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Current hygrothermal behaviour prediction models neglect the hysteresis phenomenon. This leads to a discrepancy between numerical and experimental results, and a miscalculation of buildings' durability. In this paper, a new mathematical model of hysteresis is proposed and implemented in a hygrothermal model to reduce this discrepancy. The model is based on a symmetry property between sorption curves and uses also a homotopic transformation relative to a parameter s ∈ [ 0 , 1 ]. The advantage of this model lies in its ease of use and implementation since it could be applied with the knowledge of only one main sorption curve by considering s = 0 , in other words, we only use the axisymmetric property here. In the case where the other main sorption curve is known, we use this curve to incorporate the homotopy property in order to calibrate the parameter s.The full version of the proposed model is called Axisymmetric + Homotopic. Furthermore, it was compared not only with the experimental sorption curves of different types of materials but also with a model that is well known in the literature (CARMELIET's model). This comparison shows that the Axisymmetric + Homotopic model reliably predicts hysteresis loops of various types of materials even with the knowledge of only one of the main sorption curves. However, the full version of Axisymmetric + Homotopic model is more reliable and covers a large range of materials. The proposed model was incorporated into the mass transfer model. The simulation results strongly match the experimental ones. [ABSTRACT FROM AUTHOR]

The goal of this work is first to include a hysteresis model in the classical equivalent circuit model (ECM) for a battery system and then to improve the estimation of the state of charge (SoC) by applying the Extended Kalman Filter (EKF). The hysteretic behavior of the open circuit voltage (OCV) is modelled with the classical Preisach model used for magnetic materials. The construction of the Preisach operator is made by means of the Everett function identified from experimental data which only involve the charging curves of the battery. Thus, a significant reduction in the time necessary to obtain the measurements is achieved. The model is assessed with some laboratory experiments performed on a lithium-ion battery and the results show that with this procedure hysteresis is very well reproduced, even when interior loops are present. In addition, the use of the EKF allows us to eliminate the measurements noise and ensure the accuracy of SoC estimation. The high computational efficiency and precision of the method, joined to the limited computational resources needed for the numerical implementation, make it particularly suitable for real-time embedded battery management system (BMS) applications. In addition, the proposed methodology is well-adapted to any battery type, independently of the SoC-OCV profile of the hysteresis cycle. [ABSTRACT FROM AUTHOR]

Magnetorheological gel (MRG) excels in the material properties in term of adjustability and sedimentation performance, which could upgrade the performances of the current magnetorheological fluid based adjustable devices for structural control and vibration mitigation. However, the characterization and modelling of the stress-strain hysteresis responses of MRG has not been reported in the past, which are fundamental steps towards engineering applications. In this study, the stress-strain hysteresis of polyurethane based MRG sample with 60% carbonyl iron particle weight fraction was characterized under sinusoidal shear excitations with broad ranges of strain amplitude (5%–100%), excitation frequency (0.1 Hz–2 Hz) and magnetic fields (0–0.91 T). Significant stress overshooting phenomenon were observed under the application of low magnetic fields (0.27 T). A structurally-simple and accurate phenomenological model has been established to capture this unique nonlinearity. By validating the experimental results, the proposed model accurately predicts the hysteretic behaviour and the overshoot of the MRG under the excitation scenarios and the magnetic fields considered. Finally, the support vector machine (SVM) was implemented to provide the solution to the model generalization. The SVM-assisted model showed good agreement with the experimental data and can benefit the efficiency and viability in developing controllable MRG-based devices and system.

Soft actuators (SAs) have been used in many compliant robotic structure and wearable devices, due to their safe interaction with the wearers. Despite advances, the capability of current SAs is limited by scalability, high hysteresis, and slow responses. In this paper, a new class of soft, scalable, and high-aspect ratio fiber-reinforced hydraulic SAs is introduced. The new SA uses a simple fabrication process of insertion where a hollow elastic rubber tube is directly inserted into a constrained hollow coil, eliminating the need for the manual wrapping of an inextensible fiber around a long elastic structure. To provide high adaptation to the user skin for wearable applications, the new SAs are integrated into flexible fabrics to form a wearable fabric sleeve. To monitor the SA elongation, a soft liquid metal-based fabric piezoresistive sensor is also developed. To capture the nonlinear hysteresis of the SA, a novel asymmetric hysteresis model which only requires five model parameters in its structure is developed and experimentally validated. The new SAs-driven wearable robotic sleeve is scalable, highly flexible, and lightweight. It can also produce a large amount of force of around 23 N per muscle at around 30% elongation, to provide useful assistance to the human upper limbs. Experimental results show that the soft fabric sleeve can augment a user’s performance when working against a load, evidenced by a significant reduction on the muscular effort, as monitored by electromyogram (EMG) signals. The performance of the developed SAs, soft fabric sleeve, soft liquid metal fabric sensor, and nonlinear hysteresis model reveal that they can effectively modulate the level of assistance for the wearer. The new technologies obtained from this work can be potentially implemented in emerging assistive applications, such as rehabilitation, defense, and industry.

Part 1 [1] of this two-part paper presented an experimental study of the cyclic behaviour of a novel beam-to-column sleeve connection system for pultruded glass fibre reinforced polymer (GFRP) tubular profiles, and the numerical simulation of such behaviour. This Part 2 presents an experimental and numerical study on the sway behaviour of full-scale GFRP plane frames comprising the same tubular profiles and the aforementioned connection system. The GFRP frames were tested under quasi-static monotonic and cyclic loading, with and without infill walls, materialized by composite sandwich panels. The results of the tests show that high-load carrying capacity infill walls have a remarkable effect on the frames' structural behaviour, significantly increasing their stiffness and load carrying capacity, as well as their cyclic performance, namely regarding energy dissipation. On the other hand, such improvement involved extensive damage in the frame elements, particularly in the beams, which at some point compromised their structural integrity. The numerical study included the simulation of the cyclic tests of the unfilled walls, by means of relatively simple finite element (FE) models, comprising frame elements and spring joints simulating the behaviour of the connections, in which the Pivot hysteresis model calibrated in Part 1 [1] was used. The comparison between experimental and numerical results shows that these simple and design-oriented FE models can provide an effective (and conservative) tool for the simulation of pultruded GFRP frames under horizontal cyclic loads. [ABSTRACT FROM AUTHOR]

Highlights • A new mathematical approach based on isoparametric elements is proposed in this work to model ferromagnetic hysteresis phenomenon. • The proposed approach requires few data points to model a complete hysteresis loop. • The model does not require any optimization or curve fitting techniques to determine the model parameters. • The proposed approach is applied to model symmetrical minor loops considering anisotropic behaviour of grain oriented materials. Abstract Modelling hysteresis behaviour is an essential task in transient analysis of electrical machines. A curve fitting approach based on isoparametric elements is proposed in this work. A hysteresis loop is split into sub-curves and each sub-curve has been modelled in terms of a second degree polynomial using three data points. Thus the model requires few data points to model a complete loop. The model equations can be easily derived using predefined shape functions of an isoparametric element without using any curve fitting algorithms. The proposed approach has been applied to model hysteresis data of two different materials, namely, grain-oriented (GO) laminations and soft magnetic composites (SMC). Symmetrical minor loops of GO materials with magnetization along any arbitrary direction are modelled for the first time. The calculated results are in close agreement with measured values. Compared to existing methods, the proposed technique in this paper is simple to understand and computationally efficient. [ABSTRACT FROM AUTHOR]

This paper describes the CO 2 geological sequestration process in unconventional reservoirs in northern and southern United States such as Bakken tight oil and Eagle Ford shale gas condensate reservoirs. The hysteresis modelling and retention mechanism was performed in this research and this is one of the efficient and proven method to store CO 2 in the subsurface. This can be achieved through CO 2 EOR process while injecting CO 2 , the fluid will be trapped in the pore spaces between the impermeable rocks and oil can be recovered simultaneously. A total of four cases was taken for the analysis, such as the Bakken and Eagle Ford reservoirs with CO 2 huff-n-puff process and another two cases with CO 2 Flooding. Injection pressure, injection rate, injection time, number of cycles, carbon dioxide soaking time, fracture half-length, fracture conductivity, fracture spacing, porosity, permeability, and initial reservoir pressure as is taken as inputs and cumulative oil production, and oil recovery factor was taken as outputs. The reservoirs were modelled for 30 years of oil production and the factor year was taken as Decision Making Unit (DMU) and the models was calculated at each year. The retention was successfully calculated in all four models and percentage of retention above 90% was observed in all four cases and the injection pressure has the most dominating effect on the CO 2 geological sequestration. It was also revealed that the CO 2 huff-n-puff performance in Bakken reservoir is not that much more effective since the retention rate decreases during soaking period and flooding was found to be a suitable method in this formation. Even in Eagle Ford formation, the average performance of CO 2 flooding process is better than the huff-n-puff, but the latter process was quite effective in this shale gas condensate reservoir. [ABSTRACT FROM AUTHOR]

Magnetorheological elastomers (MRE) based semi-active isolators utilize MREs whose mechanical properties, such as stiffness and damping, change in response to an external magnetic field. MREs implementation in semi-active isolation remains challenging due to their slow response time caused by the suspension of the magnetic particles inside the elastomeric matrix and limited damping capabilities. Hybrid MREs, a combination of MREs and MRFs, have been developed to improve semi-active isolation's material properties and performance. However, modelling the nonlinear and hysteretic behavior of hybrid MRE-based isolators remains a challenge and needs to be adequately addressed. To bridge the gap, this study presents a parametric model for a hybrid semi-active isolator's nonlinear and hysteretic behavior that utilizes a hybrid MRE (H-MRE). The behavior of conventional and hybrid MRE-based isolators are experimentally tested under varying loading conditions of excitation frequency and input current. Simulation models are created using combinations of three different phenomenological models, Bouc-Wen, Modified-Dahl and LuGre friction. The experimental data are used to optimize and fit the simulated response of each model, and hence optimal values of the MRE and MRF hysteresis parameters are determined. The parameter estimation results indicate that a combination of LuGre friction for the MRE and Bouc-Wen for the MRF improves the accuracy of predicting the dynamic behaviour of the hybrid isolator. The relationship between the model parameters and loading conditions is also investigated and described through polynomial equations of the third order. These findings could provide valuable insights for the system identification and control of hybrid semi-active isolators and pave the way for developing smart base isolation systems utilizing hybrid MREs in future research. • Parametric model predicts hybrid MRE-based isolator's nonlinear and hysteretic behavior accurately. • Parallel hysteresis model improves computational efficiency and prediction accuracy. • Combination of LuGre friction for MRE and Bouc-Wen for MRF accurately predicts hysteretic response. • Polynomial equations describe relationships between model parameters and loading conditions. [ABSTRACT FROM AUTHOR]

This paper attempts to fill the gap in the literature by introducing and discussing an enhanced physical model of the MR damper. The essence of the presented model is to combine the effect of compressibility of the MR fluid enclosed in each chamber with the effect of blocking the flow between the chambers in the case of a low pressure difference. As it will be shown, the concurrence of both considered phenomena significantly affects mechanical behaviour of the damper, influences its dissipative characteristics, and in particular, it is the reason behind the distinctive ‘z-shaped’ force–velocity hysteresis loops observed in experiments. The paper presents explanation of the observed phenomena, detailed derivation of the thermodynamic equations governing response of the damper, their implementation for various constitutive models of the magnetorheological fluid and, finally, formulation of the corresponding reduced and parametric models. Experimental validation shows that proper identification of physical parameters of the proposed mathematical model yields the correct shapes of force–velocity hysteresis loops. [ABSTRACT FROM AUTHOR]

Water-alternating-gas (WAG) injection has demonstrated encouraging results for improving oil recovery. However, numerical simulation of three-phase flow and the associated hysteresis effects are not well-understood. Currently, modelling of hysteresis phenomena occurring in WAG cycles is based on updating two-phase relative permeabilities (krs) to account for three-phase characteristics, which is not a trivial task. In this work, a new assessment on the WAG-hysteresis model, which was originally developed for water-wet conditions, was carried out by automatic history-matching of two coreflood experiments in water-wet and mixed-wet conditions. Here in this work, it was attempted to estimate a set of more reliable two-phase krs within active saturation ranges of coreflood experiments performed under water-wet and mixed-wet conditions. Using the first cycle of the WAG experiments (first waterflood and the subsequent gas flood), the two-phase krs (oil/water and gas/oil) were estimated assuming minimal hysteresis occurs in the first cycle. For subsequent cycles, pertinent parameters of the WAG-hysteresis model are included in automatic history-matching process. The outcome of these history-matching exercises would indicate how the WAG-hysteresis model would perform under different wettability conditions using a more representative set of two-phase krs. Also, using these experiments, the ability of the WAG-hysteresis model in simulating the full cycles of WAG injections would be assessed. In other words, auto-history-matching of whole WAG coreflood experiments would enable integrated simulation of two and three-phase flow regions co-existing in cyclic WAG injection. The results indicate that history-matching the whole WAG experiment would lead to significantly improved simulation outcome. Values of the tuned Land trapping coefficient and the reduction factor for residual oil saturation were close to experimentally extracted information, which highlights the importance of two elements in evaluating WAG experiments; (i) including full-WAG experiments in history-matching and (ii) using a more representative set of two-phase krs. Therefore, employing our new methodology to estimate two-phase krs from first cycle of a WAG experiment could make the estimated unsteady-state krs more reliable for simulating hysteresis effects. Furthermore, the results show that the WAG-hysteresis model failed to reasonably predict the coreflood experiment performed at mixed-wet conditions. The failure can be attributed to two sources; 1) non-wet behaviour of water in mixed-wet systems, which should be reflected in three-phase water relative permeability curves and 2) over-simplifications assumptions embedded in the WAG-hysteresis model such as the linear Som reduction models. Hence, a series of modifications should be applied to change the formulations of the WAG-hysteresis model to develop a versatile model for mixed-wet conditions. [ABSTRACT FROM AUTHOR]

In the current work we present the results of 3D micromagnetic modelling of magnetostrictive strain and magnetic hysteresis under uniaxial stress in ferrite. The simulations are performed on artificial microstructures with different grain orientations that allow to take into account the anisotropy of magnetic and mechanical properties of iron-based alloys. The obtained results are in reasonable agreement with experimental observations. The proposed method opens a path to predictive modelling of the magnetic properties of different textured steels in the context of in-line non-destructive testing. • Micromagnetic simulation of iron-based microstructures. • 3D micromagnetic modelling of magnetostriction in steels. • Simulation of magnetostriction behaviour of multi-grains microstructures. • Modelling of longitudinal magnetostrictive strain as a function of magnetization in iron. • Micromagnetic modelling of magnetic hysteresis under uniaxial stress. [ABSTRACT FROM AUTHOR]

Hysteresis of piezoelectric actuators is rate-dependent at high frequencies, but most of the hysteresis models are rate-independent and cannot describe the rate-dependent hysteresis nonlinearity independently. In this paper, a modified Prandtl-Ishlinskii (P-I) model is proposed to characterize the rate-dependent hysteresis of piezoelectric actuators under sinusoidal excitation. This model is formulated by a mth-power velocity damping model in conjunction with the rate-independent P-I model. The parameter identification of this model is divided into two steps using different experimental data and algorithms. The particle swarm optimization is introduced first to identify the rate-independent parameters, and the nonlinear least square method is adopted afterwards to identify the rate-dependent parameters which are functions of the excitation frequency. Moreover, the proposed P-I model is developed to describe hysteresis nonlinearity under triangular excitation by introducing weighted functions, i.e., λi. Finally, the model results attained under the sinusoidal and triangular inputs at different frequencies are compared with the corresponding experimental data. The comparisons demonstrate that the proposed P-I model can well describe hysteresis nonlinearity under sinusoidal excitation up to 1,500 Hz and triangular excitation up to 250 Hz, respectively. [ABSTRACT FROM AUTHOR]

Magnetic nanoparticle hyperthermia and thermal ablation have been actively studied experimentally and theoretically. In this review, we provide a summary of the literature describing the properties of nanometer-scale magnetic materials suspended in biocompatible fluids and their interactions with external magnetic fields. Summarised are the properties and mechanisms understood to be responsible for magnetic heating, and the models developed to understand the behaviour of single-domain magnets exposed to alternating magnetic fields. Linear response theory and its assumptions have provided a useful beginning point; however, its limitations are apparent when nanoparticle heating is measured over a wide range of magnetic fields. Well-developed models (e.g. for magnetisation reversal mechanisms and pseudo-single domain formation) available from other fields of research are explored. Some of the methods described include effects of moment relaxation, anisotropy, nanoparticle and moment rotation mechanisms, interactions and collective behaviour, which have been experimentally identified to be important. Here, we will discuss the implicit assumptions underlying these analytical models and their relevance to experiments. Numerical simulations will be discussed as an alternative to these simple analytical models, including their applicability to experimental data. Finally, guidelines for the design of optimal magnetic nanoparticles will be presented. [ABSTRACT FROM AUTHOR]

Cutting leads to a certain local magnetic material degradation of the electrical steel sheet. Moreover, the material properties near the cutting edge contribute significantly to the global performance. This material degradation mostly occurs in the vicinity of critical parts of electromagnetic devices, such as stator and rotor teeth. Therefore, the need exists to characterize the local magnetic hysteresis properties due to cutting. We couple the non destructive measurements of needle signals, which are dependent on the local variations in magnetic hysteresis properties, with a numerical inverse algorithm. The inverse algorithm interprets the needle signals so that the unknown magnetic hysteresis properties can be reconstructed. The paper mainly deals with the construction of an accurate material model (numerical forward model), the correct solution of the inverse procedure and the validation of the obtained results. We reconstructed local magnetic hysteresis properties of differently cut steel sheets and we observed that it is possible to recover the material characteristics using a material model, which fully characterizes the hysteresis properties. [ABSTRACT FROM AUTHOR]

The paper deals with an analytical model for hysteresis cycle representation. The hysteresis curve is decomposed in a series of arcs of circles and segments of lines. Each arc of circle or segment of line is expressed using analytical geometry as a function of some given parameters or calculated ones. The simplicity of the model proposed is given by the small amount of input data needed to represent the hysteresis cycle in a satisfactory way. [ABSTRACT FROM AUTHOR]

Abstract: We report measurements and modelling of magnetic effects due to plastic deformation in 2.2% Si steel, emphasizing new tensile deformation data. The modelling approach is to take the Ludwik law for the strain-hardening stress and use it to compute the dislocation density, which is then used in the computation of magnetic hysteresis. A nonlinear extrapolation is used across the discontinuous yield region to obtain the value of stress at the yield point that is used in fitting Ludwik''s law to the mechanical data. The computed magnetic hysteresis exhibits sharp shearing of the loops at small deformation, in agreement with experimental behavior. Magnetic hysteresis loss is shown to follow a Ludwik-like dependence on the residual strain, but with a smaller Ludwik exponent than applies for the mechanical behavior. [Copyright &y& Elsevier]

Abstract: Continuously variable signal transformers utilise the variation of the incremental permeability of ferromagnetic or ferrimagnetic materials with an applied DC magnetisation. The hysteresis losses play the dominant role determining the losses of the transformer. The losses mainly depend on the amplitude of the AC excitation and DC magnetisation. The energetic model for ferromagnetic hysteresis is used to calculate major and minor hysteresis loops and approximately determine the losses (Rayleigh law). [Copyright &y& Elsevier]

Soft actuators (SAs) have been used in many compliant robotic structure and wearable devices, due to their safe interaction with the wearers. Despite advances, the capability of current SAs is limited by scalability, high hysteresis, and slow responses. In this paper, a new class of soft, scalable, and high-aspect ratio fiber-reinforced hydraulic SAs is introduced. The new SA uses a simple fabrication process of insertion where a hollow elastic rubber tube is directly inserted into a constrained hollow coil, eliminating the need for the manual wrapping of an inextensible fiber around a long elastic structure. To provide high adaptation to the user skin for wearable applications, the new SAs are integrated into flexible fabrics to form a wearable fabric sleeve. To monitor the SA elongation, a soft liquid metal-based fabric piezoresistive sensor is also developed. To capture the nonlinear hysteresis of the SA, a novel asymmetric hysteresis model which only requires five model parameters in its structure is developed and experimentally validated. The new SAs-driven wearable robotic sleeve is scalable, highly flexible, and lightweight. It can also produce a large amount of force of around 23 N per muscle at around 30% elongation, to provide useful assistance to the human upper limbs. Experimental results show that the soft fabric sleeve can augment a user's performance when working against a load, evidenced by a significant reduction on the muscular effort, as monitored by electromyogram (EMG) signals. The performance of the developed SAs, soft fabric sleeve, soft liquid metal fabric sensor, and nonlinear hysteresis model reveal that they can effectively modulate the level of assistance for the wearer. The new technologies obtained from this work can be potentially implemented in emerging assistive applications, such as rehabilitation, defense, and industry. [ABSTRACT FROM AUTHOR]

Magnetorheological gel (MRG) excels in the material properties in term of adjustability and sedimentation performance, which could upgrade the performances of the current magnetorheological fluid based adjustable devices for structural control and vibration mitigation. However, the characterization and modelling of the stress-strain hysteresis responses of MRG has not been reported in the past, which are fundamental steps towards engineering applications. In this study, the stress-strain hysteresis of polyurethane based MRG sample with 60% carbonyl iron particle weight fraction was characterized under sinusoidal shear excitations with broad ranges of strain amplitude (5%–100%), excitation frequency (0.1 Hz–2 Hz) and magnetic fields (0–0.91 T). Significant stress overshooting phenomenon were observed under the application of low magnetic fields (0.27 T). A structurally-simple and accurate phenomenological model has been established to capture this unique nonlinearity. By validating the experimental results, the proposed model accurately predicts the hysteretic behaviour and the overshoot of the MRG under the excitation scenarios and the magnetic fields considered. Finally, the support vector machine (SVM) was implemented to provide the solution to the model generalization. The SVM-assisted model showed good agreement with the experimental data and can benefit the efficiency and viability in developing controllable MRG-based devices and system. Unlabelled Image • Comprehensive experimental characterization of the stress-strain hysteresis relationship of magnetorheological gel. • Discovered the stress overshoot behaviour in magnetorheological gel upon on the application of low level magnetic field. • Establishment of a four-parameter overshoot model to portray the nonlinear behaviour of magnetorheological gel. • Generalization of the four-parameter overshoot model by support vector machine method. [ABSTRACT FROM AUTHOR]

Abstract: When modelling electrical devices, one has to estimate quite accurately the iron losses for the sake of efficiency. The use of non-sinusoidal electrical sources increases the harmonic content in electrical systems and, consequently, increases significantly the magnetic losses in devices feed by these sources. The harmonic content adds non-centred minor hysteresis loops over the classical major one. The numerical tool used for the material modelling must be able to represent the magnetic behaviour in such conditions. Then, the use of a hysteresis model is the more suited solution, but the chosen model has to take into account correctly the minor loops. The Jiles–Atherton hysteresis model is one of the most employed, due its well-known properties, but it is not able to represent closed minor loops. In this work, we propose a simple approach based on experimental observations and empirical considerations, to improve the representation of minor loops in this model by keeping its simplicity of use and implementation in a FE calculation code. Differently to other approaches found in the literature, the previous knowledge of the magnetic field evolution is not needed. A comparison between measured and calculated curves, as well with the Preisach model, is performed to validate the model. [Copyright &y& Elsevier]

Abstract: An identification technique for the parameters of phenomenological models of hysteresis is presented. The basic idea of our technique is to set up a system of equations for the parameters of the model as a function of known quantities on the major or minor hysteresis loops (e.g. coercive force, susceptibilities at various points, remanence), or other magnetization curves. This system of equations can be either over or underspecified and is solved by using the conjugate gradient method. Numerical results related to the identification of parameters in the Energetic, Jiles–Atherton, and Preisach models are presented. [Copyright &y& Elsevier]