deposition, for fatigue strengthening of cracked steel components. Different steel plates with a central crack were tested under high-cycle fatigue loading regime, including a reference plate, a plate repaired by WAAM with as-deposited profile, and a plate repaired by WAAM and subsequently machined to reduce stress concentration factors. Corresponding finite element simulation was conducted to provide a better understanding on the mechanism of WAAM-repair. The existing central crack in the reference plate propagated and led to a rupture after 0.94 million cycles, while those in the two WAAM-repaired plates did not propagate, due to the increased net cross-section and the compressive stresses induced by the depositing process. However, in the second plate, a new crack initiated at the root of WAAM profile as a result of local stress concentration, and the fatigue life reached 2.2 million cycles (2.3 times as the reference plate). The third plate, on the other hand, survived more than 9 million fatigue cycles with no visible degradation, thanks to its smooth machined profile. The findings of this work indicate that WAAM repair shows great potential as a technique to address fatigue-related damages in steel structures
Microstructure, mechanical and functional behavior
Funding Information:
JS acknowledges the China Scholarship Council for funding the Ph.D. grant (CSC NO. 201808320394). JPO acknowledges funding by national funds from FCT - Fundação para a CiĂȘncia e a Tecnologia, I.P., in the scope of the projects LA/P/0037/2020 of the Associate Laboratory Institute of Nanostructures, Nanomodelling and Nanofabrication â i3N. This activity has received funding from the European Institute of Innovation and Technology (EIT) â Project Smart WAAM: Microstructural Engineering and Integrated Non-Destructive Testing. This body of the European Union receives support from the European Union's Horizon 2020 research and innovation programme.
Publisher Copyright:
© 2023 The AuthorsShape memory alloys (SMA) are a class of smart materials with inherent shape memory and superelastic characteristics. Unlike other SMAs, iron-based SMAs (Fe-SMA) offer cost-effectiveness, weldability, and robust mechanical strength for the construction industry. Thus, applying these promising materials to advanced manufacturing processes is of considerable industrial and academic relevance. This study aims to present a pioneer application of a FeâMnâSiâCrâNiâV-C SMA to arc-based directed energy deposition additive manufacturing, namely wire and arc additive manufacturing (WAAM), examining the microstructure evolution and mechanical/functional response. The WAAM-fabricated Fe-SMAs presented negligible porosity and high deposition efficiency. Microstructure characterization encompassing electron microscopy and high energy synchrotron X-ray diffraction revealed that the as-deposited material is primarily composed by Îł FCC phase with modest amounts of VC, Δ and Ï phases. Tensile and cyclic testing highlighted the Fe-SMA's excellent mechanical and functional response. Tensile testing revealed a yield strength and fracture stress of 472 and 821 MPa, respectively, with a fracture strain of 26%. After uniaxial tensile loading to fracture, the Îł â Δ phase transformation was clearly evidenced with post-mortem synchrotron X-ray diffraction analysis. The cyclic stability during 100 load/unloading cycles was also evaluated, showcasing the potential applicability of the fabricated material for structural applications.publishersversionpublishe
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