Search

In large-format pouch cells for electric vehicles, the issues of elevated and non-uniform temperatures resulting from heat generation are intensified, necessitating the use of liquid cooling systems. The design factors of the liquid cooling system influence the maximum temperature and temperature differences in the module as well as the pumping power of the cooling system. Although it is known that these design factors interact, research on these interactions and their effects is currently lacking. In this study, the individual as well as interaction effects of design factors on the performance of the liquid cooling system for a large-format pouch cell module were investigated using design of experiment and analyzed through statistical methods. Electrochemical–thermal fluid coupled analysis was used to calculate the performance according to the design factors of the liquid cooling system. The wall and channel widths are factors that directly determine the coolant flow velocity and cooling plate heat capacity, and they exhibited major effects on all three responses. Moreover, the influence of each design factor tended to change in response to variations in the other design factors. Thus, the effects of each factor individually and of interactions between factors were quantitatively compared and evaluated for significance. The width of the walls was found to contribute the most to the maximum temperature (36.00%) and pumping power (57.56%), while the width of the channels contributed the most to the temperature difference (38.24%), indicating that they are the main influencing factors. [ABSTRACT FROM AUTHOR]

Roads are exposed to various degradation mechanisms during their lifetime. The pavement deterioration caused by the surrounding environment is particularly severe in winter when the humidity and subfreezing temperatures prevail. Frost heave-induced damage is one of the winter-related pavement deterioration. It occurs when the porewater in the soil is exposed to freezing temperatures. The study of frost heave requires conducting a multiphysics analysis, considering the thermal, mechanical, and hydraulic fields. This paper presents the use of a coupled thermo-mechanical approach to simulate frost heave in saturated soils. A function predicting porosity evolution is implemented to couple the thermal and mechanical field analyses. This function indirectly considers the effect of the water seepage inside the soil. Different frost heave scenarios with uniform and non-uniform boundary conditions are considered to demonstrate the capabilities of the method. The results of the simulations indicate that the thermo-mechanical model captures various processes involved in the frost heave phenomenon, such as water fusion, porosity variation, cryogenic suction force generation, and soil expansion. The characteristics and consequences of each process are determined and discussed separately. Furthermore, the results show that non-uniform thermal boundaries and presence of a culvert inside the soil result in uneven ground surface deformations. [ABSTRACT FROM AUTHOR]

When a long cable is included in power conversion systems, it causes adverse effects, such as voltage spikes and ringing at load terminals. These nonideal voltages can break the insulation of electric machines, such as transformers and motors, and reduce their lifespan. To estimate such voltage characteristics, cable impedance should be modeled on the basis of the cable length. In this paper, two cable impedance models, a multiphysics model and an equivalent circuit model, are introduced. The multiphysics model using Ansys Q3D Extractor is suggested in consideration of the structure, material, and length of a practical cable. Meanwhile, the equivalent circuit model can be quickly utilized to examine voltage spikes and frequency. The accuracy of the proposed models is verified through simulation and the experimental results based on a motor drive system equipped with 30 and 100-m cables. [ABSTRACT FROM AUTHOR]

Copyright of Nuclear Safety is the property of Nuclear & Radiation Safety Center and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

High-intensity ultrasound systems for medical therapy must be carefully designed, implemented, and applied to avoid tissue damage or injury considering stimulation and relaxation time, frequency, and intensity of ultrasound. Based on these concerns and considering a test three-layer animal tissue consisting of skin, muscle, and bone, we determined the frequency and intensity at which ultrasound effectively stimulates the test animal tissues. In addition, from these ultrasound frequencies and intensities, and taking care the critical temperature recommended to preserve the integrity of the human tissue and avoid any tissue injury, we determine the stimulation and relaxation times. For this purpose, we performed a multiphysics simulation that describes the spatial and temporal dynamics of the thermoacoustic effect of ultrasound applied to test animal tissues. To practically demonstrate this ultrasound behavior, we perform an experimental setup based on an electronic HITU device designed and implemented to freely adjust the ultrasound intensity and frequency, as well as the stimulation time of the test animal tissues. Finally, we conclude that, depending on the test tissue, an ultrasound therapy system should allow the selection of the intensity and frequency of applied ultrasound, as well as the stimulation time to avoid tissue injury, which can be considered by health ministries around the world.

This article presents the design and comprehensive multiphysics analysis of a permanent magnet synchronous motor (PMSM) intended for small electric podded propulsion systems in marine applications. Minimizing vibration related to underwater radiated noise (URN) and ensuring thermal stability to allow prolonged continuous operation are crucial aspects of propulsion motor design. To reduce URN, particular attention is given to the stator vibration mode order, determined by the slot/pole combination (SPC) of the PMSM. Structure-borne noise analysis is used to evaluate the equivalent radiated power level of three designed PMSMs with different stator vibration mode orders. One-way multiphysics analysis using finite element analysis (FEA) is performed in a water environment for the finally-selected PMSM with pod housing structure. URN generated from the electromagnetic force is predicted by structural-acoustics analysis. Through lumped-parameter thermal network (LPTN) and computational fluid dynamics (CFD) analyses, it is proposed that, based on the cylindrical housing shape, the thermal stability of the podded propulsor can be evaluated using LPTN analysis instead of CFD analysis. A prototype motor is fabricated to validate the results obtained using FEA.

In large-format pouch cells for electric vehicles, the issues of elevated and non-uniform temperatures resulting from heat generation are intensified, necessitating the use of liquid cooling systems. The design factors of the liquid cooling system influence the maximum temperature and temperature differences in the module as well as the pumping power of the cooling system. Although it is known that these design factors interact, research on these interactions and their effects is currently lacking. In this study, the individual as well as interaction effects of design factors on the performance of the liquid cooling system for a large-format pouch cell module were investigated using design of experiment and analyzed through statistical methods. Electrochemical–thermal fluid coupled analysis was used to calculate the performance according to the design factors of the liquid cooling system. The wall and channel widths are factors that directly determine the coolant flow velocity and cooling plate heat capacity, and they exhibited major effects on all three responses. Moreover, the influence of each design factor tended to change in response to variations in the other design factors. Thus, the effects of each factor individually and of interactions between factors were quantitatively compared and evaluated for significance. The width of the walls was found to contribute the most to the maximum temperature (36.00%) and pumping power (57.56%), while the width of the channels contributed the most to the temperature difference (38.24%), indicating that they are the main influencing factors.

With the development of nuclear energy, microreactors have received increasing interest among researchers in recent years. In this paper, a megawatt heat pipe reactor with metal hydride moderators and burnable poisons is proposed. The hydrogen stability of the reactor under accident conditions, including reactivity insertion accidents, loss of power conversion unit heat sink accidents, and heat pipe failure accidents are analyzed. In this work, Gd2O3 is introduced as a burnable poison in the form of mixing with the UO2 fuel. According to the results of the burnable poison design, the 0.1% mass fraction of Gd[sub 2]O[sub 3] is selected as the burnable poison loaded in the core. Safety analysis indicates that the introduction of burnable poisons can be beneficial during the positive reactivity insertion accident as it can reduce the excessive reactivity at BOL, thus reducing power peak and preventing hydrogen dissociation in ZrH1.4 rods. However, during the loss of PCU heat sink accident, ZrH1.4 rods will dissociate regardless of the presence of burnable poisons, whereas YH1.7 rods show better hydrogen stability. Moreover, in the event of the heat pipe failure accident, ZrH1.4 rods aremore susceptible to dissociation than YH1.7 rods. As a result, the YH1.7+BP core is a better choice compared with other designs proposed in this paper as it provides a relatively high temperature margin. [ABSTRACT FROM AUTHOR]

A new formulation for the displacement‐only partitioned equations of motion for linear structures is presented, which employs: the partitioned displacement, acceleration, and applied force (d,d¨,f$$ \mathbf{d},\ddot{\mathbf{d}},\mathbf{f} $$); the partitioned block diagonal mass and stiffness matrices (M,K$$ \mathbf{M},\mathbf{K} $$); and, the coupling projector (풫d), yielding the partitioned coupled equations of motion: Md¨=풫d(f−Kd). The key element of the proposed formulation is the coupling projector (풫d) which can be constructed with the partitioned mass matrix (M$$ \mathbf{M} $$), the Boolean matrix that extracts the partition boundary degrees of freedom (B$$ \mathbf{B} $$), and the assembly matrix (Lg$$ {\mathbf{L}}_g $$) relating the assembled displacements (dg$$ {\mathbf{d}}_g $$) to the partitioned displacements (d$$ \mathbf{d} $$) via (d=Lgdg)$$ \left(\mathbf{d}={\mathbf{L}}_g{\mathbf{d}}_g\right) $$. Potential utility of the proposed formulation is illustrated as applied to six proof‐of‐concept problems in an ideal setting: unconditionally stable explicit‐implicit transient analysis, static parallel analysis in an iterative solution mode; reduced‐order modeling (component mode synthesis); localized damage identification which can pinpoint damage locations; a new procedure for partitioned structural optimization; and, partitioned modeling of multiphysics problems. Realistic applications of the proposed formulation are presently being carried out and will be reported in separate reports. [ABSTRACT FROM AUTHOR]

Roads are exposed to various degradation mechanisms during their lifetime. The pavement deterioration caused by the surrounding environment is particularly severe in winter when the humidity and subfreezing temperatures prevail. Frost heave-induced damage is one of the winter-related pavement deterioration. It occurs when the porewater in the soil is exposed to freezing temperatures. The study of frost heave requires conducting a multiphysics analysis, considering the thermal, mechanical, and hydraulic fields. This paper presents the use of a coupled thermo-mechanical approach to simulate frost heave in saturated soils. A function predicting porosity evolution is implemented to couple the thermal and mechanical field analyses. This function indirectly considers the effect of the water seepage inside the soil. Different frost heave scenarios with uniform and non-uniform boundary conditions are considered to demonstrate the capabilities of the method. The results of the simulations indicate that the thermo-mechanical model captures various processes involved in the frost heave phenomenon, such as water fusion, porosity variation, cryogenic suction force generation, and soil expansion. The characteristics and consequences of each process are determined and discussed separately. Furthermore, the results show that non-uniform thermal boundaries and presence of a culvert inside the soil result in uneven ground surface deformations. [ABSTRACT FROM AUTHOR]

Permanent magnet motors have become an important component of industrial production, transportation, and aerospace due to their advantages of high torque density, high power density, high reliability, low losses, and high efficiency. Permanent magnet claw pole motor (PMCPM) is a special type of transverse flux motor which has a higher torque density compared to traditional permanent magnet motors. Due to the absence of winding ends, its axial space utilization is high, and the usage of windings is greatly reduced, reducing the cost and weight of the motor. PMCPM has the advantages of small space, a light weight, a high torque density, a high efficiency, and simple production, which have potential for use in the field of electric vehicles. The double-stator structure design can improve the torque density, efficiency, and radial space utilization of PMCPM, which helps to expand their applications in the field of electric vehicles. This article designs two PMCPM with concentrated winding while different rotor structures (PMCPM1 and PMCPM2) and a three-dimensional finite element method is employed to compare and analyze the performance of PMCPM1 and PMCPM2 and the traditional PMCPM (TPMCPM). Multiphysics analysis is carried out for PMCPM1 and PMCPM2. The stress of the inner and outer stators during interference assembly are analyzed. In this paper, a hybrid material core design is proposed, in which the stator yoke is rolled by silicon steel material and the stator claw pole is pressed by the SMC die method. The multiphysics simulation performance of the PMCPM1 and PMCPM2 with hybrid cores is analyzed. [ABSTRACT FROM AUTHOR]

Single‐crystal LiNixCoyMnzO2 (SC‐NCM, x+y+z=1) cathodes are renowned for their high structural stability and reduced accumulation of adverse side products during long‐term cycling. While advances have been made using SC‐NCM cathode materials, careful studies of cathode degradation mechanisms are scarce. Herein, we employed quasi single‐crystalline LiNi0.65Co0.15Mn0.20O2 (SC‐NCM65) to test the relationship between cycling performance and material degradation for different charge cutoff potentials. The Li/SC‐NCM65 cells showed >77 % capacity retention below 4.6 V vs. Li+/Li after 400 cycles and revealed a significant decay to 56 % for 4.7 V cutoff. We demonstrate that the SC‐NCM65 degradation is due to accumulation of rock‐salt (NiO) species at the particle surface rather than intragranular cracking or side reactions with the electrolyte. The NiO‐type layer formation is also responsible for the strongly increased impedance and transition‐metal dissolution. Notably, the capacity loss is found to have a linear relationship with the thickness of the rock‐salt surface layer. Density functional theory and COMSOL Multiphysics modeling analysis further indicate that the charge‐transfer kinetics is decisive, as the lower lithium diffusivity of the NiO phase hinders charge transport from the surface to the bulk. [ABSTRACT FROM AUTHOR]

Heat-pipe-cooled microreactors (HPRs) have advantages such as a compact design, easy transportation, and improved system reliability and stability. The core of an HPR consists of fuel rods and heat pipes in a monolith, which is a solid block structure containing many holes for the fuel rods and heat pipes. When designing the core of an HPR, high thermal stress and reactivity feedback owing to thermal expansion are important considerations. Therefore, a high-fidelity multiphysics analysis tool is required for accurately analyzing an HPR core. When performing a multiphysics analysis, it is necessary to couple the heat pipe thermal analysis code, thermal-structural analysis code, and neutronics code. To develop a multiphysics analysis tool, OpenFOAM, an open source Computational Fluid Dynamics (CFD) tool, and ANLHTP, a heat pipe thermal analysis code, were coupled. In this process, the structural analysis solver of OpenFOAM was verified, and its limitations were improved. To confirm the proper working of the code, the mini-core problem was analyzed using the OpenFOAM-ANLHTP coupled code. Next, to consider the reactivity feedback, coupling with PRAGMA, a GPU-based continuous-energy-Monte Carlo neutronics code was performed, and the multiphysics analysis capability of the OpenFOAM-ANLHTP-PRAGMA coupled code was confirmed through an analysis of the MegaPower reactor core. To reduce the temperature distribution within the monolith, the temperature distribution of the heat pipe sink was adjusted, and the reduced thermal stress of an HPR core was observed.

The heart of the present-day MRI scanners is a superconducting magnet that produces a highly homogeneous field at the centre. A multi-coil actively shielded superconducting magnet is designed, having dry winding i.e. free from any epoxy, for a whole-body 1.5 T MRI scanner. The magnet produces a homogeneity of ± 3.3 ppm in a 45-cm field of view. The multi-coil magnet would experience the stresses from the various sources during operation. The winding pre-tension; the thermal strains, due to cooling; and the Lorentz forces that contribute to the overall operational stress are considered to calculate various parameters of the dry wound magnet. The winding pretension has been determined after a thorough analysis of the hoop stress and the radial displacement of various components of the winding pack at various winding prestress ranging from 30 to 80 MPa. The role of the slip plane and the material (SS 304L and AA5083) of the bobbin in determining the operational stress in the dry magnet has been studied. The operational stresses have been analysed in minimizing the radial gaps between the coil and the bobbin. The role of the number of over-binding layers and their winding pretension has been studied for the multi-coil 1.5 T MRI magnet. [ABSTRACT FROM AUTHOR]

This article presents the design of high-power ultra-high-speed (HP-UHS) rotors of permanent magnet machines for a mechanical-based ultra-very low frequency (ULF-VLF) antenna (AMEBA) application. The conventional communication system in an RF-denied environment (e.g., underground and under seawater facilities) is power demanding with very low efficiency and low power density. Thus, a portable communication system was not available until recently. Such a critical limitation could be overcome by utilizing an HP-UHS motor as a mechanical communication transmitter. This is a first attempt to the best of the authors’ knowledge. However, the unprecedentedly high-speed and HP AMEBA exhibits new design challenges, including the critical mechanical resonance of the rotor, coupled with wireless communication bandwidth (ULF-VLF). It limits the highest possible efficiency and power density of portable AMEBA systems while achieving a required design safety margin (DSM). In this article, such critical constraints of HP-UHS rotors are analytically derived and integrated into a design model. This new design model will effectively couple the electromagnetic, thermal, structural, and rotordynamic analyses for the successful AMEBA rotor design. In the optimization, the Kriging method is adopted to create the efficient approximation model of the design nonlinearities. Multiple objectives and Pareto-front analysis are used to obtain an efficient rotor design with high DSM. The proposed approach is applied to design a 2-kW 500 000 r/min rotor considering AMEBA requirements. The effectiveness of the rotor for the AMEBA application has been validated through 3-D finite-element analysis and experimental testing. [ABSTRACT FROM AUTHOR]

Permanent magnet motors have become an important component of industrial production, transportation, and aerospace due to their advantages of high torque density, high power density, high reliability, low losses, and high efficiency. Permanent magnet claw pole motor (PMCPM) is a special type of transverse flux motor which has a higher torque density compared to traditional permanent magnet motors. Due to the absence of winding ends, its axial space utilization is high, and the usage of windings is greatly reduced, reducing the cost and weight of the motor. PMCPM has the advantages of small space, a light weight, a high torque density, a high efficiency, and simple production, which have potential for use in the field of electric vehicles. The double-stator structure design can improve the torque density, efficiency, and radial space utilization of PMCPM, which helps to expand their applications in the field of electric vehicles. This article designs two PMCPM with concentrated winding while different rotor structures (PMCPM1 and PMCPM2) and a three-dimensional finite element method is employed to compare and analyze the performance of PMCPM1 and PMCPM2 and the traditional PMCPM (TPMCPM). Multiphysics analysis is carried out for PMCPM1 and PMCPM2. The stress of the inner and outer stators during interference assembly are analyzed. In this paper, a hybrid material core design is proposed, in which the stator yoke is rolled by silicon steel material and the stator claw pole is pressed by the SMC die method. The multiphysics simulation performance of the PMCPM1 and PMCPM2 with hybrid cores is analyzed.

The conventional ultra-high-speed motor (UHSM) has been mostly developed for light load (or low power) applications (e.g., ~100W, 500 kr/min). However, the new mechanical antenna system requires a high-power UHSM. Accordingly, the conventional design approach of low-power UHSM cannot address the new challenges, especially with high-power design. The new challenges include lowered critical bending resonance (CBR) due to higher rotor aspect ratio ( $L/D$ ), ineffective electrical loading in the slotless stator due to commonly used three-phase winding, and significant temperature variation unusually in the axial direction and its mutual impact on the electromagnetic and mechanical performances. To address these new challenges, this paper proposes a quasi-3D thermal model to estimate critical temperature variations, a Rotordynamic model to limit CBR frequencies above the rated speed, and an electromagnetic model with multiphase winding to increase electrical loading in the slotless stator effectively. These models are systematically integrated to develop a unique Multiphysics multi-objective optimization (MMO) method, which enables (i) the mutual influence analysis among Multiphysics performances, such as thermo-electrical and thermo-physical that are critical in HP-UHSM, and (ii) a precise trade-off analysis between the efficiency and design safety margin (DSM). To validate the effectiveness of the proposed new MMO method, a 2-kW 500 kr/min UHSM, the highest power rated motor at this speed to the best of author’s knowledge, is designed for a mechanical antenna system and experimentally validated. It provides 94.5% efficiency with 30% DSM at 500 kr/min and no CBR below 11 kHz.

Magnetorheological (MR) fluid devices are widely used in active automotive control applications. However, MR fluid-based valve actuators are not in the limelight. This paper proposes a new flexible valve train with an MR fluid control system; the valve train can enhance the performance of internal combustion engines. A major component of this valve train is the magnetic plate block filled with MR fluid and surrounded by a magnetic coil. This plate block controls the magnetic field in this MR fluid and eventually facilitates flexible valve lifts and valve opening timings. This study overviewed the conceptual design, two-way coupled multi-physics numerical simulations, manufactured an MR valve prototype, and conducted experimental tests on a test bench to understand the real-time performance of the MR valve train. First, computer simulations were performed using a coupled magnetic and thermal multiphysics model to consider the Joule-heating effect of the magnetic coil in the MR magnetic plate block. The simulation results indicated that although the temperature of the MR fluid increased noticeably, it did not exceed the prescribed operating limits. The dimensions of the MR magnetic plate block were optimized. After computer simulations and optimization, a prototype of the proposed MR valve was fabricated and tested to understand its performance in real time. The experimental test results indicated the reliability of the proposed MR valve train in practical scenarios. [ABSTRACT FROM AUTHOR]

In this paper, a design is presented for a high-speed, high-power motor for a four-legged robot actuator that was optimized using the weighted sum method (WSM) based on the Taguchi method, and the response surface method (RSM). First, output torque, torque constant, torque ripple, and efficiency were selected as objective functions for the optimized design. The sampling method was implemented to use a mixed orthogonal array and the single response characteristics of each objective function were compared using the Taguchi method. Moreover, to consider the multi-response characteristic of the objective functions, WSM was applied. Second, the 2D finite element analysis result of the RSM was compared with that using the WSM. Finally, an experiment was carried out on the manufactured motor and the optimized model is presented here.

High temperature proton exchange membrane electrolyzer cells (HT-PEMECs) show faster reaction kinetics than the low temperature PEMECs (LT-PEMECs) and are suitable for utilizing waste heat from the industry. However, dynamic modeling and control of HT-PEMECs are still lacking, which is critical for integrating the HT-PEMECs with fluctuating renewable power. In this study, hierarchical models are developed to investigate the transient behavior of the HT-PEMEC system with hydrogen recirculation. It is observed that the maximum efficiency point of the reference power can be reached by cooperatively adjusting the current density and anode inlet gas flow rate, and the application of artificial neural networks can accurately predict the operating conditions at the points of maximum efficiency. Moreover, the proposed cooperative model predictive control strategy not only improves the efficiency (about 1.2%) during dynamic processes but also avoids the problem of reactant starvation. This study provides useful information to understand the dynamic behaviors of HT-PEMECs driven by excess renewable power. [Display omitted] • The hierarchical system model is used to study the dynamic behavior of HTPEMEC. • Reactant starvation problems are analyzed through multiphysics simulation. • Maximum efficiency points of different reference power are calculated by the ANN. • Cooperative predictive control strategy is designed for better dynamic performance. [ABSTRACT FROM AUTHOR]

The rectangular profile conductor with a large cross section requires less slot space and has better heat dissipation ability than the traditional round profile one. But its application in automotive propulsion electric machines is thwarted by high ac winding losses and temperature rise under high-speed operations. This article proposes a novel stator winding topology with hybrid strands based on the ac losses' distribution characteristics and the theoretical relationship between the eddy current suppressing ability and the geometric parameters. The new winding can effectively reduce the ac loss and the peak temperature in the winding at high-speed operation. Meanwhile, it can maintain a high filling rate. Therefore, the machine's maximum rotating speed and power density can be effectively improved. In experimental validation, a winding sample with this new topology is manufactured and compared with the conventional one formed by rectangular wires. It shows the proposed method can reduce the winding ac loss by up to 12% and the temperature rise by 10–21%. It is validated to have considerable industrial potential in the future development of automotive motors. [ABSTRACT FROM AUTHOR]

The short-circuit fault is the severest fault that threatens the reliability of the modular multilevel converter (MMC) submodule busbar. When the short-circuit fault occurs, a huge overcurrent will flow through the busbar. Since the discharge time is very short and the discharge current is too large, the discharge current produces a strong skin effect on the busbar, resulting in overheating and deformation of the busbar, which may cause the permanent failure of the busbar. The busbar is the key component of the MMC submodule. It is therefore crucial to evaluate the fault ride-through capability of the MMC submodule busbar. The key feature of the short-circuit behavior of the busbar is that the large electromagnetic force is induced by the fault current, which causes the deformation of the busbar in a very short transient. The fast deformation of the conductor will generate the electromotive force induced current by the fast deformation of the conductor in a strong magnetic field. Plasticity of the conductor also significantly influences the deformation of the conductor. The existing researches on the failure mechanism of the busbar did not take these two important factors into account. This paper proposes an improved multiphysics analysis model which considers both the dynamic electromotive force and plasticity for analyzing the reliability of the MMC submodule busbar under the short-circuit fault. The fault current through the busbar is derived by numerical calculation. Utilizing the fault current as the input, an improved multiphysics analyzing model, which takes both features into account is proposed. Simulation results show that the dynamic electromagnetic force induced current and plasticity play dominant roles in the deformation of the busbar and are key factors that need to be taken into account in the short-circuit analysis of the busbar.

This study presents the results of a refined numerical investigation meant at understanding the time‐dependent cyclic behavior of reinforced concrete (RC) bridge columns under chlorides‐induced corrosion. The chloride ingress in the cross‐section of the bridge column is simulated, taking into account the effects of temperature, humidity, aging, and corrosion‐induced cover cracking. Once the partial differential equations governing such multiphysics problem are solved through the finite‐element method, the loss of reinforcement steel bars cross‐section is calculated based on the estimated corrosion current density. The nonlinear cyclic response of the RC bridge column under corrosion is, thus, determined by discretizing its cross‐sections into several unidirectional fibers. In particular, the nonlinear modeling of the corroded longitudinal rebars exploits a novel proposal for the estimation of the ultimate strain in tension and also accounts for buckling under compression. A parametric numerical study is finally conducted for a real case study to unfold the role of corrosion pattern and buckling mode of the longitudinal rebars on the time variation of capacity and ductility of RC bridge columns. [ABSTRACT FROM AUTHOR]

Magnetorheological (MR) fluid devices are widely used in active automotive control applications. However, MR fluid-based valve actuators are not in the limelight. This paper proposes a new flexible valve train with an MR fluid control system; the valve train can enhance the performance of internal combustion engines. A major component of this valve train is the magnetic plate block filled with MR fluid and surrounded by a magnetic coil. This plate block controls the magnetic field in this MR fluid and eventually facilitates flexible valve lifts and valve opening timings. This study overviewed the conceptual design, two-way coupled multi-physics numerical simulations, manufactured an MR valve prototype, and conducted experimental tests on a test bench to understand the real-time performance of the MR valve train. First, computer simulations were performed using a coupled magnetic and thermal multiphysics model to consider the Joule-heating effect of the magnetic coil in the MR magnetic plate block. The simulation results indicated that although the temperature of the MR fluid increased noticeably, it did not exceed the prescribed operating limits. The dimensions of the MR magnetic plate block were optimized. After computer simulations and optimization, a prototype of the proposed MR valve was fabricated and tested to understand its performance in real time. The experimental test results indicated the reliability of the proposed MR valve train in practical scenarios.

There has been a tendency to embed the theoretical thermal model of electric machines into vehicle thermal management systems to realize real-time temperature prediction and advanced cooling adjustment. The construction process of the high-precision analytical model is the most difficult part for engineering application. However, the electric machines used in electric vehicles usually work in a wide operation space, in which the alternating electromagnetic fields produce different heat production behavior in different operating states. Meanwhile, the major loss components and the main heat transfer paths are highly affected by the temperature variation. The traditional modeling methods usually ignore these effects and oversimplify the model, which will lead to obvious deviations. The main contribution of this article is to propose a theoretical modeling approach with high predicting accuracy in the whole operation space of the electric machines. The experimentally test shows the real-time predicting accuracy has been improved by nearly 60% in a standard test cycle. The computation cost when using the proposed thermal model in the thermal management system is also evaluated to ensure engineering application. [ABSTRACT FROM AUTHOR]

• The vibro-acoustic noise analysis of SR motors in electric vehicles is investigated. • Elaborated the significance and role of transient model-based multiphysics analysis in SR motor. • Multiple vibro-acoustic noise sources of EM forces were extensively investigated and analyzed. • The maximal vibration and noise level is observed in the frequency range of 250 and 1250 Hz in SR motor. • The experimental results are validated through simulation using model analysis of SR motor. The SR motor is acquiring popularity due to its dynamic characteristics such as higher power, torque, and efficiency. Even though, Vibro-acoustic noise is a significant issue in SR motors, which are caused by radial electromagnetic forces. This research adopted a novel methodology to investigate the various vibro-acoustic noise sources to enhance the performance of real-time SR motors. This methodology integrates transient model-based multiphysics and experimental analysis to predict the vibro-acoustic noise sources in SR motors. A multiphysics model incorporates not only the EM and acoustic fields, but also the structural geometry and variably distributed EM forces, to predict and analyse the EM vibro-acoustic noise in SR motor. The experimental results reveal that the maximum vibro-acoustic noise amplitudes are observed at 150, 240, 570, 920, 1210, and 1650 Hz due to uneven EM forces. To verify the presence of experimental vibro-acoustic noise levels at different frequencies, a transient model-based multiphysics analysis is investigated. The vibro-acoustic noise distribution trends seen in the simulation are consistent with those seen in the experiments. Finally, based on the simulation and experimental results revealed that EM forces, load-current changes, flux density, torque ripples are the significant reasons for greatest vibro-acoustic noise levels in the SR motor. [ABSTRACT FROM AUTHOR]

According to an understanding of wearable robot systems, this article suggests an appropriate design process for surface-mounted permanent magnet synchronous motor (SPMSM) for the joints of wearable robots. The major requirements of SPMSM for the wearable robot are investigated and categorized into the dimensional constraints, electromagnetic performances, and thermal restrictions. Given the defined requirements, the electric motor design process for an actual robot is proposed, considering electromagnetic and thermal characteristics. For thermal analysis, the lumped parameter thermal network (LPTN) is adopted, and the process to compose a precise LPTN for the SPMSM is presented. With given controller and electric motor specifications, the numbers of poles and slots are determined, and fractional-slot concentrated winding is adopted considering the overall behavior of the SPMSM such as torque density and noise and vibration. As a preliminary design, the shape of the rotor including permanent magnets, shape of the stator, and the number of turns are designed via space harmonic analysis which is fast. Subsequently, a detailed design process is performed via finite-element analysis. At this stage, the thermal characteristics considering the driving cycle are analyzed via the LPTN, which is appropriate for parametric design. The final model is determined from electromechanical and thermal viewpoint. Finally, experiments are conducted to validate the proposed design process. [ABSTRACT FROM AUTHOR]

The electrical insulation is one of the main sources of failures in hydro-generators, therefore it is important to research the insulation system of stator bars. In this paper, it is developed a steady-state multiphysics analysis of a stator bar using the Finite Element Method to assess its steady-state behavior in the electrical, magnetic and thermal domains. Different aspects are analyzed in simulations, such as capacitance, mechanical stress and thermal effects. Numerical results are compared with experimental measurements for validation. [ABSTRACT FROM AUTHOR]

This work presents a thermal–elastic–plastic constitutive equation based on the radial basis function (RBF) artificial neural network and application with the finite element (FE) analysis. In order to capture the stress data in the coupled temperature-strain doamin, a constitutive equation was defined based on the RBF model, and the trained model was validated by test data that were not used in the training. The RBF based constitutive model was then combined with the stress integration and tangent modulus formulation of FE analysis to apply the new model to a warm V-bending process that includes elastic–plastic deformation and elastic recovery under non-isothermal conditions. The heating method was the infrared (IR) local heating method. The results show that the RBF constitutive model can provide good agreement with the experimental data for V-bending in the non-isothermal conditions. The effects of the parameters of the basis function are also discussed in this work. [ABSTRACT FROM AUTHOR]

The insulation material applied on the stator windings of automotive electric machines are susceptible to the excessive temperature rise. Typically, several thermocouples are embedded in the end-winding and the active winding in the slot to detect the peak temperatures in real-time to avoid thermal damage and adjust cooling. However, in the slot windings, the uneven distribution of power loss will change with frequency. This phenomenon causes the movement of the hotspot in the slot winding at different operating states, while it is not so obvious in the end-winding. As a result, the peak temperature in the slot winding cannot always be detected exactly by the fixed thermocouples, which has never been realized and valued. In this article, we analyze the movement of the hotspot in both of the slot winding and end-winding. In order to improve the detecting precision, we use an offline theoretical thermal-magnetic model to deduce the relationship between the temperatures at the measured position and real hotspot at various operating states. Then the thermocouple reading can be corrected in real-time according to the deduced relationship. The experimental test validates the performance of the proposed method in elevating the precision of peak temperature detection. [ABSTRACT FROM AUTHOR]

Carrying on SiC devices, the air-cooled inverter of the electric vehicle (EV) can eliminate the traditional complicated liquid-cooling system in order to obtain a light and compact performance of the powertrain, which is considered as the trend of next-generation EV. However, the air-cooled SiC inverter lacks strategic design methodology and heterogeneous integration routine for critical components. In this article, a stepwise design methodology is proposed for the air-cooled SiC inverter in the power module, dc-link capacitor, and heat sink levels. In the power module level, an electrical–thermal–mechanical multiphysics model is proposed. The multidimension stress distribution principles in a six-in-one SiC power module are demonstrated. An improved power module is presented and confirmed by using the observed multiphysics design principles. In the dc-link capacitor level, ripple modeling of the inverter and capacitor are created. Considering the tradeoffs among ripple voltage, ripple current, and cost, optimal strategies to determine the material and minimize the capacitance of the dc-link capacitor are proposed. In the heat sink level, thermal resistance of air-cooled heat sink is modeled. Structure and material properties of the heat sink are optimally designed by using a comprehensive electro-thermal analysis. Based on the optimal design results, the prototypes of the customized SiC power module and heterogeneously integrated air-cooled inverter are fabricated. Experimental results are presented to demonstrate the feasibility of the designed and manufactured air-cooled SiC inverter. [ABSTRACT FROM AUTHOR]

Shape memory polymers (SMPs), classified as smart materials, have emerged as promising candidates for microfluidic devices due to their significant potential. In this study, we present the design and analysis of an SMP microvalve. The thermomechanical response of the SMP microvalve is studied using a recently introduced nonlinear constitutive model that incorporates nonlinear hyperelasticity and viscoelasticity for SMPs. This model is coupled with the fluid field and accounts for heat transfer in both fluid and solid physics. The governing equations for the multiphysics behavior are discussed. Then an overview of the finite element model is provided. The most important characteristics of the SMP valve, such as SMP thickness, flow rate, contact pressure, and pressure distribution, are examined numerically. The results expound upon the significance of employing fluid-solid interaction conjugated heat transfer analysis as a crucial factor in the proficient development of microvalves for diverse applications, with the primary objective being the prevention of overheating and the mitigation of potential failures. [Display omitted] • Fluid-Solid-Thermal analysis of thermally responsive shape memory polymer microvalve. • In-depth numerical examination of SMP valve characteristics. • The importance of multiphysics analysis in shape memory polymer microvalve design. [ABSTRACT FROM AUTHOR]

The main equipment responsible for connection and transmission of electric power from generating centers to consumers are power transformers. This type of equipment is subject to various types of faults that can affect its components, in some cases also compromising its operation and, consequently, the electric power supply. Thus, in this paper, electromagnetic, thermal, and structural analysis of power transformers was carried out with the objective of providing the operator with information on the ideal moment for performing predictive maintenance, avoiding unplanned shutdowns. For this, computational simulations were performed using the finite element method (FEM) and, from that, the different transformer operation ways, nominal currents, inrush current, and short-circuit current were analyzed. In this perspective, analyses of the effects that thermal expansion, axial forces, and radial forces exerted were carried out, contributing to possible defects in this type of equipment. As a study object, simulations were carried out on a 50 MVA single-phase transformer. It is important to emphasize that the simulations were validated with real data of measurements and with results presented in the current literature.

The aim of the paper is to assess the applicability of a multi-objective biogeography-based optimisation algorithm in MEMS synthesis. In order to test the performances of the proposed method in this research field, the optimal shape design of an electrostatic micromotor, and two different electro-thermo-elastic microactuators are considered as the case studies.

A 325 MHz, 3.0 MeV Radio Frequency Quadrupole (RFQ) is being developed for 1 GeV proton accelerator for proposed Indian Spallation Neutron Source (ISNS) facility at Raja Ramanna Centre for Advanced Technology, Indore. RFQ will be a normal conducting four vane resonating structure made of Oxygen Free Electronic (OFE) copper. During high power operation of RFQ, Radio Frequency (RF) field induced heating results in temperature rise, thermal deformations and shift in resonant frequency from designed values. Therefore thermal stability of RFQ is one of the important design issues. Various RF–thermal–structural coupled multiphysics analysis methodologies for thermal management of RFQ have been attempted in past and reported in literature. However, these efforts are primarily limited to 2D simulations for a thin slice of RFQ cross section and do not addresses for longitudinal temperature rise of cooling water, distribution of frequency tuners, vane tip modulations and vane cut back at the inlet and exit of RFQ structure. This paper proposes a finite element method (FEM) based multiphysics analysis methodology for numerical simulation of RFQ structure. The methodology consists of a complete 3D-RF-fluid–thermal–structural–RF coupled analysis for predicting temperature rise, thermal deformations and frequency shift of RFQ structure due to RF heating. All analysis (electromagnetic, fluid, thermal and structural) and their coupling are carried out using a single code namely ANSYS Mechanical. The simulated results from proposed methodology are compared with published work and a maximum error of less than 7% is obtained. The numerical comparison of described methodology with other multiphysics analysis methodologies (such as importing 2D field maps and using heat transfer coefficient from empirical relations) has been carried out. The described methodology is paving the way for the design and development of ISNS RFQ structure. [ABSTRACT FROM AUTHOR]

This paper proposes a temperature compensation design for TE011 mode resonator based on multiphysics analysis. The relationship between structure and electrical performance of circular waveguide resonator is specifically analyzed. Furthermore, a novel temperature compensation structure with bimetal material is proposed by using multiphysics analysis. The proposed TE011 mode resonator is fabricated and tested to verify the design method. The temperature drift coefficient of the compensated TE011 mode resonator can be dramatically reduced from 21.387 ppm/°C to 0.93ppm/°C. [ABSTRACT FROM AUTHOR]

Gearless and compact motors rotating at speeds above 10,000 rpm are finding many applications nowadays. This study presents the multiphysics modelling and analysis of a multilayer printed circuit board (PCB) stator for high‐speed, low‐power axial flux permanent magnet motor. The possibility of circulating current in the multilayer PCB is studied. The two major effects of eddy currents at high frequencies: skin effect and proximity effect are investigated for the PCB winding. The losses in the PCB stator are estimated, and thermal analysis is performed to ensure reliable operation of the motor. MagNet 3‐D and COMSOL Multiphysics are used, respectively for the finite element analysis and optimisation of the motor; and the simulation results are presented. A prototype of the motor is fabricated and tested to validate the simulation results. [ABSTRACT FROM AUTHOR]

The pin-socket connector susceptibility under vibration stress constitutes one of the electrical engineer breakthroughs. Only single electrical engineering is not enough to treat this challenging issue. The Multiphysics analysis is expected to be a solution to analyze this electromechanical dynamic pin-socket structure. This paper develops a dynamic contact Multiphysics analysis with the tensorial analysis of networks (TAN) formalism. The Multiphysics model integrates the pin relative velocity and position coupled with the instantaneous contact resistance implemented in an RC-network. An innovative method enabling to determine the vibration stress signature via the signal-to-noise (SNR) amplitude is established. The relevance of the Multiphysics TAN model is illustrated with an example of a 10-mm-length pin-socket under arbitrary waveform uniaxial vibration stress with 20-kHz bandwidth. It was shown that the contact resistance may fluctuate with more than thousand-time relative variation. More importantly, the vibration stressed pin-socket SNR in function of the RC-network parameters is discussed. The proposed Multiphysics analysis can be potentially applied to the electromagnetic compatibility and signal integrity investigation of assembled electronic equipment and printed circuit boards under vibration stress. [ABSTRACT FROM AUTHOR]

The ETC (Electric Turbo Charger) consists of high speed PMSM, ball or air foil bearings, impeller and controller. KERI (Korea Electrotechnology Research Institute) is developing a high speed surface permanent magnet (SPM) type of synchronous motor and a Pulsed Width Modulation (PWM)-driven inverter. This system operates at a power density of 3 kW/kg at 100,000 rpm and is intended to fit the 1,600 cc diesel vehicles to reduce turbo-lag within 0.5 s. The design and analysis of the PMSM for the ETC has been developed successfully considering the several losses and current overload rates using transient computational fluid dynamics (CFD). [ABSTRACT FROM AUTHOR]

This paper deals with a 16-pole, 18-slot fractional-slot concentrated-winding permanent-magnet synchronous machine (PMSM) for articulated robot applications considering several multiphysics analyses. Optimized PMSMs are compared analytically and experimentally considering electrical and mechanical aspects. The electrical and mechanical analysis results are well matched with the experimental results in terms of the efficiency and temperature. The design, analysis and experiment with the PMSM for articulated robot applications were performed successfully. [ABSTRACT FROM AUTHOR]

ITER is the world’s largest fusion device currently under construction in the South of France with >50 diagnostic systems to be installed inside the port plugs (PPs), the interspace (IS), or the port cell (PC) region of various diagnostic ports. Four tenant diagnostic systems will be integrated into the upper port 14 (U14), the upper wide angle viewing system, the disruption mitigation system, the glow discharge cleaning (GDC) system and the plasma position reflectometry, an ex-vessel tenant installed in the U14 IS region. Multiphysics analyses were performed for an in-vessel and ex-vessel component design integration following the ITER port integration requirements and the ITER guideline for load specification. Electromagnetic (EM), inertial, and heating loads of the main U14 components under various conditions for the diagnostic shield module (DSM) and its internal shielding block attachment design have been summarized. The structural design of in-port components is based on an optimization of the EM load distribution to limit the load impact to the diagnostic first wall and the tenant diagnostics and to mitigate the effect of dynamic amplification from asymmetric plasma vertical displacement event inertial loads. The DSM needs to provide a sufficient stiffness for the protection of onboard diagnostics and structural integrity of the port integration under the design-driving EM and inertial loads. The in-port diagnostics and mounting supports, on the other hand, are designed to meet the remote handling requirement, while taking into account the thermal loads due to temperature gradient from nuclear heating, as well as matching the relative stiffness among the structural components within the port assembly. Progress on an integrated design and analysis is reported including a seismic analysis of the IS/PC region for extracting tenant interface loads. The design-driving loads for tenant systems are presented for the attachment structure design as part of the PP engineering tasks. [ABSTRACT FROM AUTHOR]

ITER is the world’s largest fusion device currently under construction in the South of France with >50 diagnostic systems to be installed inside the port plugs (PPs), the interspace (IS), or the port cell region of various diagnostic ports. The plasma facing diagnostic first wall (DFW) and its supporting diagnostic shield modules (DSM) are designed to protect front-end diagnostics from plasma neutron and plasma radiation, while providing apertures for diagnostic access to the plasma. The design of ITER port plug structures including the DFW and the DSM is largely driven by the electromagnetic loads included on the PP structural components during plasma major disruptions and the vertical displacement events (VDEs). Unlike DFW and DSM, the design of diagnostic system, however, is likely driven by the steady-state thermal loads from plasma volumetric and surface heating and the dynamic response of the in-port components attached to the port-specific DSM or closure plate under transient loads induced on the vacuum vessel and the port extension during asymmetric VDEs. Three tenant diagnostic systems are integrated into the equatorial port 09. The toroidal interferometer/polarimeter, or TIP system, is installed in the left drawer (DSM3, left looking from plasma) for measuring the plasma density so to control the fuel input. The electron cyclotron emission (ECE) system is installed in the middle drawer (DSM2) to provide the high spatial and temporal resolution measurements of electron temperature evolution and the electron thermal transport inferences. The visible/infrared wide angle viewing system is installed in the right drawer (DSM1) to provide visible and infrared viewing and temperature data of the first wall for its protection in support of machine operation. The port plug integration design and multiphysics analyses are performed following port integration requirements including the weight limit (45 tones total), shut down dose rate limits, the cooling/heating and structural integrity validation. Mass distribution for TIP and ECE DSMs has been optimized to minimize the total weight by a new design of the boron carbide shielding pocket. The lightened DSM maintains its front-end load distribution and the structural stiffness with minimum impact to the DFW so to better protect on-board diagnostics; while still provides sufficient front-end stiffness for its structural integrity as well as the diagnostics function requirements. [ABSTRACT FROM AUTHOR]

Boron Neutron Capture Therapy (BNCT) promises a bright future in cancer therapy for its highly selective destruction of cancer cells, using the 10 B +n → 7 Li + 4 He reaction. It offers a more satisfactory therapeutic effect than traditional methods for the treatment of malignant brain tumors, head and neck cancer, melanoma, liver cancer and so on. A CW 4-vane RFQ, operating at 162.5 MHz, provides acceleration of a 20 mA proton beam to 2.5 MeV, bombarding a liquid lithium target for neutron production with a soft neutron energy spectrum. The fast neutron yield is about 1.73× 10 13 n∕s . We preliminarily develop and optimize a beam shaping assembly design for the 7 Li(p, n) 7 Be reaction with a 2.5 MeV proton beam. The epithermal neutron flux simulated at the beam port will reach up to 1 . 575 × 10 9 n/s/cm 2 . The beam dynamics design, simulation and benchmark for 2.5 MeV BNCT RFQ have been performed with both ParmteqM (V3.05) and Toutatis, with a transmission efficiency higher than 99.6% at 20 mA. To ease the thermal management in the CW RFQ operation, we adopt a modest inter-vane voltage design ( U = 65 kV), though this does increase the accelerator length (reaching 5.2 m). Using the well-developed 3D electromagnetic codes, CST MWS and ANSYS HFSS, we are able to deal with the complexity of the BNCT RFQ, taking the contribution of each component in the RF volume into consideration. This allows us to optimize the longitudinal field distribution in a full-length model. Also, the parametric modeling technique is of great benefit to extensive modifications and simulations. In addition, the resonant frequency tuning of this RFQ is studied, giving the tuning sensitivities of vane channel and wall channel as −16.3 kHz/°C and 12.4 kHz/°C, respectively. Finally, both the multipacting level of this RFQ and multipacting suppressing in the coaxial coupler are investigated. [ABSTRACT FROM AUTHOR]

We present the development of a low-loss, high-power, and ferriteless balun that operates over 0.1–1.6 GHz bandwidth. The proposed balun employs a novel compensated circuit, a single quarter-wave semirigid coaxial cable and an on-board inductor on a thermoset ceramic board to achieve high power and ultrawide bandwidth performance. The experimental results show that the balun achieves a measured average insertion loss of less than 0.5 dB and return loss of better than 10 dB from 100 MHz to more than 1.6 GHz. Within the measured bandwidth, the amplitude and phase imbalances are within ±1 dB and ±5°, respectively. Multiphysics analysis and high-power measurements demonstrate that the balun can handle more than 600 W and above at 1.6 GHz. To the best of our knowledge, the reported balun has the highest measured power handling capability per the largest 16:1 bandwidth ratio to date. [ABSTRACT FROM PUBLISHER]

For the fifth generation wireless communication system, millimeter-wave absorber has been frequently used in the measurement of high-power devices, such as transmitting antennas of base stations or satellite communication antennas, etc. The overheat inside the absorber can always be a matter of concern because it may lead to catastrophic fire in the anechoic chamber. A novel pyramidal structure with vent holes and heat sinks was proposed to improve the heat dissipation. The power-handling capability of the wave absorber could be improved by increasing the heat dissipation path without changing the characteristics of the base material. Multiphysics simulation was carried out to analyze the thermal-electromagnetic interaction. This absorber can be used to measure the high-power antenna and the radar system inside anechoic chambers, with power density up to 7 kW/m2. [ABSTRACT FROM PUBLISHER]