bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Investigation for Moment Redistribution in Continuous RC Beams Top Strengthened with CFRP and Steel Plates
Authors: Ibrahim Amr , Salem Shady , Khalil Ayman , El-Kateb Mahmoud 
Published: June 2020

Abstract
An experimental study was conducted on eight T-section continuous reinforced concrete beams top strengthened with CFRP and steel plates. The beams had a constant cross section and flexural steel reinforcement which was designed to prevent brittle failure due to crushing of concrete before steel yielding. The plates were installed on both sides of the slab above the beam web as near surface mounted or externally bonded to investigate the effect of different plating techniques on the moment redistribution in reinforced concrete beams. The number of plates in each specimen was changed. Steel stirrups were used and designed so that no premature shear failure occurs. The experimental results show that the steel plating can cause up to 40 % redistribution of moments from the sagging to the hogging regions compared to the control specimen as well as a significant increase in the loading capacity of the beams. The results also revealed that the application of CFRP plates can lead to substantial amounts of moment redistribution when they are installed as near surface mounted plates, but without enhancing the load carrying capacity.
Study on Working Behavior of Cage-type Flexible Retaining Wall
Authors: Jie Liu , Yanyu Chen , Yehan Geng , Kaixuan Li 
Published: June 2020

Abstract
Cage-type flexible retaining wall is a new type of anti-seepage structure with broad market prospects due to its low cost and convenient installation. In order to study the working behavior of flexible cage-type retaining wall in flood control during the flood season, a three-dimensional finite element model of the structure was established, and the stress and deformation characteristics of the structure were analyzed. The results show that the maximum tensile stress is 17.1MPa, the maximum compressive stress is 12.6MPa, and the maximum structural deformation is 0.35mm, which are less than the allowable value, meaning the stress and deformation of the structure can meet the requirements of engineering construction. The reliability of the structure is verified by the full-scale model water retaining test. The vertical flow frame on the backwater side is a relatively weak part of the structure. When designing the structure, the cross-sectional dimensions of the vertical flow frame on the upstream side and the downstream flow frame can be reduced appropriately, while the cross-sectional dimensions of the vertical flow frame on the backwater side can be increased appropriately, so as to give better play to the material characteristics and save project cost.
Water Permeability Properties of Concrete made from Recycled Brick Concrete as Coarse Aggregate
Authors: Ahmad Syed Ishtiaq , Rahman Md. Shafiqur , Alam Md. Shahrior 
Published: June 2020

Abstract
Water Permeability characteristic of concrete made from recycled brick concrete as coarse aggregate was investigated and compared with concrete made from crushed virgin clay brick and natural stone aggregate. For this, concrete samples of three different compressive strengths 17.2, 20.6 and 24.1 MPa were prepared as per ACI mix design methods from each of these aggregates. These concrete samples were then tested for compressive strength and water permeability using the AT 315 machine as per BS EN 12390-8: “Depth of Penetration of Water under Pressure”. Apart from these, porosity and bulk density were also measured in hardened concrete. Compressive strength of concrete produced from virgin brick and recycled brick concrete was found to be lower than the design strength at 28th day. Coefficient of water permeability of concrete made from recycled brick concrete as coarse aggregate was found to be higher than that of virgin brick and natural stone aggregate concrete of equivalent strength by 350 to 400%. Water permeability was found to be directly related to compressive strength and porosity in hardened concrete.
Investigation of the Significance of Factors Affecting Long-Term Creep of Concrete using Screening Designs
Authors: Daou H , Raphael W 
Published: June 2020

Abstract
Creep has a main role in predicting delayed strain in concrete members and in estimating losses in prestressed concrete, such as nuclear containment vessels, bridges girders, etc. For that, the interest in studying creep has grown significantly. This study aims to investigate the significance of different factors affecting creep of concrete using the Northwestern University (NU) creep database. Experiments have been carried out at different conditions of water-cement ratio (w/c), aggregate-cement ratio (a/c), cement content (c), cement type (R or RS), admixtures, mean compressive strength (fcm), volume-surface ratio (v/s), relative humidity (RH), age at loading (t0) and stress level (sigma). In order to determine the significance of these factors, three statistical methods have been used: Daniel Plot, Lenth Plot and Bayesian screening. The results of this analysis can be used to build accurate computational models to predict creep of concrete by considering the major effects identified.
Effect of Humidity on Concrete Creep Predictions
Authors: Zgheib E H , Raphael W E 
Published: June 2020

Abstract
An accurate estimation of creep strains is mandatory to maintain the stability and integrity of concrete structures. Different parameters and conditions affect concrete creep predictions more precisely the relative humidity. To study its effect, a large database coming from international laboratories and research centers was applied to compare the experimental measurements to the theoretical values predicted by Eurocode 2 model. An inaccurate estimation was detected; therefore, an amelioration of the Eurocode 2 model was elaborated according to the relative humidity parameter. These calculations allow to predict accurately concrete creep and to avoid prejudicial consequences in structures due to creep phenomenon.
Obtaining Chitin/Chitosan-Melanin Complexes from Black Soldier Fly Hermetia Illucens
Authors: Khayrova Adelya , Lopatin Sergei , Varlamov Valery 
Published: June 2020

Abstract
Chitosan, obtained by deacetylation reaction of chitin, is a regular biopolymer with unique properties, including high biological and sorption activities. Melanin is considered as a natural photo and radio protector. Depending on the source and the isolation method, melanin possesses various physicochemical properties that can complement the radioprotective activity of chitosan and be used to solve important scientific and practical issues. Insects are relatively understudied natural sources of chitin-melanin complexes, whereas these components are linked by strong covalent bonds. This study developed a technology for the production of this natural conjugate, based on which its deacetylated derivative, the chitosan-melanin complex, was obtained, taking the black soldier fly as an example.
Influence of Surface Modification of BaTiO3 Nanoparticles by Sodium Oleate and Chitosan on their Optical Properties and Agglomeration in Aqueous Solutions
Authors: Roldan Lopez J A , Angelats-Silva L M , León-León H , Céspedes-Vásquez R , Aldama-Reyna C W , Emelianov N A 
Published: June 2020

Abstract
Spherical titanium barium nanoparticles with an average size about 100 nm in the tetragonal crystal phase were obtained by peroxide synthesis. To prevent their agglomeration and reduce the toxic effect, the surface of nanoparticles was chemically modified with sodium oleate and chitosan. Influence of surface modification by these compounds on agglomeration of nanoparticles in aqueous solutions, their spectral features, as well as generation of the second optical harmonic were investigated.
Comparing mesoscopic models for dendritic growth
Authors: Tourret D , Sturz L , Viardin A , Založnik M 
Published: June 2020

Abstract
We present a quantitative benchmark of multiscale models for dendritic growth simulations. We focus on approaches based on phase-field, dendritic needle network, and grain envelope dynamics. As a first step, we focus on isothermal growth of an equiaxed grain in a supersaturated liquid in three dimensions. A quantitative phase-field formulation for solidification of a dilute binary alloy is used as the reference benchmark. We study the effect of numerical and modeling parameters in both needle-based and envelope-based approaches, in terms of their capacity to quantitatively reproduce phase-field reference results. In light of this benchmark, we discuss the capabilities and limitations of each approach in quantitatively and efficiently predicting transient and steady states of dendritic growth. We identify parameters that yield a good compromise between accuracy and computational efficiency in both needle-based and envelope-based models. We expect that these results will guide further developments and utilization of these models, and ultimately pave the way to a quantitative bridging of the dendrite tip scale with that of entire experiments and solidification processes.
Reduced order models for welding and solidification processes
Authors: Mendez P F 
Published: June 2020

Abstract
This paper reviews the foundations of modelling of materials processing and methodologies of analysis outside the traditional discretization of the domain (e.g. finite elements, finite volume, etc.). It starts with a review of the mathematical framework with a focus on dimensional analysis and characteristic values. The methodology of minimal representation and correction factor is discussed with emphasis on computational methods to obtain the minimal representation and on the methodology of blending to obtain the correction factors. Welding on a thin plate with surface heat losses is used as a case study, and the results obtained are validated against published data for many materials, processes, and researchers.
Columnar-to-equiaxed transition in a laser scan for metal additive manufacturing
Authors: Yuan L , Sabau A S , StJohn D , Prasad A , Lee P D 
Published: June 2020

Abstract
In laser powder bed fusion additive manufacturing (LPBFAM), different solidification conditions, e.g., thermal gradient and cooling rate, can be achieved by controlling the process parameters, such as laser power and laser speed. Tailoring the behaviour of the columnar to equiaxed transition (CET) of the printed alloy during fabrication can facilitate the production of highly customized microstructures. In this study, effective analytical solutions for both thermal conduction and solidification are employed to model solidifying melt pools. Microstructure textures and solidification conditions are evaluated for numerous combinations of laser power and laser speed under bead-on-plate conditions. This analytical-based high-throughput tool was demonstrated to select specific process parameters that lead to desired microstructures. Two selected process conditions were examined in detail by a highly parallelized microstructural solidification model to reveal both nucleation and grain growth. Both numerical solutions agree well with experiments that are performed based on bead-on-plate conditions, indicating that these numerical models aid evaluation of the nucleation parameters, providing insights for controlling CET during the LPBFAM processing.
Thermomechanical modeling of additively manufactured structural parts - different approaches on the macroscale
Authors: Thorborg J , Esser P , Bayat M 
Published: June 2020

Abstract
Modeling the metal additive manufacturing process can be done on different length scales depending on the field of interest. However, due to the moving heat source and the narrow heat affected zone, a fine mesh and fine time resolution are required to analyze detailed information on various length scales. In this paper, the focus is on macro-scale temperature, deformation and residual stresses. The inherent strain method is applied layer by layer on the full part, to include the thermal contraction and inelastic strains generated by the moving heat source. The inherent strain components are mapped from the mesoscale simulations, where different boundary conditions can be used to resemble different regions from the macroscale. As an alternative to the inherent strain method and to include the thermal simulation on macroscale without simulating the moving heat source, a layer-by-layer approach is proposed and applied in the paper. The price to pay is the loss in detail of the thermal load. However, for the suggested layer-by-layer approach, the energy corresponds to the energy delivered from the laser. The proposed and implemented methods are applied to two examples and compared to measurements. Finally, large structural parts are simulated to evaluate the application on new trends in the automotive industry.
Study of thermoelectric magnetohydrodynamic convection on solute redistribution during laser additive manufacturing
Authors: Kao A , Gan T , Tonry C , Krastins I , Pericleous K 
Published: June 2020

Abstract
Melt pools formed in laser additive manufacturing (AM) are subject to large thermal gradients, resulting in the formation of thermoelectric currents due to the Seebeck effect. When in the presence of an external magnetic field, a Lorentz force is formed which drives fluid flow in the melt pool. This Thermoelectric Magnetohydrodynamics (TEMHD) phenomenon, can have a significant impact on the melt pool morphology and can alter the microstructural evolution of the solidification process. By coupling steady-state mesoscopic melt pool calculations to a microscopic solidification model, predictions of the resulting microstructure for multiple deposited layers have been obtained. The results indicate that the magnetic field can have a transformative effect on the microstructure and solute redistribution. This study highlights the theoretical potential for using magnetic fields as an additional control system to tailor AM microstructures.
Effect of evaporated gas flow on porosity and microstructure of IN718 parts produced by LPBF-processes
Authors: Jakumeit J , Huang C , Laqua R , Zielinski J , Schleifenbaum J H 
Published: June 2020

Abstract
Laser Powder Bed Fusion (LPBF) is the most widely used metal additive manufacturing (AM) process. A laser beam melts metal powder and partly the underlying solid metal to add metal layer by layer in selected regions. Temperatures up to the boiling temperature are reached resulting in a violent gas stream which affects solidification and can lead to porosity. Due to the small size of the melting zone, a detailed experimental analysis of the process is very difficult and simulation is an important tool to understand the manufacturing process and the influence of process parameter on the quality of components. In this work a three-phase melting and solidification simulation methodology has been used to investigate the melting, evaporation and solidification in a LPBF process. The methodology, originally developed to model casting processes, was extended by a model to calculate the heating of the metal powder by the laser beam and a metal evaporation model to include the effect of the evaporated metal gas on the total gas flow. The methodology was applied to analyse the melting, evaporation and solidification of single track experiments with IN718 powder. The simulation results were validated by comparing the calculated melt pool depth with the experimental findings. High laser power combined with slow laser speed leads to high energy densities at the melt pool, which result in a deep keyhole and increased porosity. The simulations revealed that evaporation of melt leads to a violent gas flow with velocities up to 100 m/s.
Part-scale mechanical modelling of LPBF including microstructural evolution effects
Authors: De Baere D , Bayat M , Mohanty S , Hattel J H 
Published: June 2020

Abstract
Due to its nature as a layer-by-layer production technique, the stresses and subsequent deformation from laser-based powder bed fusion are different from the ones observed in other manufacturing techniques. Additionally, because of the cyclic heating and cooling, the material undergoes significant microstructural changes during the process. Especially for the material Ti-6Al-4V, this microstructural change is pronounced, since the microstructure changes from β to α+β during the LPBF process. In this work, two models are coupled together in a novel way. First, a reduced-fidelity part-scale thermo-mechanical model will predict the stresses and deformation. This model uses both the meta-layer concept, and flash heating as methods for decreasing the computational cost. Secondly, a Johnson-Mehl-Avrami-Kolmogorov-based non-isothermal microstructural model is implemented as a state variable to estimate the change in phase fraction of the constituting phases. The results show that the part is made up mostly of a mix of α and α’ phases, and that the microstructural change only leads to a small change in the residual stress after the LPBF process.
Columnar-equiaxed transition in continuous casting based on a micro-macro solidification model with long-range solutal mixing
Authors: Uddagiri M , Spee J , Hubig S , Steinbach I 
Published: June 2020

Abstract
A novel model is proposed to describe the columnar to equiaxed transition (CET) in continuous casting. The model bases on Rappaz and Thevoz’s solute diffusion model for equiaxed dendritic growth, combined with a 1-Dimensional solidification model normal to the slab surface. The unique feature of the proposed model is the combination with a mixing term between interdendritic and extradendritic melt, representing long-range solutal mixing by convection. The model can also be applied to predict equiaxed to columnar transition (ECT), i.e. the chill zone thickness. The model consists of modules such as nucleation, growth kinetics, solute and heat balance, and a solute mixing module. Nucleation is considered with a fixed nucleation undercooling. The growth kinetics of the dendrites are treated according to the LGK model. A finite difference scheme is employed for solving 1-Dimensional heat transfer equations and finally, volume averaged solute balance equations are solved in a staggered scheme. Mixing of inter- and extradendritic liquid is, as a first step, treated ideally fast. When applied to Fe-C binary system with the thermo-physical properties obtained from literature and CALPHAD simulations, the model successfully predicts recalescence, phase fraction evolution, and concentration profiles in different phases. Realistic boundary conditions of the continuous casting process are obtained from macroscopic FEM simulation.
Simulation of longitudinal surface defect in steel continuous casting
Authors: Zappulla M L S , Thomas B G 
Published: June 2020

Abstract
Cracks and depressions in steel continuous casting often start during initial solidification in the mold and evolve later in the process. To understand the mechanism(s) of formation of these defects, a finite-element model of transient thermal-mechanical behavior during steel solidification has been developed and applied to simulate longitudinal depressions. The thermal model features a detailed analysis of heat transfer across the interfacial gap, which is fully coupled with a thermal-mechanical elastic-viscoplastic finite-element model that calculates the evolving size and shape of surface depressions. The results are compared with analysis of a sample with a longitudinal surface depression and crack from a commercial continuously cast slab. In this scenario, a thermal event caused a local drop in heat transfer, followed by frictional tension on the domain due to slab shrinkage, led to shell necking and the formation of a localized U-shaped depression. Finally, a new visualization methodology has been developed to better reveal defect formation in real time, such as longitudinal depressions, which persist as they move down the mold at the casting speed.
Integrated numerical simulation of the industrial continuous casting process
Authors: Fainberg J , Hepp E , Schäfer W , Krafthöfer C 
Published: June 2020

Abstract
The production of a continuously cast strand involves a large number of coupled phenomena involving flow, heat transfer, solidification and thermo-mechanics. In this paper, different approaches are described for the numerical modelling of industrial continuous casting processes at different levels of detail, dependent on the questions to be investigated. In the simplest case to obtain a rough estimate of the process conditions, the solidification of the strand is considered with a prescribed convective flux profile in the strand body based on the withdrawal speed. In the most complicated case, the process phase of filling of the empty mould is first calculated, followed by the phase of the withdrawal of the strand including consideration of the flow in both strand and tundish.
A meshless thermomechanical travelling-slice model of continuous casting of steel
Authors: Mavrič B , Dobravec T , Vertnik R , Šarler B 
Published: June 2020

Abstract
The travelling slice approximation of continuous casting process is widely used in industrial practice to model the heat transfer and solidification. Short computational times that are possible due to the reduction from three to two dimensions compensate for lower accuracy introduced by the approximation. In the same spirit, the travelling slice approximation is also used for the thermomechanical model in the present paper. The model includes contributions from metallostatic pressure, thermal contraction and viscoplastic deformation to describe the stress in the material slice. It incorporates simple models to predict the hot tearing and cracking. The model is solved with a novel strong-form meshless method. It allows flexible adaptive node distribution to accurately describe the behaviour in the solidifying region. In this paper we focus on the two-way coupling of the heat transfer and deformation of the strand to model the air-gap formation in the initial stage of the casting process and to study the emergent behaviour that is the result of this coupling. We find that the inclusion of the air-gap model significantly changes the stress distribution in the corners of the strand because of the reheating caused by the reduced heat-transfer.
Performance of turbulence models for flow prediction in a mould of continuous steel caster
Authors: Gregorc J , Kunavar A , Šarler B 
Published: June 2020

Abstract
The flow of molten steel in a mould during continuous casting process is nowadays most often studied using numerical approach. With such an approach, appropriate numerical tools have to be selected to achieve physically sound results. Within this work we focus on performance of different turbulence models for the case of casting of steel billets with single SEN port oriented in vertical, downward direction. Only fluid dynamics aspect of the casting process is considered, while all other phenomena are disregarded at this stage. Simulations were performed with commercial CFD package ANSYS Fluent with k-ε, k-ω and SAS turbulent models. The geometric model, material properties and process conditions are closely matched to those from our experimental water model studies, which is typically not done. Hence, the difference between the experiments and the numerical simulation originates only due to turbulence model performance. The experimental PIV data from the water model experimental system is used to benchmark the performance of various turbulence models. The models are compared based on lateral dispersion of the liquid jet exiting submerged entry nozzle (SEN) and formation of recirculation zones around the SEN. The results show that while all three models are capable of capturing general flow features, only the SAS model predicts finer turbulent structures and reasonably captures the flow behaviour in temporal domain.