Showing papers in "Advanced Materials Research in 2017"

Nonlinear Ultrasonic Properties of Stress in 2024 Aluminum

Abstract: Perturbation method is used to resolve one-dimensional wave equation under the assumption of small strain conditions. The relationship of the second order relative nonlinear coefficients (SORNC) β', the third order relative nonlinear coefficient (TORNC) δ' as the functions of fundamental and harmonic amplitudes is determined. The specimens are loaded from-200 MPa to 320 MPa at increments of 40 MPa by the electron universal testing machines. The SORNC β' and TORNC δ' are detected by the nonlinear ultrasonic testing system when ultrasonic waves propagate in the specimens. Results show that the relative nonlinear coefficients increase with the stress. The SORNT β' is approximately linear with the stress when stress is lower than 84.6% of the yield strength. The TORNC δ' is approximately linear with the stress when stress is lower than 76.9% of the yield strength.

Influence of the Honeycomb Geometry on the Sandwich Composite Plate Behavior

Abstract: In this paper the influence cell honeycomb geometry on the mechanical behaviour of a composite sandwich plate is analyzed. Three cell geometries (circular, hexagonal and square) are static analysed so that to select the best type of honeycomb that will be used in the manufacturing the sandwich plate core. The main aim is to develop approach models of equivalent orthotropic materials to replace the real model of honeycomb core with their properties so that to quickly calculate the sandwich plate made out of composite when is used a finite element analysis code. Geometry and material properties of the honeycomb are delivered by the material provider. Comparative analysis, by using Finite element analysis is performed for all geometries, in the same boundary conditions. Since in the impact loading of the composite sandwich plate the core is mainly loaded to compression, comparative study of the three cell geometries honeycomb was performed for this type of compressive loading. Since the cell is the basic element of the honeycomb core, the calculus is performed for one unit volume of sandwich, concerning also the part of skins.

Damping Properties of Magnetorheological Elastomers

Abstract: Magnetorheological elastomers (MREs) are a kind of smart materials, which change the mechanical properties (viscoelastic characteristics) under the magnetic field action. In the paper the determination of damping properties (reactive force) of specimens made out of magnetorheological elastomers is presented. The specimens made out of MREs have been fabricated as a composite with matrix made out of silicone rubber with certain contents of magnetisable particles (carbonyl iron powder). The cylindrical specimens have been tested in compression loading, controlled by an electro-mechanic system. The MRE characteristics of the specimens have been determined in the presence of a magnetic field produced with an electromagnet (coil device). The reactive force occurring in the MRE specimen has been determined on the basis of the measured data during loading. The variation curves of the reactive force versus magnetic field induction are drawn. As a conclusion, the rigidity of the MRE specimen is increasing since the magnitude of the magnetic field induction is increasing.

Wettability in Aluminium-Graphite Particles Composites (Review)

Abstract: The paper presents some aspects regarding the wetting conditions in aluminium – graphite composite. The wettability depends on several factors like the presence of the oxide skin at the melt surface, formation Al4C3 at the interface between Al and particles, temperature, pressure etc. In this paper, the conditions of perfect wettability of carbon by molten Al achieved under MCl–K2TiF6 molten salts (fluxes), alloying of the melt with surface active elements, heat treatment of reinforcement material and coating of the particles with a metallic thin layer.

Microwave Absorption Properties of BaFe12O19 Prepared in Different Temperature with Polyaniline Nanocomposites

Abstract: The BaFe12O19 nanoparticles was prepared by sol-gel method in different temperature (750°C,850°Cand 950°C), and then BaFe12O19/polyaniline nanocomposites was synthesized by in situ polymerization. The XRD, FTIR spectra, SEM and vector network analyzer were used to analyze the "" chemical component, morphology and microwave absorption property of the nanocomposites. The result show that BaFe12O19 can be generated at 750°C without any impurity ,and its size increased with increase of calcination temperature.BaFe12O19 nanoparticle was coated with polyaniline partially, and we can get it have interaction with polyaniline through FTIR spectra. While the ferrite calcined at 850°C,the thickness of the absorbing material is 4.5mm,the nanocomposites have the largest reflection loss of-17.6 dB at 6 GHz,and its reflection loss values less than−10 dB in the range of 5-7.4GHz.

Flexural and Compressive Strength of the Cement Paste with Recycled Concrete Powder

Abstract: In previous work focused on using recycled concrete powder as cement replacement the basic dependency of the mechanical properties on the amount of recycled concrete powder was defined. Influence of the amount of recycled concrete powder on the flexural and compressive strength was shown on 0, 33, 67 and 100 wt. % cement replacement. Based on the previous data the strength properties of the cement paste with recycled concrete powder below 33 wt. % was almost constant and strength properties were comparable with reference sample made of cement only. After the recycled concrete powder in cement paste exceeded amount of 33 wt. % the flexural and compressive strength decrease rapidly. In case of 67 wt. % amount of recycled concrete powder the compressive strength decrease about 65 %. The aim of this article is define critical amount of recycled concrete powder in cement paste when strength properties start decrease rapidly and cement replacement is no longer beneficial. This critical amount will be located somewhere between 30 and 50 wt. % of recycled concrete powder. Replacement below critical amount could lead to cost reduction of cement composites and also the negative impact of the cement production and concrete disposal on environmental could be reduced.

Machining of SiCp/Al Composites: Effect of Tool Corner Radius on Residual Stresses, Cutting Force and Temperature

Abstract: SiCp/Al composite is widely used in the aerospace, electronics and automobile industries due to its ultrahigh strength and wear resistance. Surface integrity in the machining process can be influenced by tool corner radius. A finite element model is developed by DEFORM-2D to study on the effect of tool corner radius on residual stresses, cutting force and temperature in machining SiCp/Al composite process. The results show the large corner radius can improve cutting force, but hardly influence cutting temperature. Meanwhile, value of residual stresses is influenced by tool corner radius, but distribution of residual stress is not. The larger corner radius is, the greater the curve fluctuation of residual stresses is. And the large tool corner radius can effectively improve surface residual compressive stress.

Stress-Strain Behavior of an Octahedral and Octet-Truss Lattice Structure Fabricated Using the CLIP Technology

Abstract: In the rapidly growing field of additive manufacturing (AM), the focus in recent years has shifted from prototyping to manufacturing fully functional, ultralight, ultrastiff end-use parts. This research investigates the stress-strain behavior of an octahedral-and octet-truss lattice structured polyacrylate fabricated using Continuous Liquid Interface Production (CLIP) technology based on 3D printing and additive manufacturing processes. Continuous Liquid Interface Production (CLIP) is a breakthrough technology that grows parts instead of printing them layer by layer. Lattice structures such as the octahedral-and octet-truss lattice have recently attracted a lot of attention since they are often structurally more efficient than foams of a similar density made from the same material, and the ease with which these structures can now be produced using 3D printing and additive manufacturing. This research investigates the stress-strain behavior under compression of an octahedral-and octet-truss lattice structured polyacrylate fabricated using CLIP technology

Mechanical Behaviour of Welded Joints Achieved by Multi-Wire Submerged Arc Welding

Abstract: The paper addresses the development of advanced welding technologies with two and three solid wires for joining of HSLA API-5l X70 (High-strength low-alloy) steel plates with thickness of 19.1 mm. The experiments were performed using a multi-wire Submerged Arc Welding (SAW) system that was developed for welding of steels with solid, tubular and cold wires, in different combinations. The main goal of the research was to assess the mechanical performances of the welded joints achieved by multi-wire SAW technology and then to compare them with the single wire variant, as reference system. The welded samples were firstly subjected to NDT control by examinations with liquid penetrant, magnetic particle, ultrasonic and gamma radiation, with the aim of detecting the specimens with flaws and afterwards to reconsider and redesign the corresponding Welding Procedure Specifications (WPS). The defect-free welded samples were subjected to tensile, Charpy V-notch impact and bending testing in order to analyse and report the mechanical behaviour of API-5l X70 steel during multi-wire SAW process. The experimental results were processed and comparatively discussed. The challenge of the investigation was to find the appropriate welding technology which responds simultaneously to the criteria of quality and productivity. Further research on metallurgical behaviour of the base material will be developed, in order to conclude the complete image of the SAW process effects and to understand how the multi-wire technologies affect the mechanical and metallurgical characteristics of the API-5L X70 steel used in pipelines fabrication.

Pyrolysis Behaviour of Boron Phenolic Resin-Based Ceramicable Composites by Introducing of MgO-Al2O3-SiO2

Abstract: Ceramifying composites based on boron phenolic resin (BPF) were prepared with the modification additives of nanoMgO-Al2O3-SiO2 (MAS). The effects of fillers on the thermal stability of BPF-based composites were investigated. MAS inorganic fillers could enhance the heat-resistance with a high residue yield and a near-net shape at elevated temperature. The effect of elevated temperature on microstructure and phase composition of composites was also characterized by scanning electron microscope (SEM) and X-ray diffraction analyses (XRD) when samples were heated at 600°C, 800°C, 1000°C and 1200°C respectively. SEM showed the presence of the skin and compact ceramic structure formation, more pronounced at higher temperature. XRD patterns manifested that the formation of new phases (main glass phase) in 1200°C stemmed mainly from the reaction between the porous activated carbon from the decomposed resin matrix and MAS fillers.

Fe-Doped ZnO Nanoparticles: Structural, Morphological, Antimicrobial and Photocatalytic Characterization

Abstract: Oxide semiconductors have attracted increasing interest due to their potential in solving environmental problems. ZnO-based nanoparticles (NPs) are among the most investigated for efficient disinfection and microbial control.Iron-doped zinc oxide nanoparticles (Fe:ZnO NPs) were successfully fabricated through precipitation method at low temperature followed by thermal treatment. The obtained Fe:ZnO NPs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and ultraviolet-visible (UV–Vis) spectroscopy. The effect of iron content on structural, morphological, antimicrobial and photocatalytic properties was investigated and discussed.The photocatalytic activity of the nanoparticles was tested by degradation of methylene blue (MB) solution under UV light for 60 min irradiation. The antibacterial activity was determined by paper disc method on Mueller-Hinton agar against the Gram-negative bacteria Escherichia coli (E. coli) and the Gram-positive bacteria Staphylococcus aureus (S. aureus) and compared to that of the undoped ZnO NPs. Consistent improvement on the photocatalytic and antimicrobial activity of Fe-doped ZnO nanoparticles was noticed.

Microstructure and Wear Resistance of FeNiCrMnCu High Entropy Alloy

Abstract: In this paper it is presented the microstructure and wear resistance of FeNiCrMnCu high entropy alloy. High entropy alloys are composed by at least five metallic elements in equimolar or non-equimolare proportions. High entropy alloys a brand new category of metallic materials, appeared to be a new effort in materials science and engineering, which attracted great interest. To obtain FeNiCrMnCu high entropy alloy we used an 8000 Hz induction furnace. The chemical composition was determined by EDAX. Microstructural analysis was performed using optical microscopy and SEM (scanning electron microscopy), which showed that the FeNiCrMnCu high entropy alloy has a dentritic structure and form a solid solution. Choosing copper as the main element (copper tends to segregate in interdentritic region due to its positive enthalpy of mixing with many common elements) [1], along with the iron, nickel, chromium and manganese, led to obtaining a dentritic structure specify for solid solution, which, however, did not lead to a significant hardness for FeNiCrMnCu high entropy alloy. In this work we selected pure metallic elements like: Fe, Ni, Cr, Mn and Cu. The quantity of alloy developed has 1.5 kg. Friction and wear resistance were the studied by using a reciprocating sliding test machine, in a pin on disk configuration, using aluminum as counter face. Hardness value regarding FeNiCrMnCu high entropy alloy was 184 HV and medium friction coefficient value for FeNiCrMnCu high entropy alloys was 0.86 for 28 minutesc and 1.13 for the first 20 seconds.

Preparation and Properties of Ethylene Propylene Diene Rubber/SiO2/Carbon Nanotubes Composites

Abstract: This paper studies how the addition of Carbon nanotubes (CNT) influencing the properties, especially the mechanical properties and colorimetry of ethylene propylene diene rubber (EPDM)/SiO2 composites. The results show that the increased content of CNT can turn EPDM/SiO2 composites from lighter, redder, and yellower to darker, greener and bluer, respectively. The total color change (ΔE) of EPDM/SiO2 composites would be acceptable when the CNT content is below 3%. When the CNTs content reaches 4%, the tensile strength of EPDM is the maximum.

Intercalation of Fenoprofen into Layered Double Hydroxide for the Formation of Controlled Release Anti-Inflammatory Drug

Abstract: Synthesis of a new hybrid nanocomposite materials, zinc-aluminium-fenoprofen, ZAF was successfully accomplished by self-assembly method with molar ratio of Zn to Al; R=2 at concentration of fenoprofen=0.3 M. As a result of the successful intercalation, the interlayer spacing expanded from 9.8 A in the zinc-aluminium-layered double hydroxide, ZAL to 20.1 A in the ZAF hybrid nanocomposite. The FTIR spectra of the ZAF show resemblance peaks of ZAL and fenoprofen indicating the inclusion of the organic compound into the LDH interlamellae. The percentage loading of the guest anion, fenoprofen in ZAL was estimated to be about 63.4% (w/w) calculated from the carbon content.

Effect of Severe Plastic Deformation on the Structure and Magnetic Behaviour of an Fe-Mn-Si Shape Memory Alloy

Abstract: This work focuses on the relation between severe plastic deformation process via HSHPT and magnetic properties of an Fe–Mn–Si-Cr shape memory alloy. High speed high pressure torsion (HSHPT) was applied on cast state of alloy. Microstructure evolution of severe plastic deformed iron based alloy subjected to different deformation degree were investigated. The microstructure and phase compositions of alloy were characterized using optical microscopy, scanning electron microscopy and transmission electron microscopy. The magnetic properties are discussed on the basis of the severe plastic deformation process and the underlying martensitic transformation. Thermomagnetic curves, between 150 K and 390 K and magnetic hysteresis loops at 300 K temperatures were measured. The thermo-resistivity measurements were done by standard four-probe. The magnetic properties are interpreted and correlated with microstructure.

Dependence of Tensile Bending Strength of Rammed Earth on Used Clay Composition and Amount of Mixture Water

Abstract: Clay is a traditional construction material which has got to background with introduction of modern materials to building practice. There is not proper material available for clay constructions design due to a lack of proper examination of its mechanical properties. This article focuses on tensile bending strength of rammed earth. The mechanical properties depend on the amount of mixture water and on the amount and type of clay minerals. The clay minerals play role of the binder similarly like a cement in concrete. This paper is focused on the tensile bending strength and its dependence on the composition and quantity of clay mineral and its dependence on the amount of mixture water. Five earth mixtures were tested. Mechanical properties were examined on small test bodies made of these mixtures. The mechanical properties of the five mixtures are compared at the end of the paper.

Mechanical Properties of Cement Composite with Material Based on Waste Marble Powder and Crushed Limestone

Abstract: This paper deals with the use of waste materials from processing of stone in the construction industry. The tested mixtures consisted of Portland cement CEM I 42.5 R, micronized waste marble powder and crushed waste limestone. The article examines the effect of varying the amount of waste on the mechanical properties of the cement composite. At first, samples were tested non-destructively for determine the dynamic modulus of elasticity and then were tested destructively for determine tensile bending and compressive strength.

The Effect of Micronized Waste Marble Powder as Partial Replacement for Cement on Resulting Mechanical Properties of Cement Pastes

Abstract: This article was focused on the influence of the micronized waste marble powder on mechanical properties of cement pastes. Resulting blended cement was composed of Portland cement CEM I 42.5 R and micronized marble powder with different percentage amounts (0 wt. %, 5 wt. %, 10 wt. % and 15 wt. %). Testing was carried at prismatic samples of dimension 40 × 40 × 160 mm. The investigated mechanical properties were dynamic modulus of elasticity, dynamic shear modulus, flexural strength and compressive strength for the 28 days old samples. The results obtained from these materials were compared with reference material.

Quasicontinuum Method Combined with Anisotropic Microplane Model

Abstract: The quasicontinuum method (QC) is a multiscale simulation technique used in computational mechanics. The QC combines fast continuum and exact atomistic approaches. In the present work, the QC idea is applied to particle systems with elastic links representing the material microstructure. The material model based on the idea of microplanes is used to provide a continuous representation of microstructure. In the microplane model, the constitutive relations are defined on planes with various orientations and the macroscopic stress is obtained by integration over all possible directions of microplanes. But this approach do not work well in combination with the QC approach if the microplane orientations are assumed to be uniformly distributed. Therefore, an anisotropic version of the microplane model, which takes into account the specific directions of individual links, is proposed and implemented in finite element solver OOFEM. Accuracy and specific properties of QC-inspired approaches with different types of microplane models are evaluated by comparison with the fully resolved particle model.

Automatic Grain Size Determination in Microstructures Using Computer Vision Algorithm Based on Support Vector Machine (SVM)

Abstract: The properties of materials are identified as the results of its microstructures characteristics. Consequently the task of analysis of microstructure is very important in engineering. There are several methods such as the visual inspection and the semi-automatic inspection by image analysis. Visual inspection by an operator is subject to human error and can take important time. The semiautomatic method using specific algorithm and technique improves performance of the work, however still needs specific knowledge concerning image filters and image analysis technique. This research’s objectives are to present automatic image analysis algorithm to measure grains in microstructure images.

Role of Bulky Retained Austenite in Austempered Ductile Iron

Abstract: In this investigation, the characteristics of bulky retained austenite in an austempered ductile iron are evaluated in two tempered conditions. which were intially tempered at 200oC for 1h before cooling to room temperature, and then tempered at 350oC for 1h. The result shows that the hardness within retained austenite areas is distributed unevenly with a range from 423 HV to 897 HV, which is attributed to the transformation from austenite to martensite during austempering. Also, the mechanism regarding the quenched marteniste formation is discussed. The poor fatigue resistance of ADI is hypothesized to be due to the amount of austenite transformed to martensite.

An Experimental Research on Basic Properties of Ceramsite Cellular Concrete

Abstract: Ceramsite cellular concrete (CCC for short) is a kind of lightweight aggregate concrete. In this paper, the selection of materials and design of mix proportion have been discussed, and basic property tests has been done. The compressive strength was proved up to the National Standards of P. R. GB50003-2001(code for design of masonry structures), furthermore, elastic modulus and Poisson's ratio were also introduced. Questions remain regarding the quality control of the product, and further work is needed to resolve this contradiction.

Study on the Aging and Pore Structure of Hydraulic Concrete

Abstract: The aging of hydraulic concrete structure is a highly complicated problem. To reasonably evaluate the aging situation of a long-term operating concrete sluice, the core samples are obtained by field sampling from the sluice piers and the mercury injection experiment is carried out in this paper. The main objectives of this experimental investigation are to analyze the pore structure characteristics of the different parts in core samples and discuss the concrete aging rule of hydraulic concrete structure. The experimental results show that the aging of the hydraulic concrete has a certain relationship with the evolution of the concrete pore structure. It is feasible to use the pore structure of concrete to express the concrete aging of the hydraulic structure. The research in this paper will provide a basis for further study on the aging mechanism of the hydraulic concrete structure.

Effect of PTFE Content on Microstructure and Tribological Properties of Cu-Sn Coating

Abstract: The aim of this paper is to obtain the Cu-Sn-PTFE composite coating with wear-resistant and antifriction properties, which can improve the comprehensive performance of Cu-Sn coating and satisfy the self-lubricating property in special working condition. This coating was prepared by pulse current on the basis of non-cyanide pyrophosphate-stannate Cu-Sn plating bath. The effect of PTFE content on the microstructure, composition, microhardness, and tribological properties were analyzed and compared in detail. Results show that with appropriate PTFE content, the composite coating of Cu-Sn-PTFE displays preferable low friction and anti-wear behavior.

Preparation and Luminescent Properties of 0.1%Ce3+:BaF2 Laser Ceramics by Vacuum Sintering

Abstract: 0.1% Ce3+:BaF2 powders were prepared by coprecipitation method. Then the transparent ceramics were prepared by vacuum sintering. The effectts of sintering temperature and holding time on transparent ceramics were studied. The results show that the 0.1% Ce3+:BaF2 powders prepared by coprecipitation are approximately spherical with the size ranging from 200~300nm and good dispersion. The maximum light transmittance of the 0.1% Ce3+:BaF2 transparent ceramics reaches 69.2% when the sintering temperature is 1275°C. The fluorescence intensity of the transparent ceramics enhances with the increase of the sintering temperature. There are two characteristic f-f transition emission peaks at 610nm and 650nm when the excitation peak is at 290nm. The maximum transparency of 71.4% emerges when the holding time is 6h at 1275°C and the fluorescence intensity reaches the maximum. The 528nm (5D1→2F7/2) appears when excitated by the 524nm excitation light.

Adaptive Boundaries of Wang Tiles for Heterogeneous Material Modelling

Abstract: This contribution deals with algorithms for the generation of modified Wang tiles as a tool for the heterogeneous materials modelling. The proposed approach considers material domains only with 2D hard discs of both equal and different radii distributed within a matrix. Previous works showed potential of the Wang tile principles for reconstruction of heterogeneous materials. The main advantage of the tiling theory for material modelling is to stack large/infinite areas with relative small set of tiles with emphasis on a periodicity reduction in comparison with the traditional Periodic Unit Cell (PUC) concept. The basic units of the Wang Tiling are tiles with codes (colors) on edges. The algorithm for distribution of hard discs is based on the molecular dynamics to avoid particles overlapping. Unfortunately the nature of the Wang tiling together with molecular dynamics algorithms cause periodicity artefacts especially in tile corners of a composed material domain. In this paper a new algorithm with adaptive tile boundaries is presented in order to avoid edge and corner periodicity.

The Influence of the Deformation Degree on the Mechanical Properties and Microstructures of the Blanks Obtained by Tube and Wire Drawing

Abstract: In this paper is describe the influence of the deformation degree on the mechanical properties and microstrucure of the blanks obtained by tube and wire drawing. The materials used for this study are represented by two different samples: hot rolled wire rod and wire for concrete reinforcement with periodic profile (drawn wire) with three dimensions of obtained diameter ( d1 = 5.00 mm, d2= 4 mm and d3= 3,5 mm). The results reveal that the strength properties of the samples are increasing with an increase in the degree of deformation, while the plasticity properties are lowering.The purpose of this paper is to evidence the changes in the structure, the strength and plasticity properties depending on the deformation degree and section reducing of the metallic material.

Utilization of Plasma Treated Polymeric Macro-Fibers as Reinforcement in Concrete Constructions

Abstract: Polymeric macro fibers BeneSteel having diameter equal to 480 μm and length 55 mm were treated in low pressure oxygen plasma by different treatment duration from 5 to 480 s to attain the better interaction with cement matrix (focused on both, chemical and physical bond). An effect of realized treatment was examined through fiber surface water wettability observation by direct horizontal optical method enabling contact angle measurements. Next, the pertinent negative impact of plasma treatment on fibers mechanical properties was examined by several methods. It was shown that the most effective plasma treatment duration is up to 30 s. Thus treated fibers exhibited the better wettability by ca. 110 % in comparison with reference fibers, while its mechanical properties were not negatively affected. Finally, reference and 30 s plasma treated fibers were used as randomly dispersed reinforcement in concrete specimens. Mechanical properties of these composites were examined by four-point bending tests. Specimens containing treated fibers exhibited bigger fracture toughness by ca. 30 % beside the reference ones, while the first cracking strength stayed constant in all cases.

Extended Constitutive Model for FRP-Confined Concrete in Circular Sections

Abstract: This study presents an extended finite element (FE) model based on concrete damage-plasticity approach for fiber-reinforced polymer (FRP)-confined normal-strength and high-strength concrete (NSC and HSC). The proposed model is based on Lubliner’s model and it accurately incorporates the effects of confinement level, concrete strength, and nonlinear dilation behavior. Failure surface and flow rule were established using an up-to-date database. In order to validate the extended damage-plasticity model, finite element (FE) model is developed for specimens under a wide range of confining pressures. The results indicate that the model predictions of FRP-confined NSC and HSC are in good agreement with the experimental results.

Comparison of Semidefinite Solvers for Topology Optimization of Cantilever Trusses Subject to Fundamental Eigenvalue Constraint

Abstract: Optimal design of trusses is a widely developed field of structural optimization. In topology optimization the infinite design space is usually discretized into a finite ground structure defining the set of all feasible joints and bars. In this paper we adopt semidefinite programming (SDP) formulation of the topology optimization that enables us to obtain a globally optimal least compliant truss subjected to the constraints on structural volume and on the fundamental eigenvalue of free vibrations. For a model problem of 3D cantilever truss, we present a comparison of six solvers, namely CSDP, MOSEK, PENLAB, SDPA, SDPT3 and SeDuMi, from which it follows, that SDPA delivers the best computational performance.