Analysis Of Hysteresis Loops Research Articles

Structural, FTIR and Ferro electric analysis of pure TGS and L-Cysteine doped TGS crystals for infrared device applications

Abstract This paper aims at investigating the line broadening of powder X-ray diffraction peaks as a result of compositional disorder in L -Cysteine doped triglycine sulfate crystals. Various methods such as Williamson-Hall and size-strain plot methods were used in this study. The analysis indicates that L -Cysteine substitution in triglycine sulfate crystals results in anisotropic strain in the crystal. The crystalline quality and cell parameter values were found using XRD analysis. The presence of L -Cysteine in TGS was estimated qualitatively by Fourier transform infrared analysis. The ferroelectric nature of the crystals was identified by P–E hysteresis loop analysis.

A study of friction microslip modeling for dynamic analysis of bladed discs with root joints

In machinery structures with joints, the contact pressures at contact interfaces are usually high enough to ensure that the contacting components stay joined and the gross slip does not occur. Nevertheless, the small relative slip over parts of the contact interface, i.e. the microslip, contributes significantly to the vibration damping. In the high-fidelity analysis of practical bladed discs, the macroslip model cannot provide sufficient accuracy for the predictive analysis of the properties of the friction damping in the contact interfaces. In this article, numerical studies of microslip damping effects is performed using 2D and 3D models of blade root joints. Analysis of hysteresis loops is performed to assess the influence of modeling parameters: choice of reference points, mesh configurations, and other physical parameters. The impact of the physical parameters, such as the contact geometry, friction coefficient, contact stiffness and tangential and normal loading, on the friction damping is numerically examined. The numerical results demonstrate the possibilities of microslip prediction using finite element modeling and show the microslip friction damping effects using simplified and realistic blade root models.

Rheological Properties of Xanthan Gum, Hydroxypropyl Starch, Cashew Gum and Their Binary Mixtures in Aqueous Solutions

Large volumes of drilling fluids are used while drilling oil wells. Water‐based fluids are widely used because they are generally less expensive and more environmentally correct than synthetic fluids. Polymers are used in drilling fluids with different functions. This article reports a study of the rheological behavior of solutions containing xanthan gum (XG), hydroxypropyl starch (HPS) and cashew gum (CG), as well as their binary mixtures, to evaluate the applicability of CG (an abundant product in Brazil's northeastern region) in aqueous fluid formulations. The results show the potential to use CG in mixtures with XG. The thixotropic effect is confirmed by hysteresis loop analysis; the rheological behavior is satisfactorily described by the Ostwald‐de Waele and Casson models; the aqueous solutions containing XG/HPS mixtures present higher consistency indexes than the XG/CG mixtures; and the activation energy values of the XG/CG mixtures are governed by the CG fraction.

Measuring, Processing, and Analyzing Hysteresis Data

AbstractMagnetic hysteresis loops are important in theoretical and applied rock magnetism with applications to paleointensities, paleoenvironmental analysis, and tectonic studies, among many others. Information derived from these data is among the most ubiquitous rock magnetic data used by the Earth science community. Despite their prevalence, there are no general guidelines to aid scientists in obtaining the best possible data and no widely available software to allow the efficient analysis of hysteresis loop data using the most advanced and appropriate methods. Here we outline detrimental factors and simple approaches to measuring better hysteresis data and introduce a new software package called Hysteresis Loop analysis box (HystLab) for processing and analyzing loop data. Capable of reading a wide range of data formats, HystLab provides an easy‐to‐use interface allowing users to visualize their data and perform advanced processing, including loop centering, drift correction, high‐field slope corrections, and loop fitting to improve the results from noisy specimens. A large number of hysteresis loop properties and statistics are calculated by HystLab and can be exported to text files for further analysis. All plots generated by HystLab are customizable and user preferences can be saved for future use. In addition, all plots can be exported to encapsulated postscript files that are publication ready with little or no adjustment. HystLab is freely available for download at https://github.com/greigpaterson/HystLab and in combination with our simple measurement guide should help the paleomagnetic and rock magnetic communities get the most from their hysteresis data.

BIODEGRADABLE GELATIN DECORATED Fe3O4 NANOPARTICLES FOR PACLITAXEL DELIVERY

The objective of this study is to prepare biodegradable iron oxide nanoparticles with gelatin (GEL) for paclitaxel (PTX) delivery. In detail, Fe3O4 nanoparticles were prepared and then coated them with GEL (Fe3O4@GEL) conjugate by co–precipitation method. Furthermore, the formation of Fe3O4@GEL was demonstrated by Fourier transform infrared (FT–IR) and powder X–ray diffraction (XRD). The superparamagnetic property of Fe3O4@GEL was also showed by hysteresis loop analysis, the saturation magnetization reached 20.36 emu.g–1. In addition, size and morphology of Fe3O4@GEL nanoparticles were determined by transmission electron microscopy (TEM). The results indicated that Fe3O4@GEL nanoparticles were spherical shape with average diameter of 10 nm. Especially, PTX was effectively loaded into the coated magnetic nanoparticles, 86.7 ± 3.2 % for drug loading efficiency and slowly released up to 5 days. These results suggest that the potential applications of Fe3O4@GEL nanoparticles in the development of stable drug delivery systems for cancer therapy.

Obtaining of Ni nanotubes with specified properties

The paper presents the results of a study of the dependence of the change in synthesis conditions from structural and magnetic characteristics of Ni nanotubes. Dependences of the effect of deposition conditions from the concentration of microstresses and dislocations in the crystal structure, as well as the change in the main parameters characterizing the crystal lattice, are established. Analysis of hysteresis loops made it possible to determine that the synthesized nanotubes belong to the class of magnetically soft materials with small coercivity and sufficiently large saturation magnetization. At the same time, the presence of oxide impurities in the structure leads to a deterioration of structural properties, the appearance of amorphous inclusions in the structure, which cause the deterioration in magnetic characteristics of synthesized nanotubes.

Damage Identification for Hysteretic Structures Using a Mode Decomposition Method

AbstractThis article investigates structural health monitoring (SHM) of multidegree of freedom (MDOF) structures after major seismic or environmental events. A recently developed hysteresis loop analysis (HLA) SHM technique has performed robustly for single degree of freedom (SDOF) and single mode dominant MDOF structures. However, strong ground motions can trigger higher vibration modes, resulting in irregular hysteresis loops and making this otherwise robust identification difficult. This study presents a new filtering tool, enabling reconstruction of single mode dominant restoring force‐displacement loops which can be readily used for HLA.The proposed filtering tool is based on a classic modal decomposition using optimized mode shape coefficients. The optimization process is carried out in a modal space and is based on decoupling frequency response spectra of interfering modes. Application of modal decomposition using the optimized mode shape coefficients allows for reconstruction of single‐mode dominant hysteresis loops, which can be effectively identified using HLA. The proposed filtering tool is validated on the reconstruction of hysteresis loops on an experimental bridge pier test structure with notable contributions from at least two modes.The results show the method eliminates the influence of all higher modes that contain significant energy content and yields the reconstruction of “smooth” single mode dominant hysteresis loops. The resulting SHM analysis on the reconstructed experimental hysteresis loops identified degradation in the elastic stiffness profiles, indicating damage within the structure and matching prior published results based on physical inspection of damage. The overall method presented increases the breadth of potential application of the HLA method and can be readily generalized to a range of MDOF structures.

Silicone phantom validation of breast cancer tumor detection using nominal stiffness identification in digital imaging elasto-tomography (DIET)

Abstract Background and objective Cancerous tumors exhibit considerably higher stiffness than healthy breast tissues. This research develops a hysteresis loop analysis detection method for breast cancer diagnosis, which is validated using silicone phantom tests to provide an initial proof of concept of the overall DIET diagnostic approach. Methods Steady state sinusoidal displacements induced by mechanical actuation are captured using the DIET system for 4 silicone breast phantoms (1 homogeneous “healthy”; 3 with 10–20 mm stiffer inclusion “tumors” at different locations). Hysteresis loops for each measured reference point on the breast surface (N≈14,500/phantom) are constructed from the measured displacements and a calculated mass normalized restoring force. The distribution of nominal elastic stiffness over breast surface is estimated using a hypothesis test and regression analysis. A small motion threshold, Δ d , is used to reduce errors in identified elastance and its values determined from sensitivity analysis. Results Sensitivity analysis shows displacement reconstruction errors from very small motions can be eliminated using a threshold Δ d = 6 μ m to clearly reduce errors in identified nominal elastance. Results for all 4 phantoms indicate stiffer inclusions induce a greater number of reference points with stiffness ≥2 × higher in the segment with the inclusion than the nominal stiffness in the “healthy” segments in the x , y and total net 2D displacement directions. Therefore, the presence of a stiffer “tumor” inclusion is automatically detected and located by comparing the nominal stiffness to a calculated threshold, k t . Inclusion segments are finally localized algorithmically using an inclusion indicator, K index . Conclusions The overall results validate the capability of the proposed method to accurately detect and locate a stiff inclusion in typical, representative silicone breast phantoms without misidentifying other regions or a healthy no-inclusion phantom in the non-invasive DIET system. The methods are entirely generalizable to human clinical data from a DIET system, and the results justify such clinical trials.

Efficient hysteresis loop analysis-based damage identification of a reinforced concrete frame structure over multiple events

Reinforced concrete (RC) structures are common in seismic zones. However, damage assessment after earthquake events can be problematic and subjective due to their highly nonlinear and time-varying behaviour when damaged. This research develops a hysteresis loop analysis (HLA)-based method for rapid structural health monitoring of an experimental, scaled 12-storey RC frame building subjected to two levels of input ground motions. A six equivalent degree-of-freedom (DOF) system model is proposed to represent the 12-storey test structure, where the accelerations of every two floors are recorded during earthquake excitations. Hysteresis loops are then reconstructed for each DOF using the calculated equivalent restoring force and divided into a number of half cycles in chronological order. Finally, changes in elastic storey stiffness used as a damage index are tracked over time for damage identification of each DOF based on the statistical analysis of the selected half cycles. The identification results clearly show that the proposed algorithm is capable of identifying damage that was not evident by external visual appearance, and also offers significant advantages in identifying the location and severity of damage over traditional methods for realistic RC structures immediately after an event.

Fatigue life assessment of electromagnetic riveted carbon fiber reinforce plastic/aluminum alloy lap joints using Weibull distribution

Electromagnetic riveting (EMR) has received increasing attention asa new kind of riveting technique in engineering industry. In this paper, EMR process was used to connect carbon fiber reinforced plastics (CFRP) and aluminum alloy (Al) hybrid joints. The mechanical behaviors (including static and fatigue properties) of the electromagnetic riveted lap joints were comprehensively investigated. The microstructure observation and the mechanical property tests were conducted to evaluate the joints performance. The mechanical test results showed that the failure modes of shear specimens were bending of the Al sheet and damage of the CFRP sheet, which was caused by rivet squeezing effect under static loading. However, the failure mode of fatigue specimens under each stress level was all ruptured at the Al sheet and the fracture analysis showed that cracks firstly initiated around the hole of Al sheet. This was caused by the fretting wear between Al sheet and rivet under cyclic loading. Two-parameter Weibull distribution was employed to analyze statistically fatigue cycles results. The S-N curves were drawn for different reliability levels (10%, 36.8%, 50% and 90%) for engineering applications. In addition, Hysteresis loop analysis implied that the specimens had no obvious flaw after EMR.

Ferroelectric Behavior of Organic Terahertz Radiating DAST Crystal

Bulk terahertz emitting and technologically advanced DAST crystal is grown using a simple, cost effective and efficient seed rotation technique from a saturated methanol solution. The grown crystal is identified by a single crystal XRD analysis and powder X-ray diffraction studies. HRXRD experiments substantiate a good crystalline perfection without interior grain boundaries. The ferroelectric nature of the crystal has been described by P–E hysteresis loop analysis, which corroborates with better ferroelectric behavior than other benchmarked inorganic materials. The hardness, elastic stiffness, and yield strength shows decreasing trend for increasing loads and the work hardening coefficient confirm that the DAST is a soft material. Two-dimensional nucleation growth with minimum dislocation is evident from the etch patterns.

A magnetic polypeptide nanocomposite with pH and near-infrared dual responsiveness for cancer therapy

A magnetic polypeptide nanocomposite with pH and near-infrared (NIR) dual responsiveness was developed as a drug carrier for cancer therapy, which was prepared through the self-assembly of Fe3O4 superparamagnetic nanoparticles, poly(aspartic acid) derivative (mPEG-g-PDAEAIM) and doxorubicin (DOX) in water. Fe3O4 nanoparticles were prepared to provide the superparamagnetic core of nanocomposites for tumor targeting via chemical co-precipitation. The protonable imidazole groups of mPEG-g-PDAEAIM with a pKa of ~7 were accountable for the pH-responsiveness of nanocomposites. The photothermal effect of nanocomposites under the irradiation of NIR laser was induced via the interactions between dopamine groups of mPEG-g-PDAEAIM and Fe3O4 superparamagnetic nanoparticles to trigger the drug release. NMR, FT-IR, TEM, hysteresis loop analysis and MRI were utilized to characterize the materials. The DOX loaded nanocomposites exhibited pH-responsive and NIR dependent on/off switchable release profiles. The nanocomposites without drug loading (Fe3O4@mPEG-g-PDAEAIM) showed excellent biocompatibility while DOX loaded nanocomposites caused MCF-7 cells’ apoptosis due to the photothermal/chemotherapy combination effects. Overall, the pH and near-infrared dual responsive magnetic nanocomposite had a great potential for cancer therapy.

Damage assessment by stiffness identification for a full-scale three-story steel moment resisting frame building subjected to a sequence of earthquake excitations

This research experimentally investigates a practical hysteresis loop analysis method for damage assessment through stiffness identification using a full scale three-story steel moment resistant frame structure subjected to a sequence of 6 shake table tests with different magnitudes of 3D excitations. The effective elastic stiffness, k e , is calculated based on the analysis of the experimentally measured and reconstructed hysteresis loops. Structural degradation is then evaluated by tracking changes in identified stiffness over time and across different earthquake events. Finally, the fundamental frequency of the building is calculated using the identified stiffness to compare with the experimental frequency from experimental transfer functions. Results show average differences between the final stiffness of one event and the initial stiffness of the following event are less than 5% in both horizontal directions, indicating a good continuity and accuracy of the identification over events. The average difference between the experimental and calculated fundamental frequency are less than 0.1 Hz in both directions over all events. The overall results clearly delineate the capability of the method to accurately and consistently quantify and localize structural damage that may not be detected by external visual detection over several earthquake events of different magnitude, indicating its ability to be used in long term monitoring.

Nominal Stiffness Identification for Tumor Detection of Women Breast in a Digital Image Elasto Tomography (DIET) System

This research develops a hysteresis loop analysis (HLA) based method for breast cancer diagnosis in a Digital Imaging Elasto-tomography (DIET) system. Dynamic displacements induced by mechanical actuation for 4 silicone breast phantoms (1 homogeneous healthy, 3 with 10-20mm stiffer inclusion “tumors”) are captured using the DIET system. Hysteresis loops for each measured reference point across the breast surface are reconstructed using the measured displacement and a calculated mass normalized restoring force. The distribution of the nominal elastic stiffness over the breast surface is estimated using an F-type hypothesis test and regression analysis. A higher stiffness is identified in the region of the inclusions, which is at least 2x greater than the nominal stiffness in other areas of the phantom. Thus, the method accurately detects and locates the inclusion in typical, representative silicone breast phantoms without misidentifying other regions or a healthy no-inclusion phantom. The overall results show the capability of the proposed method, based on the identification of the local nominal stiffness over the phantom surface as an efficient index, to accurately detect inclusion presence and location in a rapid, objective fashion using the non-invasive DIET approach.

Sensitivity Analysis for Stiffness Identification Using a DIET Breast Cancer Screening System

Cancerous tumors exhibit significantly higher stiffness than healthy breast tissues. a hysteresis loop analysis method is used to identify the nominal elastic stiffness in different horizontal directions for breast cancer diagnosis in a Digital Imaging Elasto-tomography (DIET) screening system. The sensitivity of the method to measurement errors from the DIET system is first evaluated using a homogeneous healthy phantom with different camera angles. The identification method is then validated against 4 phantoms with stiffer inclusions of 10-20mm diameter over a range of actuation frequencies. Results show displacement reconstruction errors from very small motion can be eliminated by using a threshold ∆d to significantly reduce errors in identified nominal elastane. The stiffer inclusion induced a greater number of reference points with higher stiffness in the inclusion segment than other segments in x and y directions. The presence of a stiffer “tumor” inclusion is detected by comparing the nominal stiffness to an automatically defined threshold, kt. Inclusion segments can then be localized using an inclusion indicator, Kindex. The overall results validate the method is capable of providing robust estimations of nominal stiffness over a realistic range of actuation frequencies, and inclusion sizes and angle for the DIET concept.

A study of the back stress and the friction stress behaviors of Ti-6Al-4V alloy during low cycle fatigue at room temperature

Low cycle fatigue (LCF) tests were performed on Ti-6Al-4V alloy at room temperature. The fatigue hardening/softening of the Ti-alloy were determined. Both the back stress (X) and the friction stress (σF) were evaluated from analysis of fatigue hysteresis loops and their cycle-dependent behaviors during fatigue tests were obtained experimentally. It is shown that the cyclic stress response or the fatigue hardening/softening of the Ti-alloy actually results from the competition effect of the back and the friction stress behaviors during fatigue cycling. A two-slope behavior in both the εpa-2Nf and the X-2Nf plots was also obtained. The micro-mechanisms associated with the back and friction stress behaviors as well as the two-slope behavior in the εpa-2Nf and X-2Nf plots were further discussed with the help of OM and TEM observations of fatigue failure specimens at representative strain amplitudes. In this study, the DIC technique was also introduced to characterize quantitatively the cyclic deformation heterogeneity of the Ti-alloy at the grain scale.

Influence of Sputtering Power on the Structure and Electrical Properties of Bi2Fe4O9 Thin Films

Bismuth ferrite (Bi2Fe4O9) thin films were grown on p-type Si (100) substrate by radio-frequency magnetron sputtering at 873 K. X-ray diffraction, field emission scanning electron microscopy and Raman spectroscopy studies revealed that the grown films have single-phase polycrystalline nature and are crystallized in orthorhombic structure. The grain size of the grown thin films was found to increase (56–130 nm) with sputtering power. Atomic force microscopy images clearly illustrated that the grown thin films have smooth surface. Energy-dispersive X-ray analysis revealed the presence of Bi, Fe and O elements with desired ratio and also the absence of impurities in the grown films. Analysis of ferroelectric hysteresis loops revealed that the remanent polarization and coercive field increase with the increase in sputtering power. Vicker’s hardness analysis showed that the hardness of films strongly depends on the grain size and film thickness, which are mainly determined by the sputtering power. The above observations revealed that Bi2Fe4O9 thin film deposited at higher sputtering power has good crystallinity and shows better electrical properties.

Scaling effects of riparian peatlands on stable isotopes in runoff and DOC mobilisation

We combined 13months of daily isotope measurements in stream water with daily DOC and 15 min FDOM (fluorescent component of dissolved organic matter) data at three nested scales to identify how riparian peatlands generate runoff and influence DOC dynamics in streams. We investigated how runoff generation processes in a small, riparian peatland-dominated headwater catchment (0.65km2) propagate to larger scales (3.2km2 and 31km2) with decreasing percentage of riparian peatland coverage. Isotope damping was most pronounced in the 0.65km2 headwater catchment due to high water storage in the organic soils encouraging tracer mixing. At the largest scale, stream flow and water isotope dynamics showed a more flashy response. The isotopic difference between the sites was most pronounced in the summer months when stream water signatures were enriched. During the winter months, the inter-site difference reduced. The isotopes also revealed evaporative fractionation in the peatland dominated catchment, in particular during summer low flows, which implied high hydrological connectivity in the form of constant seepage from the peatlands sustaining high baseflows at the headwater scale. This connectivity resulted in high DOC concentrations at the peatland site during baseflow (∼5mgl−1). In contrast, at the larger scales, DOC was minimal during low flows (∼2mgl−1) due to increased groundwater influence and the disconnection between DOC sources and the stream. High frequency data also revealed diel variability during low flows. Insights into event dynamics through the analysis of hysteresis loops showed slight dilution on the rising limb, the strong influence of dry antecedent conditions and a quick recovery between events at the riparian peatland site. Again, these dynamics are driven by the tight coupling and high connectivity of the landscape to the stream. At larger scales, the disconnection between the landscape units increases and the variable connectivity controls runoff generation and DOC dynamics. The results presented here suggest that the processes occurring in riparian peatlands in headwater catchments are less evident at larger scales which may have implications for the larger scale impact of peatland restoration projects.

Effective Stiffness Identification for Structural Health Monitoring of Reinforced Concrete Building using Hysteresis Loop Analysis

Structural Behavior of reinforced concrete (RC) buildings under earthquake excitation are highly nonlinear, particular for cracked RC structures with stiffness changing across elastic, pinched and hybrid regimes. This study investigates a structural health monitoring (SHM) method for an experimental scaled 12-storey RC frame building with cracks visually observed in the beam-column joints prior to a sequence of 4 shaking table tests. Hysteresis loops for every two floors are reconstructed using corrected acceleration and displacement measurements based on a multi-rate Kalman filter. The changes of nonlinear stiffness over time are calculated for divided half cycles using a hysteresis loop analysis (HLA). The effective elastic pinching stiffness are then extracted from the identified nonlinear stiffness values to examine the evolution of structural degradation during these events. A critical validation analysis is whether the final identified stiffness values match the initial values in a subsequent event, to ensure the method is robust in finding an accurate and repeatable value. In addition, fundamental frequencies, often used for SHM, are assessed using the identified effective stiffness and compared to those from modal analysis before-after each event. Results show the effective pinching stiffnesses for each floor are identified consistently between larger and small events. Final stiffness values for one event are within 9.7% of initial values for the next. The fundamental frequency results compare well further validating the method, but also show little sensitivity to large changes in effective stiffness. The overall results indicate the capability of the HLA to accurately identify damage that may not be found by vibration-based methods for highly nonlinear RC structures.

A Surface Vibration-based Method for Tumor Detection of Women Breast in a DIET System

This paper presents a hysteresis loop analysis (HLA) method based on dynamic force-displacement relationship to detect and localize cancerous tumors that exhibit significantly higher stiffness than soft healthy tissues in women breast. Steady state sinusoid displacements induced by mechanical actuation for 2 silicone phantoms (1 homogeneous “healthy”; 1 with 20mm stiffer inclusion “tumor”) are captured using a non-invasive Digital Image Elasto Tomography (DIET) system. Hysteresis loops for each measured reference point across the phantom surface are reconstructed using the measured displacement and a calculated mass normalized restoring force. The distribution of the elastic nominal stiffness over the breast surface is estimated using an F-type hypothesis test and regression analysis. The sensitivity of the method to measurement errors from the DIET system is evaluated using a homogeneous healthy phantom with different camera angles. Results show displacement reconstruction errors from very small motion can be eliminated by using a threshold ∆d to significantly reduce errors in identified nominal elastance. The stiffer inclusion induced a greater number of reference points with higher stiffness in the inclusion segment than other segments in the x and y directions, while a consistent distribution of stiffness for the homogeneous control phantom was identified. The overall results show the capability of the method to accurately detect and locate the inclusion in typical, representative silicone breast phantoms without misidentifying other regions or a healthy no-inclusion phantom.