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The paper deals with the dynamics of a resistance spot welding system. At the core of this system is a transformer, which is powered on the primary side by a pulse-width modulated inverter and has a full-wave output rectifier on the secondary side that provides a direct welding current. The entire system is nonlinear, due to magnetic hysteresis and electronics. The electronics prevent the current from flowing in all parts of the welding transformer at separate time intervals during the voltage supply period; therefore, not all the parameters affect the dynamic of currents and voltages all the time so the system is also time-variant. To design a high-performance welding system and to predict the maximum possible welding current at a specific load, it is necessary to know the welding and primary currents. The leakage inductances of the system can reduce the maximum welding current significantly at higher frequencies and the same load. There are several methods to determine these currents, each with its drawbacks. Measurements are time-consuming, using professional software is expensive and requires time to learn and free open-source software has many limitations and does not guarantee the correctness of the results. The article presents a new, fourth option—a theoretical derivation of analytical expressions that facilitate straightforward and rapid calculation of the welding and primary currents of the resistance spot welding system with symmetrical secondary branches. The derivation of the mathematical expressions is based on the equivalent circuits that describe the system in different operating states. The results of the numerical simulations confirmed the derived expressions completely. [ABSTRACT FROM AUTHOR]

Information technology applications are crucial to the proper utilization of manufacturing equipment in the new industrial age, i.e., Industry 4.0. There are certain fundamental conditions that users must meet to adapt the manufacturing processes to Industry 4.0. For this, as in the past, there is a major need for modeling and simulation tools in this industrial age. In the creation of industry-driven predictive models for machining processes, substantial progress has recently been made. This paper includes a comprehensive review of predictive performance models for machining (particularly analytical models), as well as a list of existing models' strengths and drawbacks. It contains a review of available modeling tools, as well as their usability and/or limits in the monitoring of industrial machining operations. The goal of process models is to forecast principal variables such as stress, strain, force, and temperature. These factors, however, should be connected to performance outcomes, i.e., product quality and manufacturing efficiency, to be valuable to the industry (dimensional accuracy, surface quality, surface integrity, tool life, energy consumption, etc.). Industry adoption of cutting models depends on a model's ability to make this connection and predict the performance of process outputs. Therefore, this review article organizes and summarizes a variety of critical research themes connected to well-established analytical models for machining processes. [ABSTRACT FROM AUTHOR]

Handoff mechanisms are very important in fifth-generation (5G) mobile networks because of the cellular architecture employed to maximize spectrum utilization. Together with call admission control (CAC) mechanisms, they enable better optimization of bandwidth use. The primary objective of the research presented in this article is to analyze traffic levels, aiming to optimize traffic management and handling. This article considers the two most popular CAC mechanisms: the resource reservation mechanism and the threshold mechanism. It presents an analytical approach to occupancy distribution and blocking probability calculation in 5G mobile networks, incorporating connection handoff and CAC mechanisms for managing multiple traffic streams generated by multi-service sources. Due to the fact that the developed analytical model is an approximate model, its accuracy was also examined. For this purpose, the results of analytical calculations of the blocking probability in a group of 5G cells are compared with the simulation data. This paper is an extended version of our paper published in 17th ConTEL 2023. [ABSTRACT FROM AUTHOR]

The difficulties in establishing an analytical model for plain woven fabric composites (PWFC) and its implementation are well-accepted due to the complexity of yarn architecture, approximations assumed, and lack of experimental validations. In this paper, a practical engineering approach is proposed to predict the tensile properties of PWFC. The approach assumes PWFC as cross-ply, the undulation angle an elliptical shape. The approach tremendously simplifies the calculation keeping a close agreement with the tensile experimental results of PWFC. The approach is remarkably compatible with other theoretical models and experiments that existed in the literature. [ABSTRACT FROM AUTHOR]

This paper describes the composites of silane cross-linked polyethylene (PEXb) mixed with four different fillers dedicated to improving thermal conductivity, such as multi-walled carbon nanotubes, graphite, boron nitride, and mineral filler. Using the mathematical modeling, the concentration of each filler was estimated to reach the value of 0.675 W m−1 K−1 suitable for the usage PEXb in the production of geothermal pipes. From tested fillers, all improve the thermal conductivity of pure PEXb; however, above the required value, only 28 mass% of boron nitride (0.937 W m−1 K−1). It was associated with its perfect dispersion and the highest gel content achieved, also resulting in the highest flexural modulus. Graphite at 5 mass% and mineral filler at 35 mass% allowed the thermal conductivity to equal 0.622 W m−1 K−1 and 0.624 W m−1 K−1, respectively, with a simultaneous medium effect on the mechanical properties. Carbon nanotubes increased PEX's conductivity to a small extent, due to their occurrence as agglomerates. [ABSTRACT FROM AUTHOR]

AbstractThe increasing interest in adhesives, such as pressure-sensitive adhesives (PSAs), is often held back by uncertainties regarding their long-term behavior, which includes creep behavior. However, little information exists in the literature regarding creep behavior of PSAs. In this paper, a unified phenomenological creep model for PSAs is applied in SLJs for static and cyclic creep, seeking to develop a tool to predict creep behavior of PSAs. The model was validated by comparing the predicted creep curves with experimental data. It captured the three creep phases and predicted the creep curves for different stresses and temperatures, which is uncommon in literature. [ABSTRACT FROM AUTHOR]

This paper studies the mechanical properties of the 2-D tri-axial braided composite. A volume element is established, so that the classical laminate plate theory and the series-parallel model can be adopted to study a bi-directional stress--strain response. Failure criteria are given and the failure strength is determined. The finite element simulation is used to verify the reliability of the present theoretical model. [ABSTRACT FROM AUTHOR]

The central components influencing future grid stability in the future are inverters and their controllers. This paper delves into the pivotal role of inverters and their controllers in shaping the future stability of grids. Focusing on grid-supporting inverters, the study utilizes a microgrid test setup to explore their impact on overall grid stability. Employing impedance-based stability analysis with the Nyquist criterion, the paper introduces variations in internal inverter parameters and external grid parameters using pole-zero map considerations. The inverter's control structure, resembling standard generators with droop control, facilitates the application of grid operators' knowledge to inverter control. Mathematical insights into stability principles are provided, highlighting the influence of poles related to the phase-locked loop and the strategic placement of additional poles for enhanced stability. Furthermore, the paper evaluates the effects of rotating inertia, revealing that a 50% increase in system inertia can stabilize unstable microgrid behavior, enabling grid-supporting inverters to actively contribute to grid reliability. [ABSTRACT FROM AUTHOR]

Analytical modeling presents symmetries and aesthetic-mathematical characteristics which are not catchable in numerical computation for science and technology; nanoscience plays a significant role in unification attempts, considering also models including holistic aspects of reality. In this paper we present new discovered results about the complete analytical quantum-relativistic form of the mean square deviation of position R 2 (t) related to a recently introduced Drude–Lorentz-like model (DS model), already performed at classical, quantum and relativistic level. The function R 2 (t) gives precise information about the distance crossed by carriers (electrons, ions, etc.) inside a nanostructure, considering both quantum effects and relativistic velocities. The model has a wide scale range of applicability; the nanoscale is considered in this paper, but it holds application from sub-pico-level to macro-level because of the existence of a gauge factor, making it applicable to every oscillating process in nature. Examples of application and suggestions supplement this paper, as well as interesting developments to be studied related to the model and to one of the basic elements of a current unified holistic approach based on vacuum energy. [ABSTRACT FROM AUTHOR]

Adequate mathematical description of magnetization curves is indispensable in engineering. The accuracy of the description has a significant impact on the design of electric machines and devices. The aim of this paper was to analyze the capability of Bézier curves systematically, to describe the nonlinear static magnetic properties of non-oriented electrical steels, and to compare this approach versus the established mathematical descriptions. First, analytic functions versus measurements were analyzed. The Bézier curves were then compared systematically with the most adequate analytic functions. Next, the most suitable orders of Bézier curves were determined for the approximation of nonlinear magnetic properties, where the influence of the range of the input measurement dataset on the approximation process was analyzed. Last, the extrapolation capabilities of the Bézier curves and analytic functions were evaluated. The general conclusion is that Bézier curves have adequate flexibility and significant potential for the approximation and extrapolation of nonlinear properties of non-oriented electrical steels. [ABSTRACT FROM AUTHOR]

Coreless fault current limiter with variable series reactor is an emerging technology for limiting the amplitude and shortening the fault duration in the power network with simple and reversible operation. The device includes two coaxial, coreless reactors with axial mobility to vary and increase the effective inductance of the network during the short circuit fault. The reactors are automatically returned back to their initial position after the fault is cleared, with minimal net inductance. This paper aims to analytically describe the electromagnetic theory and validate the functionality of the device. For this purpose, the resistance and inductance of the device are first computed at normal condition via the basic theory of engineering electromagnetics. Next, the respective electromechanical performance characteristics such as force, positional displacement of the reactors, and the effective inductance are calculated at the faulty condition. For verification purposes, analytical results are compared against the finite element model. [ABSTRACT FROM AUTHOR]

In this paper, both numerical and analytical method were developed for computing, in strip or plate rolling, the distribution of roll pressure, rolling force, and rolling torque (from which also rolling power can be estimated), assuming an homogeneous deformation of the rolled material. Unlike other similar models present in the literature, which solve the resulting rolling differential equation for the roll pressure, the model presented in this work solves the problem for the horizontal force. In this way, it is possible to avoid the calculation of the derivative of material flow stress curve, which is not always analytically easy and possible (i.e., point material flow stress data). The proposed numerical model is based on the friction law proposed by Chen and Kobayashi while the analytical one is based on the simple shear friction model and brings to useful analytical formulas for a quick calculation of rolling torque and force. Moreover, a relationship between the shear friction factor and Coulomb friction coefficient in rolling was found. The developed models show good agreement with experimental measures, in terms of rolling force and torque, found in literature. [ABSTRACT FROM AUTHOR]

The physical models of MOS transistors used in the design of modern integrated circuits are accurate, which makes it possible to simulate their operation with the given degree of reliability, but they are highly complex. Therefore, less accurate but more compact analytical models of transistors and devices based on them are usually used. However, in the calculations and evaluation, the values of the parameters that make up the model equations might not be known in all cases sufficiently accurately. This paper presents a technique for the iterative refinement of parameter values in analytical models that describe devices based on integrated MOS transistors. Using the results of modeling carried out with Cadence EDA with the connection of a precise BSIM4 MOS transistor model, the possibility of the practical application of the proposed technique is shown using the example of a previously developed analytical model of a voltage multiplier. It is found that the use of the parameter refinement technique significantly reduces the errors of models of electronic devices based on integrated MOS transistors. [ABSTRACT FROM AUTHOR]

Factors such as insufficient heat dissipation and excessively high temperature can easily lead to demagnetization of the PMs in permanent-magnet (PM) motors. As a result, the magnetic field distribution of the motor will not be uniform, producing fault harmonics and lowering the operational performance of the motor. An essential stage in the diagnosis of faults and the monitoring of motor condition is the establishment of an accurate model of motors with demagnetization faults. In this paper, demagnetization faults are modeled by changing the Fourier coefficients in the Fourier expansion of the magnetization of PMs. This model can be used to determine the motor performance under various types of demagnetization, including radial air gap flux density, back electromotive force (EMF), and torque. On this basis, the corresponding relationship between the demagnetization degree and the fault signature is established, to provide a theoretical foundation for the subsequent demagnetization fault diagnosis. The finite element analysis (FEA) verifies the effectiveness and superiority of the proposed analytical model. The modeling method proposed in this paper can be applied to PM motors with PMs having different magnetization directions and shapes because it is based on the demagnetization region of PMs. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive study on applying the two-scale asymptotic homogenization method to derive the effective properties of piezoelectric composite materials characterized by generalized periodicity in curvilinear coordinates. The methodology involves formulating the homogenization problem in a general curvilinear framework suitable for materials with complex geometric configurations. By systematically deriving the homogenized equations and effective coefficients, the paper provides a robust theoretical foundation for understanding the macroscopic behavior of piezoelectric composites under various loading conditions. The model's versatility is demonstrated through its application to specific curvilinear coordinate systems, including the helix coordinate system and cylindrical coordinates with wavy geometry. These examples highlight the potential of the proposed approach in analyzing and designing piezoelectric materials with intricate geometries. The state-of-the-art numerical homogenization methods have also validated the proposed homogenization method, ensuring its accuracy and robustness. [ABSTRACT FROM AUTHOR]

The electrohydrodynamic (EHD) actuator system, which produces thrust by ionizing a gas and accelerating it, is a novel propulsion system for near space vehicles. In this paper, an analytical model for EHD actuators, called EHD-AM, has been presented to estimate the thrust produced by the actuators in a wire-to-cylinder configuration. Experimental data from six previous studies have been used to validate the model and the mean absolute percentage error (MAPE) between each configuration and EHD-AM has been calculated under different environmental conditions. Based on the evaluations, the MAPE between EHD-AM and the experimental results for different pressures and wire-to-airfoil structures is 7.18% and 6.16%, respectively. The MAPE between EHD-AM and the experimental data measured by particle image velocimetry (PIV) method and with conventional experimental setups is 10.59% and 6.76%, respectively. Based on the EHD-AM, at a constant voltage, the relation between thrust and pressure has a local minimum and a local maximum point in the range of 0.05–1 atm. From 0.05 atm to 0.5 atm, as the pressure increases, the thrust decreases and then increases. As the pressure increases from 0.5 to 1 atm, the thrust decreases. In addition, a higher voltage can result in a higher pressure at which thrust is maximized. Furthermore, the generated thrust is monotonically increasing as the voltage amplitude increases. By implementation of EHD-AM thrust scale in a simple numerical model, the thrust generated by the actuator has been computed and simulated numerically. Initially, the numerical model was verified using experimental results from a previous study. The MAPE between the numerical model and the EHD-AM is 24.08%. Finally, when the interelectrode gap, the collector radius and the emitter radius are relatively large, the thrust of the actuator is predicted by EHD-AM and compared with the numerical results. EHD-AM can be used in the design and optimization of EHD actuators, and also for controller design and related analyses in a control system. • In EHD actuator, the relation between the thrust and the pressure is determined. • The relationship between corona current and voltage has been considered based on the space-charge-limited current relations. • In high and low mobility of ions, the thrust is obtained as a function of voltage. • Analytical model for corona discharge-based EHD plasma actuator is obtained by incorporating environmental conditions. [ABSTRACT FROM AUTHOR]

Abstract The dynamic response of the hybrid honeycomb sandwich panel under low-speed impact is studied. According to Hamilton’s principle and first-order shear deformation theory, the motion equation of the hybrid honeycomb sandwich panel is deduced. Then the Navier method and Duhamel’s integral are used to solve the vibration displacement of panels. Besides, the mass-spring (MS) model is used to calculate the contact force between the honeycomb sandwich panel and the impactor. The results of this model are compared with those of Abaqus and published studies, which verifies the feasibility of the theoretical model in this paper. Based on the developed theoretical model, the influences of the unit cell angle, cell wall length, cell wall thickness, core layer height and impact speed on the dynamic response of sandwich panels have been studied. The results show that under the same low-speed impact, the maximum lateral displacement of hybrid sandwich panels was 11.65% smaller than that of conventional sandwich panels when honeycomb parameter θ = 60°, and was 15.45% when honeycomb parameter β  =0 .3 . The energy absorption character of the hybrid honeycomb sandwich panel are better than those of the traditional hexagonal honeycomb sandwich panel and the concave hexagonal honeycomb sandwich panel. [ABSTRACT FROM AUTHOR]

This paper solves the problem of modeling the scheme for developing software systems, which can be used in building solutions for secure energy networks. A development scheme is proposed in a set of representations through which each program of the software complex passes, namely the following representations: idea, conceptual model, architecture, algorithm, source code, graphic code, abstract syntax tree, assembler code, machine code, byte code, executed code. The main properties of each representation are indicated, such as the form (text, graphic, programming language, binary, and decoded), development (transformation) methods, as well as vulnerabilities that are detected in it. An example of each representation is given, particularly as applied to the energy networks. The scheme elements (representations, vulnerabilities, forms, etc.) and the main operations for working with their elements (representation transformation, vulnerability injection, and detection) are presented in an analytical form. An example of a development scheme for a simple software complex of energy networks is given. The classification of vulnerabilities is introduced; it divides the vulnerabilities according to the structural level, functioning disruption, and information impact. The vulnerabilities in each of the views are substantiated using the common vulnerabilities and exposures (CVE) database. An experiment was conducted to demonstrate the vulnerability spread across representations during the development of a software complex example for the energy network. The features of the applications of the obtained results for energy networks are taken into account. The advantages, disadvantages, and limitations of the study, as well as ways to eliminate them, are discussed. [ABSTRACT FROM AUTHOR]

Highlights: Analytically modeling the effect of eccentricity on flexible crankshaft and piston secondary motion; Analytically modeling the eccentricity of the crankshaft; Analytically modeling the absolute value of the dynamic displacement of the center of the crankshaft; Showing how sensitive the dynamic displacement in flexible crankshafts is to the changes in its independent variables; Double experimental validation of the analytical models based on the eccentricity of the crankshaft and based on fatigue analysis; A proposed approach of fatigue failure analysis for vehicular dynamic components; A proposed nanostructure of crankshafts for improved structural mechanics. In spite of the fact that the flexibility of the crankshaft of diesel engines exhibits notable nonlinearities, analytical modeling of such nonlinearities is not yet realized. The present study thus analytically models the effect of eccentricity on flexible crankshaft and piston secondary motion. The eccentricity of the crankshaft is modeled as the summation of the hydrodynamic eccentricity and the dynamic mass eccentricity of the crankshaft. The study also models the absolute value of the vibrational dynamic displacement of the center of the crankshaft. The paper proves that such dynamic displacement of the center of the crankshaft is sensitive to the changes in its independent variables. It was found that the most influential parameters on the dynamic displacement of the center of the crankshaft due to vibration are the natural frequency and the eccentricity of the crankshaft. The modeling of the dynamic displacement in a flexible crankshaft was validated using a case study based on the eccentricity of the crankshaft showing a relative error of 4%, which is less than the relative error in the CMEM and GT-Power. Furthermore, the analytical modeling of the dynamic displacement in the flexible crankshaft was validated using another case study based on fatigue analysis of the crankshaft showing a relative error of 9%, which is less than that the relative error in Newman's model of diesel engine fuel consumption and Lansky's model of diesel engine cylinders. The paper also presents a proposed approach of fatigue failure analysis for vehicular dynamic components and presents a proposed nanostructure of crankshafts for improving such fatigue performance. The developed models would help develop efficient diesel engines and help prolong their service life. [ABSTRACT FROM AUTHOR]

In the framework of the Cost Action CERTBOND (Reliable roadmap for certification of bonded primary structures), a wide group of researchers from 27 European Countries have had the opportunity to work on the topic of certification of bonded joints for primary structural applications from different engineering sectors such as the aerospace, automotive, civil engineering, wind energy and marine sectors. Since virtual testing and optimization are basic tools in the certification process, one of the key objectives of CERTBOND is to critically review some of the available models and failure theories for adhesive joints. The present paper summarizes the outcome of this task. Nine different models/theories are described in detail. Specifically, reviewed are the Classical Analytical Methods, the Process Zone Methods, Linear Elastic Fracture Mechanics (LEFM), the Virtual Crack Closure Technique (VCCT), the Stress Singularity Approach, Finite Fracture Mechanics (FFM), the Cohesive Zone Method (CZM), the Progressive Damage Modeling method and the Probabilistic methods. Also, at the end of the paper, the modeling of temperature effects on adhesive joints have been addressed. For each model/theory, information on the methodology, the required input, the main results, the advantages and disadvantages and the applications are given. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to develop efficient and simple models for thermal distribution, melt pool dimensions and controlled phase change in the laser additive manufacturing (AM) of bulk and powder particles ceramic materials. Design/methodology/approach: This paper proposes new analytical models for the AM of bulk and powder bed ceramic materials. A volumetric moving heat source, along with the complete melting of bulk and powder particle materials, is taken into account. Different values of laser absorption coefficient in solid and liquid states have been used to investigate the phase transformation. Furthermore, the pores and voids dimensions are also included in the modeling. Theoretical predictions have been compared with the experimental analyses and finite element simulations in laser to silicon nitride and laser to alumina interaction. The analysis focuses on the impact of laser power and scanning speed on the melt pool width and depth evolution into the bulk substrate and powder bed. Findings: This study shows that the powder particles exhibit a higher thermal distribution value than the bulk substrate because of voids in the powder layer. The laser beam experiences multiple reflections in the presence of porosity/voids, thus increasing the surface absorption coefficient, which becomes relevant with the increment in the pore/void dimension. A direct relationship has been found between the laser power and melt pool dimensions, while the scanning speed displayed an inverse relationship for the melt pool width and length. Larger melt dimensions were inferred in the case of laser–powder particle interaction compared with laser–bulk substrate interaction. A close correlation was found between the analytical simulations, experimental investigations and numerical simulation results within the range of 4%–8%. Originality/value: This paper fulfills an identified need to develop efficient and simplified models for ceramics laser AM by taking into account different laser absorption coefficients in solid and liquid form, voids and pores dimensions and controlled phase transformation to avoid vapors and plasma formation. The limitation of the finite element simulation model is that the solution is strongly dependent on the mesh quality and accuracy directly linked to the computation efficiency and time. A finer mesh requires a longer computing time than a coarse mesh. Finite element simulations require, however, specialized skills. [ABSTRACT FROM AUTHOR]

The current study analyzes the potential of an environmentally benign integration of a parabolic trough solar collector (PTSC) with a heat-intensive multi-effect evaporator (MEE) used in pulp and paper industry. Actual plant data was used to simulate the MEE and estimate the steam economy (SE) and steam consumption (SC), which are used to judge the performance of PTSC-MEE system. Four distinct alternatives for the integration are investigated with Self-adaptive Differential Evolution (SaDE) utilized for optimization. Initially, a normal PTSC with four different model configurations of MEE, basic or with energy reduction schemes (ERSs) are tested and found that SE is slightly increased for each. Next, a geometrically optimized/combinatorial optimized PTSC with basic MEE is examined, a rise of ∼3.4% in SE is noted for both, with current integration outperforming one out of three ERSs. Subsequently, geometrical plus combinatorial optimized PTSC with basic MEE is inspected, increase in SE reached 7.59% and two of the three ERSs outperformed. Economic analysis is conducted to estimate the steam saving with different PTSC-MEE systems and corresponding payback periods. The possibility of decarbonization with the various integration possibilities is also explored by evaluating the fuel savings and related CO 2 savings. • Integration of PTSC with an MEE used in pulp and paper industry is investigated. • The fusion of PTSC with MEE is studied with various possibilities. • Self-adaptive Differential Evolution (SaDE) is used for various optimizations. • The steam savings and payback times are estimated for various PTSC-MEE systems. • Decarbonization is studied by analyzing fuel savings and CO 2 reductions. [ABSTRACT FROM AUTHOR]

Miura-ori core sandwich structures are promising substitutes to conventional honeycomb core sandwich structures for both load bearing and multifunctional applications. While quasi-static or impact behaviors have been widely studied, no theoretical work has been done yet for free vibration analysis of carbon-fiber-reinforced Miura-ori core sandwich beams (MSBs). This paper presents a simple and effective methodology to investigate the free vibration behavior of MSBs under simply supported boundary conditions. The governing equation of motion is built by Hamilton's principle. Carbon-fiber-reinforced Miura-ori core is transformed to a continuous homogeneous material and the analytical expression of its equivalent transverse shear modulus is derived based on an energy approach. According to the deformation contributions of different components and shear modulus analysis of Miura-ori core, the differences of natural frequencies between the theoretical prediction and numerical simulation are analyzed. It indicates that the analytical model presented in this paper is effective to estimate the natural frequencies of carbon-fiber-reinforced MSBs, which may provide some references for further practical engineering applications of such kinds of composite sandwich structures. [ABSTRACT FROM AUTHOR]

In machining carbon fiber-reinforced polymer (CFRP) materials of different fiber orientations, the uncut material fracture occurs at different chip formation angles owing to either the fiber-dominated failure or matrix failure. For the matrix failure mode, it is found that the cracks in the damaged material can still affect the chip formation by providing additional Coulomb friction on the closed crack surfaces. To investigate the effect of the damage state of the matrix on the chip formation mechanism, this paper proposes a new cutting mechanics model for CFRP, by attributing the increase of the matrix shear strength to the Coulomb friction on the closed fracture surface. The frictional damage of matrix material, including damage initiation, propagation, and complete failure, is considered to provide a physical explanation for the increase of matrix shear strength and prove that the damaged matrix still influences the chip formation after complete failure. The proposed model determines the transition of chip formation mode, the variation of chip formation angle, and the cutting forces with the fiber orientation, considering the friction in the damaged area and the elastic stress in the undamaged area. According to the comparison with the models which do not consider the material damage state and attribute the increase of shear strength to the "internal friction" without a physical explanation, it is found that the proposed frictional damage model is able to capture the matrix failure in chip formation in the fiber orientation of [0deg,66deg] and [90deg,180deg] and explains the change of chip formation mechanism from matrix compression failure to fiber tension failure in the fiber orientation range of [67deg,89deg]. The necessity of considering the friction on the fractured surfaces in the machining process of CFRP is experimentally validated by cutting experiments at various fiber orientations. [ABSTRACT FROM AUTHOR]

The flexible and cost-effective service provided by cloud computing has led to the development of a vast array of applications in smart cities. Nevertheless, their traditional security approaches presented the concept of a static target for attacks, leading to an asymmetric situation between defenders and attackers. Adaptive cyber defense (ACD) has, therefore, recently emerged as a game-changer to reverse this asymmetry by reconfiguring the system according to the network scenario. Analyzing and quantifying the effectiveness of these ACDs are of high importance. Previous research on ACD analysis focused more on either studying the system properties using experiment-based approaches or on evaluating its effectiveness by different mathematical modeling approaches. However, little effort has been made to overcome the problems of isolated solutions. In this paper, we described the defensive process as a racing game between the attacker and the defender. On this basis, we conducted a thorough ACD effectiveness evaluation and suggested a comparison strategy using three methods, namely semi-Markov, stochastic reward net, and experimental methods. The obtained simulation results were approximate, and the error rate was less than 3.36% reflecting the reliability of the proposed methods. Based on the assessments, we finally summarized the features of these methods to specify and deduce different scenarios and their corresponding suitable evaluation method. [ABSTRACT FROM AUTHOR]

Analytical predictions of woven plain fabric composite (WPFC) mechanical properties based on the existing models still remain a formidable task due to complex fiber architecture. Therefore, there has been a strong need for a simplified, practical approach to determining the mechanical properties of structural members laminated with WPFC. This paper proposes a practically useful engineering approach to predict the flexural properties of WPFC. The analytical solution of the developed approach was compared to the results of experimental flexural tests performed with three-point bending test specimens. Experimental findings and the results obtained from the practical engineering approach showed a good agreement. [ABSTRACT FROM AUTHOR]

• New analytical solutions for free vibration of edge-cracked thick plates are derived. • New free vibration results of edge-cracked thick plates are provided as benchmarks. • The present symplectic approach has the advantages of strictness and high accuracy. • The effects of crack length and crack location on vibration behaviors are revealed. Analytical modeling for cracked plates' free vibration is of great significance as a crack alters the properties of plate structures and thus greatly affects the mechanical behaviors of such key engineering components. This paper presents novel analytical solutions for the free vibration of thick rectangular plates with a crack normal to an edge, a kind of typical edge-cracked plates. To resolve the jump discontinuity caused by the edge crack, an original plate is decomposed into four elementary plates, whose free vibration problems are solved analytically via an unusual symplectic superposition method (SSM). The SSM is implemented in the Hamiltonian system-based symplectic space, where several mathematical treatments such as the variable separation and the symplectic eigenvector expansion are valid, rendering rigorous step-by-step derivations without pre-defining solution forms. By incorporating the solutions of the elementary plates, the eventual solutions of the edge-cracked thick plates are obtained. Such a symplectic framework provides a new route to solving various complicated plate problems that cannot be analytically handled previously. Comprehensive free vibration results such as natural frequencies and vibration modes of edge-cracked thick plates are presented. High accuracy and fast convergence of the framework are confirmed. The present analytical solutions are also utilized to study the effects of both the crack length and crack location on free vibration behaviors of edge-cracked thick plates. [ABSTRACT FROM AUTHOR]

As oil-free rotor support technology, active magnetic bearings (AMBs) are increasingly applied in turbinmachinery, including steam turbines. The compact multiple disksrotor bearing system of maglev steam turbines leads to complicated dynamic behaviors, which is the basis of AMBs controllers design. In this paper, an analytical modeling method is proposed to describe the dynamic characteristics of AMBs-rotor system of maglev steam turbines. The analytic rotor dynamic model consists of multiple rigid disks on a flexible shaft and AMBs. In modeling the rotor bearing system, the flexible shaft is discretized by Euler Bernoulli beam elements. The connection between rigid disks and flexible shaft is equivalent to spring dampers. Angular stiffness and angular damping coefficients are introduced to model the spring dampers and identified by 3D finite element simulation results. The bearings force takes the control system of AMBs into consideration. Moreover, experiments of a test rig are carried out. The results show that the proposed analytical rotor dynamic modeling method is effective. [ABSTRACT FROM AUTHOR]

This paper focuses on the experimental and analytical behavior assessment of novel sandwich panels fabricated with recycled glass-fiber/polyester resin (GFRP) core and PVC face sheets. The originality of the present work is based on sustainable development and waste recovery to design lightweight and eco-friendly structures. In this respect, the panels cores were fabricated using fully recycling of fiber-glass waste issued form the boats building. Accordingly, a set of sandwich panels with various core configuration and fibers orientation were manufactured and tested up to failure under three-point bending to characterize flexural and shear properties. In addition, validated analytical equations were advocated to assess the bearing capacity of the studied panels. The obtained results in terms of mechanical, thermal and physical features are emphasized, discussed and confronted with a good agreement to literature ones. A principal component analysis was conducted to optimize the effect of the geometrical parameters on the panel failure mechanisms. As main outcomes, the work can provide environmental and economic solutions for the design of sandwich structures. • Lightweight and eco-friendly sandwich structures-based GFRP waste core were designed • Validated analytical equations were advocated to assess the bearing capacity of the studied panels under bending • A principal component analysis was conducted to optimize the geometric parameters of the panels • The paper results provide environmental and economic solutions for the design of sandwich structures [ABSTRACT FROM AUTHOR]

In this work, we present a comprehensive analytical model for the Spacer-Engineered Reconfigurable Silicon Nanowire Schottky Barrier Transistor (SE R–Si NW SBT) for biosensing applications. This device operates in both n-mode and p-mode configurations by incorporating dual gates located near the source and drain terminals. The electrostatic integrity of the device is enhanced by incorporating high-K spacers on both sides of the gate electrode, facilitating improved interaction between the gate and the Schottky barrier. The biomolecules present on the silicon dioxide layer within the underlap cavity at the channel center, significantly impact the electrostatic properties throughout the device channel, including channel surface potential, drain current, electric field, and threshold voltage. By utilizing the 2D Poisson equation, we effectively capture the behavior of these key electrostatic properties. The primary metrics for biomolecule detection in this device are the changes observed in the threshold voltage and drain current. Furthermore, the variations in threshold voltage are analyzed to evaluate the sensitivity of the proposed biosensor and compared with that of state-of-the-art FET-based biosensors. The reliability of our analytical approach is validated using a virtual model of the proposed biosensor and performing simulations using the Silvaco TCAD device simulation tool. Through a meticulous comparison of our analytical findings with the simulated results, we establish the accuracy and dependability of our model. • The paper introduces a novel physics-based analytical model for detecting charged and neutral biomolecules. • The model accurately estimates channel surface potential, drain current, electric field, and threshold voltage profiles. • The analytical model is calibrated with experimental results. • The paper benchmarks the performance of proposed biosensors against state-of-the-art FET-based biosensors. [ABSTRACT FROM AUTHOR]

An analytical approach for performance prediction of saturated brushed permanent magnet direct current (DC) motors is proposed in this paper. In case of a heavy saturation in the stator back core of electrical machines, some flux completes its path through the surrounding air, and the conventional equivalent circuit cannot be used anymore. This issue has not been addressed in the literature. The importance of considering the effect of the flux penetrating the surrounding air is shown in this paper using finite element simulations and experimental results, and an analytical approach is proposed to consider this effect on magnet operating point determination and performance prediction of saturated brushed permanent magnet DC motors. An analytical method is also presented to determine the boundary radius of the surrounding air for obtaining accurate results in finite element (FE) solutions and analytical calculations. An analytical approach based on Carter's coefficient is also proposed to calculate the effective length of the magnet when the length of the magnet and rotor length are not the same. The accuracy of the proposed analytical model is illustrated using finite element simulations and experimental results. With this accuracy, this analytical model is very suitable to be used for reliable and quick mathematical design optimization. [ABSTRACT FROM AUTHOR]

The contradiction between the scarcity of natural resources and the demand for construction materials has given rise to the application of recycled aggregates. Microbial self-healing concrete (SHC) is a clean and smart material, and its carrier has a great influence on repair performance. In this paper, recycled coarse aggregate (RCA) and recycled fine aggregate (RFA) were used as carriers, and their different repair effects over time were intensively investigated. The results showed that the RCA carrier had a better repair effect compared with that of RFA, and the maximum healing width could reach 0.27 mm by 28 day. The microbial repair efficiency was significantly influenced by the distribution of old mortar, with the RFA specimen having a small volume and wide distribution of repair products, while the RCA repair showed a centralized tendency. In addition, SEM, MIP and XRD characterization were used to analyze the repair mechanism. The time-dependent repair model was developed, and the applicability of the model for concrete enhancement under microbial repair was verified through experimental results. The research results could promote industrial applications by giving intelligent and green properties to recycled aggregates. [ABSTRACT FROM AUTHOR]

The paper focuses on the nonlinear vibration of functionally graded graphene nanoplatelet reinforced composite doubly curved shallow shells resting on elastic foundations. The graphene nanoplatelet reinforced composites are assumed to be distributed uniformly and functionally graded through the thickness. The material properties are assumed to be temperature-dependent and are estimated through the Halpin–Tsai micromechanical model, while the Poisson's ratio, density mass, and thermal expansion are implemented by the rule of mixtures. The mathematical formulation is developed based on the classical shell theory and Von Karman-Donnell geometrical nonlinearity assumption. The dynamical responses of a simply supported functionally graded-graphene nanoplatelet reinforced composite doubly curved shallow shells are obtained by employing the Airy's stress function and the Galerkin's method. The responses of nonlinear vibration as time history, frequency-amplitude curve, phase plane graphs, and Poincare maps are carried out in this paper. In addition, the effects of the environment, graphene nanoplatelets weight fraction, graphene nanoplatelets distribution patterns, and thickness-to-length ratio are scrutinized. The obtained results are also compared and validated with those of other studies. [ABSTRACT FROM AUTHOR]

This paper presents an analytical model to describe the transient fluid flow to a horizontal fracture in frac‐packed vertical wells. A physical model is first established where a horizontal frac‐packed fracture is located in the middle of a cylindrical reservoir. The pressure distribution in the fracture is then derived concerning time and the distance to the wellbore. The analytical model assumes a homogeneous and isotropic reservoir where Darcy's law applies to a single‐phase fluid flow, a radial fracture with a radius much greater than pay zone thickness, and a constant fracture width. For ease of application, a Type Curve Matching approach is introduced which features the matching of a defined dimensionless pressure between field pressure data and model data, and some exemplar curves are illustrated in this paper. The principle of applying curve matching here is to tune model parameters to match the measured pressure/rate data. Once the curves are matched, the model parameters, that is, fracture permeability, etc, are naturally obtained. The validity of the derived model is informed in two ways. The results show that the model will degenerate to the classic radial flow equation for practical values of certain model parameters and upon reasonable simplification. Model validity is further verified by applying the type curve matching technique using field data. This model can be used as a quick and reasonable method to analyze the transient pressure/rate test data to reveal fundamental fracture and reservoir properties for a frac‐packed horizontal fracture at shallow depths where the vertical formation stress is the least in situ stress. [ABSTRACT FROM AUTHOR]

The estimation of temperature evolution in a solid material irradiated by a high-intensity laser beam is important for modelling of various laser-based heating processes. This paper proposes a three-dimensional analytical solution of temperature field based on the integral transform technique considering intensive convective boundary conditions. The proposed model evaluates the temperature of a laser-heated sheet as a function of geometric, material and laser attributes of the sheet. By comparing the findings of experimental investigation performed on 1.5 mm thick Al 6061-T6 sheets under the considered process conditions, the effectiveness of the proposed model is evaluated. Laser power and scanning speed varied during the experiments keeping laser beam radius and specimen geometry constant. The surface temperature of the laser-heated sheet is found to rise with increasing laser power. In contrast, the surface temperature drops with high scan speeds. The analytical and experimental results are in close agreement with errors less than 3 %. Eventually, the temperature evolution predicted by the analytical solution is compared numerically and it is found that the analytical model can effectively reduce the computing time for evaluating the temperature in the laser heating process. To broaden the application of the analytical model, the effect of process parameters, namely, laser beam radius, workpiece thickness and material properties on the temperature evolution are analyzed under different cooling schemes. This investigation is of significance towards developing an inverse method for determining laser process parameters quickly and inexpensively for various laser-based heating processes in near future works. [ABSTRACT FROM AUTHOR]

With more stringent IEC energy efficiency standards, electrical machine industry increasingly focuses on new motor technologies. Amongst others, the line-start permanent magnet synchronous machine (LSPMSM) is considered as an attractive alternative to induction machine, especially for low power and fixed-speed applications. However, the design of LSPMSMs is rather complex as both steady-state and transient synchronization performances need to be considered. The synchronization capability determination of a LSPMSM design usually relies on time-consuming transient finite-element simulations, which is impractical for use in an iterative design optimization process. This paper compares and evaluates various existing analytical synchronization analysis methods in an attempt to identify most suitable equations and methods for fast synchronization analysis. Using the selected methods, a software tool is developed that can seamlessly work with ANSYS Electronics Desktop to perform rapid transient synchronization analysis. Given its ability to quickly determine the critical inertia factor of a LSPMSM design, the software tool is further adapted for use in a highly iterative, multi-objective design optimization procedure. It shows that the developed software tool can be successfully used in the design of LSPMSMs. [ABSTRACT FROM AUTHOR]

Physical models of MOS transistors used in the design of modern integrated circuits are typically accurate, which makes it possible to model their operation with a specified degree of reliability. However, they are also highly complex, which makes them impractical to use when analyzing and predicting the operation of designed devices. Therefore, less accurate, but more compact analytical models of transistors and devices based on them are usually used for estimation and prediction. At the same time, for calculations and estimations, the values of all parameters contained in the model equations cannot be always known sufficiently accurately. In the paper, using the example of a previously developed analytical model of a voltage multiplier and the results of modeling a voltage multiplier developed using 180-nm CMOS technology, we present a method for refining the parameter values of analytical models describing devices based on integrated MOS transistors. [ABSTRACT FROM AUTHOR]

Given the increasing penetration of converter-interfaced resources in power systems, properly estimating the short-circuit current (SCC) contribution in large networks has become a growing challenge and necessity to ensure the security and stability of the systems and assets. This paper presents two novel methods to estimate the SCC contribution of type IV wind turbines at both the transient and steady-state stages of unbalanced and balanced faults: (1) a machine learning-based method trained with electromagnetic transient (EMT) simulations and capable of estimating some of the initial peak and transient current magnitudes; (2) an analytical approach to estimate the steady-state SCC based on the voltage and grid code dependency of the converter during the fault. The methods are coupled into a single framework and compared to field-validated EMT models of a real turbine. The results show that the majority of the estimated currents in the transient stages present errors below 5%. In steady-state, the errors are not greater than 1.21%. Given the complexity of the problem, these margins may be deemed acceptable for short-circuit studies. [Display omitted] • Short-Circuit Current Contribution from IBRs is becoming increasingly important. • The novel framework has been verified against field-validated EMT Models. • For the steady-state stage, the power-flow-based algorithm shows high accuracy. • Due to the complexity of the transient stage, a Machine-Learning model is used. [ABSTRACT FROM AUTHOR]

This paper presents an in-depth study of electrostatic actuators based on flexible side-electrodes focusing on the available electrostatic force and the derived useful force. A design tool is proposed considering technological aspects as aspect ratio, insulating layer material and voltage level. A space discretized mechanical approach based on Euler-Bernoulli beam theory is developed to model the bending deflection of the flexible movable electrode and "zipping" contact. Analytical developments and simplifications are achieved, rapidly and efficiently implemented in a proposed algorithm. ANSYS® simulations validate the procedure for updating the contact zone through the updating of the electrostatic pressure distribution. Optimum movable electrode width and appropriate "opposable" stiffness for guiding system are discussed. A "residual air thickness" parameter is introduced to address imperfect contact between the electrodes. characterization studies various prototypes with different structural parameters as thickness (50 µm and 200 µm), gaps (5 µm and 15 µm) and material for insulating layers (silicon oxide and parylene C). The metrology campaign highlights the impact of aspect ratio and oxidation/deoxidation on electrode sidewall quality and hence mechanical performance. A comparison with well-known comb-drive shows higher electrostatic force for flexible side-electrode actuators. As an example, for a 10 µm stroke, the available electrostatic force for flexible electrodes with irregular sidewalls (residual air thickness 0.6 µm) is 2.2 times greater and rises to 7.3 times greater for perfect sidewalls (no residual air). [Display omitted] • An analytical model and its algorithm are proposed for flexible side-electrodes electrostatic actuators. • Useful force is maximized according to an optimum electrode width and an appropriate "opposable" guiding stiffness. • Experimental characterization is conducted on set-ups including different aspect ratio and insulating layer material. • A relationship between performances and imperfection of the contact is established through a "residual air thickness". [ABSTRACT FROM AUTHOR]

The IEEE 802.11ah is an amendment to the IEEE 802.11 standard to support the growth of the Internet of Things (IoT). One of its main novelties is the restricted access window (RAW), which is a channel access feature designed to reduce channel contention by dividing stations into RAW groups. Each RAW group is further divided into RAW slots, and stations only attempt channel access during the RAW slot they were assigned to. In this paper, we propose a discrete-time Markov chain model to evaluate the average aggregate throughput of IEEE 802.11ah networks using the RAW mechanism under saturated traffic and ideal channel conditions. The proposed analytical model describes the behavior of an active station within its assigned RAW slot. A key aspect of the model is the consideration of the event of RAW slot time completion during a station's backoff operation. We study the average aggregate network throughput for various numbers of RAW slots and stations in the network. The numerical results derived from our analytical model are compared to computer simulations based on an IEEE 802.11ah model developed for the ns-3 simulator by other researchers, and its performance is also compared to two other analytical models proposed in the literature. The presented results indicate that the proposed analytical model reaches the closest agreement with independently-derived computer simulations. [ABSTRACT FROM AUTHOR]

In this paper, silicon carbide‐based analytical model for gate‐stack dual metal nanowire field effect transistor (gate‐stack DM NW FET) has been analyzed by solving the 2D Poisson's equation using parabolic approximation method for electric potential, subthreshold current and subthreshold slope. The results have been examined for various silicon carbide film depth and channel length. The results predicted by the analytical model have excellent agreement with simulated results obtained by ATLAS 3D device simulator. A gate‐stack having high k‐dielectric material, that is, Hafnium oxide (HfO2) along with aluminum oxide (Al2O3) has been used. Also, performance characteristics of gate‐stack DM NW FET have been compared with the performance characteristics of nanowire field effect transistor (NW FET), Nanowire field effect transistor (NW FET) (Sic) and dual metal nanowire field effect transistor (DM NW FET) (SiC). It is so proved that our proposed device, that is, gate‐stack DM NW FET (4H‐SiC) exhibits superior performance in terms of drain current (Ids), transconductance (gm), output conductance (gd) and cut off frequency (fT) than the existing devices. [ABSTRACT FROM AUTHOR]

The autonomous vehicle storage and retrieval system (AVS/RS) significantly improves the responsiveness and throughput of the traditional automated storage and retrieval system (AS/RS) in regard to handling unit loads. The AVS/RS consists of multiple tiers connected to an elevator system and is equipped with at least two autonomous vehicles, that is, a shuttle and satellite. Other necessary equipment are the lifts and input/output buffer areas. This paper aims to present and apply an original hybrid analytical-simulative model for the design of a deep-lane and multisatellite AVS-RS by evaluating and controlling the system performance. This AVS-RS is equipped with multiple free and non-free satellites for each tier. As an original contribution, this study reviews the literature on AVS/RS according to the introduction of multiple features categorized into five homogeneous groups: (1) rack configuration, (2) vehicle kinematics and configuration, (3) dispatching rules, (4) modeling approach, and (5) validation. Two of the most critical issues in existing research studies are the random arrival time of storage and retrieval transactions and the random storage policy. The proposed modeling approach is data-driven and based on realistic assumptions, filling the gap between the literature and real applications. This hybrid model is applied to a case study of the beverage industry according to a what-if comparative and competitive multiscenario analysis. This data-driven assessment supports the decision-making process on the number of satellites for each tier, while simultaneously controlling the service and waiting times, system throughput, and vehicle utilization. The analysis based on the maximum system throughput estimation demonstrates that introducing more than two satellites does not increase the productivity of the system. [ABSTRACT FROM AUTHOR]

To date, determining with high accuracy the optical parameters (extinction coefficient k and refractive index n) of a slab from the sole transmittance data requires an inverse method based on numerical iteration procedures. In this paper, we propose a new inverse analytical method of extracting (k, n) without numerical iterative processes. The high accuracy of this new inverse method is assessed, and as an application example, the optical parameters of CaF2 and Si substrates are determined in the IR spectral range of 4–8 µm. Graphical Abstract [ABSTRACT FROM AUTHOR]

In order to predict the performance of a permanent magnet linear braking (ECB) with cylindrical structure, an analytical model is established in this paper. The model is based on the magnetic equivalent circuit (MEC) method with the consideration of the often ignored magnetic saturation in pole shoe. The influence of induced eddy current is taken into account by introducing the magnetomotive force (MMF) in the model. To obtain braking force, a simple method for approximating the cross-section of the electric field with mean value method is proposed. The proposed model that can predict the braking force performance of ECB in a wide range of structural dimensions is obtained through referring to a small number of finite element models. A prototype test is carried out. The validity of the proposed method is verified through experiment and FEM. Results show that the braking force predicted by the presented method are in good agreement with experimental results and FEM results under different design parameters. The proposed model can accurately represent the variation trend of braking force and critical speed with design parameters. [ABSTRACT FROM AUTHOR]

In this paper, the bending behavior of prestressed concrete joists strengthened by fiber‐reinforced polymer (FRP) laminates is described. An experimental investigation on 18 large‐scale beams is conducted, allowing determination of the strengthening influence of FRP in the general behavior of prestressed joists. The mechanical parameters considered in the study are the ultimate and elastics loads and the deflection or initial stiffness of joists. The analytical verification is done to calculate the design load values of the floor system. The results indicate that the application of FRP laminates significantly increases the response of prestressed concrete joists. [ABSTRACT FROM AUTHOR]

• Design, modelling and prototype of the novel Axial Active Magnetic Bearing. • Validated analytical model is convergent with experiments and numerical simulation. • Schwarz-Christoffel transformation is utilized in study of the actuator end effect. • Three-dimensional complex permeance function represents the stator pole pieces. • Computational time of analytical model is significantly shorter then numerical one. The article presents a novel design of the axial active magnetic bearing with six poles. An analytical magnetic bearing model was developed to provide the axial magnetic induction distribution in 3D. The model utilizes magnetic vector potential formulation and Schwarz-Christoffel mapping. The paper covers in-depth deliberations on the end effect influence and the conjugate complex permeance function. Numerical model and simulations were provided in 3D mode with support of COMSOL Multiphysics software. The six pole axial active magnetic bearing was manufactured and investigated experimentally. Identification of the magnetic field distribution was carried out with a single axis magnetic induction sensor using custom automatic field scanner. High convergence of the modeling results and experimental research was demonstrated. The main advantage of the proposed analytical method is significantly shorter computation time compared to the numerical one that is useful from the modeling and controller study point of view. The configuration, modeling, simulation and experimental investigation results are well illustrated for the better overview. [ABSTRACT FROM AUTHOR]

This paper presents an analytical modeling method of the temperature evolution in the planar scanning induction heating, which can be applied into various heat treatment processes. Due to the uneven distribution and hard control of the electromagnetic fields in the planar induction coils, it is difficult to achieve the precisely prediction and control of the temperature evolution. In view of the low computational efficiency and the complexity in the establishment of the general finite element numerical simulation models, in this work, analytical models of this planar scanning induction heating enhanced by the magnetic flux concentrator are established by using the moving points and line heat source. The magnetic field and the eddy power density in the workpiece generated by the induction coils are calculated by Maxwell equations and then can be applied into the analytical model of the temperature evolution using the moving points and line heat source. Several sets of the corresponding finite element simulation tests and experimental tests are conducted to validate the analytical calculation results. In addition, sensitivity analysis of the main factors influencing the temperature evolution is conducted. By comparison, it is investigated that the final temperature in the surface of the heat workpiece by the analytical model in this work has a good match with the finite element simulation and the experimental results and the errors are reasonable and acceptable considering the inevitable factors. It is also obviously that the computing time of the analytical model is much less than the finite element simulation model. Thus, it is believed that the analytical model established in this paper can be used to predict the temperature evolution in the planar scanning induction heating and extends this heating method to a broader application, which has less computational time and experimental complexity. [ABSTRACT FROM AUTHOR]

Progressive collapse can be triggered by impact loading from vehicles or other objects and propagated by impact loading from falling debris. Therefore, the correct modeling of impact loading is necessary to assess the resistance of a structure against progressive collapse. As the number of timber buildings increases, the importance of adequate considerations of impact loading is growing. Previous research on impact loading of wood or timber was carried out on small clearwood specimens or on single boards. However, modern timber buildings use advanced wood-based composites, such as glued laminated timber and laminated veneer lumber. The characteristics of these materials are widely different from clearwood and single boards. In this paper, energy-based equations are derived for the peak impact force and the dynamic strength increase factor. These are quantified by pendulum impact hammer tests on 95 full-size glued laminated timber beams. The results are applied in a calculation example to demonstrate their potential use in practice. • Energy-based models for impact loading of timber beams are presented. • Results from 95 impact tests on full-size timber beams are discussed. • High-speed imagery reveals the impact process and five distinct failure modes. • The energy-release properties of timber beams are found to be strength class independent. • The dynamic increase or load duration factor is found for impact loading of timber beams. [ABSTRACT FROM AUTHOR]

• The creep in compaction was correlated with the recovery in the relaxation phase. • A unified viscoelastic-plastic model with one set of parameters was proposed. • Elevated temperature and in-plane tension intensify creep/recovery behavior. • Model captured temp. and time-related creep/recovery considering in-plane strain. In the manufacturing process of fiber-reinforced composite materials, the preforming of dry fiber fabrics is typically carried out under specific out-of-plane pressure, in-plane tension, and at designated temperatures. The fabric exhibits significant time and temperature-dependent permanent deformation as well as creep/recovery behavior. Gaining a better understanding of these phenomena and harnessing predictive capabilities will be instrumental in achieving more precise control over fiber volume fraction and material composition. In this paper, creep/recovery experiments and cyclic loading-unloading tests were conducted on CF3031 dry fiber preforms under various in-plane tensions and temperatures, measuring in-plane strains using Fiber Bragg Grating (FBG) sensors. Based on this data, a modified Burgers viscoelastic-plastic model has been proposed to describe the time-dependent creep/recovery behavior of dry fiber fabric preforming under the coupled effects of in-plane tension, out-of-plane pressure, and temperature variations. This model employs a single set of equations and parameters to represent the complete creep/recovery process of the material. The experimental results align well with the predicted outcomes across different compression scenarios. [ABSTRACT FROM AUTHOR]