Hysteresis Curves Research Articles

Overstrength and plastic rotation of two-segment replaceable link with separated splicing plate

To enhance the seismic performance and post-earthquake reparability of traditional eccentrically braced frame structures, this study proposes a two-segment replaceable links with separated splicing plate: one featuring specimens with standard holes in the separated splicing plate (TSRL1), and the other featuring specimens with slotted holes in the separated splicing plate (TSRL2). Through cyclic loading tests, it was observed that the hysteresis curves of the links exhibited a relatively complete response, characterized by plastic rotations of 0.09 rad and 0.17 rad respectively. The overstrength coefficient ranged from 1.66 to 2.08, indicating commendable performance in terms of both overstrength and plastic deformation capacity. Subsequently, finite element simulations of the link were conducted using ABAQUS. Based on the congruity between simulation and test results, a parametric analysis was performed to determine the optimal seismic performance of the two-segment replaceable links with separated splicing plate by varying the length of the energy dissipation zone and hole type of the bolts.

Degradation of Mechanical Performance of Hoop Head Tenon-Mortise Joint of Tusi Manor with Decay Disease in Tibetan Areas in Yunnan

(1) The Hoop Head Tenon-mortise Joint (HHTMJ) in the Tusi Manor in Tibetan areas in Yunnan, China, has a serious decay phenomenon. To understand the effect of decay on the seismic performance of HHTMJ, (2) the five groups of HHTMJ and small-size Pinus kesiya var. langbianensis wood mechanical property testing specimens were placed in an artificially set decay environment and cultivated together with wood decay fungi for 0, 6, 12, 18, and 24 weeks, respectively. Low-cycle repeated loading tests were conducted to compare the failure mode, hysteresis curve, skeleton curve, and cumulative energy consumption of the HHTMJ under different decay cycles. (3) The results indicate that the failure mode of the HHTMJ is fractured at the tenon shoulder, and the deformation and failure of the tenon increase with the increase in decay. Compared with the non-decayed specimens, the ultimate bearing performance of the specimens after 6, 12, 18, and 24 weeks of decay decreased by 8.83%, 16.97%, 19.69%, and 30.22%, respectively. The cumulative energy consumption decreased by 21.6%, 27.4%, 33.2%, and 41.3%, respectively. (4) Decay primarily occurs on the exterior of the tenon, with minimal decay on the interior. The degradation of seismic performance in HHTMJ is relatively close to the degradation observed in small-size wood specimens during mechanical property testing.

An experimental investigation of selective laser melting parameters effects on ferromagnetic properties of pure iron in both the as-built and annealed conditions

In this study, the effect of selective laser melting (SLM) parameters on the magnetic properties of pure iron has been experimentally extracted both in the as-built (A-Built) and stress-relieved (H-Treat) conditions, and the optimum levels of the parameters have been determined for optimum magnetic properties. The SLM process parameters include laser power, scanning speed, and hatch spacing, and the design of experiments was done by the Taguchi method. After manufacturing and preparing the specimens, their hysteresis curves were measured using vibrating-sample magnetometer (VSM), and the magnetic properties of the SLMed pure iron were calculated. Signal-to-noise analysis was used to determine the optimal levels of parameters for achieving the best magnetic properties. For samples’ permeability and coercivity, the best possible regression equations were extracted, and SOBOL sensitivity analysis was used to determine the most contributing input variable to the outputs. The results indicate that the laser power parameter has the most significant impact on the magnetic properties of the produced parts. Two of samples were annealed at 820 °C for 1 h, and then magnetic properties were remeasured. Although there was not a significant change in permeability, and magnetization saturation of the samples, coercive force has decreased approximately 60 %. This reduction in annealing is desirable for some AC electrical devices.

Paleomagnetism of the Rio Perdido mafic dike swarm (1110 Ma) and the paleogeography of Amazonia and its role for supercontinents Rodinia and Gondwana

The Rio Apa Terrane (RAT) is situated at the south end of the Amazonian Craton (AC) separated from it by the aulacogen Tucavaca belt. It encompasses basement rocks that evolved mainly during the Paleoproterozoic. Its relationship to the AC during Proterozoic is yet undefined, although geologic, geochronologic and isotopic evidence suggest it was close to the Ventuari-Tapajós and Rio Negro-Juruena Provinces at Paleoproterozoic and linked to southwestern AC at ca. 1320 Ma. Aiming to elucidate the paleogeographic relation of the RAT to the AC during the Proterozoic, we performed a paleomagnetic study of the 1110 Ma Rio Perdido mafic dike swarm that crosscut the RAT. These dikes strike preferentially WNW-ESE and are mostly undeformed and unmetamorphosed. Magnetic experiments (hysteresis curves, isothermal remanent magnetization (IRM) curves, thermomagnetic curves and first order reverse curves-FORCs) revealed pseudo-single domain (PSD) Ti-poor titanomagnetite as the main magnetic carrier in these dikes. Alternating field (AF) and thermal demagnetization were efficient in isolating southwestern and northeastern directions with low inclinations, whose mean direction (Dec = 51.8°, Inc = −0.8°, N = 14, α95 = 13.8°, k = 9.3) yielded the paleomagnetic pole (RP) at 34.8°S/197.3° (A95 = 10.9°). This pole passed a baked contact test and meets 6 out of 7 pole reliability criteria (R = 6). The Rio Perdido pole implies that RAT could be linked to the southwestern AC at 1110 Ma but rotated counterclockwise ∼ 110° related to its present position. The AC linked to RAT probably belonged to the 1100 Ma Umkondia megacontinent which later collided with Laurentia during the formation of Rodinia at ca. 1000–900 Ma. Also, paleomagnetic data suggest that the RAT and the southwestern AC (Paraguá Terrane) were linked to Ventuari-Tapajós and Rio Negro-Juruena provinces at ca. 1780 Ma and had a joint geological evolution during the Paleo- and Mesoproterozoic. Finally, during the amalgamation of West Gondwana, the RAT rotated clockwise to its present position.

Hysteresis identification of joint with harmonic drive transmission based on Monte Carlo method

In this study, we analyze the hysteresis behavior of robotic joints equipped with harmonic drivers under various speeds and loads, focusing on a range of hysteresis models including the Bouc–Wen (BW), Fractional Order Bouc–Wen (FOBW), and their integration with the Krasnoselskii–Pokrovskii (KP) model. This integration, which forms the KP-FOBW model, is a novel aspect of our research, offering an enhanced understanding of non-linear and hysteresis behaviors in robotic joints. We employ the Monte Carlo method, particularly focusing on the Stochastic Gradient Hamiltonian Monte Carlo (SGHMC), for precise parameter identification. Our results demonstrate that the FOBW model, especially when combined with the KP model, provides a more accurate representation of the hysteresis curves under varying operating conditions. The KP-FOBW combination emerges as a powerful tool to predict the output torque in robotic joints. This study contributes to a deeper understanding of hysteresis in joints with harmonic drivers, showcasing its potential for complex dynamic modeling in robotics.

Reinforcement for earthquake-damaged glued-laminated timber knee-braced frames with self-tapping screws and CFRP fabric

Glued-laminated Timber Post and Beam Structure (GTPBS) is favored in timber engineering, primarily due to its commendable seismic resistance. Nonetheless, under severe earthquakes, these structures are susceptible to damage. This study aims to understand the impact of diverse reinforcement techniques on the lateral resistance of earthquake-damaged GTPBS. For this purpose, two full-scale frames were reinforced using self-tapping screws and Carbon Fiber Reinforced Polymer (CFRP) fabric before being subjected to horizontal low-cycle reversed loading tests. An in-depth comparison was made considering failure modes, hysteresis curves, and other pertinent parameters of the specimens both before and after reinforcement. Evidently, the employment of both self-tapping screws and CFRP fabric reinforcements curtailed the initiation and progression of joints cracks, averting premature structural failures. In addition, the better ductility of knee brace makes it more suitable for reinforcing earthquake-damaged GTPBS. These reinforcement techniques managed to recover over 90% of the bearing capacity of earthquake-damaged GTPBS, with a notable boost in their stiffness and ductility. The study culminates with an energy analysis that delves into the transformation and relative contributions of hysteresis energy and elastic strain energy during loading. From this analysis, it emerged that reinforcements using self-tapping screws and CFRP fabric not only ensure structural robustness but also maintain consistent energy dissipation.

Seismic behavior of an improved drilled flange connection for I-beam to CFST column

The use of cold-formed steel tubes in the concrete-filled steel tubular (CFST) columns makes the design of the moment connections between beams and CFST columns much more challenging. This is because setting the internal diaphragms in the CFST column to transfer the bending moment of the beam end becomes impossible, and thus new joints are needed. A novel joint was proposed in a previous study by the authors, where two end plates were used for the force transmission between CFST columns and beam flanges. Moreover, to satisfy the “weak member strong joint” requirement, the I-beams were reduced by drilling a series of circular holes in their flanges. However, most of the tested specimens failed by the unexpected rupture of the complete joint penetration (CJP) groove welds between the beam flanges and end plates. In this paper, three specimens are redesigned and tested, where modifications are made to improve their behaviors under the seismic load. In this test, the local buckling of beam flanges at the drilled sections was observed in all specimens, and two specimens failed due to the fracture at the drilled sections, while CJP weld fracture and significant bending of beam flanges both occurred at the failure of the rest specimen. The hysteresis curves of all specimens are fusiform, indicating their good energy dissipations (the maximum equivalent viscous damping coefficients between 0.35 and 0.40). The failure rotation angles are about 2.44–3.01, and the ductility coefficients are between 2.26 and 2.66. According to EC3, all specimens can be classified into the rigid and full-strength joints. Subsequently, the parametric analyses using the validated finite element model are carried out, where the effects of main parameters are investigated on the seismic behavior of the presented joint. This study brings insights into the moment connections between the steel beam and CFST column with the outer cold-formed section.

Vector hysteresis loops of rare earth magnets measured in a biaxial vibrating sample magnetometer

Vector hysteresis loops of rare earth magnets measured in a biaxial vibrating sample magnetometer

Synthesis and Exploring structural, magnetic, morphology and optical properties of La2−xAlxCuO4 (0 ≤ x ≤ 0.25) perovskite nanoparticles by microwave-assisted combustion method

La2CuO4 perovskite nanoparticles doped with aluminum were synthesized through the microwave-assisted combustion technique. Comprehensive studies on the structural, magnetic optical, functional and morphological properties were conducted using various techniques, including XRD, EDX, VSM, DRS-UV, FT-IR and FESEM respectively, .The XRD patterns of pristine La2CuO4 and Al-doped La2CuO4 unequivocally validated the exclusive development of a perovskite structure, devoid of any impurities. Nevertheless, the augmentation in Al3+ content (x = 0–0.25) induced a noteworthy phase shift from orthorhombic to cubic configuration. The average crystallite dimensions spanned from 54 to 41 nm. Distinct FT-IR bands at approximately 687 and 434 cm-1 were intricately linked to the La-O and Cu-O stretching modes inherent to the orthorhombic La2CuO4 phase. The energy gap determined through the Kubelka–Munk (K–M) methodology, experienced an elevation concomitant with the heightened Al3+ content (1.67–1.72 eV), attributable to quantum confinement phenomena. Within the La2-xAlxCuO4 (x = 0 to 0.25) system, the genesis of nanoscaled crystallized grains, interspersed with pores resulting from the amalgamation of grains, was evident. Analysis of hysteresis curves unveiled the emergence of soft ferromagnetic behavior at ambient temperature.

Realization of a composite ferroelectric characterization test system using a modified constant current method and a modified virtual ground method.

A composite ferroelectric characterization test system constructed using a modified constant current method (CCM) and a modified virtual ground method (VGM) has been successfully designed and implemented. By sending instructions to the microcontroller through software, the system's test mode can be easily changed by arranging the switching status of six switching elements. When validating the system, a dual-channel precision source/measure unit B2912B was used to verify this design. There is also parasitic capacitance that cannot be ignored in this commercial machine. This parasitic capacitance affects the appearance of the entire hysteresis curve. However, the parasitic capacitance values also differ in various test current ranges. In addition, to confirm the data credibility of this composite ferroelectric test system, Keysight B1530A and Radiant Premier II were used to conduct cross-verification between different systems. The results obtained between different systems show good consistency. Furthermore, reproducible and recoverable imprint phenomena were found in this composite system during interactive validation using VGM and CCM methods. After designing different voltage profiles for verification, it was found that the root cause of this imprint phenomenon was the difference between the final polarization state of the previous test and the pre-initialized polarization state. This imprint phenomenon exists in traditional Pb(Zr, Ti)O3(PZT) ferroelectric capacitors and Hf0.5Zr0.5O2-based ferroelectric capacitors. Fortunately, this imprint phenomenon is reversible. Moreover, this imprint phenomenon disappears through the design of the time-varying voltage profile on the ferroelectric capacitor of the CCM method.

Structural performance of detachable precast concrete column-column joint

A novel type of detachable precast concrete column-column joint (DPC) is proposed in this study to solve the problems in current column-column dry connections including complex load path, uncertainty of structural stiffness of beam-column joints and inconvenience for disassembly. The dry connection technology is applied by composing of steel plate and concrete. Finite element models of DPC were created to study its structural performance including hysteresis curve, skeleton curve, ductility, and energy dissipation capacity. The benchmark models are firstly established and validated against the test data and after that a small-scale parametric study is prepared. The effect of axial pressure ratio and eccentricity distance size on the seismic performance of DPC was studied. Results indict that the optimal value of axial pressure ratio ranges from 0.5 to 0.7. With increase of the axial pressure ratio, the ductility coefficient shows a decreasing trend in general. The eccentricity has little effect on the energy dissipation capacity of the joint.

A New Eulerian Iceberg Module for Climate Studies

AbstractIcebergs modulate the effective location of freshwater input from ice sheets into the ocean and therefore play an important role for the climate, especially during times of increased ice discharge (e.g., Heinrich events). None of the models participating in the Paleo Modeling Intercomparison Project simulations of the Last Glacial Maximum or the last deglaciation included icebergs. Here, we present a newly developed dynamic/thermodynamic iceberg module that was specifically designed to be incorporated in climate models used for long‐term climate simulations with interactive ice sheets. In contrast to the widely used Lagrangian iceberg models, it is formulated in an Eulerian framework. This simplifies coupling to ocean models and enhances computational efficiency for glacial climates. In a set of sensitivity experiments, where the module was implemented into an Earth System Model, we validate the model for present‐day climate conditions and test its sensitivity to key parameters. Further, we investigate the effect of iceberg hosing on the Atlantic meridional overturning circulation (AMOC) as compared to traditional freshwater hosing. Varying the hosing rate slowly in time yields a good approximation of the hysteresis curve of the AMOC. We find that the sensitivity of the AMOC to iceberg hosing is stronger than to freshwater hosing in the same ocean point, but weaker as compared to a latitude belt forcing in the North Atlantic. This emphasizes the 2e necessity to include interactive icebergs in long‐term coupled climate simulations to realistically represent melt patterns and the response of the AMOC to freshwater input from melting ice sheets.

The Effect of Magnetoelastic Anisotropy on the Magnetization Processes in Rapidly Quenched Amorphous Nanowires.

In this paper, we report for the first time on the theoretical and experimental investigation of Fe77.5Si7.5B15 amorphous glass-coated nanowires by analyzing samples with the same diameters in both cases. The hysteresis curves, the dependence of the switching field values on nanowire dimensions, and the effect of the magnetoelastic anisotropy on the magnetization processes were analyzed and interpreted to explain the magnetization reversal in highly magnetostrictive amorphous nanowires prepared in cylindrical shape by rapid quenching from the melt. All the measured samples were found to be magnetically bistable, being characterized by rectangular hysteresis loops. The most important feature of the study is the inclusion of the magnetoelastic anisotropy term that originates in the specific production process of these amorphous nanowires. The results show that the switching field decreases when the nanowire diameter increases and this effect is due to the reduction in anisotropy and in the intrinsic mechanical stresses. Moreover, the obtained results reveal the importance of factors such as geometry and magnetoelastic anisotropy for the experimental design of cylindrical amorphous nanowires for multiple applications in miniaturized devices, like micro and nanosensors.

Nanomechanical-ferroelastics behavior, and the low-temperature ferroelectric manifestation of BiMnO3 thin films

Ferroelastic-nanomechanical behavior of BiMnO3 thin films on (100) Nb-doped SrTiO3 substrate is studied at the nanoscale, for the first time using the theories of depth sensing indentation and finite element analysis. This was to understand the redirection of polarization in ferroelastic behavior using piezoelectric direct effect and applying a controlled local force by nanoindentation. The values of the nanomechanical properties Young’s modulus (E), hardness (H), and Stiffness (S) were measured to be E = 142 ± 3 GPa, H = 8 ± 0.2 GPa, and S = 44072 ± 45 N m−1 respectively. Using the experimental mechanical properties, a finite element analysis was carried out to understand the relationship between the irreversible work versus depth curve and plastic-deformation evolution of the thin film-interface-substrate system, associated with the pop-in observed. Von Mises stress maps are presented to clearly illustrate the deformations, mechanical failures, and influences between the BiMnO3 film and the SrTiO3 Substrate. The ferroelastic range for BiMnO3 material was observed between 0 to 12 nm, and the yield strength was Y = 2.6 ± 0.7 GPa. The ferroelectric properties through hysteresis curves were evaluated at two different temperatures of 200 K and 300 K in order to observe the effect of polarization with temperature. Providing better polarization performance at lower temperatures; P s = 9.14 ± 0.01 ( μ C cm–2), P r = 2.23 ± 0.02 ( μ C cm–2) and H c = 0.77 kV cm−1.

Accurate asymmetrical minor loops modeling with the modified arctangent hysteresis model

In the area of automotive propulsion, electric motors experience core losses due to the presence of higher harmonic frequencies, particularly those arising from pulse width modulation switching. Consequently, it is required to establish a practical model capable of characterizing the hysteresis loops in electrical steel when subjected to harmonic excitations. Nonetheless, existing dynamic models may be inappropriate for real-world applications due to their inherent complexity and their tendency to neglect the influence of minor loops arising from harmonics. In the present work, the minor and major hysteresis curves of non-oriented silicon steel sheets are measured under variable frequency excitation containing harmonic components. To reproduce the asymmetrical minor hysteresis loops, a modified arctangent model is employed. The evaluation of the accuracy of this hysteresis model is conducted by comparing the fitted results of static and dynamic hysteresis loops against experimental data, both with and without harmonic excitation.

Experimental research on lateral performance of CLT shear walls with novel dissipative angle brackets and hold-downs

Cross-laminated timber (CLT) structures offer a prospective solution to mid- and high-rise buildings. This paper reports experimental research on the lateral performance of CLT shear walls with novel dissipative angle brackets and hold-downs adopting soft-steel bracket and rubber. Quasi-static tests were performed on seven full-scale walls, comprising five walls with dissipative connections, one with in-situ replaced dissipative connections on already used CLT panels, and one with conventional metal connections, to investigate the influence of vertical load distributions, aspect ratios, and reparability. Failure modes, mechanical properties, and energy dissipation capacity were obtained and analyzed. The results show that the damage of the walls with dissipative connections primarily occurred at the connections, and these walls have excellent lateral deformation capacity, whose inter-story drift ratio can be up to 4.35%. Compared with the conventional metal connections, the walls with dissipative connections exhibit 26% higher ductility, 37.6% greater energy dissipation capacity and higher equivalent viscous damping ratios. Meanwhile, the repaired CLT shear walls maintained similar mechanical properties as the original wall, showing satisfactory reparability. Furthermore, non-linear numerical models were established to predict the walls’ lateral behavior, and the analytical hysteresis curves agree well with the test results.

Seismic performance of joints of prefabricated corrugated steel utility tunnels Part(II) – Numerical analysis

Based on the comprehensive test results of an actual project, the simulated static test of the utility tunnel was carried out. The numerical models were developed based on the finite element code ABAQUS. The material and mechanical parameters adopted in the model were calibrated through laboratory testing. Also, the numerical model was validated by comparing the computational results against the experimental outputs from Part I [1]. Employing the validated model, a series of parametric analyses was carried out to assess the impact of various parameters on the seismic performance of the structure. From the results analysis, it was revealed that the presence of the flanges at the connection joints hurts the seismic performance of the structure, and the hysteresis curve of the model without flange was fuller. However, these flanges serve as stiffening ribs, effectively enhancing the load-bearing capacity and stiffness of the structure. The thickness of the corridor and the corrugated steel plate waveform were identified as crucial factors influencing the hysteresis performance of the tunnel. Conversely, the influence of flange thickness was identified to be not significant. It was recommended to position the bolts as close as possible to the connection between the flange and the corrugate plate to minimize disconnection occurrences, subject to meeting installation requirements. Furthermore, welding the four pieces together can enhance the seismic performance of the tunnel. The findings in this paper provide a reliable theoretical and experimental basis for the seismic research design calculation and engineering application of the prefabricated corrugated plate integrated utility tunnel.

Impact of Hysteresis Curve on Subthreshold Swing in Ferroelectric FET

The changes in Subthreshold Swing (SS) were observed for changes in remanent polarization Pr and coercive field Ec, which determine the characteristics of the P-E hysteresis curve of ferroelectric in Ferrolectric FET (FeFET). A multilayer structure of Metal-Ferroelectric-Metal-Insulator-Semiconductor (MFMIS) was used for the junctionless double gate structure. To obtain the SS value, the analytical SS model was used. The ranges of 15≤Pr ≤30 μC/cm2 and 0.8≤Ec≤1.5 MV/cm, which were reasonable in various experiments and did not generate unstable regions in the relationship of drain current and gate voltage, were considered. As a result, the SS decreased as Pr decreased and Ec increased due to the capacitance change in the ferroelectric. This phenomenon is because the controllability of channel carriers by the gate voltage increases due to the increasing of change in the ferroelectric voltage for the gate voltage as Pr decreases and the memory window increases. Since the SS decreased linearly in the memory window, the SS constantly changed according to the ratio of Pr and Ec, Pr/Ec. As the ferroelectric thickness increased, the SS decreased significantly, but the change of SS with respect to the Pr/Ec was severe. In general, as the channel length decreases, SS increases. However, when the Pr/Ec decreased to 10 pF/cm, the SS tended to decrease as the channel length decreased. The reason for this can be attributed to the fact that the relative thickness of ferroelectric increases with small channel length.

Experimental study on the seismic performance of concrete-filled steel tube columns with a multiple-chamber round-ended cross-section

Reinforced concrete bridge piers with round-ended sections are susceptible to bending, bending–shear, and shear failure after earthquakes in high-intensity areas, thus necessitating improved seismic performance. This study introduced a novel design for a concrete-filled steel tube (CFST) column, featuring a multi-chambered, round-ended cross-section. The use of longitudinal and transverse stiffeners divided the column section into distinct chambers, thereby enhancing the seismic performance of the columns. A total of 12 groups of static tests were performed to examine the effect of chamber layout, axial compression ratio, and aspect ratio on columns’ hysteresis behavior, and the hysteresis curves, skeleton curves, failure modes, stiffness degradation, ductility, and energy dissipation capacity were obtained. Results demonstrated the favorable seismic performance of composite columns. Additionally, an increase in chambers led to a full hysteresis curve, enhancing bearing and energy dissipation capacities. The displacement ductility coefficient (μ) ranged between 3.88 and 7.45, and the design parameters have minimal influence on the stiffness degradation of the composite beam. Based on the results, the long and short sides of the CFST columns with a large length–width ratio should be arranged to be relatively close in length.

Barkhausen noise in disordered striplike ferromagnets: Experiment versus simulations.

In this work, we present a systematic comparison of the results obtained from the low-frequency Barkhausen noise recordings in nanocrystalline samples with those from the numerical simulations of the random-field Ising model systems. We performed measurements at room temperature on a field-driven metallic glass stripe made of VITROPERM 800R, a nanocrystalline iron-based material with an excellent combination of soft and magnetic properties, making it a cutting-edge material for a wide range of applications. Given that the Barkhausen noise emissions emerging along a hysteresis curve are stochastic and depend in general on a variety of factors (such as distribution of disorder due to impurities or defects, varied size of crystal grains, type of domain structure, driving rate of the external magnetic field, sample shape and temperature, etc.), adequate theoretical modeling is essential for their interpretation and prediction. Here the Random field Ising model, specifically its athermal nonequilibrium version with the finite driving rate, stands out as an appropriate choice due to the material's nanocrystalline structure and high Curie temperature. We performed a systematic analysis of the signal properties and magnetization avalanches comparing the outcomes of the numerical model and experiments carried out in a two-decade-wide range of the external magnetic field driving rates. Our results reveal that with a suitable choice of parameters, a considerable match with the experimental results is achieved, indicating that this model can accurately describe the Barkhausen noise features in nanocrystalline samples.