•The acoustic FE simulation is used to obtain the optimal drive signal parameters for the acoustic-based weight’s volume measuring system.•The optimal sound source driving signal in the volume ...measurements of 1–100 g weights based on the acoustic method is verified in this study.•The uncertainty evaluation of the optimized acoustic volumetric measurement results is provided in this paper.
The purpose of this study is to investigate the existence of the optimal sound source driving signal toward a laboratory-designed acoustic-based volumeter for weights. The finite element (FE) simulation method is used for simulating the measuring system and predictively determining the qualities of the optimal sound source driving signal, including frequencies and amplitudes. Then, experimental studies are conducted to verify the predictions acquired by the FE simulation method. The volume measurement of 1–100 g weight is carried out, and the sound source driving signals that minimize the error of the weights’ volume measurements are treated as optimal. As the results, experimental measurements verify that the findings carry out by simulations. The uncertainty evaluation of the optimized acoustic volumetric measurement results is provided and shows that the extended uncertainties of the volumetric measurement of 50–100 g weights are less than 6 × 10−4. The relative expanded uncertainty of 1–20 g weights satisfy the requirement of the volumetric measurement expanded uncertainty for Class E1 weights according to OIML Recommendation R111.
This article presents a comprehensive exploration of negative corona discharges and Trichel pulses in air, focusing on different needle electrode geometries with a constant radius of curvature at the ...needle's tip. Three distinct needle electrode shapes are mathematically defined and introduced: 1) a standardized hyperboloid-shaped needle; 2) ellipsoid-shaped needles; and 3) tangent-circular needles. Through a comparative sensitivity analysis, we investigate how variations in these needle cathode shapes-characterized by eccentricity values or intertangent angles-affect negative corona discharge behavior and Trichel pulse characteristics. Employing a hydrodynamic numerical model, we simulate the initiation and evolution of low-temperature plasma between electrodes. The numerical and comparative analysis covers a range of Trichel pulse aspects, including their amplitude and temporal attributes. Simulation results reveal intriguing trends, where narrower needles in the body induce earlier onset and intensified Trichel pulses. Meanwhile, temporal attributes such as rise, decay, and total pulse times demonstrate close clustering around mean values for needles sharing the same radius of curvature. These findings underscore the multifaceted influence of electrode geometry on discharge behavior and Trichel pulses dynamics, emphasizing the necessity for accurate needle electrode geometry definition beyond the mere radius of curvature and shape type in numerical simulations of corona discharge.
This paper presents the development and validation of moment-rotation backbone curve parameters for self-centering steel endplate connections with superelastic SMA bolts. In terms of influential ...design factors, surrogate models of response parameters are proposed using detailed finite element models of self-centering beam-column connections and statistical analysis of response parameters. The predictive surrogate models are useful for characterizing the connection backbone and self-centering response, which is essential for the performance-based design and assessment of extended endplate connections equipped with SMA bolts. Through a verification study, the accuracy of predictions using the proposed models is confirmed. The proposed surrogate models are used to assess the fragility of SMA-based beam-column connections. The results demonstrate that endplate beam-column connections with SMA bolts can provide an acceptable level of deformation capacity. Furthermore, it is found that larger diameter SMA bolts and smaller depth beam sections can reduce the probability of experiencing SMA bolt fracture by 31% and 77%, respectively.
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•Surrogate models developed for connections with shape memory alloy (SMA) bolts.•Self-centering response of endplate moment connections with SMA is characterized.•Accuracy of the proposed predictive equations are verified.•Fragility of endplate beam-column connections with SMA bolts is evaluated.•The SMA connections can provide an acceptable level of deformation capacity.
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•A new anisotropic microcomposite (AMC) joint utilizing a lotus-type porous Cu (LPC) sheet and Sn-based solder was developed.•A simple reflow process allowed joint formation via ...infiltration of the molten solder into the LPC sheet.•AMC joints exhibited thermal conductivity of 142.4 W/m·K, 2.5 times higher than that of the solder.•A stable shear strength of > 46 MPa was achieved after the aging test at 200 °C for 1008 h.•LPC utilization exploited the full potential of the solder for high-temperature electronic applications.
The miniaturization of power conversion systems requires high-power density operation of power modules, causing the heat-density increase. Therefore, it is essential to develop bonding technology to realize highly thermally conductive and reliable high-temperature joints. In this study, we propose a novel anisotropic microcomposite (AMC) joint that integrates a lotus-type porous Cu (LPC) sheet and Sn-based solder for high-temperature electronic applications. The AMC joint was successfully fabricated by infiltrating the molten solder into the unidirectional pores of the LPC sheet during a simple reflow process. Steady-state thermal conductivity measurements for a uniquely designed specimen revealed its equivalent thermal conductivity (142.4 W/m·K), 2.5 times higher than the solder. Finite element simulations supported its excellent thermal performance by investigating the heat flux distribution and thermal conductivity prediction that utilize a three-dimensional image-based constructed model. In addition, the aging test at 200 °C for 1008 h clarified a stable shear strength of over 46 MPa. This indicates a reliable mechanical performance at 200 °C, which is only 20 °C below the melting point of the solder. These experimental and numerical studies proved the potential of the novel joint as a high-temperature electronics joint and offered possible mechanisms for its thermal and mechanical property enhancement.
Thermography has been used in some research works to evaluate the residual life of laminated composites under fatigue loading. In this method, the temperature-rise distribution at the outer surface ...of the composite specimen is monitored. However, thermography may not be able to provide detailed information on temperature rise and the fatigue damage that occurs in each ply of laminated composites with stress concentration. In the present paper, the Self-Heating model, recently developed by the authors, was modified and improved to simulate the evolution of temperature rise and fatigue damage in laminated composites with stress concentrations. The present model was called the Temperature-Damage Evolution (TDE) model. To verify the results of the present TDE model, an extensive experimental program was conducted on carbon/epoxy laminated composites with different stress concentrations, layups, and fatigue load levels. The present model successfully simulates the cycle-by-cycle temperature distribution and damage states in each ply of laminated composites under fatigue loading.
The wear of automotive chain drive systems after high mileages is numerically calculated based on Fleischer’s energetic wear equation. This equation is embedded in a FE-model, consisting of one ...single chain link only. Their time-variant positions and acting forces are taken from a multi-body simulation. A focus is on ensuring the quality of the FE-model and the contact between pin and bush, where here a penalty approach has provided a stable solution schema. The parameters of the wear model are derived from measurements. After each time increment the wear results in a changed surface geometry, which is used for the simulation of the next time increment. The enormous computation time is reduced by the development of a convenient extrapolation factor. The complex simulation approach is applied to the chain drive of a test vehicle after a mileage of about 50000 km. The comparison of the simulated and measured data demonstrates an agreeing correlation.
•For calculating the wear of automotive chains an energetic based wear model is embedded into a FE-Model of the chain.•Only one chain link model is required; its time dependent positions and forces are taken from multi-body simulations.•After each simulation step the wear results in a new surface geometry, which is used for the next time increment.•The enormous computation time is reduced by the development of a convenient extrapolation factor.•The chain wear simulation is in a proper correlation with measurements of a test vehicle after ∼50000 km mileage.
Abstract Hydraulic tortuosity is a crucial parameter affecting the movement of fluid in porous media. Currently, researchers have used different methods to construct porous media models and studied ...the variation of hydraulic tortuosity with porosity. In this paper, we use Monte Carlo random particle, quartet structure generation set (QSGS), and CT-scan reconstruction to construct porous media models with different porosity. The finite element method is used to simulate the fluid passing through the models. The effectiveness of the QSGS algorithm in constructing porous media is verified. The hydraulic tortuosity of the three types of model is computed using the streamline length ratio method, and its variation law with porosity is explored. The results show that the change law of the three models is consistent. The law of power function change is satisfied between the two for all models, which means the increase in porosity causes a decrease in tortuosity. Different models are constructed to explore the effect of tortuosity on permeability. An increase in tortuosity results in a smaller permeability when other conditions are equal. This paper aims to provide effective methods for constructing porous media models and a reference for studying hydraulic tortuosity.
At mesoscale, the blade of micro impeller with Ti-6Al-4V titanium alloy (micro thin wall with mixed boundaries) is a thin-walled structure, characterized by small size, low stiffness, high surface ...precision, complex boundaries, and difficult-to-control machining deformation. To control and reduce the deformation of micro thin wall, it is necessary to study the micro-deformation mechanisms during milling micro thin-wall parts. In side milling of micro thin wall with mixed boundaries, the micro thin wall suffers from dynamic alternating forces, and the deformation modes are complex, so the direct and accurate theoretical modelling is difficult to make. Since the feed speed in milling micro thin wall is less, the small deformation of micro thin wall can be described based on the flexure deformation model of the thin plate subjected to elastic loadings. Firstly, accompanied by the reciprocal theorem of work for a curved thin plate, Kirchhoff-Love small deformation model of micro thin wall is used to establish the deformation equation and boundary conditions of micro thin wall with mixed boundaries under concentrated milling forces. Thus, the obtained boundary conditions are mainly applied to the subsequent finite element simulation of three-dimensional milling deformation of micro thin wall. Then a three-dimensional deformation simulation of the micro thin wall under different milling parameters is carried out by considering the micro-walled structure, material elasto-plastic constitutive model, the stiffness and geometric structure of micro milling tools in finite element method. In the workpiece constitutive modelling, considering the strain gradient plastic model in micro milling of Ti-6Al-4V titanium alloy, the workpiece plastic constitutive model is modified by introducing the intrinsic characteristic length of the material to describe the size effects in mesoscale micro milling. Finally, a series of the corresponding experiments on the milling of titanium alloy micro thin walls are carried out. By comparing and analyzing the experimental values and finite element numerical results of the micro thin-walled deformation, the micro deformation mechanisms in milling of thin wall are revealed. It also verifies the accuracy and effectiveness of this established milling finite element model of thin wall, and provides theoretical basis and technical support for controlling the milling deformation of micro thin-walled parts.
•The deformation equation and boundary condition of micro thin wall are established under the action of micro milling force.•The three-dimensional deformation simulation of the micro thin wall under different milling parameters is carried out by FEM.•By analyzing the experimental and simulated values, the deformation mechanism and rule of micro thin wall are revealed.
The local modification of the material properties, especially in the case of Aluminium alloys, is considered a promising solution to overcome the poor formability at room temperature. According to ...this approach, the Aluminium blank is preliminary subjected to a short-term local heat treatment (usually by laser heating) and then, once cooled down to room temperature, subjected to the forming operations. The present work proposes a numerical methodology to predict the effect of a laser heating, locally bringing a AA5754-H32 blank to the fully annealed state. The Gleeble 3180 physical simulator was used to reproduce the annealing laser treatment by heating AA5754-H32 striped samples under different conditions of time and temperature: specimens, once cooled down to room temperature, were then subjected to hardness measurement and the resulting data used to calibrate a sigmoid function describing the level of annealing according to the time and the maximum temperature reached during the heat treatment. The logistic function was then implemented in a python script able to post-process the results from a thermal transient simulation and, by extracting the temperature history from each node, predict the final distribution of properties. The methodology is then validated by comparing the predicted distribution of properties and the measured one on AA5754-H32 samples subjected to different laser heating strategies.
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•The proposed methodology is based on data efficiently obtained by physical simulation tests.•Degree of Annealing (DoA) is related to time and temperature by a sigmoid function.•FE simulations implementing the DoA sigmoid function accurately predicts the laser annealing.•FE predictions are validated by Vickers hardness measurements.•The proposed methodology is versatile and can be applied to different alloys.
•Overview on development of functionally graded W/EUROFER protective coating.•Smart development combining simulation, processing and characterisation.•Ultrasonic testing highlights importance of ...temperature management during upscaling.•First successful tungsten coating on curved surface, accompanied by simulation.
The First Wall is a crucial component for the realisation of DEMO. It has to protect the tritium breeding blanket from erosion by high-energy particles while letting neutrons pass to enable breeding of tritium fuel. Furthermore, the First Wall needs to pass incoming heat in the MW/m² range to a cooling system for conversion to electric power. These requirements sum up to one of the harshest environments imaginable for a man-made material. Structural steel components alone cannot withstand these conditions. Tungsten is a viable armour material for the First Wall because of its low sputtering yield, high melting point, low activation and good thermal conductivity. It is not suitable though as bulk structural material because of its brittleness. Instead, the DEMO design foresees a First Wall of reduced-activation EUROFER steel, covered with a protective layer of tungsten. Direct tungsten-steel joints suffer from failure during processing or operation because of the thermal expansion mismatch between the two materials. This is solved by application of a functionally graded material as intermediate layer between steel and tungsten. Such coatings made of both tungsten and EUROFER, with a compositional gradient, have been produced with vacuum plasma spray technology. This technology enables manufacturing of the required millimetre-thick coatings and is suitable for upscaling. The development was supported by thermo-mechanical finite element simulations of load scenarios during processing and in-vessel service. Driven by promising results of high heat flux tests on larger, coated mock-ups the technology was transferred to industry for upscaling. Plates with a record size of 500 × 250 mm² and cooling channels were successfully coated. This contribution presents an overview of the development process, covers the latest results of ongoing research on the coating of curved First Wall structures and addresses future requirements.
