bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Beam Model for Simulation of the Mechanical Behaviour of Variable Thickness Functionally Graded Material Beams Based on Modified First Order Shear Deformation Theory
Authors: Nam Vu Hoai , Vinh Pham Van , Chinh Nguyen Van , Thom Do Van , Hong Tran Thi
Published: January 2019

There are many beam models to simulate the variable thickness functionally graded material (FGM) beam, each model has advantages and disadvantages in computer aided engineering of the mechanical behavior of this beam. In this work, a new model of beam is presented to study the mechanical static bending, free vibration, and buckling behavior of the variable thickness functionally graded material beams. The formulations are based on modified first order shear deformation theory and interpolating polynomials. This new beam model is free of shear-locking for both thick and thin beams, is easy to apply in computation, and has efficiency in simulating the variable thickness beams. The effects of some parameters, such as the power-law material index, degree of non-uniformity index, and the length-to-height ratio, on the mechanical behavior of the variable thickness FGM beam are considered.
Thermal Modeling of Tool Temperature Distribution during High Pressure Coolant Assisted Turning of Inconel 718
Authors: D'Addona Doriana , Raykar Sunil
Published: January 2019

This paper presents a finite-element modeling (FEM) of tool temperature distribution during high pressure coolant assisted turning of Inconel 718, which belongs to the heat resistance superalloys of the Nickel-Chromium family. Machining trials were conducted under four machining conditions: dry, conventional wet machining, high pressure coolant at 50 bar, and high pressure coolant at 80 bar. Temperature during machining plays a very important role in the overall performance of machining processes. Since in the current investigation a high pressure coolant jet was supplied in the cutting zone between tool and work material, it was a very difficult task to measure the tool temperature correctly. Thus, FEM was used as a modeling tool to predict tool temperature. The results of the modeling showed that the temperature was considerably influenced by coolant pressure: the high pressure jet was able to penetrate into the interface between tool and work material, thus providing both an efficient cooling and effective lubricating action.
Modelling and Analysis of the Corrosion Characteristics of Ferritic-Martensitic Steels in Supercritical Water
Authors: Li Yanhui , Xu Tongtong , Wang Shuzhong , Fekete Balazs , Yang Jie , Yang Jianqiao , Qiu Jie , Xu Aoni , Wang Jiaming , Xu Yi , Macdonald Digby D.
Published: January 2019

The dependencies of weight gain of 9-12 Cr ferritic-martensitic steels in supercritical water on each of seven principal independent variables (temperature, oxygen concentration, flow rate, exposure time, and key chemical composition and surface condition of steels) have been predicted using a supervised artificial neural network (ANN). The relative significance of each independent variable was uncovered by fuzzy curve analysis, which ranks temperature and exposure time as the most important. The optimized ANN, not only satisfactorily represents the experimentally-known non-linear relationships between the corrosion characteristics of F-M steels and the key independent variables (demonstrating the effectiveness of this technique), but also predicts and reveals that the effects of oxygen concentration on the weight gains, to a certain degree, is influenced by the flow rate and temperature. Finally, according to the ANN predicted-results, departure of oxidation kinetics from the parabolic law, and basic cause of chromium content in steel substrate influencing the corrosion rate, and the synergetic effects of dissolved oxygen concentration, flow rate, and temperature, are discussed and analyzed.
Tailoring the Mechanical Properties of Laser Cladding-Deposited Ferrous Alloys with a Mixture of 410L Alloy and Fe–Cr–B–Si–Mo Alloy Powders
Authors: Huang Sheng , Li Dichen , Zhang Lianzhong , Zhang Xiaoyu , Zhu Weijun
Published: January 2019

The effects of different ratios of 410L alloy and Fe–Cr–B–Si–Mo alloy powders on the microstructure and mechanical properties of laser cladding-deposited ferrous alloys were investigated. The experimental results revealed that the 410L alloy had good strength and excellent ductility due to its microstructure consisting of large elongated ferrite dendrites surrounded by a small number of martensite grains, while the Fe–Cr–B–Si–Mo alloy had high strength and poor ductility because of its eutectic microstructure composed of ferrite and Fe2B/Cr2B. As the concentration of Fe–Cr–B–Si–Mo alloy powder added to the 410L alloy powder increased, the ferrite grains became finer and the volume fraction of the eutectic increased, which eventually improved the strength and reduced the plasticity. Then, 410L + 12.5% Fe–Cr–B–Si–Mo alloy powder was successfully deposited onto AISI 1060 steel substrate via laser cladding deposition, and the mechanical properties met those of the substrate, which verified that tailoring the mechanical properties of the laser cladding-deposited alloys with a mixture of 410L and Fe–Cr–B–Si–Mo alloy powders for steel repairing applications is a feasible solution.
Photocatalytic Performance of CuxO/TiO2 Deposited by HiPIMS on Polyester under Visible Light LEDs: Oxidants, Ions Effect, and Reactive Oxygen Species Investigation
Authors: Zeghioud Hichem , Assadi Aymen Amine , Khellaf Nabila , Djelal Hayet , Amrane Abdeltif , Rtimi Sami
Published: January 2019

In the present study, we propose a new photocatalytic interface prepared by high-power impulse magnetron sputtering (HiPIMS), and investigated for the degradation of Reactive Green 12 (RG12) as target contaminant under visible light light-emitting diodes (LEDs) illumination. The CuxO/TiO2 nanoparticulate photocatalyst was sequentially sputtered on polyester (PES). The photocatalyst formulation was optimized by investigating the effect of different parameters such as the sputtering time of CuxO, the applied current, and the deposition mode (direct current magnetron sputtering, DCMS or HiPIMS). The results showed that the fastest RG12 degradation was obtained on CuxO/TiO2 sample prepared at 40 A in HiPIMS mode. The better discoloration efficiency of 53.4% within 360 min was found in 4 mg/L of RG12 initial concentration and 0.05% Cuwt/PESwt as determined by X-ray fluorescence. All the prepared samples contained a TiO2 under-layer with 0.02% Tiwt/PESwt. By transmission electron microscopy (TEM), both layers were seen uniformly distributed on the PES fibers. The effect of the surface area to volume (dye volume) ratio (SA/V) on the photocatalytic efficiency was also investigated for the discoloration of 4 mg/L RG12. The effect of the presence of different chemicals (scavengers, oxidant or mineral pollution or salts) in the photocatalytic medium was studied. The optimization of the amount of added hydrogen peroxide (H2O2) and potassium persulfate (K2S2O8) was also investigated in detail. Both, H2O2 and K2S2O8 drastically affected the discoloration efficiency up to 7 and 6 times in reaction rate constants, respectively. Nevertheless, the presence of Cu (metallic nanoparticles) and NaCl salt inhibited the reaction rate of RG12 discoloration by about 4 and 2 times, respectively. Moreover, the systematic study of reactive oxygen species’ (ROS) contribution was also explored with the help of iso-propanol, methanol, and potassium dichromate as •OH radicals, holes (h+), and superoxide ion-scavengers, respectively. Scavenging results showed that O2− played a primary role in RG12 removal; however, •OH radicals’ and photo-generated holes’ (h+) contributions were minimal. The CuxO/TiO2 photocatalyst was found to have a good reusability and stability up to 21 cycles. Ions’ release was quantified by means of inductively coupled plasma mass spectrometry (ICP-MS) showing low Cu-ions’ release.
Key Role of Precursor Nature in Phase Composition of Supported Molybdenum Carbides and Nitrides
Authors: Tišler Zdeněk , Velvarská Romana , Skuhrovcová Lenka , Pelíšková Lenka , Akhmetzyanova Uliana
Published: January 2019

In this work, we studied the effect of molybdenum precursors and the synthesis conditions on the final phase composition of bulk and supported molybdenum carbides and nitrides. Ammonium heptamolybdate, its mixture with hexamethylenetetramine, and their complex were used as the precursors at different temperatures. It was investigated that the synthesis of the target molybdenum nitrides strongly depended on the structure of the precursor and temperature conditions, while the synthesis of carbide samples always led to the target phase composition. Unlike the carbide samples, where the α-Mo2C phase was predominant, the mixture of β-Mo2N, MoO2 with a small amount of metal molybdenum was generally formed during the nitridation. All supported samples showed a very good dispersion of the carbide or nitride phases.
Porosity and Pore Size Distribution of Native and Delignified Beech Wood Determined by Mercury Intrusion Porosimetry
Authors: Vitas Selin , Segmehl Jana S. , Burgert Ingo , Cabane Etienne
Published: January 2019

The complex hierarchical structures of biological materials in combination with outstanding property profiles are great sources of inspiration for material scientists. Based on these characteristic features, the structure of wood has been increasingly exploited to fabricate novel hierarchical and functional materials. With delignification treatments, the density and chemistry of wood can be altered, resulting in hierarchical cellulose scaffolds with enhanced porosity for the fabrication of novel hybrid materials. In the present study, focusing on acidic delignification of beech wood and its influence on porosity, we report on a structural characterization and qualitative assessment of the cellulose scaffolds using mercury intrusion porosimetry (MIP). To account for the effect of water removal from the hygroscopic structure, different drying methods—e.g., standard oven and freeze-drying—were applied. While native beech wood is characterized by the presence of macro, meso and micro pores, delignification altered the porosity, increasing the importance of the macropores in the pore size distribution. Furthermore, we showed that the final porosity obtained in the material is strongly dependent on the applied drying process. Samples delignified under harsh conditions at high temperature (mass loss of ~35%) show a 13% higher porosity after freeze-drying compared to oven-dried samples. The obtained results contribute to a better understanding of the impact of the delignification and drying processes on the porosity of cellulose scaffolds, which is of high relevance for subsequent modification and functionalization treatments.
Estimates for the Commutators of p-Adic Hausdorff Operator on Herz-Morrey Spaces
Authors: Sarfraz Naqash , Hussain Amjad
Published: January 2019

In this paper, we investigate the boundedness of commutators of matrix Hausdorff operator on the weighted p-adic Herz-Morrey space with the symbol functions in weighted central bounded mean oscillations (BMO) and Lipschitz spaces. In addition, a result showing boundedness of Hausdorff operator on weighted p-adic λ -central BMO spaces is provided as well.
Search Acceleration of Evolutionary Multi-Objective Optimization Using an Estimated Convergence Point
Authors: Pei Yan , Yu Jun , Takagi Hideyuki
Published: January 2019

We propose a method to accelerate evolutionary multi-objective optimization (EMO) search using an estimated convergence point. Pareto improvement from the last generation to the current generation supports information of promising Pareto solution areas in both an objective space and a parameter space. We use this information to construct a set of moving vectors and estimate a non-dominated Pareto point from these moving vectors. In this work, we attempt to use different methods for constructing moving vectors, and use the convergence point estimated by using the moving vectors to accelerate EMO search. From our evaluation results, we found that the landscape of Pareto improvement has a uni-modal distribution characteristic in an objective space, and has a multi-modal distribution characteristic in a parameter space. Our proposed method can enhance EMO search when the landscape of Pareto improvement has a uni-modal distribution characteristic in a parameter space, and by chance also does that when landscape of Pareto improvement has a multi-modal distribution characteristic in a parameter space. The proposed methods can not only obtain more Pareto solutions compared with the conventional non-dominant sorting genetic algorithm (NSGA)-II algorithm, but can also increase the diversity of Pareto solutions. This indicates that our proposed method can enhance the search capability of EMO in both Pareto dominance and solution diversity. We also found that the method of constructing moving vectors is a primary issue for the success of our proposed method. We analyze and discuss this method with several evaluation metrics and statistical tests. The proposed method has potential to enhance EMO embedding deterministic learning methods in stochastic optimization algorithms.
Multiple Tensor Train Approximation of Parametric Constitutive Equations in Elasto-Viscoplasticity
Authors: Olivier Clément , Ryckelynck David , Cortial Julien
Published: January 2019

This work presents a novel approach to construct surrogate models of parametric differential algebraic equations based on a tensor representation of the solutions. The procedure consists of building simultaneously an approximation given in tensor-train format, for every output of the reference model. A parsimonious exploration of the parameter space coupled with a compact data representation allows alleviating the curse of dimensionality. The approach is thus appropriate when many parameters with large domains of variation are involved. The numerical results obtained for a nonlinear elasto-viscoplastic constitutive law show that the constructed surrogate model is sufficiently accurate to enable parametric studies such as the calibration of material coefficients.
Data Pruning of Tomographic Data for the Calibration of Strain Localization Models
Authors: Hilth William , Ryckelynck David , Menet Claire
Published: January 2019

The development and generalization of Digital Volume Correlation (DVC) on X-ray computed tomography data highlight the issue of long-term storage. The present paper proposes a new model-free method for pruning experimental data related to DVC, while preserving the ability to identify constitutive equations (i.e., closure equations in solid mechanics) reflecting strain localizations. The size of the remaining sampled data can be user-defined, depending on the needs concerning storage space. The proposed data pruning procedure is deeply linked to hyper-reduction techniques. The DVC data of a resin-bonded sand tested in uniaxial compression is used as an illustrating example. The relevance of the pruned data was tested afterwards for model calibration. A Finite Element Model Updating (FEMU) technique coupled with an hybrid hyper-reduction method aws used to successfully calibrate a constitutive model of the resin bonded sand with the pruned data only.
High-Order Methods Applied to Nonlinear Magnetostatic Problems
Authors: Friedrich Léo A. J. , Curti Mitrofan , Gysen Bart L. J. , Lomonova Elena A.
Published: January 2019

This paper presents a comparison between two high-order modeling methods for solving magnetostatic problems under magnetic saturation, focused on the extraction of machine parameters. Two formulations are compared, the first is based on the Newton-Raphson approach, and the second successively iterates the local remanent magnetization and the incremental reluctivity of the nonlinear soft-magnetic material. The latter approach is more robust than the Newton-Raphson method, and uncovers useful properties for the fast and accurate calculation of incremental inductance. A novel estimate for the incremental inductance relying on a single additional computation is proposed to avoid multiple nonlinear simulations which are traditionally operated with finite difference linearization or spline interpolation techniques. Fast convergence and high accuracy of the presented methods are demonstrated for the force calculation, which demonstrates their applicability for the design and analysis of electromagnetic devices.
Which Should Be Used First for ALK-Positive Non-Small-Cell Lung Cancer: Chemotherapy or Targeted Therapy? A Meta-Analysis of Five Randomized Trials
Authors: Lee Yen-Chien , Hsieh Chung-Cheng , Lee Yen-Ling , Li Chung-Yi
Published: January 2019

Background and objectives: Targeted therapy is widely used in the era of precision medicine. Whether the sequence in which targeted therapy and chemotherapy are performed matters, is however not known. We examined the impact of the sequential treatment of targeted therapy and chemotherapy among advanced anaplastic lymphoma kinase (ALK), non-small cell lung cancer (NSCLC) patients. Materials and Methods: Randomized controlled trials comparing the use of ALK inhibitors with chemotherapy were included in this meta-analysis. We estimated the hazard ratios (HRs) and 95% confidence intervals (CI), for progression-free survival (PFS) and overall survival (OS) from a random effects model. Two-sided statistical tests were used to determine the significance of these estimates. Results: In five eligible studies (1404 patients), ALK targeted therapy, in comparison with chemotherapy, had a significantly higher PFS (HR = 0.48; 95% CI, 0.42–0.55), but not significantly higher OS (HR = 0.88; 95% CI, 0.72–1.07). Crossover from chemotherapy to ALK inhibitors was allowed after progression in all trials. The sensitivity analysis of the use of ALK inhibitors as either the first- or second-line treatment, showed improvements in PFS but not in OS. Conclusions: Our results indicate that using targeted therapy first improved PFS, but that the sequence in which the treatments were performed did not cause a significant difference in overall survival.
Search for Drugs Used in Hospitals to Treat Stomatitis
Authors: Hara Yaeko , Shiratuchi Hiroshi , Kaneko Tadayoshi , Sakagami Hiroshi
Published: January 2019

Stomatitis is an inflammatory disease of the oral mucosa, often accompanied by pain. Usually it is represented by aphthous stomatitis, for which treatment steroid ointment is commonly used. However, in the cases of refractory or recurrent stomatitis, traditional herbal medicines have been used with favorable therapeutic effects. Chemotherapy, especially in the head and neck region, induces stomatitis at higher frequency, which directly affects the patient’s quality of life and treatment schedule. However, effective treatment for stomatitis has yet to be established. This article presents the clinical report of Kampo medicines on the stomatitis patients in the Nihon university, and then reviews the literature of traditional medicines for the treatment of stomatitis. Among eighteen Kampo medicines, Hangeshashinto has been the most popular for the treatment of stomatitis, due to its prominent anti-inflammatory activity. It was unexpected that clinical data of Hangeshashinto on stomatitis from Chinese hospital are not available. Kampo medicines have been most exclusively administered to elder person, as compared to pediatric population. Supplementation of alkaline plant extracts rich in lignin-carbohydrate complex may further extend the applicability of Kampo medicines to viral diseases.
Thermal Fatigue Characteristics of Type 309 Austenitic Stainless Steel for Automotive Manifolds
Authors: Zhan Jianming , Li Moucheng , Huang Junxia , Bi Hongyun , Li Qian , Gu Hui
Published: January 2019

The thermal fatigue behavior of type 309 austenitic stainless steel was investigated by cyclic tests ranged from 100 °C to the maximum temperatures 800 and 900 °C. The microstructures of the specimens were characterized by optical microscope, scanning electron microscope and X-ray diffraction. With changing the maximum temperature from 800 to 900 °C, the stainless steel exhibits much lower strength, higher elongation and a decrease of fatigue life about 56.6%. After the thermal fatigue failure, the specimens show micro-void coalescence fractures caused by the creep during the holding period at the maximum temperatures, and the quasi-cleavage feature also appears in the case of the maximum temperature 800 °C. During the thermal fatigue processes, the cavities usually form at the grain and twin boundaries, facilitating the initiation and growth of cracks. Furthermore, the high-temperature oxidation produces oxides on the specimen surfaces and in the cracks, deteriorating thermal fatigue properties. With an increase in the maximum temperature, the enhanced synergetic effect of strength, grain size, creep and oxidation is responsible for the accelerated fatigue failure of 309 stainless steel during the thermal cycles.
Strain Behavior of Nickel Alloy 200 during Multiaxial Forging through Finite Element Modeling
Authors: Djavanroodi Faramarz , Hussain Zahid , Irfan Osama M. , Al-Mufadi Fahad
Published: January 2019

Multiaxial forging (MAF) is one of the appealing methods of severe plastic deformation (SPD) techniques to fabricate ultrafine-grained (UFG) materials. In this study; the influence of process parameters such as strain rate; friction; and initial temperature has been assessed through finite element simulation of Nickel 200 alloy. The Johnson–Cook equation was applied in simulating the MAF process. The homogeneous microstructure of a material processed by MAF is an important requirement to obtain uniform mechanical and other properties. The uniformity in properties was evaluated by the investigation of the hardness measurements; effective strain (ES), and inhomogeneous factor (IF) or coefficient of standard deviation. The results showed that the inhomogeneous factor decreases with an increase in strain rate and decrease in temperature. It was found that a more homogeneous structure is observed with an increasing number of MAF cycles and the strain rate strain. Furthermore; the average grain size reduced from 850 nm to 220 nm after three cycles of MAF. Finally; experimental work was performed to validate the results.
Surface Integrity of Laser Beam Welded Steel–Aluminium Alloy Hybrid Shafts after Turning
Authors: Nothdurft Sarah , Prasanthan Vannila , Denkena Berend , Breidenstein Bernd , Grove Thilo , Ohrdes Hendrik , Twiefel Jens , Wallaschek Jörg , Hassel Thomas , Hermsdorf Jörg , Overmeyer Ludger , Kaierle Stefan
Published: January 2019

The demands for high-performance solid components are constantly increasing. The reason for this development are the steadily growing requirements such as weight reduction, higher resistance to load stresses, and more functional integration. By using material compounds, for example high-strength steel and aluminium alloy, hybrid massive components, whose properties are specially adapted to the specific application, can be manufactured. The first challenge is the joining of two dissimilar materials like steel and aluminium alloy by laser beam welding. In particular, the formation of hard and brittle intermetallic phases (IMP) has a high influence on the mechanical properties of the joining zone. The second challenge is to examine the machinability of such dissimilar compounds. The machining process is mandatory in order to reach an adequate level of accuracy of shape and dimensions. Furthermore, the functionalization of the hybrid compounds will be realized with the machining process where required surface roughness and lifetime-determining residual stresses are adjusted. Connections between induced residual stresses and material properties have been investigated. A significant influence of machining parameters on the surface and subsurface properties is evident. In particular, the cutting edge rounding has a deep impact on the residual stresses as well as on surface roughness.
Numerical Simulation Analysis of Dual-Beam Laser Welding of Tailored Blanks with Different Thicknesses
Authors: Zhang Xinge , Li Liqun , Chen Yanbin , Zhu Xiaocui , Ji Shijun
Published: January 2019

In order to meet the requirements of alignment capability, gap tolerance and welding track control, dual-beam laser welding has been put forward to weld tailored blanks with different thicknesses. The arrangement mode and power ratio of dual-beam laser determine the heat transfer and temperature field distribution, and then influence the weld profile and weld quality. In this study, based on consideration of the temperature dependence of material physical properties, convection and radiation heat transfer, and material latent heat, the finite element model was developed. The model validated was conducted to compare with experimental results and it showed good agreement. The arrangement mode and power ratio of dual-beam laser welding were compared and optimized based on the consideration of the weld width on top surface and gap tolerance. Finally, the temperature field characteristics with the preferable process were analyzed in detail according to the numerical simulation. The calculated results indicated the weld width is mainly controlled by the laser irradiation on the thin plate, and dual-beam laser welding of tailored blanks has great advantages on improving heat transfer, weld profile and gap tolerance, which helps to reduce welding defects and enhance welding quality.
Effect of Small Additions of Cr, Ti, and Mn on the Microstructure and Hardness of Al–Si–Fe–X Alloys
Authors: Aranda Víctor A. , Figueroa Ignacio A. , González Gonzalo , García-Hinojosa J. Alejandro , Lara-Rodríguez Gabriel A.
Published: January 2019

The Al–Si–Fe system has drawn the attention of the scientific community due to its capacity to replace parts in several manufacturing industries, as this alloy system is very sensitive to small additions of transition metals. Therefore, the aim of this work is to study the effect of Cr, Ti, and Mn additions in the Al–20Si–5Fe (wt. %) alloy and to study the modification of the iron intermetallic and the microstructural refinement through the formation of secondary phases. Al–20Si–5Fe–X (X = Cr, Mn and Ti at 1.0, 3.0, and 5.0 wt. %) alloy ingots were prepared by arc melting furnace. The elemental chemical analysis was performed by X-ray fluorescence spectrometry (XRF). The microstructure of all samples was investigated by scanning electron microscopy and X-ray diffraction. Finally, microhardness was measured in order correlate the hardness with the formation of the different compounds. The highest hardness was found for the alloy with the 5 wt. % Cr. The addition of Ti and Mn raised the hardness by ~35 HVN (Vickers microhardness) when compared to that of AlSiFe master alloy. Important changes were also observed in the microstructure. Depending on the Cr, Ti, and Mn additions, the resulting microstructure was dendritic (CrFe), acicular (Ti5Si3), and “bone like” (Mn0.2Fe0.8), respectively.
Metallic Additive Manufacturing: Design, Process, and Post-Processing
Authors: Gibson Ian , Khorasani Amir Mahyar
Published: January 2019

The first modern additive manufacturing machines, developed in the early 1990s, primarily made parts using polymers [...]
Combined Effects of Deformation and Undercooling on Isothermal Bainitic Transformation in an Fe-C-Mn-Si Alloy
Authors: Zou Hang , Hu Haijiang , Xu Guang , Xiong Ziliu , Dai Fangqin
Published: January 2019

Both ausforming and transformation temperature affect the successive bainitic transformation and microstructure. The individual influence of each case is clear, whereas the combined effects are still unknown. Thermomechanical simulation and metallography were used to investigate the combined effects of ausforming and transformation temperature on bainitic transformation and microstructure. The kinetics of isothermal bainitic transformation in non-deformed and deformed materials was analyzed. A lower transformation temperature can lead to more bainite formation without deformation. However, ausforming with small strains can partially compensate for the decrease of bainite amount caused by the decreased undercooling. The larger the applied strain is, the smaller the difference between the final amounts of bainite with different undercooling. Ausforming at a relatively higher temperature is more favorable to the acceleration of subsequent isothermal bainitic transformation. The results in the present work provide reference for optimizing the fabrication technology of medium-carbon nanobainite steels.
Wear Behavior of CuSn Coated Piston Ring Sliding against Nodular Cast Iron Cylinder Liner under Heavy-Duty Conditions
Authors: Li Wenhua , Yu Baihong , Lv Yutao , Shen Yan , Huang Ruoxuan , Du Fengming
Published: January 2019

In order to investigate the friction and wear behavior between the nodular cast iron cylinder liner (Fe) and CuSn coated piston ring under heavy-duty conditions, piston rings with chromium(Cr) coating and CuSn-Cr coating were tested using the piston ring reciprocating liner test rig at the simulated working conditions of 56 MPa, 200 r/min, 190 °C. Compared with the Cr/Fe pair, the CuSn coating consumption of the CuSn-Cr/Fe pair made friction coefficient and cylinder wear loss decrease by 2.8% and 51.5%, respectively. Different size Sn patches worn from the CuSn coated piston ring were embedded into the cylinder liner surface based on the surface topography. This process was shown to reduce the surface roughness of a cylinder liner and form flatter plateau structures. Chemical elements analysis indicated that plateau structures on the cylinder liner surface matched with CuSn-Cr coated ring are helpful to promote the tribo-chemical reaction and generate the reactive products to protect the mutually contacted asperities.
Strengthening Al-Zn-Mg Alloys via Ultra-Fine Lamella Structures Containing a High Density of Dislocations and Clusters
Authors: Qin Yonggui , Lin Sicong , Jin Shenbao , Liu Jizi
Published: January 2019

A new method of thermo-mechanical processing has been designed by introducing pre-aging before general cold rolling for an Al-Zn-Mg alloy. This process results in an increase of 200 MPa in yield strength compared to that of the peak-aged samples. The microstructures were examined by transmission electron microscope and X-ray diffraction. It has been found that the enhanced strength is mainly contributed to by ultra-fine lamella structures containing a high density of dislocations pinned by nanoprecipitates. Extra strength is provided by the “interlocking” of precipitates and dislocations. Fractographic features analysis shows that crack propagation along the interface of the lamella structures is the direct reason for resulting in fracture, due to intra-granular strength exceeding grain boundary cohesion.
Inconel 625/TiB2 Metal Matrix Composites by Direct Laser Deposition
Authors: Promakhov Vladimir , Zhukov Alexander , Ziatdinov Mansur , Zhukov Ilya , Schulz Nikita , Kovalchuk Sergey , Dubkova Yana , Korsmik Rudolf , Klimova-Korsmik Olga , Turichin Gleb , Perminov Anton
Published: January 2019

This work presents results in the field of synthesis of new metal matrix composites with matrix NiTi and particles TiB2, and their use as additives to fabricate metal matrix composites based on the Inconel 625 alloy. NiTi-TB2 powders were obtained using self-propagating high-temperature synthesis. Composite NiTi-TiB2 particles were spheroidized on a high-frequency induction plasmatron. Composite NiTi-TB2 particles were mixed with metallic Inconel 625 powder with particle sizes of 50–150 µm. We used direct laser deposition by means of mixture of powders to grow samples with different contents of ceramics in the metal matrix. The process of direct laser deposition during the experiment was investigated. We have determined the peculiarities of the formation of the structure in metal matrix composites with different contents of titanium diboride. We have demonstrated the possibility of using Direct Laser Deposition (DLD) for fabricating items from ceramic metal materials. We have determined promising fields of further research for the purpose of obtaining efficient metal matrix composites using additive manufacturing technologies.
Fatigue Limit Improvement and Rendering Defects Harmless by Needle Peening for High Tensile Steel Welded Joint
Authors: Fueki Ryutaro , Takahashi Koji , Handa Mitsuru
Published: January 2019

The effects of needle peening (NP) on the bending fatigue limit of a high tensile steel (HTS) HT780 (JIS-SHY685)-welded joint containing an artificial semicircular slit on the weld toe were investigated. Three-point bending fatigue tests were conducted at a stress ratio of R = 0.05 for NP-treated welded specimens with and without a slit. The fatigue limits of all specimens increased by 9–200% due to the NP treatment. Furthermore, NP-treated specimens with slit depths of a = 1.0 mm exhibited high fatigue limits that were equal to those of NP-treated specimens without a slit. Therefore, a semicircular slit of less than a = 1.0 mm could be rendered harmless through NP treatment. This result indicates that the reliability of HTS-welded joints can be significantly improved via NP for surface defects with depths that are less than 1 mm, which are not detected through non-destructive inspection (NDI). Therefore, the problem regarding the reliability of HTS-welded joints that restricts the industrial utilization of HTS can be solved by performing both NDI and NP. The dominant factor that contributed to the improvement of the fatigue limit and increase in the acceptable defect size was the introduction of large and deep compressive residual stress with non-propagating cracks.
High-Velocity Impact Welding Process: A Review
Authors: Wang Huimin , Wang Yuliang
Published: January 2019

High-velocity impact welding is a kind of solid-state welding process that is one of the solutions for the joining of dissimilar materials that avoids intermetallics. Five main methods have been developed to date. These are gas gun welding (GGW), explosive welding (EXW), magnetic pulse welding (MPW), vaporizing foil actuator welding (VFAW), and laser impact welding (LIW). They all share a similar welding mechanism, but they also have different energy sources and different applications. This review mainly focuses on research related to the experimental setups of various welding methods, jet phenomenon, welding interface characteristics, and welding parameters. The introduction states the importance of high-velocity impact welding in the joining of dissimilar materials. The review of experimental setups provides the current situation and limitations of various welding processes. Jet phenomenon, welding interface characteristics, and welding parameters are all related to the welding mechanism. The conclusion and future work are summarized.
Elastic Properties of FeCr20Ni8Xn (X = Mo, Nb, Ta, Ti, V, W and Zr) Austenitic Stainless Steels: A First Principles Study
Authors: Dou Yuchen , Luo Hong , Zhang Jing
Published: January 2019

Austenitic stainless steels suffer from intergranular corrosion and stress corrosion cracking when exposed to elevated temperature (500–800 °C). Under these environments, Cr-carbides and Cr-carbontrides precipitate at the grain boundaries, which results in the formation of Cr-depleted zone. In practice, alloying elements could be added into austenitic stainless steels to modify the precipitation processes. Besides the precipitation processes, the elastic properties of the iron matrix would be influenced. Using the exact muffin-tin orbitals (EMTO) method, the solute effects on the elastic properties of FeCr20Ni8 austenitic stainless steels were studied. Based on the simulated shear modulus (G) and bulk modulus (B), we proposed a design map for FeCr20Ni8 based alloys, aiming to provide a basis for the design of high-performance austenitic stainless steels.
A Fast Method for Predicting the Mechanical Properties of Precipitation-Hardenable Aluminum Alloys
Authors: Toenjes Anastasiya , von Hehl Axel
Published: January 2019

Most heat treatment simulations of precipitation-hardenable aluminum alloys are incomplete or restricted to sub-steps of the process chain. In general, the studies addressing the heat treatment of aluminum components have only provided a qualitative guidance of heat treatment, which does not match the heat treatment that is necessary for specific parts with specific requirements. Thus, a quick and accurate simulation of the whole heat treatment process would hold great economic benefit for industrial applications in predicting suitable heat treatment processes that are able to meet the required mechanical properties of proposed novel aluminum components. In this paper, the development of a time and cost efficient method for generating such prediction models is presented by means of an example aluminum alloy EN AW-6082. During the process sub-steps of solution annealing, quenching and aging, the time-temperature correlations connected to the precipitation-hardening conditions were analyzed. The precision of the prediction model depends on the size of the material database, which should be able to be adjusted to the individual requirements of the simulation user. In order to obtain the greatest time and cost efficiency in generating such a model, a specific experimental design was developed. The results of the method development are presented and discussed.
Comparative Investigation on the Ablation of Uncoated and Coated Mild Steel Inflicted by the 2 ms 2 kA Rectangular Current
Authors: Dai Mingqiu , Liu Yakun , Fu Zhengcai , Liu Juan , Bi Xiaolei
Published: January 2019

The micro ablation characteristics of steel inflicted by the lightning currents and the influence of anti-corrosion coating on these characteristics are seldom investigated, even though fundamental to applications of steel. In this work, ablation tests on uncoated and coated mild steel plates were conducted with the 2 ms rectangular current simulating the component B of lightning currents. The macro-morphology, microstructure, and Vickers hardness of ablation zones were investigated systematically. The ablation characteristics and mechanisms of coated and uncoated steel were analyzed comparatively. It was found that the energy density of the 2 kA 2 ms rectangular current arc exceeded 106 W/cm2 causing the steel near the arc root melted within 2 ms and ablation formed. The width-depth-ratio of the ablated zone was 43.7 for uncoated plate, and only 7.5 for coated plate, since coating constricted the splashing effect of steel melt occurring on uncoated plate and confined the arc root. The metallographic microstructure and EBSD results showed the ablated zones of uncoated and coated steel both consisted of quenched martensite mixed with a handful of ferrite. There were fined equiaxed grains both in the fusion zone (FZ) and heat affected zone (HAZ) of uncoated plates whereas coarser columnar grains and fined equiaxed grains in the FZ and HAZ of coated plates, respectively. In the HAZ of uncoated plate, the average Vickers hardness of steel increased by 113%, while, in the HAZ and FZ of the coated plate, it increased by 209% and 136%, respectively.
Effect of SiO2 on the Mechanical Property and Reduction of Calcium Ferrite
Authors: Yang Daiwei , Wang Wei , Xu Runsheng , Li Jingxuan , Song Mingming
Published: January 2019

SiO2-Fe2O3-CaO (SFC) is believed to be the transition phase during the SiO2-Fe2O3-CaO-Al2O3 (SFCA) formation process. The effect of SiO2 on the mechanical property and reduction of the CaO-Fe2O3-SiO2 system was inspected in this study. Experiments were carried out under air at 1200 °C with different amounts of SiO2 mixed with Fe2O3 and CaO. The mechanical properties and reduction of samples were studied. Results indicate that the hardness of samples gradually increases with the increase of SFC content. That may be caused by SiO2 solid solution in calcium ferrite. The larger the amount and smaller size of acicular calcium ferrites in samples, the greater the fracture toughness. The solid solution of SiO2 in calcium ferrite is beneficial to decrease the initial reduction temperature. The apparent activation energy values of the samples with the different content of SiO2 from 0% to 5% are 167.23, 84.36, 87.90, 96.02, 92.44 and 107.83 kJ·mol−1, respectively. The microstructure of lump samples after reduction consists of four phases, i.e., CF (CaFe2O4), SFC, calcio-wüstite (CW) and Fe. It was not difficult to find the Fe in the samples reduced from CW. Scanning electron micrograph images have revealed that the acicular-like calcium ferrites are more easily reduced than the platy-like ones.
Measurement and Time Response of Electrohydrodynamic Direct-Writing Current
Authors: Zheng Gaofeng , Xue Wendong , Chen Huatan , Sun Lingling , Jiang Jiaxin , Wang Xiang , Guo Shumin , Li Wenwang
Published: January 2019

The micro/nano current is an important characteristic to reflect the electrohydrodynamic direct-writing (EDW) process. In this paper, a direct-written current measurement system with a high signal to noise ratio was proposed to monitor the charged jets, providing the data basis for the promotion of stability and precision of the EDW jet. The electrical characteristics of the printing process were studied, the electrohydrodynamic direct-written current was associated with the stability of charged jet and the accuracy of direct-written patterns. There was an impulse current when the front end of the jet reached the collector and then a stable jet could be gained. With the increase of applied voltage, the severe fluctuation of measured current increased, the charged jet became more unstable and the accuracy of direct-written parallel lines was lower. The effects of processing parameters on direct-written current were also investigated. The average direct-written current at the stable stage increased as the applied voltage and polymer concentration increased, and it decreased as the distance from the nozzle to the collector increased. This research will promote the development and applications of EDW technology in the fields of micro/nano manufacturing.
Simultaneous Pumping and Mixing of Biological Fluids in a Double-Array Electrothermal Microfluidic Device
Authors: Salari Alinaghi , Dalton Colin
Published: January 2019

Transport and mixing of minute amounts of biological fluids are significantly important in lab-on-a-chip devices. It has been shown that the electrothermal technique is a suitable candidate for applications involving high-conductivity biofluids, such as blood, saliva, and urine. Here, we introduce a double-array AC electrothermal (ACET) device consisting of two opposing microelectrode arrays, which can be used for simultaneous mixing and pumping. First, in a 2D simulation, an optimum electrode-pair configuration capable of achieving fast transverse mixing at a microfluidic channel cross-section is identified by comparing different electrode geometries. The results show that by adjusting the applied voltage pattern and position of the asymmetrical microelectrodes in the two arrays, due to the resultant circular flow streamlines, the time it takes for the analytes to be convected across the channel cross-section is reduced by 95% compared to a diffusion-only-based transport regime, and by 80% compared to a conventional two-layer ACET device. Using a 3D simulation, the fluid transport (pumping and mixing) capabilities of such an electrode pair placed at different angles longitudinally relative to the channel was studied. It was found that an asymmetrical electrode configuration placed at an angle in the range of 30 ° ≤ θ ≤ 45 ° can significantly increase transversal mixing efficiency while generating strong longitudinal net flow. These findings are of interest for lab-on-a-chip applications, especially for biosensors and immunoassays, where mixing analyte solutions while simultaneously moving them through a microchannel can greatly enhance the sensing efficiency.
Nano-Graphitic based Non-Volatile Memories Fabricated by the Dynamic Spray-Gun Deposition Method
Authors: Bondavalli Paolo , Martin Marie Blandine , Hamidouche Louiza , Montanaro Alberto , Trompeta Aikaterini-Flora , Charitidis Costas A.
Published: January 2019

This paper deals with the fabrication of Resistive Random Access Memory (ReRAM) based on oxidized carbon nanofibers (CNFs). Stable suspensions of oxidized CNFs have been prepared in water and sprayed on an appropriate substrate, using the dynamic spray-gun deposition method, developed at Thales Research and Technology. This technique allows extremely uniform mats to be produced while heating the substrate at the boiling point of the solvent used for the suspensions. A thickness of around 150 nm of CNFs sandwiched between two metal layers (the metalized substrate and the top contacts) has been achieved, creating a Metal-Insulator-Metal (MIM) structure typical of ReRAM. After applying a bias, we were able to change the resistance of the oxidized layer between a low (LRS) and a high resistance state (HRS) in a completely reversible way. This is the first time that a scientific group has produced this kind of device using CNFs and these results pave the way for the further implementation of this kind of memory on flexible substrates.
Modeling the AC Electrokinetic Behavior of Semiconducting Spheres
Authors: García-Sánchez Pablo , Flores-Mena Jose Eladio , Ramos Antonio
Published: January 2019

We study theoretically the dielectrophoresis and electrorotation of a semiconducting microsphere immersed in an aqueous electrolyte. To this end, the particle polarizability is calculated from first principles for arbitrary thickness of the Debye layers in liquid and semiconductor. We show that the polarizability dispersion arises from the combination of two relaxation interfacial phenomena: charging of the electrical double layer and the Maxwell–Wagner relaxation. We also calculate the particle polarizability in the limit of thin electrical double layers, which greatly simplifies the analytical calculations. Finally, we show the model predictions for two relevant materials (ZnO and doped silicon) and discuss the limits of validity of the thin double layer approximation.
The Purple Sea Urchin Strongylocentrotus purpuratus Demonstrates a Compartmentalization of Gut Bacterial Microbiota, Predictive Functional Attributes, and Taxonomic Co-Occurrence
Authors: Hakim Joseph A. , Schram Julie B. , Galloway Aaron W. E. , Morrow Casey D. , Crowley Michael R. , Watts Stephen A. , Bej Asim K.
Published: January 2019

The sea urchin Strongylocentrotus purpuratus (order Camarodonta, family Strongylocentrotidae) can be found dominating low intertidal pool biomass on the southern coast of Oregon, USA. In this case study, three adult sea urchins were collected from their shared intertidal pool, and the bacteriome of their pharynx, gut tissue, and gut digesta, including their tide pool water and algae, was determined using targeted high-throughput sequencing (HTS) of the 16S rRNA genes and bioinformatics tools. Overall, the gut tissue demonstrated Arcobacter and Sulfurimonas (Epsilonproteobacteria) to be abundant, whereas the gut digesta was dominated by Psychromonas (Gammaproteobacteria), Propionigenium (Fusobacteria), and Flavobacteriales (Bacteroidetes). Alpha and beta diversity analyses indicated low species richness and distinct microbial communities comprising the gut tissue and digesta, while the pharynx tissue had higher richness, more closely resembling the water microbiota. Predicted functional profiles showed Kyoto Encyclopedia of Genes and Genomes (KEGG) Level-2 categories of energy metabolism, membrane transport, cell motility, and signal transduction in the gut tissue, and the gut digesta represented amino acid, carbohydrate, vitamin and cofactor metabolisms, and replication and repair. Co-occurrence network analysis showed the potential relationships and key taxa, such as the highly abundant Arcobacter and Propionigenium, influencing population patterns and taxonomic organization between the gut tissue and digesta. These results demonstrate a trend of microbial community integration, allocation, predicted metabolic roles, and taxonomic co-occurrence patterns in the S. purpuratus gut ecosystem.