Induction Heating

In this paper, a precise real-time temperature control system based on infrared (IR) thermometry for domestic induction cooking is presented. The temperature in the vessel constitutes the control variable of the closed-loop power control system implemented in a commercial induction cooker. A proportional-integral controller is applied to establish the output power level in order to reach the target temperature. An optical system and a signal conditioning circuit have been implemented. For the signal processing a microprocessor with 12-bit ADC and a sampling rate of 1 Ksps has been used. The analysis of the contributions to the infrared radiation permits the definition of a procedure to estimate the temperature of the vessel with a maximum temperature error of 5 °C in the range between 60 and 250 °C for a known cookware emissivity. A simple and necessary calibration procedure with a black-body sample is presented.

A new approach to modeling of induction heating of thin plates is presented. The model of magnetic field is based on the electric vector potential T and the distribution of temperature is described by a modified equation including heat sources and sinks. The thermoelastic displacements are also respected. The methodology is illustrated by an example whose results are discussed. Streszczenie. W artykule przedstawiono nowe podejście do modelowania grzania indukcyjnego w cienkiej płytce. Model pola magnetycznego wykorzystuje elektryczny potencjał wektorowy T a rozkład temperatury opisany jest zmodyfikowanym równaniem, zawierającym źródła ciepła i wydatki ciepła. Uwzględniono również przesunięcia termoelastyczne. Metodyka tego podejścia została zilustrowana przykładem obliczeniowym z dyskusją wyników. (Model monolityczny grzania indukcyjnego cienkiej płytki przewodzącej z uwzględnieniem przesunięcia termoelastycznego)

Mathematical and computer models of induction heating of very thin plates are presented. The plate is supposed to be exposed by timevariable external magnetic field. Distribution of eddy currents and other quantities is modeled in terms of electric vector potential. The problem is solved in hard-coupled formulation and the methodology is illustrated by a typical example.

A novel mathematical model of local induction heating of very thin metal plates in an external time-variable magnetic field is suggested. Distribution of eddy currents induced in the plate is modelled by electric vector T-potential and thermal fluxes in the systems are expressed in terms of heat sources and sinks. Analysed are also the thermoelastic displacements in the plate, their back influence on the discretization mesh and distribution of the electromagnetic and thermal quantities. Numerical solution of the problem is carried out in the hard-coupled formulation. The methodology is illustrated by a typical example whose results are discussed.

A novel actuator for accurate setting of position is presented, allowing a wide-range shift. While the rougher setting of position is realized electromagnetically, its fine tuning is performed on the principle of thermoelastic dilatation of the nonferromagnetic part of the plunger. The complete mathematical model of the problem (representing a triply coupled task) is solved numerically. The methodology is illustrated by an example whose results are discussed. Streszczenie. W artykule przedstawiono nowy projekt aktuatora o szerokim zakresie przemieszczeń. Zgrubne pozycjonowanie jest realizowane za pomocą sterowania elektromagnetycznego, natomiast precyzyjne dostrojenie pozycji osiąga się przez termoelastyczną dylatację nieferromagnetycznego elementu trzpienia. Rozwiązano numerycznie kompletny matematyczny model urządzenia (uwzględniający sprzężenia pól). Zaprezentowana metody została zilustrowana przykładowymi obliczeniami, których wyniki zostały starannie przeanalizowane. (Siłownik termoelastyczny o szerokim zakresie przemieszczeń

This paper presents experimental and numerical investigations on the characteristics of residual stresses generated by induction heating (IH) on 12 mm thick steel plates. IH at 250 °C and 350 °C provided high tensile residual stresses in the heating field but high compressive stresses away from the heating field. The double heating case generated higher compressive residual stresses—around 200 MPa—than the single heating case because of the superposition of the compressive residual stresses. It will be expected to improve the fatigue performance of welded joints when IH is applied for repair work on existing steel structural members susceptible to fatigue damage. Numerical simulation models for predicting residual stresses by IH were proposed by adopting the body heat flux input and the surface heat flux input. They will be beneficial for identifying the optimum heating conditions, such as the target temperature and the heating field, for applying IH to the actual repair work of the...

This paper presents a fully coupled three-dimensional finite element model for the simulation of a tube manufacturing process consisting of roll forming and high-frequency induction welding. The multiphysics model is based on the dual mesh method. Thus, the electromagnetic field, the temperature field, the elasto-plastic deformation of the weld bead, and the phase transformations within the material can be simulated for a moving tube without remeshing. A comparison with measurements shows that the geometry of the welded tube and the weld bead, the force on the squeeze rolls, the temperature along the band edges, and the hardness distribution within the heat-affected zone can be simulated realistically.

This paper presents a fully coupled three-dimensional finite element model for the simulation of a tube manufacturing process consisting of roll forming and high-frequency induction welding. The multiphysics model is based on the dual mesh method. Thus, the electromagnetic field, the temperature field, the elasto-plastic deformation of the weld bead, and the phase transformations within the material can be simulated for a moving tube without remeshing. A comparison with measurements shows that the geometry of the welded tube and the weld bead, the force on the squeeze rolls, the temperature along the band edges, and the hardness distribution within the heat-affected zone can be simulated realistically.

This paper proposes induction hardening method of gear used in a conveyor. The heating analysisin case of treat piece needs solution with thermal diffusion problems coupled with eddy currents problem. Therefore the experiments number in designing process can be decreased for a better knowledge of the process can be obtained.

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This paper proposes induction hardening method of gear used in a conveyor. The heating analysisin case of treat piece needs solution with thermal diffusion problems coupled with eddy currents problem. Therefore the experiments number in designing process can be decreased for a better knowledge of the process can be obtained.

This paper presents the design of a Phoenix showcases comfortable using SolidWorks program it allows to elaborate 3D PDF files and programming CNC 5 or 6 axis. The modeling has as point beginning based design on constructive and technological characteristics of the pieces, continuing with the realization assemblies, dimensioning and semiautomatic generation for drawings of execution. The modeling based on characteristics eases creation and modification a piece. This type modeling helps geometric modeling process to the technological process.

This paper proposes simultaneous hardeningmethod of disk used at suspense harrow in agriculturewith eddy currents using rectangular coil. Thisproceeding remark in little clear advantage face fromindividual treatment of disk. The heating analysis of treatpiece needs solution of thermal diffusion problemscoupled with eddy currents problem. Therefore theexperiments number in designing process can bedecreased and a better knowledge of the process can beobtained.

The optimum operation of a single-switch class E transistor inverter for induction heating has been discussed in the paper. The graphs of the most important inverter parameters as a function of the values of the resonant circuit components are shown. The results presented have been illustrated with some current and voltage waveforms obtained on the basis of mathematical analysis as well as using IsSpice simulation program. A concept of a control system has also been presented, which should ensure nearly optimum operation of the inverter.

The optimum operation of a single-switch class E transistor inverter for induction heating has been discussed in the paper. The graphs of the most important inverter parameters as a function of the values of the resonant circuit components are shown. The results presented have been illustrated with some current and voltage waveforms obtained on the basis of mathematical analysis as well as using IsSpice simulation program. A concept of a control system has also been presented, which should ensure nearly optimum operation of the inverter.

This work compares an energy cost and an energy consumption results of the 4 wt.% cupper mixed aluminum based powder metal (PM) compacts processing under induction or furnace heating. Total power and energy consumptions and total energy costs per kilogram and compact have been analyzed. T6 precipitation heat treatment applications have been applied with two different methods, one with 2.8 kW, 900 kHz ultra-high frequency induction heating system (UHFIHS), other with 2 kW chamber furnace. In the first method, Al-Cu PM compacts have been heated by induction at 580 ?C in one minute and then cooled down by water. Afterwards, the samples have been heated 170, 180, 190 and 200?C respectively for artificial ageing and cooled naturally. In the second treatment, unlike the first study, Al-Cu PM compacts are heated by chamber furnace at 540?C in 5 hours and cooled by water. Then PM compacts are artificially aged at 190?C in 10 hours with same furnace. During both processes, energy and power c...

This study compares an energy consumption results of the TI-6Al-4V based material processing under the 900 kHz induction heating for different cases. By this means, total power consumption and energy consumptions per sample and amount have been analyzed. Experiments have been conducted with 900 kHz, 2.8 kW ultra-high frequency induction system. Two cases are considered in the study. In the first case, TI-6Al-4V samples have been heated up to 900 °C with classical heating method, which is used in industrial applications, and then they have been cooled down by water. Afterwards, the samples have been heated up to 600 °C, 650 °C and 700 °C respectively and stress relieving process has been applied through natural cooling. During these processes, energy consumptions for each defined process have been measured. In the second case, unlike the first study, can be used five different samples have been heated up to the various temperatures between 600 °C and 1120 °C and energy consumptions have been measured for these processes. Thereby, the effect of temperature increase on each sample on energy cost has been analyzed. It has been seen that as a result of heating the titanium bulk materials, which have been used in the experiment, with ultra high frequency induction, temperature increase also increases the energy consumption. But it has been revealed that the increase rate in the energy consumption is more than the increase rate of the temperature.

The application of the iron based Powder Metal (PM) compacts in Ultra-High Frequency Induction Sintering (UHFIS) was reviewed for different environments. The three different environments: atmosphere, argon and vacuum were applied to the PM compacts. Iron based PM compacts were sintered at 1120 °C for a total of 550 seconds by using induction sintering machines with 2.8 kW power and 900 kHz frequency. Micro structural properties, densities, roughness and micro hardness values were obtained for all environments. The results were compared with each other.

A large number of additives are introduced in asphalt concrete mixtures in purpose of improving the properties of resistance, facing the increasing traffic and more severe climatic conditions. This will guarantee the good comfort for a longer exploitation time. In this article we used graphite powder as an unconventional additive, and then investigate its effect mainly on the electrical resistivity which is in context of our research work on conductive asphalt (with a resistivity around 10 6 Ω m), As well as on its mechanical properties evaluated using the new Fenix test that gives many information of mechanical especially dissipated energy. A significant improvement was noticed in the reduction of resistivity by reaching 1.7 × 10 6 Ω m and also greater resistance to cracking based on variation of dissipated energy as a result we concluded that introducing graphite powder with an appropriate amount enhance both mechanical and electrical properties asphalt concrete.

Conductive asphalt concrete can satisfy different and multifunctional applications such as heating roads to get rid of snow and ice and assure auto-detection, auto-cure, and energy recovery. This research aims to evaluate the performance of asphalt concrete with additives like steel fibers and graphite powder. This work is based on destructive tests (direct tensile test FENIX) and non-destructive tests (electrical resistivity measures). The obtained results indicate that the tensile resistance, dissipated energy, and ductility module of asphalt concrete increased with the increasing steel fiber percentage. Direct tensile strength, cracking resistance, and dissipated energy increased as graphite percentage increased, while the ductility module decreased. Electrical resistivity decreased when it added steel fibers and graphite. Therefore, it found that tensile strength increased reversibly with electrical resistance. When adding steel fibers or graphite powder, the dissipated energy of asphalt concrete is increased while electrical resistivity is decreased. The dissipated energy of conductive asphalt concrete with steel fibers is higher than that with graphite powder. Electrical resistivity decreased significantly with increasing steel fibers, compared to electrical resistivity with graphite. The obtained results indicate that asphalt concrete cracking resistance is higher with the optimal percentage of steel fibers added at 1% and better mechanical performance.

Bearing is an important component of motor and generator, bearing is used as a buffer component of shaft rotor that has function to decrease the friction between shaft rotor and housing. The damaging on a bearing can make an increasing of power consumption and a big friction that can make many vibrations and uproar in the motor or generator. Based on SKF’s research, 16% of the bearing’s initial damage is caused by the wrong assembling method. For example the installation of the bearing in the shaft is forcefully, by hits or burns them use the asetelin weld. The heating of bearing uses assetelin, isen’t good. Because the heat is not be stread evenly. So in order to get  heating is average in bearing, we use induction heat. This making final assignment is to make a bearing heater which use induction method with  digital PI control induction method. With Microcontroller ATmega 8535 as a digital code’s processor and as their controller. This instrument can raise the increasing linear te...

This paper proposes a method to forecast the fatigue behaviour of parts treated by surface induction hardening (SIH). Surface quenching following surface induction heating is simulated taking into account all the following features of the process: (i) electromagnetic and thermal fields (ii) phase transformation (iii) residual stress field resulting from all the process. The fatigue strength of the specimens was simulated by using Crossland and Dang-Van criteria; the field of the residual stresses, the fatigue characteristics of both the untreated material and the treated layer (martensite) are considered. Fatigue tests on smooth specimens were carried out to compare simulated results with experimental data. These tests inform about the influence of the thermal treatment on the material, including its microstructure evolution and its mechanical characteristics, especially in fatigue. For that purpose, residual stresses were analyzed by X-Ray diffraction before and after the fatigue t...

This paper proposes a method to assess the high-cycle multiaxial fatigue strength of components treated by surface induction hardening (SIH). Surface quenching following surface induction heating is simulated, taking into account the following features of the process: (i) electromagnetic and thermal fields, (ii) phase transformation, and (iii) the residual stress field resulting from the entire process. The fatigue strength of the specimens was simulated using Crossland and Dang-Van criteria; the field of the residual stresses and the fatigue characteristics of both the untreated material and the treated layer (martensite) are considered. Fatigue tests on smooth specimens were carried out to compare simulated results with experimental data. These tests yield information regarding the influence of the thermal treatment on material behaviour and strength, including microstructure evolution and mechanical characteristics, especially in fatigue. For this purpose, residual stresses were analyzed by X-ray diffraction before and after the fatigue tests. Fatigue crack initiation areas (at the specimen's surface or below) are predicted depending on the depth of the hardened material layer. The simulation of the fatigue strength at 2 Â 10 6 cycles is in good agreement with experimental results.

An experimental and numerical study of the induction heat treatment applied to ISO C45 steel was carried out. Both normalised and annealed samples were considered. The process parameters were implemented in a numerical code (Sysweld 2000 Ò ) with an aim of predicting the thermal and metallurgical history of the material. The aim of this work was to create a thermo-metallurgical model of the induction heat treatment validated by experimental results. The experimental results (microstructure and micro-hardness profiles) were compared to the numerical values. A satisfactory agreement was found.

The spectroscopic diagnostic technique of two photon absorption laser-induced fluorescence (TALIF) of atomic species has been applied to single-point measurements of velocity and static temperature in the NASA Ames Interaction Heating Facility (IHF) arc jet. Excitation spectra of atomic oxygen and nitrogen were recorded while scanning a tunable dye laser over the absorption feature. Thirty excitation spectra were acquired during 8 arc jet runs at two facility operating conditions; the number of scans per run varied between 2 and 6. Curve fits to the spectra were analyzed to recover their Doppler shifts and widths, from which the flow velocities and static temperatures, respectively, were determined. An increase in the number of independent flow property pairs from each as-measured scan was obtained by extracting multiple lower-resolution scans. The larger population sample size enabled the mean property values and their uncertainties for each run to be characterized with greater confidence. The average € ±2σ uncertainties in the mean velocities and temperatures for all 8 runs were ±1.4% and ±11 %, respectively.

Electromagnetic induction is a technique for heating electrically conductive materials (metals), commonly used for many thermal processes such as fusion (welding) or hot metal. It is characteristic of generating heat directly within the material being heated. This feature has many advantages over conventional methods of heating more standard, including reduced heating times and high yields, or the ability to heat very locally. The high power densities in play can achieve speeds of very rapid heating temperatures and heating time, the magnetic flux and frequency are the parameters that govern this process.

This paper reports computational simulations and analysis in support of calibration tests in a high enthalpy arc-jet facility at NASA Ames Research Center. These tests were conducted using stagnation calorimeters and two different blunted wedge models with calibration plates at a wide range of conditions in the NASA Ames 10-MW TP3 facility. Data were obtained using four different conical nozzles with the same test configuration in which the models were placed in a free jet downstream of the nozzle. Experimental surveys of arcjet test flow with pitot and null-point heat flux probes were also performed at several archeater conditions, providing assessment of the flow uniformity and valuable data for the flow characterization. The present analysis comprises computational fluid dynamics simulations of the nonequilibrium flowfield in the facility nozzle and test box, including the models tested, and comparisons with the experimental measurements. These computational simulations provide estimates of the arc-jet test environment parameters that are not measured but are needed to evaluate the performance of thermal protection system materials, along with further valuable insights into the arc-jet testing environment. Simulation results are used to estimate centerline total enthalpy, surface shear, boundary layer thickness, and boundary layer edge Mach number and to verify that specific test requirements from the Orion program are met.

This paper reports computational simulations and analysis in support of calibration tests in a high enthalpy arc-jet facility at NASA Ames Research Center. These tests were conducted using stagnation calorimeters and two different blunted wedge models with calibration plates at a wide range of conditions in the NASA Ames 10-MW TP3 facility. Data were obtained using four different conical nozzles with the same test configuration in which the models were placed in a free jet downstream of the nozzle. Experimental surveys of arcjet test flow with pitot and null-point heat flux probes were also performed at several archeater conditions, providing assessment of the flow uniformity and valuable data for the flow characterization. The present analysis comprises computational fluid dynamics simulations of the nonequilibrium flowfield in the facility nozzle and test box, including the models tested, and comparisons with the experimental measurements. These computational simulations provide estimates of the arc-jet test environment parameters that are not measured but are needed to evaluate the performance of thermal protection system materials, along with further valuable insights into the arc-jet testing environment. Simulation results are used to estimate centerline total enthalpy, surface shear, boundary layer thickness, and boundary layer edge Mach number and to verify that specific test requirements from the Orion program are met.

The response of Min-K 1400 to temperatures in excess of its recommended service limits has been investigated. Severe, irreversible shrinkage was observed at temperatures greater than 1000°C. The shrinkage was found to be anisotropic and related to the direction of fiber reinforcement. The extent and rate of shrinkage was quantified. There was no evidence of crystallization or new phase formation associated with the densification. __ 3/4 OlSTRliiTWi OF lis iOWiEIT IS UlLlffB J

In this paper, neural networks with a finite element method (FEM) were introduced to predict eddy current distributions on the continuously moving thin conducting strips in traveling wave induction heating (TWIH) equipments. A method that combines a neural network with a finite element method (FEM) is proposed to optimize eddy current distributions of TWIH heater. The trained network used for tested examples shows quite good accuracy of the prediction. The results have then been used with reference to a double-side TWIH in order to analyze the distributions of the magnetic field and eddy current intensity, which accelerates the iterative solution process for the nonlinear coupled electromagnetic matters. The FEM computation of temperature converged conspicuously faster using the prediction results as initial values than using the zero values, and the number of iterations is reduced dramatically. Simulation results demonstrate the effectiveness and characteristics of the proposed met...

Cost-effective advanced design concepts are becoming more common in the production of thick plates in order to meet demanding market requirements. Accordingly, precipitation strengthening mechanisms are extensively employed in thin strip products, because they enhance the final properties by using a coiling optimization strategy. Nevertheless, and specifically for thick plate production, the formation of effective precipitation during continuous cooling after hot rolling is more challenging. With the aim of gaining further knowledge about this strengthening mechanism, plate hot rolling conditions were reproduced in low carbon Ti-Mo microalloyed steel through laboratory simulation tests to generate different hot-rolled microstructures. Subsequently, a rapid heating process was applied in order to simulate induction heat treatment conditions. The results indicated that the nature of the matrix microstructure (i.e., ferrite, bainite) affects the achieved precipitation hardening, while ...

A set of 2D steady state finite element numerical simulations of electromagnetic fields, eddy currents distribution and induction heating pattern has been done for different thicknesses of a metal workpiece. Comparison between the calculation results show the importance of workpiece thickness on induction heating process including electromagnetic field distribution, eddy currents pattern, heating structure and coil efficiency.

This present work investigates the effect of electromagnetic fields on cold spray processes by means of an induction-heating cold spray (IHCS) system. Aluminum powder was cold sprayed onto inductively heated Ti6Al-4V (Ti64) substrates. These materials were selected to minimize the mechanical contribution to coating adhesion. As a result, changes in coating adhesion strength can be attributed to improved metallic bond formation due to the effect of the electromagnetic field. Four different initial substrate surface temperatures were used in the study to assess the role of initial temperature as well. Deposition efficiency and adhesion and tensile strength measurements were recorded and are used to characterize the hybrid coating process and compare it with traditional techniques.

This paper describes the analysis and performance of a full-bridge LLC resonant converter based on power supplies for IH applications. The analysis contains five components: half bridge inverter, resonant tank, high frequency transformer, rectifier and coil. The switching bridge generates a square waveform to excite the LLC resonant tank, which will produce a resonant sinusoidal current which is transferred to the secondary of the converter through a high-frequency transformer. As it scales the voltage up or down according to the output requirements. The load represented by the equivalent circuit of the coil and work-piece is fed by the current transformed by the rectifiers. Considering that load parameters and resonant frequency vary greatly in all phases of system operation, this paper provides improved knowledge of output power control for high temperature applications. The validity of the analyzed converter parameters had been simulated and tested using MATLAB-SIMULINK software. The results of testing demonstrated that the proposed scheme and assembly has good efficiency, and it is well suited for magnetic induction heating systems .

Plasma heating is advantageous over induction heating in the aspects of less impact on tundish design and lower maintenance costs.On the other hand, plasma heating has a lower heating efficiency of 60% compared to that of induction heating 90%. The idea of utilizing electromagnetic stirringwas numerically investigated in combination with plasma heating. With plasma heating alone, the flow in the upper part of heating chamber is dampened due to the buoyancy force caused by the large temperature gradient of plasma heating. With EMS, one rotational flow with the velocity of 0.2-0.4 m/s is created in the heating chamber, and the temperature in the heating chamber is homogenized. The temperature response time in the outlet is reduced and heating efficiency of plasma heating can be improved with EMS.

This paper is focused on the problem of numerical modeling of electromagnetic field coupled with the thermal one in the heating process of the steel billets, using inductors with circular shape turns. As results we have: electromagnetic field lines evolution and map temperatures in piece at the ending of heating process.

It is challenging to obtain defect free welded joints of Aluminum Alloys with the help of fusion welding processes. In fusion welding, oxide layer of aluminum alloys penetrate inside, which has the tendency to thicken at higher temperatures, which in turn results in the defects like porosity and cracks in the weld joint. In contrast, Friction Stir Welding (FSW) is proved to be a very good solid state welding technique, which has got a worldwide attraction, especially in aerospace industry. FSW doesn’t involve actual melting of the materials, rather the welding is done at visco-plastic state of the materials, which helps to reduce the heat affected zone in the weld joint and original characteristics of material are protected from getting changed, as far as possible. Combination of 2xxx series and 6xxx series of aluminum alloys are highly used in aerospace and automobile industry due to their good-strength to weight ratio, mechanical properties and anti-corrosion properties. The work ...

Incremental sheet forming (ISF) is an agile process for small batch and rapid prototype production. Its hot variant has been developed because forming at elevated temperature increases the formability of materials and improves the accuracy of the worked parts reducing spring-back effects. Several hot ISF variants have been proposed reaching local or global heating. Here, a local heating solution has been presented by means of an induction system. This is done by a medium-high frequency generator and a heating head, continuously water cooled. The heating head, placed under the sheet and linked axially to the punch movement, warms the material locally generating eddy current in it. A laser pointer, focused on the sheet and following the punch movement, drives the generator in maintaining the desired temperature during the incremental forming phase. The first experimental trials were planned with the aim to investigate the process feasibility for forming magnetic (carbon steels) and non magnetic (titanium alloys) characterized by different forming and mechanical properties. Steel was chosen because it is a magnetic material and offers a natural resistance to the rapid change of the magnetic fields producing additional heat by hysteresis. For this reason, steel is a suitable material for the proposed heating solution. Furthermore, the effectiveness of the proposed heating system was tested on a titanium alloy, i.e. Ti6Al4V, selected because being not nonmagnetic is more difficult to heat by induction. In conclusion, first results were presented showing the applicability of the designed solution as an ISF variant. This solution can be used for improving the formability of materials hard to work at room temperature.

Incremental sheet forming (ISF) is an agile process for small batch and rapid prototype production. Its hot variant has been developed because forming at elevated temperature increases the formability of materials and improves the accuracy of the worked parts reducing spring-back effects. Several hot ISF variants have been proposed reaching local or global heating. Here, a local heating solution has been presented by means of an induction system. This is done by a medium-high frequency generator and a heating head, continuously water cooled. The heating head, placed under the sheet and linked axially to the punch movement, warms the material locally generating eddy current in it. A laser pointer, focused on the sheet and following the punch movement, drives the generator in maintaining the desired temperature during the incremental forming phase. The first experimental trials were planned with the aim to investigate the process feasibility for forming magnetic (carbon steels) and non magnetic (titanium alloys) characterized by different forming and mechanical properties. Steel was chosen because it is a magnetic material and offers a natural resistance to the rapid change of the magnetic fields producing additional heat by hysteresis. For this reason, steel is a suitable material for the proposed heating solution. Furthermore, the effectiveness of the proposed heating system was tested on a titanium alloy, i.e. Ti6Al4V, selected because being not nonmagnetic is more difficult to heat by induction. In conclusion, first results were presented showing the applicability of the designed solution as an ISF variant. This solution can be used for improving the formability of materials hard to work at room temperature.

A series of experiments were conducted to investigate and characterize the concept of ferrofluidic induction -a process for generating electrical power via cyclic oscillation of ferrofluid (iron-based nanofluid) through a solenoid. Experimental parameters include: number of bias magnets, magnet spacing, solenoid core, fluid pulse frequency and ferrofluid-particle diameter. A peristaltic pump was used to cyclically drive two aqueous ferrofluids, consisting of 7-10 nm iron-oxide particles and commercially-available hydroxyl-coated magnetic beads (~800 nm), respectively. The solutions were pulsated at 3, 6, and 10 Hz through 3.2 mm internal diameter Tygon tubing. A 1000 turn copper-wire solenoid was placed around the tube 45 cm away from the pump. The experimental results indicate that the ferrofluid is capable of inducing a maximum electric potential of approximately +/-20 V across the solenoid during its cyclic passage. As the frequency of the pulsating flow increased, the ferro-nanoparticle diameter increased, or the bias magnet separation decreased, the induced voltage increased. The type of solenoid core material (copper or plastic) did not have a discernible effect on induction. These results demonstrate the feasibility of ferrofluidic induction and provide insight into its dependence on fluid/flow parameters. Such fluidic/magneto-coupling can be exploited for energy harvesting and/or conversion system design for a variety of applications.

Corrosion of steel reinforcements is the main cause of damage and early failure of reinforced concrete structures in civil engineering, leading to enormous costs for inspection, maintenance, restoration and replacement of the infrastructure worldwide. Conventional methods for detecting corrosion are based on electrochemical techniques such as half-cell potential and linear polarization. These methods can be affected by a number of factors and require direct contact with the concrete. To overcome difficulties with conventional inspection techniques a benchmark project using and evaluating state-of-the-art NDE methods is set up at FHWA's Turner-Fairbank Highway Research Center. The aim is to devise a test protocol for structural health monitoring (and asset management) of concrete structures by performing periodic baseline NDE surveys. For this a typical bridge deck specimen is cast, corroded and cyclic loaded. The benchmark project incorporates the latest developments in NDE inspection methodologies. A special focus lies on the promising technique of time-resolved thermography with induction heating combined with 3-D microwave imaging-a research cosponsored by the US National Research Council NRC. La corrosion des armatures d'acier est la principale cause de pathologies et de défaillances prématurées des structures en béton armé en génie civil, entrainant des coûts énormes pour l'inspection, l'entretien, la restauration et le remplacement d'infrastructures dans le monde. Les méthodes conventionnelles pour la détection de la corrosion électrochimique sont basées sur des techniques telles que la demi-cellule et le potentiel de polarisation linéaire. Ces méthodes peuvent être affectées par un certain nombre de facteurs et nécessitent un contact direct avec le béton. Afin de surmonter les difficultés des techniques d'inspection conventionnelles, un projet utilisant des méthodes avancées NDE est développé au Turner-Fairbank Highway Research Center de la FHWA. L'objectif est de mettre au point un protocole d'essai pour la surveillance et l'évaluation structurelle des ouvrages en béton en effectuant des enquêtes périodiques de référence NDE. Pour cela un modèle de tablier de pont type est coulé, corrodé et chargé de manière cyclique. Le projet intègre les derniers développements dans les méthodes d'inspection NDE. Un accent est mis sur la technique prometteuse de la thermographie en temps résolu avec chauffage par induction, combinée avec la micro-imagerie 3-D. Cette recherche est parrainée par le US National Research Council NRC.

Non-destructive testing (NDT) has become established as an instrument of quality assurance in many areas of industrial materials testing. The cost-intensive NDT methods are worthwhile because they avoid or minimize replacement or expensive repair measures. This development is also recognizable in the building industry. This contribution presents the latest developments in the field of reinforced concrete diagnostics and discusses their possibilities and limitations and concludes with the latest development of FH Erfurt (FHE) in the field of corrosion diagnostics in reinforced concrete. The new method developed and patented by FHE of active electrochemical, ion mobility and passivation (AECIP) testing uses a semi-destructive active electrochemical approach to characterize the passivated layer of steel reinforcement in interaction with concrete mixtures, aggregates, recipes, post treatment and rehabilitation measures of structures and structural elements made of steel reinforced concrete and is the focus of this paper.

The implementation of autoclaves has been limited due to high production costs and an excess of residual stress. These drawbacks have led to the exploration and development of an alternative method known as out-of-autoclave (OoA) manufacturing process. This research study was proposed to enhance the production of high tensile strength in composite laminate by optimizing the vacuum-bagging-only (VBO) pre-forming process. The impacts of both individual and combined pre-forming parameters in VBO-oven cure processing were measured for traditional low-cost glass/epoxy composite material with respect to the tensile strength of the cured laminates. Twenty composite panels were produced according to specified parameter combinations using central composite design in a fractional factorial approach for creating a response surface model. The study examined three variables, namely the duration of vacuum debulking, the number of sides with edge breather, and the weight of the intensifier. Two laminates were manufactured without additional processing parameters using both the oven (baseline) and autoclave methods for validation purpose. Subsequently, a tensile test was carried out following ASTM D 3039. The interaction among the combined parameters was examined using analysis of variance (ANOVA). The laminates exhibited the lowest tensile strength when the intensifier was not present, while the highest tensile strength was recorded when edge breather, debulk, and intensifier were applied at varying levels. An ideal processing configuration of 30 minute-debulk, each side of edge breather and 1kg-intensifier had resulted in the production of laminate with the highest tensile strength, measuring 407.44 MPa. This value was roughly 17.2% higher than that of the baseline laminate and 3.77% higher than the autoclave laminate.

UV-induced frontal polymerization is an emergent rapid curing method for thermoset resin and its fiber composites which features the generation of a self-sustaining front that propagates within the entire material. This is different from using the commercially available UV curable resin which prohibited the curing of thermoset composites with opaque fibers (e.g., carbon fiber) due to the UV light being blocked by the fibers. In this study, we experimentally demonstrate that using the UV-induced frontal polymerization allows us to reduce the curing time of a standard tensile specimen of epoxy resin from traditionally 15 h using the oven curing method to only less than 1.5 min. The frontal polymerized epoxy specimens showed comparable and even superior tensile and flexural properties when compared to the traditional oven cured specimens. Moreover, we experimentally investigated the influence of the weight content of the photoinitiator, the UV light intensity, and the specimen geometry on the characteristics of the frontal polymerization process (i.e., front temperature, front velocity, and degree of cure) and the resulting tensile and flexural properties. The results and discussions are expected to provide guidance in scaling up this UV-induced frontal polymerization technique for the sustainable and additive manufacturing and repair of thermoset resin and its fiber composites.