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For several industrial applications, high friction surfaces with low adhesion are essential. Here, a poly (styrene-co-butyl methacrylate) polymer latex is coated on paper to achieve a high static friction at the interface between a coating and e.g. a wood pallet. At this interface, the adhesion should be low enough for easy removal of objects placed on the coated paper. The static friction is measured with a custom designed and constructed frictometer and is investigated as a function of temperature from 25 to 55 degrees C and the resting time. Furthermore, the static friction is investigated with varying coating thicknesses and coatings containing calcium based fillers. Results show that the static friction is increasing non-linearly with both temperature and resting time. Furthermore, an amount of 10 wt% filler increases static friction. In conclusion, the static friction coefficient between coated paper and wood are up to 700% of uncoated paper depending on temperature and resting time. (C) 2016 Elsevier Ltd. All rights reserved.

Fluids and lubricants are critical for the mechanical manufacturing processing of metals, due to a high amount of friction generated, also reflected as heat, could wear and damage tooling and machine components. The proper application of lubricants increases machinery lifetime, decreases long-term costs, and energy and time consumption due to the maintenance or components exchange/repairs. Besides being non-renewable, mineral oils bring consequences to the environment due to their low biodegradability and could affect the user with respiratory and skin diseases. Recently, due to an increase in environmental awareness, the search of biocompatible and efficient lubricants has become a technology goal. The vegetable oil-based lubricants are slowly emerging as ecofriendly and high-performance alternatives to petroleum-based lubricants. This study evaluates soybean, sunflower, corn and paraffinic oils reinforced with SiO2 nanoparticles. The thermal and tribological evaluations were performed varying the temperature and nanofiller concentrations. The thermal conductivity improvements were observed for all nanolubricants as the temperature and filler fraction increased. The highest thermal conductivities were observed at 323 K with 0.25 wt % SiO2. The soybean and corn oils unveiled a maximum enhancement of ~11%. The tribological evaluations showed that SiO2 addition, even in small concentration, resulted into a significant improvement on a load-carrying capacity. For instance, at 0.25 wt % enhancements of 45% and 60% were observed for soybean and sunflower oils, respectively. The coefficient of friction performance also showed enhancements between 10% and 26%.

This paper studies failure of birch pulp–polylactic acid composites. Stiffness and strength are calculated using the theory of short fibre composites and the results are compared to experimental data. The results differed from the experimental values by 0–6%. With less aligned fibres the short fibre theory is not feasible. The performance of the 40 wt% birch pulp – polylactic acid composite is predicted with X-ray microtomography based finite element modelling, and the results are compared with experiments. Stiffness results differed from experiments by 1–17% . By adding into the models a third material phase representing the interface between the fibres and the matrix, the stress–strain curve of the composite was obtained with good accuracy. The work presents finite element modelling methodology of wood plastic composites and the critical further steps needed in order to assess the stress–strain behaviour, strength and stiffness. Tools for comparing different wood plastic composite microstructures are also presented.

This paper summarizes the submissions to a recently announced contact-mechanics modeling challenge. The task was to solve a typical, albeit mathematically fully defined problem on the adhesion between nominally flat surfaces. The surface topography of the rough, rigid substrate, the elastic properties of the indenter, as well as the short-range adhesion between indenter and substrate, were specified so that diverse quantities of interest, e.g., the distribution of interfacial stresses at a given load or the mean gap as a function of load, could be computed and compared to a reference solution. Many different solution strategies were pursued, ranging from traditional asperity-based models via Persson theory and brute-force computational approaches, to real-laboratory experiments and all-atom molecular dynamics simulations of a model, in which the original assignment was scaled down to the atomistic scale. While each submission contained satisfying answers for at least a subset of the posed questions, efficiency, versatility, and accuracy differed between methods, the more precise methods being, in general, computationally more complex. The aim of this paper is to provide both theorists and experimentalists with benchmarks to decide which method is the most appropriate for a particular application and to gauge the errors associated with each one.

Modern Imaging Techniques in Fracture and Damage Analyses’: Selected papers from the 21st European Conference of Fracture (ECF 21), held in Catania, Sicily, Italy, on 20–24 June 2016; International audience; In order to study the role of Fe content on the damage mechanisms of Al-Si-Cu alloy on a microstructural level, a Digital Image Correlation (DIC) method has been developed and performed on two Al-Si-Cu alloys: a high-Fe alloy (0.1 wt.% Fe) and a low-Fe alloy (0.8 wt.% Fe). Tensile tests on flat specimens have been performed, and a Questar long distance microscope has been used for the in-situ observation during tensile tests. The field measurements allow to identify and track the development and localization of deformation, and the fracture surfaces of the tensile specimens are analyzed using Scanning Electron Microscopy and Energy-Dispersive X-ray spectrometry (SEM-EDX) to identify the damage mechanisms. The results show that crack initiation occurs through the fracture of hard inclusions, i.e. Si particles, iron-intermetallics and Al2Cu particles in the high stress concentration region. Cracks often propagate through the fracture of hard inclusions rather than by their decohesion from the matrix.

For the optimum setup of an industrial manufacturing process, it can be important to know the drilling forces and moments. In many cases, theoretical estimates are not accurate enough, especially when dealing with new materials, and experimental measurements are mandatory. This paper presents the design of a dynamometer comprising a one-spoked wheel elastic component to measure the drilling thrust force and the drilling moment. A finite element analysis was made, using Ansys software, to find the most favorable position for the strain gauges. One set of strain gauges was bonded to spokes to determine the torque, and a second set was bonded to the other two spokes to quantify the axial thrust force. After dynamometer manufacturing, a calibration operation is achieved, and tests are performed by measuring the drilling forces, thrust, and torque on American Iron and Steel Institute (AISI) 1020 steel. The analogue signals from the gauges were recorded using a computer with a data acquisition device. Tool wear is studied, and the results are presented in the paper. A good agreement between results from the literature and computations demonstrates the efficiency and accuracy of this measuring instrument.

Interlayer burrs formation during drilling of stacked plates is a common problem in the field of aircraft assembly. Burrs elimination requires extra deburring operations which is time-consuming and costly. An effective way to inhibit interlayer burrs is to reduce the interlayer gap by preloading clamping force. In this paper, based on the theory of plates and shells, a mathematical model of interlayer gap with bidirectional clamping forces was established. The relationship between the upper and lower clamping forces was investigated when the interlayer gap reaches zero. The optimization of the bidirectional clamping forces was performed to reduce the degree and non-uniformity of the deflections of the stacked plates. Then, the finite element simulation was conducted to verify the mathematical model. Finally, drilling experiments were carried out on 2024-T3 aluminum alloy stacked plates based on the dual-machine-based automatic drilling and riveting system. The experimental results show that the optimized bidirectional clamping forces can significantly reduce the burr heights. The work in this paper enables us to understand the effect of bidirectional clamping forces on the interlayer gap and paves the way for the practical application.

Austenitic stainless steels offer a suitable combination of high ductility, adequate toughness, considerable strain hardening and good fire resistance, making them excellent construction materials, especially for structures subjected to accidental loading such as seismic and/or fire events. With most of the research over the recent years devoted to the behaviour of single isolated stainless steel members, advances on structural systems are scarce, yet necessary, for the further development of design codes. Hence, an extensive experimental programme on EN 1.4301 austenitic stainless steel frames including tests at different structural levels –material, cross-section, member and frame levels– has been carried out at the Laboratory of Technology of Structures and Materials at Universitat Politècnica de Catalunya. The companion paper presents the tests carried out at cross-section and member level, and the knowledge gained from the planning of the experimental set-up for frame tests, including the adopted loading schemes, auxiliary elements and instrumentation. This paper presents the results of the four tests conducted on austenitic stainless steel frames under static vertical and horizontal loading. The analysis of the test results allowed to investigate the interaction of material and geometrical nonlinearities experimentally, as well as the assessment of the EN 1993-1-4 and EN 1993-1-1 provisions for the global analysis of stainless steel frames, where the influence of material nonlinearity on second order effects is evaluated, and which is currently limited to numerical studies only. "This experimental programme was developed in the frame of the Project BIA2016-75678-R, AEI/FEDER, UE “Comportamiento estructural de pórticos de acero inoxidable. Seguridad frente a acciones accidentales de sismo y fuego”, funded from the MINECO (Spain). The financial support received from the European Commission and Spanish Ministry for Science, Innovation and Universities through the Marie Sklodowska-Curie grant agreement No. 842395 and the FPI-MINECO PhD. fellowship Ref. BES-2017-082958 is also gratefully acknowledged. Authors would like to acknowledge the support, advice and suggestions from Professor K. Rasmussen (The University of Sydney), Professor B. Young (Hong Kong University) and Professor L. Gardner (Imperial College London) in the preparation of this experimental programme, and the support from Acerinox and MeKano4. The time and effort from the staff at the Laboratory of Technology of Structures and Materials and the Geotechnical Engineering and Geosciences Department from Universitat Politècnica de Catalunya are also much appreciated."

The National Jet Fuel Combustion Program (NJFCP) is an initiative, currently being led by the Office of Environment & Energy at the FAA, to streamline the ASTM jet fuels certification process for alternative aviation fuels. In order to accomplish this objective, the program has identified specific applied research tasks in several areas. The National Research Council of Canada (NRC) is contributing to the NJFCP in the areas of sprays and atomization and high altitude engine performance. This paper describes work pertaining to atomization tests using a reference injection system. The work involves characterization of the injection nozzle, comparison of sprays and atomization quality of various conventional and alternative fuels, as well as use of the experimental data to validate spray correlations. The paper also briefly explores the application viability of a new spray diagnostic system that has potential to reduce test time in characterizing sprays. Measurements were made from ambient up to 10 bar pressures in NRC’s High Pressure Spray Facility using optical diagnostics including laser diffraction, phase Doppler anemometry (PDA), LIF/Mie Imaging and laser sheet imaging to assess differences in the atomization characteristics of the test fuels. A total of nine test fluids including six NJFCP fuels and three calibration fluids were used. The experimental data was then used to validate semi-empirical models, developed through years of experience by engine OEMs and modified under NJFCP, for predicting droplet size and distribution. The work offers effective tools for developing advanced fuel injectors, and generating data that can be used to significantly enhance multi-dimensional combustor simulation capabilities., ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition, Monday 11 June 2018, Oslo, Norway

The use of composite floor slabs is well established and provides an opportunity to promote the use of visually exposed composite slabs. Stainless steels, with the combination of good mechanical properties and excellent corrosion resistance, are key to this strategy, specially ferritic stainless steels, whose price is lower and more stable than that corresponding to the more widely used austenitic grades, due to their low nickel content whilst still maintaining good mechanical properties and aesthetic appeal. In addition, the emissivity of these grades contributes to lowering the heating and cooling requirements of buildings, reducing the costs associated to maintenance. Generally used as cold-formed members with high resistance-to-weight ratios, stainless steel decks are slender and highly sensitive to buckling phenomena and so the study of the structural performance of composite slabs using ferritic stainless steel decking is required due to the complex nonlinear behaviour of stainless steels, which is very different from that exhibited by carbon steel. Thus, this paper presents a comprehensive experimental programme on ferritic stainless steel trapezoidal decks for composite slabs under several structural configurations occurring during construction stage: simply supported decks under positive and negative bending moment, continuous decks and internal and end support tests. All the experimental results have been compared with the predicted ultimate loads in EN 1993-1-4, which remits to EN 1993-1-3 for carbon steel, and also with some previous tests on galvanized carbon steel decks. The paper concludes that EN 1993-1-3 provisions are applicable to ferritic stainless steels.

Made available in DSpace on 2019-10-04T12:31:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-11-01 CAPEX PROEX Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG) Post Graduate Program of Mechanical Engineering of UFU Grinding is one of the most common finishing processes used in the manufacture of metal components that require a combination of both smooth surface finish and tight tolerances. Despite the abundant knowledge concerning this process, specific literature is still scarce regarding the grinding of different cast iron grades. These materials have a wide application in the automotive industry, notably in the manufacture of gears, crankshafts, and valve control shafts. In this sense, this paper presents an experimental study of the peripheral surface grinding of three grades of cast iron grades (gray, nodular, and compacted graphite) with two SiC abrasive grinding wheels. The input variables tested were two values for depth of cut (15 and 30 mu m) and two worktable speeds (5 and 10 m/min). The output variables analyzed were surface roughness, microhardness, microstructures, and SEM images of the ground surfaces. The results showed that gray cast iron provided the best performance concerning surface and sub-surface integrity among the three cast iron grades tested, whereas the nodular cast iron exhibited both worst finishing and superficial texture. No microstructural changes were observed in the samples of gray and compacted graphite cast iron grades, irrespective of the cutting conditions investigated, unlike for the nodular cast iron grade in which microstructural change was detected. The ranking order for the grindability of the three cast iron grades in terms of roughness, microhardness and surface texture investigated in this paper is gray cast iron, compacted graphite iron and nodular cast iron. Univ Fed Uberlandia, Sch Mech Engn, Av Joao Naves Avila 2121,Campus Santa Monica, BR-38408100 Uberlandia, MG, Brazil Sao Paulo State Univ Julio de Mesquita Filho, Dept Mech Engn, Bauru Campus,Av Engn Luiz Edmundo C Coube, BR-17033360 Bauru, SP, Brazil Pontificia Univ Catolica Parana PUC PR, Mech Engn Grad Program, BR-80215901 Curitiba, PR, Brazil Sao Paulo State Univ Julio de Mesquita Filho, Dept Mech Engn, Bauru Campus,Av Engn Luiz Edmundo C Coube, BR-17033360 Bauru, SP, Brazil

In order to protect industrial components, cobalt base alloys are applied as hardfacing material through welding techniques. A large number of papers have shown that controlling the chemical composition is a key point regarding the wear and corrosion resistance of coatings. This paper investigated the effect of bead overlapping on the microstructure and properties of CoCrWC alloy coatings. Mechanical properties were determined by hardness, sliding wear and microtensile tests. Bead overlapping reduces dilution during the previous bead melting, which in turn induces lower iron content. From the second bead on, an increase in the amount of interdendritic carbides and solid solution alloying was verified, accounting for the higher mechanical properties of the coatings.

A deep understanding of degradation mechanisms of metals is crucial for developing new materials with high performance. Within the different families of stainless steels, martensitic stainless steels are widely used in a great variety of industrial applications where mechanical properties, such as strength, wear resistance and fatigue behavior, need to be high. In many of those applications, such as bearings or gears, martensitic stainless steels may be subject to tribological conditions leading to wear. Furthermore, when a contact operates in a corrosive environment its deterioration can be significantly affected by surface chemical phenomena, leading to a tribocorrosion degradation mechanism. Indeed, martensitic stainless steels degrade through a great variety of wear and corrosion mechanisms. This paper aims to review the published data from 2005 to present related to wear, corrosion and tribocorrosion of martensitic stainless steels. Individual studies of tribological and corrosion behavior of martensitic stainless steels have been widely published since 2005. From the wear point of view, ploughing or abrasive wear in dry contacts involving martensitic stainless steel has been reported, while pitting corrosion is the most common mechanism for those steels. However, only nine papers were found since 2005 related to tribocorrosion of martensitic stainless steels, although most authors concluded that this joint action is the most important material degradation in martensitic stainless steels.

Appropriate S-N fatigue design curves for friction stir (FS) welded joints in aluminium alloys are currently not specified in design codes and standards. The present paper is intended to assist in enabling standardised fatigue design for such joints, through a comprehensive statistical analysis of more than 500 individual sets of data gathered from published literature. These data are used to establish the usual design fatigue curves for welds that give a 97.7% survival probability with 95% confidence. Experimental fatigue data represent defect-free butt joints and include both flat plate and tubular joints between similar aluminium alloys (across the range of 2xxx, 5xxx, 6xxx, and 7xxx series). Weld conditions include as-welded, machined, and post-weld heat treated under constant amplitude cyclic loading at various stress ratios in the range from R = -1 to 0.5. A systematic comparison is presented by categorising the data according to the alloy type, temper condition, postweld heat treatment and stress ratio and the correlation with the S-N design curves from Eurocode 9 is also considered. The fatigue curves presented in this paper will serve as a useful guideline for engineers involved in design of friction stir aluminium joints subjected to in-service fatigue loading.

The rotor is the core component of a gas turbine, and more than 80% of the failures in gas turbines occur in the rotor system, especially during the start-up period. Therefore, the safety assessment of the rotor during the start-up period is essential for the design of the gas turbine. In this paper, the transient equivalent stress of a gas turbine rotor under the cold start-up condition is investigated and the novel tie rod structure is introduced to reduce the equivalent stress. Firstly, a three-dimensional finite element model of the gas turbine rotor is built, and nonlinear contact behaviors such as friction are taken into account. Secondly, the convective heat transfer coefficients of the gas turbine rotor under the cold start-up condition are calculated using thermal dynamic theory. The transient analysis of the gas turbine rotor is conducted considering the thermal load, the centrifugal load, and the pretightening force. The temperature and stress distributions of the rotor under the cold start-up condition are shown in detail. In particular, the generation mechanism of maximum equivalent stress for tie rods and the change tendency of the pretightening force are illustrated in detail. The tie rod holes of the rear shaft and the turbine tie rod are the dangerous locations during the start-up period. Finally, a novel tie rod is proposed to reduce the maximum equivalent stress at the dangerous location. The maximum equivalent stress at this location is decreased by 15%. This paper provides some reference for the design of the gas turbine rotor.

This paper deals with standard test method for the measurement of vibration-damping properties of materials, ductile cast iron - graphitic cast iron with the spherical shape of graphite. Investigation is focused on its mechanical properties, chemical composition and microstructure, which are necessary as input parameters for computational modeling and numerical analysis. The vibration or oscillating of experimental samples is closely connected with such parameters as natural shapes (eigenshapes) and natural frequencies (eigenfrequencies). Preparation of a geometric model of a homogeneous beam sample and numerical analysis was performed by finite element method in the ADINA software environment. This paper can be used for further development and growth from the aspect of application of computational tools in the area of damping and eigenfrequency properties for construction materials. This paper deal was supported by the Slovak Grant Agency KEGA 007TnUAD-4/2017, VEGA grant No. 1/0649/17, VEGA grant No. 1/0589/17 and resulted from the project “Center for quality testing and diagnostics of materials”, ITMS code 26210120046 relating to the Operational Program Research and Development funded from European Fund of Regional Development

Recently multi-axis machining technology has improved significantly. It has become a widely accepted method of manufacturing components with complex, free form surfaces. Solid billet materials with negligible internal defects are used in this process. This provides increased durability and fatigue life over equivalent cast components. However, multi-axis machining using ball nose cutting tools leaves cusps as machining marks. The surface quality within the cusps can have a significant influence on the fatigue life and durability of a component. The main objective of this paper is to report the experimental investigation of the effect of different cutting parameters on surface roughness of Al 2618 alloy.\ud This paper reports on an experimental investigation of the effect of different cutting parameters on surface roughness of Al 2618 alloy. A full factorial experimental analysis using four different levels of spindle speed, feed-rate and cutting-tool approach angle was carried out. The results indicate that higher spindle speed, lower feed rate and a cutting tool approach angle of approximately 25° generates a better surface finish.

This paper demonstrates the application of the Johnson–Mehl–Avrami (JMA) theory to study the kinetics of the age hardening process in an A357 aluminum alloy. The precipitation hardening effect was studied at various times and temperatures. The outcomes show that the hardness can be improved via time and temperature changes. It is thus concluded that time and temperature are key variables in the precipitation hardening of the alloy. According to the results, solubilization at 823 K (550 °C) and then aging treatment at 453–463 K (180–190 °C) for 12–18 h is the optimum cycle to obtain the maximum hardness. The apparent activation energy of 40 kJ/mol was achieved through the kinetic studies. Based on the practical data, it is generally possible to estimate the hardness at a certain time and temperature by an appropriate equation. Furthermore, the maximum hardness and the time required to reach that maximum can be easily predicted through a suitable calculated relationship. Experiments by means of hardness measurement have been performed to provide the relevant information to validate the model. This paper aims to present the application of this simple modeling. The novelty of this paper is obtaining an equation that could be used to predict the hardness of an A357 alloy with a good agreement with the practical data.

Purpose 7075-T6 is the most widespread structural aluminium alloy due to its high mechanical strength. However, use of this alloy in critical aeronautic, maritime, and automotive sectors is limited by the susceptibility of T6 treatment to cracking and pitting corrosion. To improve fatigue behaviour in aggressive environments, several authors have proposed the use of different coatings to protect the substrate. Studies have investigated the application of thin hard coatings on light alloys by physical vapour deposition (PVD). Different contributions of residual stresses, thermal modification of the substrate, and mechanical interaction between the coating and aluminium substrate were investigated. The purpose of this paper is to investigate the rotating bending fatigue behaviour (R=−1) of 7075-T6 PVD diamond-like carbon (DLC)-coated specimens in air and in a corrosive environment. Tests were conducted at different applied stresses. Scanning electron micrographs of the fracture surface are provided to investigate the influences of mechanical and environmental driving forces on the failure mechanism. Design/methodology/approach The paper conducted an experimental study of the fatigue resistance of DLC coatings on a 7075-T6 substrate for corrosion protection at long and short fatigue lives, which includes rotating bending fatigue tests, step-loading fatigue test procedure, tests in aggressive environment (methanol), tests at high and low fatigue lives, analysis of the fracture surface, and analysis of the driving forces. Findings Tests performed in air showed that the coating anticipates crack nucleation for high applied loads, whereas for lower loads, the difference among fatigue curves decreases. This result is very interesting from an industrial standpoint because the obtained material shows improved corrosion and wear resistance, without the fatigue resistance loss generally associated with hard coatings. The methanol environment accelerates crack nucleation and propagation, resulting in a sensible deterioration of the fatigue behaviour. A minimum soaking time seems to be necessary before the damaging effect of the environment begins. The coating has a certain protective effect against the environment, but this protection is insufficient for the specimen to achieve fatigue limits beyond those of the uncoated specimens. This deficiency can be related to small pores or defects in the coating, which allow contact between the substrate and the environment. Further tests are necessary to verify whether there exists a load under which the fatigue behaviour of the coated specimens is better than that of the uncoated specimens. Crack nucleation due to fatigue occurs close to the outer surface for all observed samples. For coated samples tested at the lowest stress level, crack nucleation seems to be located below the surface. This observation means that premature coating cracking, which characterises the nucleation mechanism at higher loads, did not occur at lower stress levels. The fracture surface of uncoated samples was clearly damaged by the aggressive solution, justifying the poor fatigue resistance. Research limitations/implications The obtained data do not represent actual S-N curves, which would necessitate a larger number of tests with proper statistics. Nevertheless, some indications of the DLC effects on 7075-T6 specimens in air and methanol environments can be deduced. The step-loading technique seems to be critical for tests in corrosive environments, probably because the total soaking time in the corrosive environment is generally higher than it is for the single-run test. Originality/value The originality of the paper lies in the application of the step-loading test procedure to quickly detect the mechanical and chemical driving forces that control the damage and structural integrity of light alloys components in very aggressive environments.

This paper presents a 3D topology optimization approach for designing shell structures with a porous or void interior. It is shown that the resulting structures are significantly more robust towards load perturbations than completely solid structures optimized under the same conditions. The study indicates that the potential benefit of using porous structures is higher for lower total volume fractions. Compared to earlier work dealing with 2D topology optimization, we found several new effects in 3D problems. Most notably, the opportunity for designing closed shells significantly improves the performance of porous structures due to the sandwich effect. Furthermore, the paper introduces improved filter boundary conditions to ensure a completely uniform coating thickness at the design domain boundary.

In this paper an experimental, numerical and analytical investigation is presented of the wrinkling behaviour that occurs in the flange of deep drawn cylindrical cups of aluminium alloy sheet using macro-textured blankholder surfaces. A series of deep drawing experiments were performed using a range of tool textures, draw ratios and blank-holding forces. A numerical material and process model was formulated to enable the occurrence of wrinkling to be simulated. In addition, two analytical buckling models of aluminium alloy sheet in deep drawing with macro-textured blankholder based on the energy method, (namely a one-dimensional and two-dimensional model) were developed for the first-time and utilised to predict the effect of process parameters on wrinkling. The analytical buckling models investigated two boundary conditions, hinged and built-in boundary condition. It was found that texture geometry and draw ratio had a significant effect on wrinkling but the blank-holding force did not. The analytical models developed in this paper to represent sheet metal wrinkling behaviour for the macro-textured tools can be used as a design guide to determine the geometry of tool textures necessary to avoid wrinkling defects in aluminium alloy stamping processes.

Purpose The purpose of this technical paper is to investigate the friction and wear behavior of inexpensive and durable cutting tools, developed for wood machining using duplex treatment. Design/methodology/approach Cr–(WC–Co) coatings were deposited onto carburized low-alloy steel substrate by a reactive magnetron sputtering. The total coating thickness was approximately 2 μm. Unlubricated wear tests have been performed using a disc sample sliding against an alumina ball (Al2O3) and a wood (beech) pin. Findings The paper provides information about the effect of duplex treatment on the surface properties of low-alloy steel against wood and offers practical help for the researchers in coating topic. Originality/value Experimental results showed that sliding wear properties of the selected coatings are strongly dependent on the counter-face material. When tested against alumina balls, the wear mechanisms are oxidative wear followed by a combination of adhesive and abrasive wear, while a combination of an oxidative and adhesive wear was the main wear mechanism observed against a wood pin.

The purpose of this paper is twofold and therefore it has been divided in two parts. In the first part, experimental results of 25 gray cast iron notched specimens tested under torsion loading are provided. V-notch (with an opening angle of 120°) geometry is considered with root radii ranging from 0.1 to 2.0 mm. Plots of torque loads versus twist angles are recorded for all notch root radii tested. Such results can help in evaluating numerical and theoretical models for fracture of notched components under mode III loading. The second part of the paper deals with an analysis of the experimental results by using the Strain Energy Density criterion. Because of the mode III loading conditions, a non-conventional application of such criterion is carried out, showing a good agreement between the experimental results and the theoretical fracture assessments and it is used to justify the link between nominal and local fracture approaches.

The cast-iron pipeline has been utilized as the water main since the last century and continuously contributes to the present community by supplying potable water. These pipes are subjected to corrosions on the internal and external surfaces, causing pipeline breakage or leakage. For economical maintenance decisions of water distribution networks, it requires assessing the remaining strength of the pipes. Fracture mechanics has been effectively applied for evaluating the remaining strength of deteriorating structures. However, the major challenges in applying the fracture mechanics are obtaining the parameters such as the stress intensity factor (SIF) and fracture toughness. This paper presents a method for calculating the SIFs for cast-iron pipe subjected to internal surface corrosion. Finite element analysis is employed to calculate the SIFs using the contour-integral method for buried cast iron pipes considering crack only and crack with corrosion defects under internal pressure and vertical surface loads. Various aspect ratios and crack depths of semi-elliptical defects at the springline and invert/crown of the pipe are considered. In general, the surface load decreased the SIF for the springline internal crack and increased the SIF for the invert/crown crack. For the crack geometries and the loading conditions considered, the maximum reduction of the SIF for the springline crack was 85.1%, and the maximum increase for the invert/crown crack was 72.8%. A crack depth increase from 0.2t to 0.8t increased the SIFs by 130% to 243% under the internal pressure and 95% to 141% under the combined load for the invert/crown cracks.

This paper proposes a thermal method for estimating fatigue life of metallic ropes. Rotating bending fatigue tests are performed on rope specimens and their temperature evolution is monitored till specimen failure. The proposed method is justified through a theoretical framework based on thermally dissipated energy and energy spent for mechanical damage. Experimental fatigue tests are carried out in different conditions by primarily varying the bending load and the rotational speed. Experimental results are in agreement with the theoretical model allowing the estimation of damage evolution and rope life via thermal measurements.

Gas–liquid two-phase flow is widely used in many engineering fields, and bubble dynamics is of vital importance in optimizing the engineering design and operating parameters of various adsorptive bubble systems. The characteristics of gas–liquid two-phase (e.g., bubble size, shape, velocity, and trajectory) remain of interest because they give insight into the dynamics of the system. Bubble plumes are a transport phenomenon caused by the buoyancy of bubbles and are capable of generating large-scale convection. The surface flow generated by bubble plumes has been proposed to collect surface-floating substances (in particular, oil layers formed during large oil spills) to protect marine systems, rivers, and lakes. Furthermore, the surface flows generated by bubble plumes are important in various types of reactors, engineering processes, and industrial processes involving a free surface. The bubble parameters play an important role in generating the surface flow and eventually improving the flow performance. This paper studies the effects of temperature on bubble parameters and bubble motion to better understand the relationship between the various bubble parameters that control bubble motion and how they impact the formation of surface flow, with the ultimate goal of improving the efficiency of the generation of surface flow (i.e., rapidly generate a strong, high, and wide surface flow over the bubble-generation system), and to control the parameters of the surface flow, such as thickness, width, and velocity. Such flow depends on the gas flow rate, bubble size (mean bubble diameter), void fraction, bubble velocity, the distance between bubble generator and free surface (i.e., water height), and water temperature. The experiments were carried out to measure bubble parameters in a water column using the image visualization technique to determine their inter-relationships and improve the characteristics of surface flow. The data were obtained by processing visualized images of bubble flow structure for the different sections of the bubble regions, and the results confirm that temperature, bubble size, and gas flow rate significantly affect the flow structure and bubble parameters.

In the damping design of blisks with hard coating, changing coating thickness is one of the frequently used ways for achieving better damping performance. Nevertheless, for the vibration analysis with variable coating thickness by using commercial finite element software, it is necessary to regenerate the finite element mesh, which results in inconvenience in computation. In this paper, a new laminated element is developed to solve this problem, which needs solely the node coordinates corresponding to the maximum coating thickness. The additional virtual layers to simulate the variations of coating thickness are introduced for the presented element to avoid regenerating new node coordinates. By comparing the analysis results obtained by SOLID185 in ANSYS software, experiment and the developed element, this new element is verified that it remains effective for variable coating thickness parameter input. Furthermore, the effects of the coating thickness on the natural frequency and the forced response of an actual blisk are analysed and due to using the same node coordinates, the computational efficiency is improved significantly. The analysis results indicate that with the increase of coating thickness, the resonance response is reduced significantly and even the thinner coating could also achieve better damping performance.

One of the major advantages of micromachining is the high achievable surface quality at highly flexible capabilities in terms of the machining of workpieces with complex geometric properties. Unfortunately, finishing operations often result in extensive process times due to the dependency of the resulting surface topography on the cutting parameter, e.g., the feed per tooth, fz. To overcome this dependency, special tool shapes, called wipers, have proven themselves in the field of turning. This paper presents the transfer of such tool shapes to solid carbide milling tools for micromachining. In this context, a material removal simulation (MRS) was used to investigate promising wiper geometries for micro end mills (d = 1 mm). Through experimental validation of the results, the surface topography, the resulting process forces, and tendencies in the residual stress state were investigated, machining the hot work tool steel (AISI H11). The surface-related results show a high agreement and thus the potential of MRS for tool development. Deviations from the experimental data for large wipers could be attributed to the non-modeled tool deflections, friction, and plastic deformations. Furthermore, a slight geometry-dependent increase in cutting forces and compressive stresses were observed, while a significant reduction in roughness up to 84% and favorable topography conditions were achieved by adjusting wipers and cutting parameters.

The present paper investigated characteristics of fatigue fracture behavior, particularly initiation stage of fatigue fracture (Stage I), in an as-quenched martensitic steel from microstructural and crystallographic points of view. The detailed crystallographic orientation analysis using EBSD revealed that block boundaries in lath martensite structure were the most preferential initiation sites for fatigue cracks. We found that incompatibility of plastic strains between adjacent blocks was the origin for the formation of initial fatigue cracks at block boundaries. Moreover, plastic deformation along {0 1 1} slip planes also played an important role on the transgranular crack propagation.

Corrosion, wear and tribocorrosion behaviours of leaded tin bronze were examined in simulated seawater using alumina counterbody for tribological contact. Active dissolution of alloy and corrosion product development on surfaces were the dominant corrosion mechanisms. Tribological contact with counterbody removed majority of the products, thus contributing to active dissolution of freshly exposed surface. This wear-induced corrosion mechanism contributed to 45% and 60% of total material losses at the two highest potentials, 50 mV and 250 mV vs. Ag/AgCl. Pure wear of alloy occurred in the form of abrasive wear. At anodic potentials under tribological contact, corrosion raised the friction coefficient as compared to pure wear and increased wear of the alloy. These results are presented and discussed in this paper.

This paper describes the effects of uniform and non-uniform liquid co-flow on the bubbly flow in a rectangular column (with two inlets) deliberately aerated unevenly. The two vertical bubbly streams, comprising uniform bubbles, started interacting downstream of the trailing edge of a splitter plate. This study quantifies the emergence of buoyancy driven flow patterns as a function of the degree of a-symmetric gas sparging and (non-)uniform liquid co-flow by using Bubble Image Velocimetry (BIV) and dual-tip optical fibre probes. Without liquid co-flow, small differences in the gas fraction of the left and right inlet had a large effect on the mixing pattern, whereas a liquid co-flow stabilized a homogeneous flow regime and the flow pattern was less sensitive to gas fraction differences. Void fractions, bubble velocities and chord lengths were measured at two fixed position in the flow channel, whereas BIV provided a global overview of the flow structures. A correlation was developed to predict (a-symmetric) operating conditions for which the gas fraction of the left and right inlet are balanced, such that the bubble motion is governed by advection and no buoyancy driven flow structures arise. The data obtained is highly valuable for CFD validation and development purposes.

The purpose of this paper is to investigate the variation in the coefficient of friction (CoF) and also the wear in a lead bronze coating under different texture conditions. The tribological tests were performed using a tribometer with pin on disk configuration. Several kinds of textures, realised by a surface laser texturing, were tested by varying the diameter, depth, and density of the dimples under severe working conditions. The innovative aspect concerns the behaviour of the textured lead bronze coating and the lubrication conditions when the sample is subjected to extreme load conditions. Confocal microscopies and SEM (Scanning Electron Microscopy)/EDS (Energy Dispersive X-Ray Spectroscopy) analyses were performed to evaluate the texture behaviour and also the surface deterioration of the coating. The results show that the application of texture processing leads to an improvement in the tribological properties of the coating. By analysing separately the variation of the different geometric parameters of the dimples, it has been shown that the best results are obtained with a diameter of 50 μm, a density of 5%, and a depth of 5 μm.

The present paper reports an in-depth testing and numerical modelling programme, to study the post-fire local buckling behaviour and residual resistances of austenitic stainless steel circular hollow section (CHS) stub columns under combined compression and bending moment. The testing programme employed twelve austenitic stainless steel CHS stub column specimens and included heating and cooling of the stub column specimens, post-fire material testing and post-fire combined loading tests. The testing programme was followed by a numerical modelling programme, where finite element models were developed and validated against the test results and then employed to perform parametric studies to generate additional numerical data. It is worth noting that there are currently no design standards established specifically for stainless steel structures after exposure to fire. In this study, the relevant design rules (i.e. cross-section interaction curves) for stainless steel CHS under combined loading at ambient temperature, as set out in the European, American and Australian/New Zealand standards and given in the continuous strength method, were assessed for their applicability to austenitic stainless steel CHS under combined loading after exposure to fire, based on the obtained test and numerical data. The results of the assessments revealed that all the codified design cross-section interaction curves have certain shortcomings, including the lack of rational exploitation of material strain hardening and the use of linear interaction, and thus yield excessively high degrees of conservatism and scatter when used for austenitic stainless steel CHS under combined loading after exposure to fire. The continuous strength method was shown to lead to accurate and consistent post-fire residual resistance predictions for austenitic stainless steel CHS under combined loading, due principally to the rational consideration of material strain hardening. Finally, the reliability of the continuous strength method was confirmed by means of statistical analyses.

This paper introduces a new manufacturing process for vertical interconnect accesses (VIA). In contrast to industrially established VIA metallization technologies, the presented approach takes place without any chemical plating by combining copper ink and epoxy insulator coating with CO2 laser processing for VIA drilling and copper ink sintering. The minimum VIA resistances are less than 50 mΩ, fitting the theoretically calculated value. A laboratory application scenario testing a 10 × 10 contact pad array with a pitch of 800 µm successfully demonstrates routing across five printed metallization layers, including 128 blind and 112 buried VIA. © 2021 The Authors

Substantial research has been conducted in the last years into the structural responses of cold-formed and hot-rolled stainless steel equal-leg angle columns, whereas there is no experimental data on laser-welded stainless steel angle columns despite these sections being increasingly used in the modern construction industry. To fill this gap and provide benchmarks for design, a comprehensive experimental investigation into the structural strength and stability of laser-welded austenitic stainless steel equal-leg angle columns under pure axial compression was performed and described in this paper. A series of laboratory tests, performing on two test groups of specimens with nominal dimensions of 60 × 60 × 6 mm and 100 × 100 × 10 mm and different lengths, involved 6 stub column tests and 20 global buckling tests together with measurements on material properties, initial geometric imperfections and residual stresses. The experimental observations reveal that the column ultimate capacity and prevalent failure mode – major-axis flexural–torsional buckling and minor-axis flexural buckling – are highly dependent on the column slenderness and initial imperfections. The full load-lateral displacement, load-torsional rotation and load-axial strain responses of the specimens were fully reported and discussed. The results were employed to evaluate the accuracy of the current European and North American stainless steel design standards. The evaluation results revealed that the codified design procedures yield conservative resistance predictions of laser-welded stainless steel equal-leg angle columns, showing a prospective for their modification and improvement by providing more optimized and realistic results in design considering the actual residual stress distributions, material nonlinearity and strain hardening.

The paper presents results of FEM modelling as well as properties and microstructure of the ultralow-carbon ferritic steel after the unconventional SPD process—DRECE (dual rolls equal channel extrusion). Based on the conducted numerical simulation information about the deformation behaviour of a steel strip during the DRECE process was obtained. The simulation results were experimentally verified. The influence of DRECE process on hardness distribution, fracture behaviour and microstructure evolution of the investigated steel was analysed. The increase of steel strength properties after subsequent deformation passes was confirmed. The microstructural investigations revealed that the processed strips exhibit the dislocation cell microstructure and subgrains with mostly low-angle grain boundaries. The grains after processing had relatively high dislocation density and intense microband formation was observed. It was also proved that this unconventional SPD method fosters high grain refinement.

In this paper, the effect of microscale structures on the tribological and cutting behavior of cutting tools has been evaluated. A method for developing the micro structure design is presented using a statistic screening design. The micro structures are applied using ultrashort-pulsed laser technology. The effects of different structural parameters are investigated in orthogonal cutting of AW7075. Tools with structures benefit from lower cutting forces and exhibit a shorter chip morphology.

The paper proposes a novel approach to increase the performances of a sol–gel coating for biomedical applications. In particular, ultrasonic vibration-assisted turning in combination with cryogenic cooling is explored for the first time to generate a complex and isotropic texture more prone to be coated, and, in turn, less corrosion susceptible compared to the corresponding surfaces generated through conventional machining. A comprehensive characterization of the generated surfaces before and after coating gives new insights for understanding the mechanisms of increased performances, which were validated on bones fixation pins.

This paper presents a physically-based cyclic viscoplasticity model to capture the influence of welding-induced microstructural transformation on the fatigue response of the bainitic high-strength low-alloy steel, X100Q. The model incorporates the strengthening effects of dislocations, microstructural boundaries and precipitates, and the softening effects of microstructural degradation and early-life fatigue damage on yield strength and nonlinear cyclic-plastic response. The model is applied to predict the constitutive responses of X100Q parent material, physically-simulated intercritical heat affected zone (HAZ) and fine-grained HAZ, based on differences in bainitic hierarchical microstructure between the materials. A refined bainitic block structure is shown to be the primary microstructural feature contributing to monotonic and cyclic strength in the materials, whereas dislocation annihilation and the concomitant coarsening of the bainitic lath structure with cyclic-plastic deformation leads to cyclic softening behaviour. This publication has emanated from research conducted the financial support of Science Foundation Ireland as part of the MECHANNICS joint project between NUI Galway and University of Limerick under grant number SFI/14/IA/2604 and the I-Form Advanced Manufacturing Research Centre under grant number SFI/16/RC/3872. peer-reviewed

In this paper, we present a detailed example of numerical study of flm formation in the context of metal coating. Subsequently we simulate wiping of the film by a planar jet. The simulations have been performed using Basilisk, a grid-adapting, strongly optimized code. Mesh adaptation allows for arbitrary precision in relevant regions such as the contact line or the liquid-air impact zone, while coarse grid is applied elsewhere. This, as the results indicate, is the only realistic approach for a numerical method to cover the wide range of necessary scales from the predicted film thickness (tens of microns) to the domain size (meters). The results suggest assumptions of laminar flow inside the film are not justified for heavy coats (liquid zinc). As for the wiping, our simulations supply a great amount of instantaneous results concerning initial film atomization as well as film thickness., Comment: 20 pages, 20 figures

This paper presents wear and corrosion resistance analysis of carbon nanotubes coated with Ti-6Al-4V alloy processed by electro-discharge treatment. The reported work is carried out using Taguchi&rsquo, s L18 orthogonal array to design the experimental matrix by varying five input process parameters i.e., dielectric medium (plain dielectric, multi-walled carbon nanotubes (MWCNTs) mixed dielectric), current (1&ndash, 4 A), pulse-on-time (30&ndash, 60 &micro, s), pulse-off-time (60&ndash, 120 &micro, s), and voltage (30&ndash, 50 V). The output responses are assessed in terms of microhardness and surface roughness of the treated specimen. X-ray diffraction (XRD) spectra of the coated sample reveal the formation of intermetallic compounds, oxides, and carbides, whereas surface morphology is observed using scanning electron microscopy (SEM) analysis. For the purpose of the in-vitro wear behavior of treated samples, the surface with superior microhardness values in plain dielectric and MWCNTs mixed dielectric is compared using a pin-on-disc type wear test. Furthermore, electrochemical corrosion test is also conducted to portray the dominance of treated substrate of Ti-6Al-4V alloy for biomedical applications. It is concluded that the wear-resistant and the corrosion protection efficiency of the MWCNTs treated substrate enhanced to 95%, and 96.63%, respectively.

Finding effective and environmentally friendly lubrication to use in sheet metal forming operations presents a substantial environmental and economic challenge to the automotive industry. This paper examines the effectiveness of different lubricants in the reduction of the coefficient of friction (COF) in the process of sheet metal forming of the low carbon steel sheets. These lubricants are based on a combination of boric acid (H3BO3) and edible vegetable oils, both of which are natural and environmentally friendly. To evaluate the friction characteristics of the lubricants in a forming operation, a strip drawing friction test is used. This test consisted in drawing a specimen in the form of a sheet metal strip between two non-rotating counter-samples with radii of 200 and 10 mm. The effectiveness of environmentally friendly lubricants in reducing the COF was compared to the traditional petroleum-based lubricants which are used in sheet metal-forming operations. The effect of lubricant conditions and tool surface roughness on the value of COFs is studied. It was found that palm oil in both configurations of countersample radius, both as pure oil and with the addition of 5 wt.% of H3BO3, was the most effective in lowering the coefficient of friction. In most of the conditions analysed, the addition of boric acid into vegetable oils leads to an increase in the lubrication efficiency by up to 15% compared to pure oils. The effectiveness of lubrication by olive and rapeseed oils in decreasing the frictional resistances clearly depends on the nominal pressure applied.

The objective of the paper is to evaluate the impact of the morphology and the position of a casting defect on the fatigue limit of cast Al–Si alloy. Natural defects such as shrinkages reveal relatively complex morphology so the question is to understand the scale controlling the fatigue limit: the local one associated to inter dendritic porosity or the macroscopic one associated to the global geometry of the defect? In order to answer, fatigue tests are conducted on samples containing a spherical artificial defect of 700 μm. At the tip of the defect, three types of small defects aiming at representing inter-dendritic porosity are machined by EDM and FIB. Results show that there is no influence of a small defect at the tip of a big defect, meaning that the local morphology of the defect seems not to be the governing parameter. In addition, Finite Element simulations are conducted assuming that the global geometry of the defect could be described by an Equivalent Inertia Ellipsoid. Results show that this approximation of the defect gives good results for shrinkages. Finally, in order to understand the role of the position of the defect through the global volume of the sample, several samples have been analyzed through μCT before fatigue tests. Results are analyzed using Finite Element simulations taking into account for local cyclic plasticity and show that the defect can be considered as internal when the size of the shortest distance from the defect to the surface is bigger than the size of the defect.

International audience; Permittivity is a widespread property used to estimate the water content in concrete. To improve the reverse conversion from permittivity measurements to moisture content, we suggest the building of an electromagnetic model of concrete. In this paper, such a model is developed for the case of cement pastes. It relies on electromagnetic homogenization schemes which require an information about the permittivity of the predominant species in the material. Estimating those properties over the frequency range [200 MHz; 1 GHz] was achieved by synthesizing model cementitious binders (C-S-H and portlandite mixtures), by characterizing their macroscopic permittivity with an open-ended coaxial probe and by identifying their intrinsic permittivity with a specific homogenization procedure combining effective medium equations. The identified values are used as inputs for a homogenization procedure estimating the water content in cement pastes. For a wide range of water content, the simulated and measured real parts of permittivity show a good agreement.

This study presents a novel analysis of the machined subsurface layer formation dealing with strain hardening phenomenon which results from complex mechanisms due to cutting edge multiple passes in drilling. On the one hand, the hardened layer during drilling is characterized in relation with the local cutting geometry and thanks to a quick-stop device (QSD) to suddenly interrupt the operation. Micro hardness is used to determine the hardened thickness of the machined subsurface layers along the local cutting edge geometry. On the other hand, orthogonal cutting performed with a complex self-designed planing experiment is used to investigate in details the hardening accumulation aspects. Then, dedicated methodologies are proposed to quantify the strain hardening as well as the incremental plastic strain generated by consecutive tool passes. In addition to the subsurface hardness evolution, the work material strain is observed during the steady-state cutting process thanks to the high-speed camera. The digital image correlation technique is exploited to analyze not only the plastic strain remaining on the workpiece after the cut but also the effect of the incremental plastic strain generated by the consecutive planing passes as the cutting edges in drilling do. One of the outcomes is that the hardened layer thickness can reach from two to three times the cut thickness in drilling or in planing. As a consequence, this work demonstrates that the cutting process affects itself by hardening. Thus, the studied austenitic stainless steel in such a way that this last is never cut in its initial state.

Purpose This paper aims to investigate numerically buoyancy-induced convection from a pair of differentially heated horizontal circular cylinders set side by side in a nanofluid-filled adiabatic square enclosure, inclined with respect to gravity so that the heated cylinder is located below the cooled one, using a two-phase model based on the double-diffusive approach assuming that the Brownian diffusion and thermophoresis are the only slip mechanisms by which the solid phase can develop a significant relative velocity with respect to the liquid phase. Design/methodology/approach The system of the governing equations of continuity, momentum and energy for the nanofluid, and continuity for the nanoparticles, is solved by a computational code based on the SIMPLE-C algorithm. Numerical simulations are performed for Al2O3 + H2O nanofluids using the average volume fraction of the suspended solid phase, the tilting angle of the enclosure, the nanoparticle size, the average nanofluid temperature and the inter-cylinder spacing, as independent variables. Findings The main results obtained may be summarized as follows: at high temperatures, the nanofluid heat transfer performance relative to that of the pure base liquid increases with increasing the average volume fraction of the suspended solid phase, whereas at low temperatures it has a peak at an optimal particle loading; the relative heat transfer performance of the nanofluid has a peak at an optimal tilting angle of the enclosure; the relative heat transfer performance of the nanofluid increases notably as the average temperature is increased, and just moderately as inter-cylinder spacing is increased and the nanoparticle size is decreased. Originality/value The two-phase computational code used in the present study incorporates three empirical correlations for the evaluation of the effective thermal conductivity, the effective dynamic viscosity and the coefficient of thermophoretic diffusion, all based on a high number of literature experimental data.

International audience; This paper investigates the deformation processes operating in α grains of Ti-6Al-4V submitted to fatigue and dwell-fatigue loadings at room temperature. With this aim, mechanical tests were interrupted after a given number of cycles or cumulated plastic strain. Slip traces analysis combined with electron back-scattered diffraction enabled to evidence the operation of and slip, twinning and interface sliding. The main parameters controlling their activity were analyzed, in particular regarding the crystallographic orientation and the load hold duration. Based on this statistically sound investigation, the differences between fatigue and dwell-fatigue behaviors are finally discussed.

The present paper deals with the development of a numerical approach to predict thermal creep in pressure tubes of CANDU nuclear power reactors. This phenomenon plays a crucial role under accident conditions, where the core can reach high temperature and the pressure tubes can suffer thermal creep with important radial deformation usually named “Ballonning”. The Balloning strain in CANDU pressure tubes is a difficult issue from the mathematical point of view due to the visco-plastic nature of the deformation, and the material properties of the tubes, which are made of a Zr–2.5%Nb alloy that presents micro-structural phase change at temperatures close to 800∘C. For this reason, an explicit strategy was implemented in OpenFOAM-5.0® assuming the uniaxial deformation in radial direction, neglecting the rotational strains. The proposed model is assessed by reproducing experimental tests before to be applied to model the response of CANDU pressure tubes under Station Blackout and Loss Of Coolant Accident conditions. Fil: Corzo, Santiago Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones en Métodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones en Métodos Computacionales; Argentina Fil: Ramajo, Damian Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones en Métodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones en Métodos Computacionales; Argentina

It is well-known in the literature that the fatigue response of specimens produced through Additive Manufacturing (AM) processes is mainly controlled by the defect population. Nevertheless, microstructure, residual stresses and building orientation must be considered as they may also play a significant role. In the present paper, the influence of microstructure, residual stresses and building orientation on the Very-High-Cycle-Fatigue (VHCF) response of SLM AlSi10Mg specimens has been experimentally assessed. Ultrasonic tests on AlSI10Mg specimens with different building orientations and subjected to different heat treatments showed that, together with the defect size, microstructure and residual stresses significantly affect the VHCF response.

The characteristics of the X-ray focal spot strongly influence XCT image sharpness and structural resolution. However, current international standards only yield a limited characterization of the focal spot as two perpendicular sizes. Therefore, this paper presents a method for full characterization of the focal spot in terms of both 2D shape and intensity distribution, by applying the inverse Radon transform on a radiograph of a Siemens star. The method is validated through simulations and applied experimentally to two XCT sources. Subsequently, an investigation on how the X-ray tube settings influence focal spot size, shape, intensity and stability is presented.