Showing papers in "Key Engineering Materials in 2017"
TL;DR: In this paper, an experimental program aimed at investigating the behavior of full scale columns made of limestone masonry blocks confined with different Fabric Reinforced Cementitious Matrix (FRCM) systems has been carried out.
Abstract: The effectiveness of FRP systems as a confinement technique to strengthen masonry columns has been widely investigated in the last decades. Recently, a new technique, Fabric Reinforced Cementitious Matrix (FRCM), based on the use of fibrous nets embedded in inorganic matrix, has been developed and investigated as a strengthening solution in masonry buildings. Actually, the number of experimental tests on masonry columns confined by using FRCM systems is very limited, especially for real scale specimens. To fill such gap an experimental program aimed at investigating the behaviour of full scale columns made of limestone masonry blocks confined with different FRCM systems has been carried out. The results of four uniaxial compression tests are illustrated and discussed. The used FRCM systems are made with glass and basalt dry nets embedded in a lime-based mortar. The influence of transverse confinement by using internal reinforcement in forms of pultruded GFRP bars has been also investigated. The mechanical properties of the confined specimens resulted increased in terms of load-carrying capacity and ultimate axial strain.
33 citations
TL;DR: In this paper, the formation of qualitative nanostructured coatings and development of methods for their application on product surfaces was carried out with the use of specially developed working chambers installed upon vibration machines as an indenter there were used metal balls 2-5 mm in diameter and made of steel of ShH15 type.
Abstract: The purpose of the investigations carried out is the formation of qualitative nanostructured coatings and development of methods for their application on product surfaces The principle of a staged study of regularities in the formation of vibration mechanical-chemical coatings from “top to bottom” and “bottom-up” formed a basis of a methodological approach to investigation carrying out Experimental researches were carried out with the use of specially developed working chambers installed upon vibration machines As an indenter there were used metal balls 2-5 mm in diameter and made of steel of ShH15 type, samples material – steel 45 The assessment of coating characteristics was carried out with the use of optical, raster scanning probe microscopy It is determined through the result in the investigations of the impact-pulse interaction of a working environment part under conditions of vibration impact that there are grindings and changes in particles dimensions up to 100 nm and lesser in coating material which allows them to penetrate into micro-and nanocavities of basic metal and, in such a way, to form coating with high antifriction properties The influence of amplitude-frequency properties of vibro-wave activation upon quality and performance attributes of coating surfaces and also process duration is determined
30 citations
TL;DR: In this article, the experimental assessment of the Textile Reinforced Mortar (TRM)-to-masonry residual bond characteristics as a function of temperature is devoted to the experimental evaluation of the textiles.
Abstract: This work is devoted to the experimental assessment of the Textile Reinforced Mortar (TRM)-to-masonry residual bond characteristics as a function of temperature. For this purpose, shear bond tests on single-lap/single-prism specimens were conducted after their exposure at different temperature levels, namely at 100°C, 200°C and 300°C. Specimens consisted of a strip of cementitious mortar reinforced with an uncoated alkali-resistant (AR) glass fiber textile unilaterally bonded on a fired clay brick masonry wallette (prism). For each heating event, a sharp temperature rise rate was opted for the achievement of the target temperature at which the specimens remained for one hour. Reference specimens were also tested at ambient conditions (20°C). Tests were carried out by varying both bond lengths and exposing temperatures. Two specimens were tested for each combination of bond length and exposing temperature. Material characterization tests were also carried out at each temperature level including ambient. The experimental results provide valuable insight on the degradation of the TRM-to-masonry bond capacity following a heating event and on the related failure modes.
26 citations
TL;DR: In this paper, a quantitative model for selecting a material supplier by using the Fuzzy Analytic Network Process and TOPSIS method is proposed, which can provide a robust approach for solving material supplier selection problems.
Abstract: Materials account for a significant proportion of engineering and construction projects budget. Therefore, selecting appropriate material supplier criteria is a critical economic decision, and it plays a significant role in the success of any engineering and construction firms. Traditional supplier evaluating decision-making methods are usually based on subjective opinions of experts, resulting in irrational and inappropriate decisions. This paper proposes a quantitative model for selecting a material supplier by using the Fuzzy Analytic Network Process and TOPSIS method. In this model, the material supplier selection criteria are weighted by using Group Fuzzy Analytic Network Process (GFANP). Then material suppliers are ranked using the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method. The proposed decision-making model can provide a robust approach for solving material supplier selection problems.
25 citations
TL;DR: In this paper, the results obtained at fixed condition of pH 7, contact time of 105 minutes, shaking speed of 150 rpm showed more than 90% uptake for both adsorbents.
Abstract: Palm oil mill efluent (POME) is the major industrial waste water in Malaysia and Indonesia. The processing of (POME) before discharge is a major challenge to researchers. In this study, the adsorption experiment of zinc ion from (POME) produced from the processed palm oil as primary treatment has been investigated using coconut shell and cow bone activated carbon. Experiments were conducted at a fixed initial concentration, contact time, shaking speed and at different adsorbent dosage to obtain optimum condition for the uptake of zinc ion from POME. The coconut shell carbon exhibited better removal efficiency than the cow bone powder. The results obtained at fixed condition of pH 7, contact time of 105 minutes, shaking speed of 150 rpm showed more than 90% uptake for both adsorbents. The result of the adsorption study was further analyzed using Langmuir and BET model to determine the experimental isotherm. The result showed that equilibrium data fitted better with BET model for coconut shell carbon and better with Langmuir model for cow bone powder. The result of the adsorption experiments showed that heavy metal of zinc can be sufficiently reduced on both coconut shell carbon and the cow bone powder. The morphology of both adsorbents was observed using the scanning electron microscope (SEM), the pore sizes of the adsorbents supported the uptake of zinc ion from the raw POME.
24 citations
TL;DR: In this article, the behavior of clay masonry columns confined by steel reinforced grout (SRG) composite with a natural hydraulic lime mortar is investigated, and the effectiveness of the confinement is studied in terms of loadbearing capacity with respect to unconfined columns.
Abstract: In this study, the behavior of clay masonry columns confined by steel reinforced grout (SRG) composite with a natural hydraulic lime mortar is investigated. An experimental study was carried out to understand the behavior of masonry prisms with a square cross-section confined by SRG composite jackets subjected to a monotonic concentric compressive load. Test parameters considered in this study are the density of steel fibers and column corner radius. The effectiveness of the confinement is studied in terms of load-bearing capacity with respect to unconfined columns.
22 citations
TL;DR: In this article, the authors investigated the regularities in structural-phase changes and mechanical-chemical processes occurred in a surface layer under the influence of outer and inner technological factors, and determined a mechanism of coating formation, technological regulations for its application were established.
Abstract: The purpose of the investigation carried out is the study of regularities in structural-phase changes and mechanical-chemical processes occurred in a surface layer under the influence of outer and inner technological factors. As experimental equipment there was used a vibration horizontal plant of UVG4x10 type. Working environment consisted of porcelain balls of 4mm diameter, PU-20 zinc powder and an aqueous solution of zinc chloride, and as abrasives – steel plates of 10x10 mm. As a result of the investigations there was determined a mechanism of coating formation, technological regulations for its application were established, surface morphology was investigated. The coating obtained exceeds the electrolytic one by a factor of 1.5 on corrosion resistance due to the absence of a hydrogenated layer.
21 citations
TL;DR: In this paper, the authors proposed the technique of guaranteed quality wear resistant plasma coatings of high-chromium powder material, where surface roughness was accepted as a criterion in the model development at the stage of preliminary mechanical processing before spraying coatings and the model of plasma coating process proper takes into account the influence of spraying on the main quality indicators, such as adhesive strength, porosity, and the level of residual stresses.
Abstract: We propose the technique of guaranteed quality wear resistant plasma coatings of high-chromium powder material The appropriate system of engineering models had to be designed in order to obtain the summarized results, as well as to manage the parameters of quality indicators at all stages of the technological processing procedure Thus, surface roughness was accepted as a criterion in the model development at the stage of preliminary mechanical processing before spraying coatings The model of plasma coating process proper takes into account the influence of spraying on the main quality indicators, such as adhesive strength, porosity, and the level of residual stresses The engineering model of finish abrasive grinding is based on ensuring the desired value of the surface roughness parameter provided the geometric and dimensional accuracy of details was achieved
21 citations
TL;DR: In this paper, the use of fiber reinforced composite materials for the retrofitting of existing masonry buildings is investigated, which represent a great alternative to traditional strengthening techniques for the improvement of the seismic performance of masonry walls.
Abstract: The use of fiber reinforced composite materials for the retrofitting of existing masonry buildings is investigated in this paper. Indeed, they represent a great alternative to traditional strengthening techniques for the improvement of the seismic performance of masonry walls. Focusing on the in-plane behavior of masonry, an experimental campaign is here presented with the objective of studying the efficiency of different strengthening solutions. Diagonal compression tests were conducted on single-leaf masonry panels reinforced with Fiber Reinforced Cementitious Matrix (FRCM) using different fibers typologies and layouts. Glass or carbon fiber grids embedded in a lime-based mortar matrix were applied on one or both sides of masonry panels, with or without mechanical anchorages. The comparison of the different strengthening techniques is analyzed in terms of failure mode, strength and ductility. The results are then discussed considering the provisions and design formula proposed for FRP strengthening by the Italian CNR Guidelines.
20 citations
TL;DR: In this paper, an experimental and numerical investigation on an innovative composite reinforced with sisal fibers for masonry strengthening is presented, and a FEM numerical approach is also developed, based on diagonal compression test results, to simulate the shear in-plane response of unreinforced masonry panels (URM) and masonry strengthened with a Fibre Reinforced Cementitious Matrix (FRCM) composite system made with Sisal fibers (RM-SISAL).
Abstract: An experimental and numerical investigation on an innovative composite reinforced with sisal fibers for masonry strengthening is presented in this paper. A FEM numerical approach is also developed, based on diagonal compression test results, to simulate the shear in-plane response of unreinforced masonry panels (URM) and masonry strengthened with a Fibre Reinforced Cementitious Matrix (FRCM) composite system made with sisal fibers (RM-SISAL).
20 citations
TL;DR: In this article, the authors reviewed various transport mechanisms involved in ingress of deleterious material and incorporation of metakaolin (MK), fly ash (FA), silica fume (SF), nano silica (NS), which not only reduces the pores in concrete but improves the mechanical, durability and microstructure of concrete.
Abstract: Concrete is widely used construction material for the development of built environment which consumes huge amount of cement, around 4.3 billion metric ton all over the world. Reinforced concrete construction exposed to harsh environment such as chloride bound air causes deterioration in concrete through its pore structure by corroding the steel bar. The use of pozzolanic material i.e. metakaolin (MK), fly ash (FA), silica fume (SF), nano silica (NS) can be used as partially cement replacing material which not only reduces the pores in concrete but improves the mechanical, durability properties and microstructure of concrete. This paper reviews various transport mechanisms involved in ingress of deleterious material and incorporation of MK, FA and NS in concrete and their effects on concrete mechanical and durability properties. However, the research work provides an extended approach to evaluate combine effect using MK, FA, and NS and to produce a concrete with more refined pore structure for aggressive environment.
TL;DR: In this paper, an experimental study was carried out to understand the behavior of masonry columns with a square cross-section confined by steel and basalt fiber sheets embedded in a mortar matrix subjected to monotonic concentric compressive load.
Abstract: The rehabilitation of existing masonry elements by means of jacketing of columns using composite materials is becoming a remarkable technique in several applications that aim to increase the strength of existing masonry buildings. Fiber reinforced cementitious matrix (FRCM) composites are a newly developed strengthening system that consist of high-strength fibers embedded in a cementitious grout and externally bonded to the substrate. High resistance to fire and high temperatures, ease of handling during application, and vapor permeability with the substrate are some of the characteristics that make FRCMs a promising alternative to traditional organic composites such as fiber reinforced polymer (FRP) composites. This work presents the results of an experimental study carried out to understand the behavior of masonry columns with a square cross-section confined by steel and basalt fiber sheets embedded in a mortar matrix subjected to monotonic concentric compressive load. The effectiveness of the confinement is studied in terms of load-bearing capacity with respect to unconfined columns. The effect of corner radius for columns confined with basalt fibers is investigated.
TL;DR: In this paper, the application of wear resistant coatings by methods of gas thermal and flame spraying is considered and the relationship between adhesion strength of the sprayed coating and surface roughness after abrasive jet machining using piston rings with steel-molybdenum coating as an example.
Abstract: The paper considers the application of wear resistant coatings by methods of gas thermal and flame spraying. It demonstrates the relationship between adhesion strength of the sprayed coating and surface roughness after abrasive jet machining using piston rings with steel-molybdenum coating as an example. The authors consider the results of studies aimed defining the relationship between surface roughness and of jet-abrasive machining conditions: the distance between the nozzle exit and the workpiece, the number of passages, the operating air pressure and frequency of the shot swapping.
TL;DR: The International Conference on Mechanics of Masonry Structures Strengthened with Composites Materials, MuRiCo5 2017 as discussed by the authors, was the first edition of this conference.
Abstract: International Conference on Mechanics of Masonry Structures Strengthened with Composites Materials, MuRiCo5 2017
TL;DR: In this article, a study of the mechanical behavior of non-metallic hybrid Basalt-PVA fiber reinforced concrete reinforced concrete was conducted, which showed that the increase in superplasticizer and fiber content decreased compression, split tensile and flexure strength because of formation of big size pores, whereas fiber enhanced the post peak load zone in the load-deflection curve.
Abstract: This study focuses on the study of the mechanical behavior of non-metallic hybrid Basalt-PVA fiber reinforced concrete. Total five mixes were investigated with one control plain concrete and four with fiber volume fraction of 0.3%, 0.6%, 0.9% and 1.2%. Basalt and PVA were used in same quantity. Fiber decreased workability, therefore superplasticizer was used to maintain workability constant. The increase in superplasticizer and fiber content decreased compression, split tensile and flexure strengths because of formation of big size pores. Whereas fiber enhanced the post peak load zone in the load-deflection curve. Fiber improved the bridging action by increasing energy absorption. Fiber vanished the brittle behavior of high strength concrete and increased first crack toughness, flexure toughness and also maximum deflection. 0.3% volume fraction of fiber was found to be optimum with the negligible decrease in compression, split tensile and flexure strength while caused the considerable increase in first crack toughness, flexure toughness, and maximum deflection.
TL;DR: In this article, the authors propose and assess the reliability of a modeling strategy which combines the homogenization of the masonry material and the use of zero-thickness interface elements.
Abstract: The aim of the paper is to propose and assess the reliability of a modeling strategy which combines the homogenization of the masonry material and the use of zero-thickness interface elements. This strategy is specifically proposed for numerically investigating the structural response of FRP-reinforced curved masonry structures. Indeed, in order to consider the influence of the geometry curvature of the masonry substrate on the local bond behavior of the FRP-strengthening system, bond-slip laws which specifically account for the geometric curvature of the substrate are introduced at the FRP/substrate interface layer. Numerical analyses concerning masonry arches selected from the current literature are presented in the paper in order to assess the reliability of the proposed modelling approach.
TL;DR: In this paper, the adsorption efficiency of Philippine natural zeolite for treating acid mine drainage is investigated, and the metal ions considered were Cu2+, Ni2+, and Pb2+ ions.
Abstract: In this study, the adsorption efficiency of Philippine natural zeolite for treating acid mine drainage is investigated. The metal ions considered were Cu2+, Ni2+, and Pb2+ ions. The natural zeolite was characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM) equipped with Energy Dispersive X-ray Spectroscopy (EDX). The XRD result revealed that the natural zeolite is mainly composed of heulandite (Ca,Na)2-3Al3(Al,Si)2Si13O36 • 12H2O. Plate-like structures having rough surface and micro-pores were observed. The natural zeolite exhibited adsorption efficiencies of 99.03%, 35.88% and 35.36% for Pb2+, Cu2+, and Ni2+ ions, respectively, which are higher than those of alumina adsorbent for the same ions. Based on these results, the Philippine natural zeolite has a great potential for removing cationic heavy metal species from acid mine drainage (AMD).
TL;DR: In this paper, the effect of galvanic corrosion caused by neutral salt spray tests on fiber-metal-laminates, the influence of an elastomer interlayer and the quantification of the residual mechanical properties.
Abstract: Fiber-Metal-Laminates (FML) show superior dynamic mechanical properties combined with low densities. The mechanical performance of for example commercially available fiber-metal-laminate, glass laminate aluminum reinforced epoxy, can be improved by the substitution of glass fibers with carbon fibers. However, carbon fiber reinforced aluminum laminate introduces a mismatch of coefficients of thermal expansion and the possibility of galvanic corrosion. The fiber-metal-laminate is altered by the integration of an elastomer interlayer which is desired to solve both problems. The high electrical resistance is supposed to inhibit the corrosion. This study focuses on the effect of galvanic corrosion caused by neutral salt spray tests on fiber-metal-laminates, the influence of an elastomer interlayer and the quantification of the residual mechanical properties. The galvanic corrosion affects the interfaces of the laminates, therefore in this study edge shear tests and flexural tests were carried out to quantify the residual properties and thereby the corrosive damage. The elastomer interlayer was found to inhibit galvanic corrosion in the salt spray chamber, whereas the fiber-metal-laminate without interlayer showed corrosive damage. Furthermore, the mechanical properties of the fiber-metal-laminate with elastomer interlayer remained constant after the corrosion tests, whilst the fiber-metal-laminate’s properties decreased with corrosive loads.
TL;DR: In this paper, a stable modified zirconia nanopowder was obtained chemically and thermally by studying the effect of sulfuric acid treatment and calcination temperature on commercial ZirconIA nanopowder.
Abstract: The modification of commercial zirconia nanopowder by sulfuric acid and heat treatment was conducted. The aim of this present research was to obtain a stable modified zirconia nanopowder chemically and thermally by studying the effect of sulfuric acid treatment and calcination temperature on commercial zirconia nanopowder. The material was prepared by dispersing the commercial zirconia nanopowder into 0.2, 0.5 and 0.8 M sulfuric acid solutions, followed by calcination at varied temperatures, i.e. 600, 700, 800 and 900 °C. The so called sulfated zirconias then were characterized their physicochemical properties using FT-IR, XRD and SEM-EDX analysis methods. The optimized condition for that modification was obtained by using sulfuric acid of 0.8 M and calcination temperature of 600 °C. The characterization results also revealed that using ammonia adsorption method, the acidity of the catalyst was found to be 1.06 mmol/g.
TL;DR: In this paper, the authors used composites like syntactic foams, spherical shells or carbon fields reinforced composites to improve the building resistance to the effects of the terrorist attacks.
Abstract: Building protection on our century is very important because of the terrorist attacks. The old buildings in Europe aren’t enough strong again blast loads. Nowadays we know many different explosives and theirs effects of walls and human bodies. The detonation caused blast effect provokes building damage and fragmentation effects. The explosion caused damages, parts of bricks and fragments produce other secondary damage in other buildings and human bodies.It can’t protect the historical and old buildings by new walls and fences because of the cityscape. It needs to find new possibilities to improve the buildings resistance again blast effects. It needs a effectively thin and strong materials to reinforced the buildings walls. The new materials innovated by material science can be good solution for this project. These materials usually composites likes syntactic foams, spherical shells or carbon fields reinforced composites.
TL;DR: It was observed that the coatings could be efficiently applied to titanium dental implants and the drug release rates can be efficiently controlled.
Abstract: The biodegradable and biocompatible antibiotic containing thin film composites are very appropriate biomaterials as coating materials for dental implants because of their adjustable drug loading and release rates for the prevention of implant related infections. Coralline hydroxyapatite (HAp) was loaded with gentamicin antibiotics and combined with a biodegradable polylactic acid (PLA) to form thin film composites. PLA-HAp, PLA-Gentamicin (GM) and PLA-HAp-GM composites were produced, and their dissolution studies were carried out in phosphate buffered saline under SINK conditions. It was observed that the coatings could be efficiently applied to titanium dental implants and the drug release rates can be efficiently controlled.
TL;DR: In this paper, a unified approach for data interpretation acquired from both static and dynamic structural health monitoring (SHM) systems installed in historical buildings is presented, aimed at: (i) introducing reference quantities for interpretation of seasonal and daily variations, (ii) providing order of magnitudes of reference quantities and (iii) identifying eventual evolutionary trends which could be related to the presence of potential structural criticalities.
Abstract: Structural Health Monitoring (SHM) has a crucial role in the diagnosis and conservation of historical buildings, which are typically characterized by articulated fabrics, constructed over decades using different materials and construction techniques. All these issues lead to very complex structural behaviour whose reliable assessment cannot disregard from a sound interpretation of data from SHM systems. SHM systems can be classified into (i) static systems, monitoring the long term time evolutions of specific quantities (such as amplitude of cracks, inclination of walls, relative distances, etc.) and (ii) dynamic systems, continuously monitoring the dynamic response (velocities, accelerations) in order to gather information upon overall dynamic properties such as natural frequencies, mode shapes and damping ratios. The recorded raw data need to be processed in order to distinguish eventual evolutionary trends from the seasonal and daily variations related to thermal effects. In the present work, a simple unified approach for data interpretation acquired from both static and dynamic SHM systems installed in historical buildings is presented. The approach is aimed at: (i) introducing reference quantities for interpretation of seasonal and daily variations, (ii) providing order of magnitudes of reference quantities and (iii) identifying eventual evolutionary trends which could be related to the presence of potential structural criticalities. The approach is illustrated referring to the “Two Towers” of Bologna.
TL;DR: In this article, a new method of layered silicate intercalation by polyvinylpyrrolidone in the solution under ultrasonic treatment is described, and the structure and thermophysical properties of the developed nanomodifier and the components rational ratio have been investigated.
Abstract: A new method of layered silicate (montmorillonite) intercalation by polyvinylpyrrolidone in the solution under ultrasonic treatment is described in this work. The structure and thermophysical properties of the developed nanomodifier and the components rational ratio have been investigated. The effect of intercalated montmorillonite on physico-mechanical, thermophysical and insulating properties of polycaproamide PA-6 has been determined.
TL;DR: In this paper, the authors evaluate the out-of-plane performance of masonry walls strengthened with fiber reinforced reinforced Cementitious Matrix (FRCM) composites when subjected to horizontal actions, by analyzing and discussing failure modes and their capacity.
Abstract: Structural strengthening by using composite materials proved to be one of the most suitable solutions for reinforcing masonry buildings. In this framework, the focus point of the presented experimental study is to evaluate the out-of-plane behaviour of masonry walls strengthened with Fiber Reinforced Cementitious Matrix (FRCM) composites when subjected to horizontal actions, by analyzing and discussing failure modes and their out-of-plane capacity. To this purpose, a new experimental set-up was developed, capable of applying an axial force and out-of-plane horizontal actions on full-scale masonry panels, placed in vertical position and subjected to a stress state similar to that present on a real masonry wall. Experimental results, obtained by using traditional and innovative techniques (such as Digital Image Correlation), will be compared with those coming from more conventional tensile and bond tests performed on FRCM coupons applied on masonry substrates, making use of simple theoretical models.
TL;DR: In this article, small-punch testing under constant deflection rate, constant force, and constant force relaxation was performed on the new austenitic steel Sanicro 25 and the results were correlated with the uniaxial stress relaxation test and good agreement was reached.
Abstract: Small punch testing under constant deflection rate, constant force and constant deflection (i.e. force relaxation) were performed on the new austenitic steel Sanicro 25. Constant deflection rate experiments were correlated to uniaxial tensile tests at room temperature and 700°C with the help of several empirical relationships. Small punch creep testing was performed in as received state. Correlation of the small punch results with uniaxial creep test results was done and the force/stress ratio Ψ and kSP parameter were determined. The constant deflection small punch test was correlated with the uniaxial stress relaxation test and good agreement was reached.
TL;DR: In this article, an upper bound approach for the limit analysis of FRP-reinforced masonry arches is proposed, which relies on the representation of the geometry of both the arch and the FRP reinforcement through Non Uniform Rational B-Spline (NURBS) functions.
Abstract: This contribution is devoted to assess the capability of a new upper-bound approach for the limit analysis of FRP-reinforced masonry arches by comparing it to both experimental tests and a number of existing numerical procedures. The approach is based on an idea previously presented by the Authors and relies on the representation of the geometry of both the arch and of FRP reinforcement through Non Uniform Rational B-Spline (NURBS) functions. This allows generating a rigid body assembly starting from the assigned geometry composed by very few elements which still provide an exact representation of the original shape. A homogenized kinematic formulation for the limit analysis of the obtained rigid blocks assembly is derived, which accounts for the main properties of masonry material. FRP material is included exploiting the Italian CNR Recommendations for the design of FRP based reinforcing interventions. The approach is capable of accurately predicting the load bearing capacity of masonry arches of arbitrary geometry, provided that the initial mesh is adjusted by means of a suitably devised Genetic Algorithm (GA) until the active interfaces among blocks (e.g. hinges) closely approximate the actual failure mechanism.
TL;DR: In this paper, the authors describe concrete durability and outline what project specifications will significantly influence concrete performance, including its environmental impacts, and argue that, despite the sustainability of concrete, concerted efforts on the part of scientists and engineers are still necessary to improve the design of concrete in order to ensure their expected sustainable quality and reliability.
Abstract: Sustainable concrete is nowadays one of the biggest challenges in the construction industry. Performance-based specifications for concrete can materially help meet this new challenge while supporting the concept of “sustainable construction”. Concrete can be found in almost every building structure, be it a pavement, a bridge, a house, a tunnel or a dam. Scholars nowadays are researching the best balanced mix in concrete in order to diminish its environmental impact, especially the cement component which is known for its high carbon emissions. This paper describes concrete durability and outlines what project specifications will significantly influence concrete performance, including its environmental impacts. The paper argues that, despite the sustainability of concrete, concerted efforts on the part of scientists and engineers are still necessary to improve the design of concrete in order to ensure their expected sustainable quality and reliability.
TL;DR: In this paper, the authors presented flexural properties related to vibration behavior of jute reinforced polyester composite and found that the configuration of the jute fiber cloth and glass fiber hybridized laminates possesses compromised properties between flexural and damping ratio.
Abstract: This paper presents flexural properties related to vibration behavior of jute reinforced polyester composite. The goal of the research is to seek green composite material that exhibits good strength and flexural properties along with good damping property designed for wind turbine blades. The material for reinforcement in the present study is jute fiber. The material for matrix is polyester resin. Glass and carbon fiber are used for hybridization. Specimens were fabricated by vacuum infusion technique. Laminates were constructed by stacking jute fiber clothes. Hybrid laminates were fabricated by stacking jute clothes covered by one ply glass cloth and jute clothes covered by one ply carbon cloth. Static flexural and free vibration tests were carried out to obtain the elastic modulus and vibration behavior of specimens, respectively. The result shows that the configuration of jute fiber cloth and glass fiber hybridized laminates possesses compromised properties between flexural properties and damping ratio.
TL;DR: In this article, the authors evaluated the durability of a burnishing tool with the working surface made of the hard alloy with different dispersion, and the acquired data presents that the roughness exceeds the tolerance during the processing by tool made of H10F alloy later than by tool making of VK6 alloy.
Abstract: The hyper productive surface plastic deformation processing technology called as wide burnishing (WB) was developed in Russian Federation. The mechanics of new WB technology is different from the classic SPD technologies (rolling or burnishing). For example applied force during processing of burnishing is 150-300 N, of WB is 2500-5000 N due to condition of process implementation in mass production with limited processing time (3-4 turnovers of workpiece). WB also has a high degree of deformation due to a multiple deformation passes. The purpose of the study was to determine the durability of a burnishing tool with the working surface made of the hard alloy with different dispersion. During the durability tests were tested VK6 alloy with the chemical composition of WC-94%, Co-6%, grain size of 2.1...3.4 micron (hardness HRA 88.5) and similar in chemical composition fine-grained hard alloy H10F (WC-90%, Co-10%) produced by Sandvik-MKTS with grain size of 0.5...0.9 micron (hardness HRA 92.1). Processing was conducted without lubricoolants. The acquired data presents that the roughness exceeds the tolerance during the processing by tool made of H10F alloy later than by tool made of VK6 alloy. At the same time increase of durability is from 60% to 80%.
TL;DR: In this paper, a comparative analysis of various diamond processing methods reveals that the minimal cutting power is observed when using the combined method of electric powered diamond processing which includes electrochemical grinding and simultaneous continuous electrochemical dressing of the grinding disk surface.
Abstract: The paper presents results of the investigation into efficiency of high-tensile composite materials grinding with metal bonded diamond abrasive tools, as well as it demonstrates the necessity to stabilize diamond disks cutting properties in order to reduce cutting power, since it is one of important economic indicators of processing. The comparative analysis of preliminary studies of various diamond processing methods reveals that the minimal cutting power is observed when using the combined method of electric powered diamond processing which includes electrochemical grinding and simultaneous continuous electrochemical dressing of the grinding disk surface. Further research into the suggested method reveals relevant mathematical dependences of metal-bonded diamond disks cutting power and electric modes. The analysis of the results shows that combining of hard-alloy surface electrochemical dissolution and electrochemical dressing of the disk surface facilitates mechanical cutting with high effectiveness and little effort. This leads to substantial reduction of cutting power as compared with other methods. The reasonable electric modes are discovered which provide the minimal cutting power without reducing efficiency of the process and quality of finished product.