bluuebunny/crossref_metadata_2025 huggingface dataset:
Experience of Replacing Basalt Aggregate by Limestone’s in Porous Asphalt Concrete
Authors: Zhou Chang Hong , Liu Shao Hua , Yuan Qiang
Published: September 2014

In order to reduce the cost of Porous asphalt concrete and the effective use cheap limestone widely distributed in local, the gradation design works of limestone-typed PAC is presented in this paper. Considering convenience of building and testing for local enterprises, Marshall Design Method, still used in local standards, is adopt. Limestone usually shows low strength and easy break, which obviously affect the performance of mixture. Therefore, Forming temperature and beat numbers of Marshall Test is researched. The results show that: a) Regular aggregate, whose shape is similar to a cube, with low flat ratio and low crushing value is important for improving the performance of limestone-typed PAC. b) Forming temperature and Beat number is suggested taking 155°C and 35 times. c) The standard of limestone-typed PAC should not be as same as basalt-typed. The indices can be suitably lessened according to the actual conditions of aggregates.
Preparation and Characterization of Matrimid-Based Carbon Membrane Supported on Tube for CO2 Separation
Authors: Salleh W.N.W. , Isa N.A.I.M. , Sazali Norazlianie , Ismail Ahmad Fauzi
Published: September 2014

A series of research had been conducted to alter the performance of carbon membranes by manipulating the parameters during the fabrication process. In this study, the effects of carbonization temperature on the performance of carbon membrane were investigated. Matrimid-based carbon membrane supported on ceramic tube was fabricated through the dip-coating technique. The prepared membranes were characterized by using the scanning electron microscopy (SEM) and pure gas permeation test for the study on morphological structure and gas separation performance, respectively. The carbonization process was performed at different carbonization temperatures (600, 700, and 800 oC) for the same heating rate of 1 oC/min under Ar flow. The increment of carbonization temperature produced carbon membrane with small size of pores. The carbon membrane prepared at 800 oC showed the highest CO2/CH4 and CO2/N2 selectivity of 79.65 and 74.76, respectively.
Effect of the Reduction Temperature on Nickel Phosphide Catalyst Structure and Catalytic Activity for Hydrodesulfurization
Authors: Song Hua , Zhang Fu Yong , Jin Zai Shun , Wang Huai Yuan , Zhu Yan Ji , Song Hua Lin
Published: September 2014

Ni2P/TiO2-Al2O3 catalysts were prepared by impregnation of nickel phosphate precursors followed by reduction in hydrogen. The catalysts were characterized by X-ray diffraction (XRD), N2-adsorption specific surface area measurements (BET), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetry differential thermal analysis (TG-DTA). The effects of reduction temperature on catalyst structure and HDS activity were studied using a lab-scale continuous flow fixed-bed reactor.. The results indicated that the catalyst prepared with reduction temperature of 973 K exhibited the best performance. At a reaction temperature of 606 K, a pressure of 3.0 MPa, a hydrogen/oil ratio of 500 (V/V), and a weight hourly space velocity (WHSV) of 2.0 h-1, the conversion of DBT HDS was 96.0%.
Numerical Modelling of Nonlinear Vibration Isolation System Free Oscillations
Authors: Smirnov Vladimir
Published: September 2014

The article deals with numerical analysis of nonlinear vibration isolation system free oscillations. According to the latest recommendations [1], vibration isolation of precision equipment should be effective over the 1 – 100 Hz range [2]. This fact sets a challenge to develop a sub-herz vibration isolator. Such vibration isolators with 0.5 Hz natural frequency have been developed in latest works [3,4]. For mathematical representation of such a dynamical system, elastic characteristic should be approximated with a polynomial. In this paper, we consider the approximation of elastic characteristic by means of 5th and 7th order polynomials. This leads to numerical solution of nonlinear dynamic equations. We construct the solution of such equation on the phase plane and determine equilibrium points. The stability of the equilibrium points is investigated using linearization technique. The law of the isolated mass oscillations is derived from numerical solution of the dynamic equation by means of Dorman – Prince 4(5) and 8(7) solver and the system’s natural frequencies are calculated using the FFT technique.
The Distinguishing Quality of Water Droplets on Insulating Surface under AC and DC Electric Field Stress
Authors: Chandavong Sackthavy , Tonmitr Kittipong , Kaewrawang Arkom
Published: September 2014

This paper presents the comparison of water droplets on insulating surface under alternating current (AC) and direct current (DC) electric field. Besides that, it is demonstrated about the insulator deterioration under both electric field stressed due to an ageing and partial discharge (PD) phenomenon. The vital parameters factors are water droplets conductivity, droplet volume, surface roughness and droplet positioning that they cause to occur the electric field intensification. The field is intensified at the interface between the droplet, air and insulating material. Thus, the PD occurred due to electric field intensification increases with the deformed droplet. The deformation of water droplet under AC electric field stress is more intense than DC field. The electrostatic forces change the droplet shapes and spread them along the electric field direction. The local electric field intensification provokes the PD giving way to reduction of hydrophobicity of insulator surfaces. In addition, the PD activity could appear as a trigger for a surface breakdown. And the localized arcs cause damage to insulating material then finally leads to deterioration of insulation materials and the pollutant contamination.
Increasing User Comfort for Public Seating - User Interaction with Materials
Authors: Gaja Vítězslav
Published: September 2014

This paper focuses on possibilities in increasing the user comfort of seating furniture in public waiting interiors. There are several aspects helping to achieve the best comfort of sitting, such as appropriate ergonomic design, shape, or material composition. While every of the said aspects have a significant impact on the final comfort, it would be better, or even essential, to adopt a complex view of this issue. One of the complex ways to increase the user comfort is to observe the interaction of the human (the “user”) with the material. The paper describes tactile properties in the interaction with basic types of materials the public gets in direct contact with when sitting in public waiting interiors. The conducted research focuses on tactile properties leading to contact comfort of the most used materials, and analyses the properties in relation to temperature, roughness, hardness and comfort. The four mentioned tactile properties are essential for our goal – an increase in user comfort. The preferred materials were defined according to a preceding terrain survey which explored what materials are most commonly used for present seating furniture. The paper then presents the methodology and results of the research focusing on interaction between the human user and the material. The results of the said research might prove useful for future designing and development of seating furniture which focuses on the user’s sensational balance and calmness, i.e. the optimal comfort.
On the Structural and Optical Properties of Lead Selenide Nanolayers
Authors: Pashaev Arif M. , Davarashvili Omar I. , Enukashvili Megi I. , Akhvlediani Zaira G. , Bychkova Larisa P. , Gulyaev Revaz G.
Published: September 2014

It was revealed that, according to the analysis by the half-width of the X-ray lines of reflection planes (200) and (600), the sizes of subgrains in the lead selenide nanolayer ~70 nm thick made up 30-45 nm. Disorientation between the subgrains of the order of the ten thousandth of a minute and the deformation (strain) in the layer was determined by the mismatch between the layer and the substrate. It is shown that the forbidden gap width Eg of the same PbSe nanolayer determined by analyzing the optical transmission spectra by two types of straightening f (hν) and (hν)2=f (hν) coincided and made up 0.445 eV, which exceeded Eg of the unstrained PbSe layer by 0.16 eV. The total contribution of quantum effects at the given subgrain sizes and degeneracy of current carriers is less than 0.03 eV, and generally the change in the forbidden gap width was associated with deformation.
Key words: dispersion, deformation, disorientation between subgrains, optical transmission, forbidden gap width.
Study of Bridge Piers Lateral Stiffness in Railway Vehicle-Bridge System
Authors: Yuan Jia Yu , Zeng Zhi Ping , Liu Can , He Xian Feng , Zhu Kun Teng
Published: September 2014

With the high-speed railway construction, studying of the vehicle-bridge vibration system increasingly important. This article established a range of high-speed trains linear model and standard high-speed railway 32 m span bridge model then a combination of both established based on ANSYS vehicle-bridge finite element model. Followed based on ANSYS high-speed train-bridge Coupled Vibration Simulation Analysis System. Analysis of a variety mound lateral stiffness, According to the analysis results of the piers of the basic principles. The bridge has been established based on the finite element model. Respectively, from the height of piers and pier-shaped two aspects to computational analysis the piers for bridge Coupled Vibration of Dynamic Response of Bridges. Provide a reference for the design of high-speed railway.
The Key Technology Research of the Pushing Closure Process about Jiashao Bridge Based on Geometric Control Method
Authors: Wang Xue Wei , Zhu Bing , Li Hong Xue
Published: September 2014

Based on the characteristics of the geometric control method during the construction of cable-stayed bridge, the key goal to complete the bridge is to ensure that the non-stress dimensions and profile of every component is constant. Because one of the key points to complete the cable-stayed bridge is to ensure that the non-stress length of the closure segments is constant, it is necessary to adjust the relative position of the final closure by the geometric closure method of incremental launching construction to satisfy the requirement of the non-stress length of the closure segments. Aimed at the critical technical problems existing in incremental launching construction process, taking Jiashao bridge as the research subject, the analysis of the incremental launching plan and the local stress of pushing bracket and bearing block are carried out. The research will provide scientific basis for the feasibility of geometric control incremental launching construction method and it will guarantee the smoothly incremental launching construction.
Seismic Performance Evaluation on Cyclic Testing of Weak-Axis Column-Tree Connections
Authors: Lee Kang Min , Yang Yang , Chen Liu Yi , Oh Keun Yeong , Hong Sung Bin
Published: September 2014

The objective of this paper is to research seismic performance of the weak-axis column-tree connections. For this purpose, two specimens CTY600 and CTY900 were fabricated and tested in this experiment. From the test results, the CTY specimen successfully achieved a 5% rad story drift ratio without brittle fracture and the total plastic rotation reached over 0.04rad.
Time History Analysis of Steel Tall Buildings
Authors: Kim Yong Chul , Yoon Sung Won
Published: September 2014

The results of wind tunnel experiments were used to conduct time history analyses of three conventional square cross-section tall buildings with different structural systems. The primary purpose of the study was the direct comparison of the effects of the wind loads on the steel tall buildings. Time history analyses were conducted by applying local wind forces to the center of each floor. The results showed that, although the bending moments in the ground-level column on the two principal axes were different, the peak normal stresses were almost the same regardless of the structural systems. Similar observations were made regarding the tip displacements. Furthermore, analyses for the various loading conditions revealed that the contribution of the bending moment in the across-wind direction was the largest, followed by that in the along-wind direction. The ratio of the peak normal stresses for different loading conditions were observed to be almost the same regardless of the structural systems.
Comprehensive Evaluation and Analysis of Water-Inrush Source in Wolonghu Coal Mine
Authors: Peng Tao , Zhang Hai Chao , Shen Shu Hao , Ren Zi Qiang
Published: September 2014

Fuzzy clustering method was used in the comprehensive evaluation on the water abundance of sandstone aquifer at the bottom of P2xs (K3) in the Wolonghu Coal Mine. Then this paper contrastively analyzed the characteristics of water-inrush and hydrogeochemistry of adjacent mines. The results show that the water abundance of northern sandstone is rich, the direct water-inrush source of working face is K3 sandstone aquifer, and there is a hydraulic relation between this aquifer and the water of sandstone in adjacent mines. They have the same water source and the north of the coal mine gets a supply from external sources.
About Verification of Discrete-Continual Finite Element Method for Two-Dimensional Problems of Structural Analysis Part 2: Deep Beam with Piecewise Constant Physical and Geometrical Parameters along Basic Direction
Authors: Akimov Pavel A. , Mozgaleva Marina L. , Aslami Mojtaba , Negrozov Oleg A.
Published: September 2014

This paper continues series of papers devoted to verification of discrete-continual finite element method (DCFEM) for two-dimensional problems of structural analysis. Formulation of the problem for deep beam with piecewise constant physical and geometrical parameters along so-called its basic direction, solutions obtained by DCFEM and finite element method (FEM) /with the use of ANSYS Mechanical/, their comparison are presented. It was confirmed that DCFEM is more effective in the most critical, vital, potentially dangerous areas of structure in terms of fracture (areas of the so-called edge effects), where some components of solution are rapidly changing functions and their rate of change in many cases can’t be adequately taken into account by the standard FEM.
Analytical Models for Determining Rotational Capacity of Clip-Angle Connections under Seismic Loading
Authors: Hu Jong Wan , Son Hong Min
Published: September 2014

This paper explores rotational capacities and demands in thick top-and-seat (cleated) angle partially restrained connections subjected to monotonic and cyclic loads. The results of test on full-scale angle connections are described first, and are then compared to published curve-fitting models for these types of connections. The data indicates that the curve-fitting constants of some existing mathematical models cannot be extrapolated to thick angles. The results indicate that these connections are capable of providing very ductile behavior and constitute an ideal back-up structural system in steel frames.
Study on the Influence of Different Supporting Point Stiffness on External Suspension Tower Crane and Supporting Structure
Authors: Luo Ji Man , Liu Yue , Li Bin , Sun Xiao Wei
Published: September 2014

Supporting system of external suspension tower crane is the key factor which impairs the safety of the tower cranes. In this article, the problem is studied about the influence of different supporting point stiffness on the force of the tower crane external suspension. Based on the structural mechanics theory, the displacement of the lower statically indeterminate beam and the horizontal displacement of the upper statically indeterminate truss are solved firstly, then the stiffness of the supporting point on the lower beam and the entirety stiffness of the upper horizontal combination struts can be obtained. We can get the optimal supporting structure by drawing the relationship of stiffness1-stiffness2-force which is of significant to the external suspension’s design and installation in Matlab software.
Reliability Modeling on Time between Failures of NC Machine Tools
Authors: Xue Yu Xia , Xu Wen , Li Jun Hong
Published: September 2014

A reliability modeling method is proposed based on the time between failures of NC machine tools. According to the field data of the time between failures of a certain type of NC machine tools, parameter estimation of reliability model is made by use of particle swarm optimization (PSO)-based correlation coefficient optimization method, and it is proved that time between failure of CNC machine tool obeyed mathematical model of 3-parameter Weibull distribution via hypothesis testing. This provides the basis for reliability assessment of NC machine tool as well as the development of maintenance strategy in the future. Meanwhile, it also provides a theoretical reference for the reliability prediction of the whole NC machine tool.
Performance Comparison of the Fabricated Planet Carrier and the Integral Planet Carrier
Authors: Zhang Hao , Zhang Suo Huai , Guo Zheng Song , Wang Hai Ming
Published: September 2014

This paper compares the performance of the fabricated planet carrier and the integral planet carrier. By using the finite element analysis, the paper will found which planet carrier has the better performance in the same structure and load conditions. And draw the conclusions.
Adaptive Active Control System of Vehicle Noise Design and Test
Authors: Jiang Ji Guang , Zeng Yue
Published: September 2014

According to the vehicle interior low frequency noise existing, vehicle interior adaptive active noise control strategy is established based on the FXLMS algorithm, designed the core circuit module active noise controller, including the vehicle interior noise signal amplification module, a main control unit, audio power amplifier module and power module, completed development of the controller hardware, and programming the control software system; using this system, on vehicle driving conditions vice driver left ear position low frequency noise cancellation control in the steady state, the 8.5 dB (Lin) and 10.2dB (Lin) the amount of noise reduction.
3D Simulation of Stress-Strain State of Plasma Arc Surfacing by CAD/CAE Software Sysweld
Authors: Dimitrova Rayna , Nedelchev Alexander , Nikolov Antonio
Published: September 2014

The deformation process during the plasma arc surfacing is analyzed by CAD/CAE software SysWeld under Visual Environment using 3D simulation. The aim of simulation is visualization of a temperature field and a stress-strain state distribution as resul ts of surfacing under typical technological parameters of plasma arc processing which could be used for education. Key w ords : CAD/CAE simulation , plasma arc surfacing , stress-strain state
Numerical Modeling and Initial Fatigue Life Estimations of Welded Structural Components
Authors: Vasovic Maksimović Ivana , Ristic Marko , Ristic Slavica , Maksimović Mirko , Stamenkovic Dragi
Published: September 2014

Numerical simulations are powerful tool for analyzing and research in domain of mechanical constructions. In welded joints is very important to determine residual stresses and temperature distribution in sample, apropos, element of construction. In some cases doing the experiment is not possible, so numerical simulations can give the required results and overview of stress state, residual stresses, critical areas, displacement, temperature distribution and other data is needed for analyzing and improvement of constructions or parts of constructions. This analysis includes finite element model for the thermal and mechanical welding simulation. Welding simulation was considered as a sequential coupled thermo-mechanical analysis. The residual stress distribution and magnitude in axial direction was obtained. The paper also shows the results obtained in a simultaneously test of a butt welded thin steel sheet specimen by conventional methods and thermography. Numerical methods are also used in order to predict the crack of specimen. The obtained results confirm that it is very useful to use thermography and Finite Element Method (FEM) for early diagnostics of the complex structures in the exploitation conditions. In this paper is obtained good agreement of results between experiment and Numerical simulations.
The Effect of Water Pressure Variation on Cut Surfaces Quality during Abrasive Waterjet Cutting of Austenitic Steels
Authors: Perianu Ion Aurel , Mitelea Ion , Şerban Viorel Aurel
Published: September 2014

In this paper research elements regarding the effect of water pressure variation on cut surfaces quality are presented in the field of abrasive water jet cutting of materials hard to process by machining such as austenitic stainless steels, in this case with a thickness of 20 mm. Selection of the optimal cutting process based on technical and economic criteria takes into consideration the type and thickness of the targeted material and also the physical and geometrical quality requirements.
The present paper contains experimental research results regarding abrasive water jet cutting of austenitic stainless steel EN 1.4306 (ASTM 304 L) at different values of water pressure. The abrasive material used is Garnet with particle granulation 80 Mesh. By making roughness measurements and hardness examinations of the cut surface an evaluation will be made of the surface quality defining the optimal pressure values.
Repair Weld Simulation of Austenitic Steel Pipe
Authors: Bézi Zoltán , Szávai Szabolcs
Published: September 2014

In this study the repair weld simulation of an austenitic steel pipe is performed to measure the residual stresses caused by the welding. The simulation consists of three work tasks. First the girth welding of the pipe is performed on simplified geometries to decrease the calculation time. The next work task is the simulation of the machining of the repair weld excavation, performed in one simulation step. The last task is the simulation of the repair welding. Residual stress measurements are performed on weld repair to provide validation of the simulation performed on the model.
Research on Argon Protection when Using WIG Welding
Authors: Ţunea Daniel , Burcă Mircea
Published: September 2014

The paper presents the theoretical bases of gas flow, as drowned jets, the device used for viewing the pure gas cone (argon) using a smoke screen infused on the edge of the argon jet and then the results of researches carried out on four sizes of nozzles often used in TIG welding. On each type of nozzle the argon flow parameter was varied and the height of the cone of pure argon was photographed and measured. The paper ends with the mathematical correlations that allow us to maximize the height of pure cone argon in relation to its flow. Keywords: TIG welding, Pure argon cone
New Ecological Technique for Soldering of Metallic Materials
Authors: Cojocaru Radu , Botila Lia-Nicoleta , Verbiţchi Victor , Ciucă Cristian
Published: September 2014

The performances, qualities and extraordinary development potential of the friction stir welding process (FSW) are well known in the world, both in the scientific and industrial areas. The innovative technical developments, based on the principle of the FSW process, conducted at ISIM Timisoara, as well as the results obtained so far have put the foundation for initiating a new method for bonding of materials, namely friction stir soldering. The principle of the new soldering process is based on important features of the FSW process. The paper presents the results of a program of experiments, which had as its main objective checking whether the new proposed soldering process is viable and applicable. Positive results were obtained by the soldering tests of copper (Cu99), brass (CuZn39Pb2) and steel (S235). Promoting this new environmentally friendly process of soldering is beneficial, because it complies with the current trends worldwide regarding both the environment and health.
Research on the Influence of Artificial Ageing on the Tensile Properties of Plastic Coated Composites with Fabric Inserts, in the Presence of Simulated Welding Imperfections
Authors: Kun Lorand , Murariu Alin Constantin
Published: September 2014

An experimental research regarding the effects of artificial ageing by UV exposure on the tensile properties of a plastic coated composite material with fabric inserts, used mainly in the production of truck covers is presented in this paper. For the purpose of artificial ageing, the authors designed and built at ISIM Timisoara an original equipment with high performance UV lamps, adjustable geometry and forced cooling system. Defects of different sized were created in the aged and not aged specimens in order to simulate potential imperfections that appear during the joining process of these materials. The influence of artificial ageing with 24h and 48h exposure and imperfection size is highlighted by comparative analysis of the results obtained from the tensile tests that were carried out on all specimens. The results are further compared to the tensile properties of aged and not aged welded specimens, obtained using high frequency current and hot air welding methods. The results show clear correlation between the imperfection size and the maximum tensile force and the elongation at break respectively. It is concluded however that further testing is necessary in the specially built equipment in order to properly describe the effect of accelerated artificial ageing by UV exposure on the tensile properties of plastic coated composite materials with fabric inserts.
Ways of Numerical Prediction of Austenitic Grain Size in Heat-Affected Zone of Welds
Authors: Moravec Jaromír , Bradáč Josef , Nováková Iva
Published: September 2014

In the present time there is a clear effort to achieve the most exact mathematical description of the behaviour of “Hi-tech” materials when exposed to temperature and stress loading. Besides the common numerically predicted values such as temperature, deformation and stress fields, or as the case may be structure changes during phase transformations, demands for prediction of the austenitic grain size in HAZ of welds become more and more frequent. That is why the present submission deals with the analysis of the determination of the grain size and grain growth kinetics of HR3C single-phase austenitic steel using the Monte Carlo Potts method. The procedure of obtaining the input data for numerical simulations will be demonstrated on HR3C steel, including the determination of grain growth kinetics and definition of all the parameters needed for a computational model. Results from the numerical simulation in Sysweld program will be then compared against the real experiment for a multi-layered weld made on HR3C tube.
Alternate Design Solutions for Reduced Stress Concentration Factor (SCF) T Joints of Circular Hollow Structures
Authors: Dima Gabriel , Machedon-Pisu Teodor , Balcu Ion
Published: September 2014

Design for fatigue of lightweight welded tubular structures is a significant concern of development teams. Based on practical design experience, alternate T joint design to usual Circular Hollow Structures (CHS) T joins are proposed. Proposed designs employ formed members within relevant dimensions range. A method based on finite element analysis including weld modelling was used, with analytical calculation of weld toe stress. Stress concentration factors (SCF) are calculated for all proposed designs for all typical load cases. Best placement and dimensions of formed members is given, together with design recommendations.
Nanostructured Materials for Cladding by Welding
Authors: Tihanov Tanasache Daniel , Florea Carmen , Binchiciu Emilia Florina , Geantă Victor
Published: September 2014

The rigorous stress conditions of active surfaces, from the components of magmatic rock processing equipment of surface pits, required finding new materials and system processes that achieve major impact on wear processes, in the sense of decreasing them. Conducted research with classic cladding by welding materials showed a high importance of the chromium carbides in the deposits, in the fight against wear. From manufacturing considerations, the participation of chromium carbides in the deposits made with traditional welding materials is 35%, which required finding new ways to obtain superior performances.The group of authors considered the nanostructure method to be convenient, hence of finishing the deposition structure, by introducing in the cladding by welding material composition centers of crystallization with colloidal size and superior temperatures, compared to the molten through welding bath temperatures. In order to achieve a new generation of cladding by welding materials, we proceeded to develop, on the above mentioned principle, rods that deposit by welding alloys like Fe-20%Cr-4%W-1%Ti, nanostructure with melted tungsten carbides and colloidal grinded. The rods thus obtained were used for cladding active surfaces of general purpose extraction and processing machines for basaltic rocks, to achieve highways.Results obtained confirm theoretical assumptions, which led to the implementation of new products in the industrial production.
Estimating the Reliability for Asphalt Milling Machines Teeth Manufactured by Claddings Processes
Authors: Iovanas Razvan Florin , Iovanas Daniela Maria , Dumitrascu Adela Eliza
Published: September 2014

The issues from the last decades related to the crisis of natural resources, raw materials, equipment, energy etc., gave rise to a new concept, namely sustainable development. The theory of sustainable development focuses on the development of quality products to provide trust and confidence, so as reliable. On this line the paper presents an approach on assessing the reliability and non-reliability of the milling teeth for asphalt machines classic manufactured and those manufactured by welding load, which give them self wear protection systems and self-lock at rotation. So in this sense there are presented comparative estimates regarding to the operating lifetime of the four batches of milling teeth for asphalt, 41Cr4 mark steel (EN 10083-1) the classic version and 3 groups of teeth load by weld on their working surface(wear) by different welding methods, namely: WIG - with filler material type tubular wire FILEUR DUR 606B, WIG – filler material with tubular type VT2, 5CrTiD rods, and MIG/MAG (CMT), the tubular wire filler material type FILEUR DUR. So, asphalt milling machines were stripped with 4 groups of teeth in order to track the behaviour during exploitation of each batch. Assuming that the product specifications properly respond customers' requirements, the level of reliability can be measured accurately by the fraction of delivered units that meet the specifications. On this line for estimating the reliability the Monte Carlo simulation method was used, which is suitable for analyzing the products that are designed to provide superior quality.
The Interface Behavior between External FRP Reinforcement and Masonry
Authors: Leone Marianovella , Sciolti Margherita Stefania , Micelli Francesco , Aiello Maria Antonietta
Published: September 2014

The need to guarantee higher safety levels of masonry structures under both short and long term conditions, have led to the use of new materials and technologies, in conjunction or in place of traditional ones. In this context, fiber-reinforced composite materials have gained an increasing success, mostly for strengthening, retrofitting and repair existing structures. As well known, the analysis of the interface performance of FRP (Fiber Reinforced Polymer) composites and masonry substrate is a critical problem as it influences the effectiveness of the technique. The present paper reports part of a large research project, still in progress, focused on the analysis of the bond performance between FRP sheet and different type of masonry substrates. The obtained experimental data were analysed in terms of bond strength and the kind of failure. The influence of the deformability of the strengthening material as well as the mechanical performance of the substrates are also discussed.
Masonry Reinforcement with IMG Composites: Experimental Investigation
Authors: Balsamo A. , Iovinella Ivano , di Ludovico M. , Prota Andrea
Published: September 2014

The interest in strengthening of historical masonry structures is significantly grown especially to techniques which combine properties like as reversibility, compatibility, and sustainability of the intervention. Among these, a promising technique is the use of inorganic matrix grid (IMG) composites. Several experimental tests have been carried out to prove the effectiveness of this system as a strengthening solution for different masonry types. The present paper presents the original results of five tests on uncoursed stone masonry panels under diagonal compression and collect the data of previous tests carried out by the authors on other masonry typologies. The tests results on several masonry types and strengthening layouts as well as Fiber reinforced Polymer (FRP) grid and mortar types are reported and discussed. The experimental programs clearly confirmed the effectiveness of the investigated strengthening technique to increase the panels shear capacity and ductility; however, a suitable theoretical expression to quantify the benefits provided by this strengthening solution, based on the reinforcement layout and on the masonry type, is still missing. The comparative analysis of the experimental data is presented in the paper in order to clarify the benefits provided by each strengthening system.
Strengthening of Masonry Elements by FRP: Influence of Brick Mechanical and Microstructural Properties
Authors: Mazzotti Claudio , Sassoni Enrico , Bellini Alessandro , Ferracuti Barbara , Franzoni Elisa
Published: September 2014

In this paper, the effect of several brick and mortar mechanical and microstructural parameters on the maximum debonding force of the same glass fiber reinforced polymer (GFRP), applied on different bricks and on corresponding masonry panels, was investigated. GFRP sheets were bonded by epoxy resin to four different types of solid fired-clay brick and four types of masonry panels, manufactured using the same bricks and a natural hydraulic lime mortar. The reinforced specimens were subjected to bond tests to evaluate the maximum debonding force. Bricks and mortar were characterized in terms of compressive strength (in the case of bricks, along two different orthogonal directions), surface roughness and pore size distribution. Based on the results of the study, alongside brick mechanical properties in different directions, also brick microstructural parameters seem to play a very important role, which should be taken into account for fully explaining the experimental results.
Tensile Behaviour and Durability of Mortar-Based Strengthening Systems with Glass-Aramid Textiles
Authors: de Santis Stefano , de Felice Gianmarco
Published: September 2014

Mortar-based composite materials are currently receiving great attention for strengthening masonry structures, especially when specific preservation criteria need to be fulfilled. Their mechanical properties and durability, however, still need to be fully investigated. An experimental campaign has been carried out to characterize the tensile behaviour of composite strengthening systems comprising glass-aramid textiles. First, textile specimens comprising either E-glass or AR-glass have been aged in alkaline environment, for different durations up to 1000 hours, and tested under tension to investigate their durability. Then, composite specimens have been manufactured with the AR-glass-aramid mesh and four different mortar matrices, ranging from strong mineral and cement mortars, to weak hydraulic lime mortars. Strength and stiffness, failure mode and response stages under tension have been identified and compared to those of the dry textiles to investigate the contribution provided by the matrix and derive design parameters for various field applications.
Durability Analysis for FRP and SRG Composites in Civil Applications
Authors: Borri Antonio , Castori Giulio , Corradi Marco , Speranzini Emanuela
Published: September 2014

In this study, an effort was made to develop an experimental protocol to study the effects of accelerated ageing on composite materials based on bamboo and steel fibers. The physic-mechanical properties of different types of steel and bamboo fibers were investigated. Specimens were subjected to environmental agents. Mechanical and physical tests were used to measure the retained properties and to observe the causes of damage and strength reduction. The experimental data showed that resin properties may strongly influence the durability of FRP reinforcement, environmental combined cycles did not take to significant damage of conditioned specimens; steel fibers are sensitive to alkaline attack when resin does not provide adequate protection to fibers.
Numerical and Experimental Analysis of Full Scale Arches Reinforced with GFRP Materials
Authors: Basilio Ismael , Fedele Roberto , Lourenço Paulo B. , Milani Gabriele
Published: September 2014

In this contribution, original limit analysis numerical results are presented dealing with some reinforced masonry arches tested at the University of Minho-UMinho, PT. Twelve in-scale circular masonry arches were considered, reinforced in various ways at the intrados or at the extrados. GFRP reinforcements were applied either on undamaged or on previously damaged elements, in order to assess the role of external reinforcements even in repairing interventions. The experimental results were critically discussed at the light of limit analysis predictions, based on a 3D FE heterogeneous upper bound approach. Satisfactory agreement was found between experimental evidences and the numerical results, in terms of failure mechanisms and peak load.
Experimental Study on Masonry Panels Strengthened by GFRP: The Role of Inclination between Mortar Joints and GFRP Sheets
Authors: Mazzotti Claudio , Ferracuti Barbara , Bellini Alessandro
Published: September 2014

For the shear strengthening of masonry walls, different configurations for FRP sheets are currently used in real application, such as vertical, horizontal or diagonal strips. In the last configuration the FRP sheet is inclined with respect to the direction of mortar joints. In the experimental campaign presented in this paper, it is investigated whether the FRP-masonry bond could be affected by this inclination. In order to analyze this issue, three different typologies of masonry panels (with different textures) retrofitted by FRP sheets, inclined of 45 degrees with respect to the vertical axis of the specimen, are subjected to single-lap shear tests. Results of shear tests are presented in terms of maximum debonding forces, force-elongation curves, failure modes and strain profiles along the specimens. The use of Digital Image Correlation (DIC) technique allowed to obtain complete strain maps on the surface of the specimens tested, with the purpose of investigating possible variations in the strain field within the bonded area.
Dry Masonry Strenghtening through Basalt Fibre Ropes: Experimental Results against Out-of-Plane Actions
Authors: Monni Francesco , Quagliarini Enrico , Lenci Stefano , Clementi Francesco
Published: September 2014

One of the most important characteristics that historical masonry should have is that of a monolithic behavior. Without these basic feature, no structural analysis could be considered reliable. If this characteristic is absent, strengthening bearing masonry giving it a transversal monolithic behavior is one of the first retrofitting actions to do so as to improve its seismic performance. Hence come out the idea to develop a new consolidation technique specially formulated for historical masonry. Stitching masonry through continuous flexible elements is an innovative technique, able to connect the several masonry components and to attribute to it a monolithic behavior according to the principles that govern the intervention on existing buildings: minimal intervention, compatibility, reversibility, respect of authenticity, matter conservation, control of the visual impact and possibility of recognizing the intervention. Basalt fibers ropes of 4 mm of nominal diameter (declared by manufacturer), have been used in this experimental program as continuous flexible element. The technique has been already tested and proved to be effective for improving the behavior against “in-plane” actions. Good results has been obtained also excluding synthetic adhesives (resins), with an enhancement about reversibility. In this paper, the results of an experimental campaign aimed to evaluate the technique effectiveness against “out-of-plane” loads are presented. Reinforced and unreinforced brick masonry specimens have been tested simulating vertical bending mechanism activation to evaluate the stitches contribute.
Collapse Mechanisms due to Earthquake in the Structural Typologies of Historic Constructions: The Case of Mirandola
Authors: Boscato Giosuè , Dal Cin Alessandra , Russo Salvatore
Published: September 2014

During the seismic event of May 2012 in the Emilia-Romagna Region (Italy), several cultural heritage structures collapsed or were severely damaged. This paper gives a description of the damage/collapse mechanisms observed on some of these buildings. The Church of Gesù, the City Hall and the tower of the Cathedral in Mirandola (MO) were analyzed. In particular, this article focuses on the behavior analysis of a church, a palace and a bell-tower, mainly masonry construction, that are the most widespread types of protected monuments proposed in the Italian code as simplified models for the verifications on the entire cultural heritage of a prior assessment of the seismic risk. The survey permitted to detect the most significant damage, mainly related to the cracks of the masonry and to understand the different collapse mechanisms.
Crack Propagation in Compression and Mounted Arrestors
Authors: Casacci Susanna , Di Tommaso Angelo , Gentilini Cristina
Published: September 2014

Strengthening of masonry walls is a key aspect during building retrofitting operations having conservation goals.
“Reinforced repointing technique” involves the application of materials having high tensile strength such as steel bars, steel textile sheets or composites thin pultruded laminae with cracks arrestors function, to reduce the vulnerability of masonry structures against in-plane and out-of-plane actions.
In this paper, a three-dimensional numerical model is developed to evaluate the efficiency of reinforcing steel bars facing crack propagation phenomenon under increasing compressive loads.
Seismic Out-of-Plane Assessment of Podestà Palace in Mantua (Italy)
Authors: Degli Abbati Stefania , Cattari Serena , Marassi Ilaria , Lagomarsino Sergio
Published: September 2014

The paper describes the seismic assessment of the Palazzo del Podestà in Mantua (Italy), hit by the Emilia earthquake (2012), focusing the attention on the activation of the out-of-plane response of the north-east façade on Piazza Broletto. In fact, even if the earthquake marginally hit Mantua, the façade highlighted its significant vulnerability mainly consequent to the lack of connection between the orthogonal walls and of tie-rods. Nonlinear kinematic analyses have been performed, referring to a macro-block model and considering both the original configuration and some possible strengthened ones. The results were coherent with the observed damage after the seismic event, highlighting in this way the reliability of the adopted modelling strategies and analysis method, and allowed to outline the most proper strengthening solution, able to minimize the impact on the monument and guarantee its preservation.
Acellular Dermis Obtainment to Fibroblastic Cell Culture and Tissue Engineering
Authors: Ribeiro Eliara Fernanda Bastos , Sayuri Higa Camila , Santos Arnaldo Rodrigues
Published: September 2014

Tissue injuries are the main factors that lead to treatment by skin culture. In cases where the damage is extensive patient has insufficient amount of tissue to recover the area lost. A possible solution is the use of tissue engineering. Dermal substitutes must provide features and functions as close as possible to the normal skin. The acellular dermis can be obtained from the own patient and represents a viable alternative as a graft. The acellular dermis is used as a dermal analogue to the implantation of cells for tissue engineering treatment. The aim of this study was to compare different ways of obtaining mouse skin acellular dermis and characterize this dermis by macroscopic visualization, light and atomic force microscopy and cell culture.
Improving the Carbon Steel Surface Treatment Process
Authors: Viomar Aline , Vanjura Bianca , de Fátima Oliveira Marilei , Pinto Rodrigues Paulo Rogério
Published: September 2014

Carbon steel is widely employed in the production of parts and machinery which supply the most diverse industrial sectors, such as the production of domestic appliances and cars. However, it presents low chemical resistance, being necessary the superficial treatment with anti-corrosion substances. Most conventional surface treatments present harmful components to the environment and to life in general, as for instance, nickel, which is used in the phosphatization processes. More recently, researchers have been pointing to surface treatments which employ nanoceramics as potential substitutes to phosphatization. This study aims to develop a nanoceramic treatment to the carbon steel 1008, based on self-assembling molecule (SAM) and titanium dioxide. Carbon steel samples were SAM treated and then immersed in a solution containing TiO2. A chemometric study was developed to evaluate the best treatment conditions, using the software Designer Expert. For the electrochemical characterization, electrochemical impedance spectroscopy (EIS) tests were carried out. Results revealed that the SAM + TiO2 coating presents higher resistance to polarization than the samples treated with zinc phosphate, in a 0.01 mol L-1 sulphur acid medium.
Sterilization of Chitosan Membranes for Use as Biomaterial
Authors: Nascimento Imarally V.S.R. , Leal Rita de Cássia A. , Fook Marcus Vinícius Lia , Meira Roberta Costa
Published: September 2014

Sterilization is a procedure which promotes complete destruction or elimination of all forms of microorganisms. It is a fundamental stage in the processing of biomaterials, and functionality of any sterilization system must be determined by its effectiveness in exterminating microorganisms without harming or adversely affect the properties of medical devices. Some sterilization techniques can react with functional groups of the polymer leading to changes in the properties, affecting the biomaterial. This study aimed to develop chitosan membranes sterilize them by following methods: an autoclave, ethylene oxide, glutaraldehyde and ultraviolet radiation and characterized by FTIR, XRD and SEM. Based on the results of this study it can be concluded that the method of sterilization indicated for the membranes of chitosan is ethylene oxide because the other altered physicochemical properties thereof.