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Manufacturing operations like in-situ welding, shrink fitting, etc. requires one among pre heating, post heating, stress relieving, etc. In such cases, resistance-based, feedback-controlled power sources is the sole option available for precise and controlled local heating. Certain cases might also demand heating within a narrow temperature range. This mandates the width of heating to be optimised through iterative experimental trials, which will then help in the establishment of heat treatment procedure. Instead of the iterative trials, Finite Element (FE) simulations can serve as an accurate and quicker alternative, so that one final trial can be conducted with the optimised width of heating. In order to achieve an FE simulation exactly resembling the heating achieved by the resistance-based technique, a few methods with varied forms of boundary conditions (heating profiles), as followed in the earlier works concerning this field are already available. However, their efficacies in evaluating the temperature distribution within a thick-walled pipe is unknown. Hence, by adopting various loading conditions as dictated by the methods found in the literature, feedback-controlled resistance heating of a butt-joined pipe, is simulated using ANSYS APDL and evaluated based on four criterions regarding heating rate and transient temperature distribution as suggested by governing standards. The outcome of the study revealed that the existing FE methods showed deviations with respect to one or more of the four criterions mentioned, and none of them were able to match the experimental temperature profiles closely. These differences were overcome by proposing a new heating profile for closer prediction of various results and for meeting all the four criterions. This will benefit the industrial and scientific communities for precise simulation of local heating applications.

The isothermal hot forming of high-elasticity titanium alloy thin-walled components often suffers from significant elastic loss. This study investigates the novel Ti–35Nb–2Zr–0.3O (Ti3523) high-elasticity titanium alloy, focusing on the effects of rapid resistance heating (RRH) compared to traditional muffle furnace heating (MFH) on its microstructure and mechanical properties via EBSD and tensile tests. The results show that RRH at a high heating rate (~45 °C/s) effectively suppresses grain coarsening and minimizes dislocation annihilation. Following air cooling, the yield strength of the alloy decreased to 503.01 MPa for RRH-treated specimens, while 405.49 MPa for MFH-treated specimens compared to the original cold-rolled sheet with a yield strength of 754.25 MPa. Additionally, RRH promoted a higher martensitic α′′ transition, leading to lower elastic modulus (40.62 GPa). After aging treatment, the RRH-treated specimens exhibited precipitation of a high-strength α phase, leading to significant improvement of yield strength (755.63 MPa) and elastic modulus (70.39 GPa). The elastic performance of RRH-treated specimens ( Ur = 4.056 MPa) was better than that of the MFH-treated specimens ( Ur = 3.333 MPa) and close to the performance of the original sheet ( Ur = 4.577 MPa). With the identical heating method (RRH), higher heating rates can preserve the high elasticity of the original sheet. Building upon these findings, the hot forming process of the Ti3523 alloy was further explored. The results revealed that dynamic recrystallization process occurs more completely in the alloy after forming and aging under the RRH process, leading to a 70.72% increase in resilience modulus compared to the original cold-rolled sheet. Due to the dynamic recrystallization, the dislocation density decreased from 6.94×10 14 /m 2 to 6.63×10 14 /m 2 and the proportion of dynamically recrystallized grains increased from 28% to 48.1% after aging treatment. This rapid heating and high-temperature forming method offers a promising technical route for manufacturing advanced aerospace components.

Conventional endovascular embolization of intracranial (or brain) aneurysms using helical detachable platinum coils can be time-consuming and occasionally requires retreatment due to incomplete coil packing. These shortcomings create a need for new biomedical devices and methods of achieving brain aneurysm occlusion. This paper presents a biocompatible and highly porous shape memory polymer (SMP) material with potential applications in the development of novel endovascular devices for treating complex intracranial aneurysms. The novel highly porous polyurethane SMP is synthesized as an open cell foam material with a glass transition temperature (Tg) of 39 °C using a sugar particle leaching method. Once heated above the Tg, the compressed SMP foam is able to quickly return to its original shape. An electrical resistance heating method is also employed to demonstrate a potential triggering design for the shape recovery process in future medical applications. The mechanical properties of the developed SMP foam are characterized at temperatures up to 10 °C above the respective Tg. The results from this work demonstrate that the porous SMP material developed in this study and the electrical resistance heating trigger mechanism provide a solid foundation for future design of biomedical devices to enhance the long-term therapeutic outcomes of endovascular intracranial aneurysm treatments.

Recently, various studies for the use of Fe-based shape memory alloy (Fe-SMA) in the construction field have been widely conducted. However, most of the studies for using Fe-SMA are carried out for applying Fe-SMA for strengthening deteriorated structures. However, if Fe-SMA is used as a reinforcement for new structures, the disadvantages of conventional prestressed concrete can be effectively solved. Therefore, in this work, an experimental study was conducted to evaluate the flexural behavior of concrete beams in which Fe-SMA rebars were used as tensile reinforcement. For the study, ten specimens were constructed with the consideration of the cross-sectional area and activation of Fe-SMA rebars as experimental variable. Activation of the Fe-SMA rebars by electrical resistance heating applied an eccentric compressive force to the specimen to induce camber. The camber increased by an average of 0.093 mm as the cross-sectional area of the Fe-SMA rebar increased by 100 mm2. It was also confirmed through the four-point bending tests that the initial crack loads of the activated specimens were 47.6~112.8% greater than those of the nonactivated specimens. However, the ultimate strength of the activated specimens showed a slight difference of 3% to those of the nonactivated specimens. Therefore, it was confirmed that the effect of Fe-SMA activation on the ultimate strength of specimens was negligible.

Aluminum powder is the most commonly used metal fuel in the industry of explosives and propellants. The research progress in preparation technology, reactivity and application of nano-aluminum in explosives and propellants is systematically reviewed in this paper. The preparation technology of nano-aluminum powder includes mechanical pulverization technology (such as the ball milling method and ultrasonic ablation method, etc.), evaporation condensation technology (such as the laser induction composite heating method, high-frequency induction method, arc method, pulsed laser ablation method, resistance heating condensation method, gas-phase pyrolysis method, wire explosion pulverization method, etc.), chemical reduction technology (such as the solid-phase reduction method, solution reduction method, etc.) and the ionic liquid electrodeposition method, each of which has its own advantages. Some new preparation methods have emerged, providing important reference value for the large-scale production of high-purity, high-quality nano-aluminum powder. The reactivity differences between nano-aluminum powder and micro-aluminum powder are compared in the thesis. It is clear that the reactivity of nano-aluminum powder is much higher than that of micro-aluminum powder in terms of ignition performance, combustion performance and reaction completeness, and it has a stronger influence on the detonation performance of mixed explosives and the combustion performance of propellants. Nano-aluminum powder is highly prone to oxidation, which seriously affects its application efficiency. In addition, when aluminum powder oxidizes or burns, a surface oxide layer will be formed, which hinders the continued reaction of internal aluminum powder. In addition, nano-aluminum powder may deteriorate the preparation process of explosives or propellants. To improve these shortcomings, appropriate coating or modification treatment is required. The application of nano-aluminum powder in mixed explosives can improve many properties of mixed explosives, such as detonation velocity, detonation heat, peak value of shock wave overpressure, etc. Applying nano-aluminum powder to propellants can significantly increase the burning rate and improve the properties of combustion products. It is pointed out that the high reactivity of nano-aluminum powder makes the preparation and storage of high-purity nano-aluminum powder extremely difficult. It is recommended to increase research on the preparation and storage technology of high-purity nano-aluminum powder.

The “electron wind effect” has long been cited as a potential catalyst of solid-state transformations in metals, particularly when high current densities are involved. However, the literature exploring similar effects at lower current densities, such as those occurring during Gleeble thermomechanical simulation, remains scarce. The present work compares recrystallization activity in cold-rolled low-carbon steel during heat treatment by conventional furnace versus direct resistance heating (Gleeble). Multiple levels of cold work, annealing durations, and soak temperatures were examined, allowing for an in-depth comparison of recrystallization rates and activation energies between samples subjected to identical time–temperature profiles in the furnace and Gleeble. In addition to the expected increase in recrystallization behavior with the increases in temperature and cold-reduction levels, the use of the Gleeble system as the heating method resulted in faster initial microstructural transformation than a conventional furnace. The variability in recrystallized fractions persisted until the microstructures had saturated to their nearly fully recrystallized levels, at which point the microhardness and electron backscatter diffraction (EBSD) revealed convergence to equivalent behavior irrespective of the heating method. Analysis of the recrystallization kinetics by fitting to a JMAK relationship reflected the increased transformation activity during Gleeble treatment, with the value of the kinetic exponent also indicating greater grain growth activity at higher temperature.

Italian legislation defines stringent groundwater chemical quality criteria, to be applied at a site’s downgradient property boundary, irrespective of whether the underlying aquifer is, or could be, used for water resource purposes. In some scenarios, the regulatory authorities may identify less stringent standards, but this rarely occurs. This means that many sites with groundwater contamination are managed using hydraulic barriers, as source zone remediation may not achieve the stringent groundwater standards required due to technology limits or time constraints; therefore, the parties responsible for contamination often decide to continue to operate these hydraulic barriers indefinitely. This article describes the first application in Italy of source treatment using Electrical Resistance Heating (ERH), a remediation technology capable of removing a large percentage of contaminant mass, at a site where a hydraulic barrier is operating within a low yielding aquifer that is not used for water supply. The implementation of this technology was possible since the source zone was far from the downgradient site boundary, thus making achievement of the stringent quality standards at the boundary possible within a reasonable timeframe. The ERH system recovered of about 600 kg of contaminants within a timeframe of 8 months and achieved a reduction of contaminant concentrations in the most impacted areas greater than 90%. This article also emphasizes that, in similar low yielding aquifers, setting less stringent groundwater standards at the site boundary whilst still protecting downgradient receptors may promote more widespread implementation of source remediation activities in Italy.

To obtain enough hardness of the die-quenched products after hot stamping using direct resistance heating, the effects of the electrifying condition and initial microstructure of the quenchable steel sheet on hardness were examined in a hot bending experiment. The steel sheet was heated up to 900 °C in 3 to 10 s. The required heating time was shortened by normalising heat treatment due to the fine grain size of the sheet. The standard deviation of the hardness of the sheet heated to 900 °C in 3.2 s without temperature holding at the austenitising temperature was 12 HV, whereas the deviation reduced to 5 HV for temperature holding at the austenitising temperature of 3 s.

This paper proposes a fusion bonding technology with electrical resistance heating for carbon fiber-reinforced plastic using polyphenylene sulfide thermoplastic resin with 60% carbon fiber (CFRTP), and suitable bonding conditions are investigated experimentally. The concept of the fusion bonding system is that the thermoplastic resin in the CFRTP sheet is heated to near its melting point of 280°C via electric charging after clamping two CFRTP sheets at high pressures, 310 kPa, using electrodes made from aluminum rods. The heating temperature was controlled using the electrical resistances (5-20 O) between the two CFRTP sheets which were controlled using the exposed carbon fiber (CF) on the CFRTP surface: a lower exposure rate gives a higher electrical resistance, e.g., 15 O for CF20% and 5 O for CF80%. In addition, the sample temperature was dependent on the electric current and the electric charging time. Two CFRTP sheets were successfully bonded using the fusion bonding system with the maximum strength of more than 30 MPa, where an electric current of 4.0 A was applied for 10 s. The bonding strength was attributed to changes in the material properties, especially the bonding resin. The hardened bonding resin was created from heat processing at 250°C, which led to a high bonding strength.

To overcome the difficulties, such as pollution, low heating efficiency, and complex heating control, in ultra-thick plate forming, a new forming technology was put forward, named as resistance heating forming technology (RHF). Experiment and finite element analysis were conducted to investigate the practicability and the advantages of RHF. The difference in temperature field between RHF and traditional flame heating forming technology (FHF) was discussed in detail. Then, the forming mechanism of RHF was illustrated deeply. The results show that the high temperature zone of resistance heating is of Π shape compared to Λ shape in flame heating method, the nominal width increased by 47.2 %, and the area of heated zone increased by 34.7 %. These result a higher energy utility for RHF. Under the similar energy input, the angular deformation of RHF is bigger than that of FHF, the relative displacement increased by 41.6 %, the angular deformation increased by 20.8 %. Both the experiment and simulation results show that RHF is an attractive and practical technology for ultra-thick plate forming.