Multiphysics Modeling of Hot-Wall CVD Deposition of W–C–B Coatings for Process Optimization

In-situ synthesis of tungsten boride-carbide composite powders from WO3-B2O3–Mg–C quaternary system via a mechanochemical route

Electrolytic deposition of tungsten and molybdenum boride particles from ionic melts is studied. Conditions are found for preparing different boride phases. If the anode material is graphite and the voltage in the bath does not exceed 2.5 V the cathode deposit consists mainly of tungsten and molybdenum metals. A mixture of phases (M, M2B, MB, MB2, M2B5) is produced on the cathode with U=2.5−3.5 V, while with U=2.3−3.5 V, while with U=3.5−4.5 V the deposit consists of the higher boride MB4. On the whole the process of electrochemical synthesis for molybdenum and tungsten borides is governed by the following interconnected parameters: electrolytic bath composition, voltage in the bath, temperature, and duration of electrolysis.

Hydrophones based on optical fiber technology are a promising alternative to ceramic detectors, when immunity to electromagnetic noise and low electromagnetic signature are a key requirement. In the present paper we analyze both through multi-physics finite element modeling via COMSOL Multiphysics and experimental test in an equipped pool some sensor configurations with the aim of developing quite inexpensive hydrophones for application in navigation of autonomous underwater vehicles.

Any engineering component possesses roughness on its surface when it is observed microscopically, including electrical connectors. Electrical connectors usually consist of a spring and a pin. In this study, the spring part is in the shape of a compliant curved beam whereas the pin one is of a flat form and these two parts are in contact during operation. This work presents a multi-physics (structural, electrical and thermal) finite element model of the bulk region of an electrical connector. The rough surfaces of the spring and pin parts are considered using a multi-scale sinusoidal rough surface (MSRS) contact model. The resulting coupled multi-physics connector model is used to analyze the performance of the connector while the applied current is incremented from 5 to 20 A. As expected, this produced a proportional rise in voltage drop and temperature across the bulk regions of the connector parts. The coupled multi-physics model together with the MSRS model should provide greater accuracy in the prediction of contact forces, electrical contact resistance (ECR) and thermal contact resistance (TCR). The present work also provides valuable information on stresses and strains distributions, current flow and temperature variations in the bulk regions of the electrical connector.

Investigation of long term stability of W/B4C multilayer structures

Reliability and life study of hydraulic solenoid valve. Part 1: A multi-physics finite element model

An equation-based multiphysics modelling framework for oxidative ageing of asphalt pavements

A multi-physics time-dependent model for the Lead Fast Reactor single-channel analysis

Current-carrying wear is a complex multi-physics coupled phenomenon in electrical contact systems, involving the interaction of mechanical friction, current conduction, and thermal effects, which critically affects the operational reliability of electrical devices. This study presents a systematic investigation of the wear behavior of a QCr0.5 chromium bronze/1080 steel friction pair under current-carrying conditions, integrating experimental measurements with numerical simulations. A multi-physics finite element model was developed within a coupled mechanical-thermal-electrical field framework, incorporating temperature-dependent material properties, definitions of thermal and electrical contact pairs, integration of friction heat and Joule heat, and calculations of friction force and wear rate. Orthogonally designed experiments under varying loads, current intensities, and sliding speeds were conducted to validate the model's predictive capability for multi-physics coupling. The results demonstrated a maximum error of 17.98% and an average error of 11.07% in wear rate prediction, indicating acceptable accuracy. A detailed analysis of worn surface morphology, combined with simulated wear depth and temperature distributions, systematically identifies the dominant wear mechanisms under different degrees of current influence. The findings reveal that under relatively weak influence of current, the dominant wear mechanisms remain mechanical, including abrasive and adhesive wear. However, under relatively strong influence of current, thermal effects such as Joule heat, friction heat, and potential arc melting lead to material softening, and a transition to electrical-mechanical coupled wear mechanisms. This study introduces a novel multi-physics coupling modeling and numerical simulation framework to investigate current-carrying wear behavior, providing a foundation for the optimization of electrical contact systems.

<div class="section abstract"><div class="htmlview paragraph">The thermal management capability of power electronic (PE) systems has a critical impact on the performance and efficiency of electric, fuel cell, or hybrid vehicles. Bus bars, high resistance sensor devices, semiconductor switches, power capacitors are the primary components, which make a major contribution in total heat generation in electrical drive unit. As PE packaging sizes are projected to become smaller, the challenge of managing increased heat dissipation becomes more critical. This paper numerically compares six different cooling strategies to determine the best possible thermal management scenario. A coupled physics co-simulation framework is used to analyze a 35W motor inverter integrated with water cooled heat sink. A multi-physics finite element model, integrating fluid, electrical, and thermal fields, is employed to analyze heat generation within the PE system and the associated cooling mechanisms. The power losses from the inverter system are dynamically computed in 1-D simulation and fed to the multi-physics finite element model as input. The Cooper-Mikic-Yovanovich (CMY) correlation is used to simulate the contact losses between busbar connections. This model considers the effect of surface roughness and topology on the electrical and thermal contact resistances. This research improves the comprehension of optimized cooling techniques, demonstrating the best design with calibrated cooling parameters. Additionally, it presents an effective numerical procedure for analyzing PE cooling phenomena.</div></div>

<div class="htmlview paragraph">A comprehensive multi-physics theoretical model of the solenoid valve used in an automobile transmission is constructed using the finite element method. The multi-physics model includes the coupled effects of electromagnetic, thermodynamics and solid mechanics. The resulting finite element model of the solenoid valve provides useful information on the temperature distribution, mechanical and thermal deformations, and stresses. The model results predict that the solenoid valve is susceptible to a coupled electrical-thermo-mechanical failure mechanism. The coil can generate heat which can cause compressive stress and high temperatures that in turn could fail the insulation between the coil wires. The model facilitates the characterization of the solenoid valve performance, life and reliability and can be used as a predictive tool in future solenoid design.</div>

Composites including silicide of tungsten and boride of tungsten intermetallic compound as reinforced agents in alumina matrix have a good mechanical properties in low and high temperature (high friction resistance, strength, resin stance to creep and relatively high thermal shock resistance), moreover, they have chemical neutral with a high corrosion resistance in a high corrosive and high temperature environment. The purpose of this study is to investigate thermal analysis, phase and microstructural evaluation during synthesis of above mentioned composite by combustion aluminothermic processing in three systems 1-Al+Si+WO3, 2-Al+B2O3+WO3 and 3-Al+B2O3+Si+WO3. A Ball-milled starting material according to stoichiometric ratio was thermal analyzed (DTA-TGA) for each of above mentioned system. The XRD results never show any new phase during ball-milling even up to 10 hours. The forming of tungsten silicide (WxSiy) is in lower temperature in comparison with tungsten boride (WxBy) during the thermal analysis experiments. The presence of Si in the Al+B2O3+WO3 system facilitates the formation of tungsten borides. The microstructural observations show a uniform and dense distribution of silicide and boride of tungsten in the alumina matrix. Silicide phases are small grain with spherical morphology whereas; the boride phases are coarser and relatively elongated with irregular morphology.

In this paper, a multi-physics computational tool has been developed to accurately model and build high performance ultra-fast actuators. The research methodology is based on a finite element method model coupled with a circuit model. Electromagnetic, thermal, mechanical, and algebraic equations are implemented in Comsol Multiphysics and verified with laboratory experiments of a built prototype. A simplified model is preferred as long as its underlying assumptions hold. However, in the presence of large current and force densities, nonlinearities such as deformations may occur. Such phenomena can only be captured by the use of the developed comprehensive multi-physics simulation model. Although this model is computationally demanding, it was shown to have an accuracy of at least 95% when compared with experiments.

This paper presents the numerical modeling of a classical switched reluctance motor (SRM) and a mutually coupled SRM (MCSRM); both have three phases with 12 slots and 8 poles. The multiphysics models have been developed, which can take into account the electromagnetic characteristics, mechanical vibration, and acoustic noise of the foregoing machines. A 2-D electromagnetic model has been used to calculate the magnetic force which is the main source of vibration of the entire motor system. The vibration of the motor is calculated by a mode superposition method, while the acoustic noise is predicted by a 3-D finite-element acoustic model. In order to validate the numerical models, experiments have been carried out. A good agreement between measured and numerical results has been observed, and it is found that the vibration and the noise levels of MCSRM are considerably lower than those of classical SRM.

This study is motivated by the need to develop an efficient numerical model to simulate non-uniform interfacial degradation of reinforcing steel in concrete in an accelerated corrosion setup considering the influence of differential aeration, moisture and conductivity. In this study, a multi-physics finite element (FE) model is presented to simulate spatially and temporally non-uniform surface topography of corroding steel with rust layer, and eliminates the assumption of uniform mass loss and its linear variation with time as per available literature that uses classical approach of Faraday’s law. The model is validated experimentally with accelerated corrosion setup. Unlike previous studies, pore saturation (PS) is continuously monitored and its existing experimental correlations with conductivity and oxygen diffusivity are adopted so that the model can be extended to simulate natural corrosion to enhance the accuracy of service life predictions. These evaluations can be made completely nondestructive and in real-time eliminating the challenges in capturing the influence of environment by the use of alternative parameters such as relative humidity from real climate change predictions. The key findings from the investigation reveal that incorporating local environmental parameters measured in situ allows for the model to naturally evolve with anodic and cathodic locations on steel surface avoiding the need to assume predefined locations. It is envisioned that the developed multi-physics FE model can be used as a reliable substitute to accelerated corrosion experiment which is frequently used for durability studies of corroding reinforced concrete (RC) members. It is shown that the daily and cumulative mass loss evaluated from the degraded surface topography of the corroded rebar using the simulated model are in good agreement with those evaluated experimentally. Further, the maximum pit depth evaluated from the simulated surface is validated that has valuable applications in estimating degraded strength of corroding steel and service life of RC members.