Measurement Of Material Properties Research Articles

Influence of Temperature on Wave Propagation in Low-Voltage Distribution Cables

Wave propagation in power cables depends on temperature. This paper explores its modeling for low-voltage cables, both main and service cables. Numerical thermal modeling combined with modal analysis, based on known and measured material properties, is employed to simulate waveforms expected in time-domain reflectometry tests. Comparison with laboratory measurements on a main cable shows that the main characteristics and their temperature dependency agree. The effect on wave propagation of rapid temperature rise in the conductor of a service cable during a fault is investigated. The predicted change in propagation velocity is confirmed by a field test. The perspectives of employing temperature dependent material characteristics, in particular the dielectric permittivity, on wave propagation for diagnostic techniques are briefly discussed. By accounting for the presence of different modes, the accuracy of locating the fault by means of time-domain reflectometry can be increased.

Effects of early-age thermal microcracking on material properties and structural performance of limestone aggregate concrete

High temperature or thermal curing is commonly applied to concrete fabrication but raises concerns for potential microcracks caused by temperature changes. This is particularly concerning for concrete using limestone coarse aggregate given the significant mismatch in thermal deformation between the aggregate and the surrounding mortar. This experimental study aimed to compare the effects of early-age thermal curing on limestone and normal concrete and included relevant tests on samples cured with either normal, or high temperature conditions. Alongside concrete specimens for microcrack observation and material property measurement, reinforced concrete beams were prepared to investigate shear behavior. It was concluded that high temperature at an early age could cause adverse impacts on basic properties of limestone concrete. However, the structural behavior was also enhanced, manifested by fracture properties and shear resistance improvements. These improvements were attributed to the microcracks’ influences on macrocracks, and to the improved shear transmission through cracks.

Heat Transfer in Multilayered Thin Film Materials Applied to Photothermal Deflection Spectroscopy

Heat transfer from a modulated laser incident on a multilayered thin film material is theoretically analyzed as a continuum system accounting for thermal contact resistance between the layers and anisotropy of thermal conductivity of the films. Formulations are obtained for the intensity-averaged deflection of a probe beam (PB) laser bounced on the surface as it passes through the thermally excited region of the gas. The PB formulations are the basis for nonintrusively measuring material properties. An algorithm is used to determine property values by matching measured and simulated PB deflections with selected properties as fitting parameters. Experiments are reported to provide data for validating the PB formulations for bulk standard reference and film/substrate materials. For the latter, a virtual film bonded to a substrate of the same material was used. Results show that predicted and measured PB deflections are in good agreement for thin films when the modulation frequency positions the thermal penetration depth inside the film. It is also shown that for increasing thermal contact resistance, anisotropy of thermal conductivity of the film materials, and modulated beam radius and frequency, the PB deflections are reduced through the effect of these variables on heat flow in the solid and gas.

Relative Density Measurement of PBF-Manufactured 316L and AlSi10Mg Samples via Eddy Current Testing

Powder bed fusion (PBF) is the most commonly used additive manufacturing process for fabricating complex metal parts via the layer-wise melting of powder. Despite the tremendous recent technological development of PBF, manufactured parts still lack consistent quality in terms of part properties such as dimensional accuracy, surface roughness, or relative density. In addition to process-inherent variability, this is mainly owing to a knowledge gap in the understanding of process influences and the inability to adequately control them during part production. Eddy current testing (ECT) is a well-established nondestructive testing technique primarily used to detect near-surface defects and measure material properties such as electrical conductivity in metal parts. Hence, it is an appropriate technology for the layer-wise measuring of the material properties of the fused material in PBF. This study evaluates ECT’s potential as a novel in situ monitoring technology for relative part density in PBF. Parts made from SS316L and AlSi10Mg with different densities are manufactured on a PBF machine. These parts are subsequently measured using ECT, as well as the resulting signals correlated with the relative part density. The results indicate a statistically significant and strong correlation (316L: r(8) = 0.998, p < 0.001, AlSi10Mg: r(8) = 0.992, p < 0.001) between relative part density and the ECT signal component, which is mainly affected by the electrical conductivity of the part. The results indicate that ECT has the potential to evolve into an effective technology for the layer-wise measuring of relative part density during the PBF process.

Modeling and validation of stray-field loss inside magnetic and non-magnetic components under harmonics-DC hybrid excitations based on updated TEAM Problem 21

Purpose This paper aims to propose and establish a set of new benchmark models to investigate and confidently validate the modeling and prediction of total stray-field loss inside magnetic and non-magnetic components under harmonics-direct current (HDC) hybrid excitations. As a new member-set (P21e) of the testing electromagnetic analysis methods Problem 21 Family, the focus is on efficient analysis methods and accurate material property modeling under complex excitations. Design/methodology/approach This P21e-based benchmarking covers the design of new benchmark models with magnetic flux compensation, the establishment of a new benchmark measurement system with HDC hybrid excitation, the formulation of the testing program (such as defined Cases I–V) and the measurement and prediction of material properties under HDC hybrid excitations, to test electromagnetic analysis methods and finite element (FE) computation models and investigate the electromagnetic behavior of typical magnetic and electromagnetic shields in electrical equipment. Findings The updated Problem 21 Family (V.2021) can now be used to investigate and validate the total power loss and the different shielding performance of magnetic and electromagnetic shields under various HDC hybrid excitations, including the different spatial distributions of the same excitation parameters. The new member-set (P21e) with magnetic flux compensation can experimentally determine the total power loss inside the load-component, which helps to validate the numerical modeling and simulation with confidence. The additional iron loss inside the laminated sheets caused by the magnetic flux normal to the laminations must be correctly modeled and predicted during the design and analysis. It is also observed that the magnetic properties (B27R090) measured in the rolling and transverse directions with different direct current (DC) biasing magnetic field are quite different from each other. Research limitations/implications The future benchmarking target is to study the effects of stronger HDC hybrid excitations on the internal loss behavior and the microstructure of magnetic load components. Originality/value This paper proposes a new extension of Problem 21 Family (1993–2021) with the upgraded excitation, involving multi-harmonics and DC bias. The alternating current (AC) and DC excitation can be applied at the two sides of the model’s load-component to avoid the adverse impact on the AC and DC power supply and investigate the effect of different AC and DC hybrid patterns on the total loss inside the load-component. The overall effectiveness of numerical modeling and simulation is highlighted and achieved via combining the efficient electromagnetic analysis methods and solvers, the reliable material property modeling and prediction under complex excitations and the precise FE computation model using partition processing. The outcome of this project will be beneficial to large-scale and high-performance numerical modeling.

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Digital Image Correlation (DIC) is a new method of measuring material properties. DIC requires a fixed camera and a separate instrument to acquire images. The measurement position and orientation for the DIC measurement of a workpiece are severely constrained. Therefore, additional devices are required. In this study, only a marker with a grid pattern was attached, and a photograph of a specimen surface was captured without additional equipment. Specimen images were moved and tilted because the camera would shake during the experiment and the camera and specimen were not parallel. The acquired specimen images might be shifted or deformed. Sample images were acquired form various angles and then calibrated with perspective transformation by a developed algorithm and software. Surface strain (or deformation) field data were obtained using the calibrated specimen images and DIC. Therefore, the developed algorithm was verified by comparing the strain field data of the corrected DIC images.

Evaluation of the correlations between laboratory measured material properties with field cracking performance for asphalt pavement

Cracking is one of the primary distresses for asphalt pavements. There are many types of laboratory tests developed to evaluate the cracking performance of asphalt material, however, relatively little attention has been dedicated to evaluating and correlating the laboratory measured properties with the actual pavement performance. The main objective of this study is to investigate the relationships between the various laboratory measured binder/mixture properties with the actual pavement cracking (including both fatigue and thermal cracking) performance while also considering the important mix design and pavement structure parameters. Field pavement performance data were collected from 23 project sites with one control HMA section and at least one WMA section at each site. Laboratory testing was performed on the field cores taken from these sections as well as the corresponding extracted and recovered binders. Advanced statistical analysis method including the Pearson correlation and Spearman rank correlation coefficient were then employed to evaluate the correlations between the disparate laboratory measurements and actual pavement performance data. Results show that T*D (thickness of HMA/WMA layer*vertical failure deformation) parameter shows the good correlation with the length of field fatigue cracking, while the Pb%*εb-low (mixture binder content*binder failure strain) parameter shows the good correlation with the length of field thermal cracking. These correlations do not change with varying the pavement type (HMA or WMA). Based on the database generated in this study, a preliminary threshold value of 50 for T*D parameter and 10 for Pb%*εb-low parameter are proposed to minimize and control the cracking problem of asphalt mixtures in general.

Analysis of electrostatic levitation control system and oscillation method for material properties measurement.

Electrostatic levitation is an important method of studying material properties. Without using a container, a physical object is levitated between electrostatic plates and melted to the liquid state using a laser. Then, measurements are made via fast cooling or oscillation. Control technology is critical to the electrostatic levitation system. Uncertainty regarding the sample charge during the start-up and laser-melting periods often causes disturbances or causes levitation to fail. In this paper, we design a two-step adaptive control strategy with charge estimation and feed-forward control. This method can better adapt to charge uncertainty during the initial stage. In addition, we propose an innovative new method of superimposing oscillation signals via software to measure the material surface tension and viscosity. Unlike the traditional method, this approach does not require extra hardware resources and is flexible with regard to regulating the frequency and amplitude. A control system model with an accurate electric field model is established and used to simulate control progress in order to illustrate the advantage of our control method. Experiments based on a high-speed vision-servo system also validate the effectiveness of the adaptive and oscillation control strategies.

Py4DSTEM: A Software Package for Four-Dimensional Scanning Transmission Electron Microscopy Data Analysis

Scanning transmission electron microscopy (STEM) allows for imaging, diffraction, and spectroscopy of materials on length scales ranging from microns to atoms. By using a high-speed, direct electron detector, it is now possible to record a full two-dimensional (2D) image of the diffracted electron beam at each probe position, typically a 2D grid of probe positions. These 4D-STEM datasets are rich in information, including signatures of the local structure, orientation, deformation, electromagnetic fields, and other sample-dependent properties. However, extracting this information requires complex analysis pipelines that include data wrangling, calibration, analysis, and visualization, all while maintaining robustness against imaging distortions and artifacts. In this paper, we present py4DSTEM, an analysis toolkit for measuring material properties from 4D-STEM datasets, written in the Python language and released with an open-source license. We describe the algorithmic steps for dataset calibration and various 4D-STEM property measurements in detail and present results from several experimental datasets. We also implement a simple and universal file format appropriate for electron microscopy data in py4DSTEM, which uses the open-source HDF5 standard. We hope this tool will benefit the research community and help improve the standards for data and computational methods in electron microscopy, and we invite the community to contribute to this ongoing project.

Achieving a high dielectric tunability in strain-engineered tetragonal K0.5Na0.5NbO3 films

Using a modified Landau-Devonshire type thermodynamic potential, we show that dielectric tunability η of a tetragonal ferroelectric film can be analytically solved. At a given electric field E, η is a function of the remnant polarization (P_0^f) and the small-field relative dielectric permittivity (chi _0^f), which are commonly measured material properties. After a survey of materials, a large η~80% is predicted to be achievable in a (001)-oriented tetragonal (K0.5,Na0.5)NbO3 film. This strain-stabilized tetragonal phase is verified by density functional theory (DFT) calculations. (K0.5,Na0.5)NbO3 films based on this design were successfully prepared via a sputtering deposition process on SrRuO3-buffered (100)SrTiO3 substrates. The resulted epitaxial films showed a sizable P_0^f (~0.21C m−2) and a large chi _0^f (~830–860), as well as a large η close to the theoretical value. The measured dielectric tunabilities as functions of E are well described by the theoretical η(E) curves, validating our integrated approach rooted in a theoretical understanding.

Effects of anti-resorptive treatment on the material properties of individual canine trabeculae in cyclic tensile tests.

Osteoporosis is defined as a decrease of bone mass and strength, as well as an increase in fracture risk. It is conventionally treated with antiresorptive drugs, such as bisphosphonates (BPs) and selective estrogen receptor modulators (SERMs). Although both drug types successfully decrease the risk of bone fractures, their effect on bone mass and strength is different. For instance, BP treatment causes an increase of bone mass, stiffness and strength of whole bones, whereas SERM treatment causes only small (4%) increases of bone mass, but increased bone toughness. Such improved mechanical behavior of whole bones can be potentially related to the bone mass, bone structure or material changes. While bone mass and architecture have already been investigated previously, little is known about the mechanical behavior at the tissue/material level, especially of trabecular bone. As such, the goal of the work presented here was to fill this gap by performing cyclic tensile tests in a wet, close to physiologic environment of individual trabeculae retrieved from the vertebrae of beagle dogs treated with alendronate (a BP), raloxifene (a SERM) or without treatments. Identification of material properties was performed with a previously developed rheological model and of mechanical properties via fitting of envelope curves. Additionally, tissue mineral density (TMD) and microdamage formation were analyzed. Alendronate treatment resulted in a higher trabecular tissue stiffness and strength, associated with higher levels of TMD. In contrast, raloxifene treatment caused a higher trabecular toughness, pre-dominantly in the post-yield region. Microdamage formation during testing was not affected by either anti-resorptive treatment regimens. These findings highlight that the improved mechanical behavior of whole bones after anti-resorptive treatment is at least partly caused by improved material properties, with different mechanisms for alendronate and raloxifene. This study further shows the power of performing a mechanical characterization of trabecular bone at the level of individual trabeculae for better understanding of clinically relevant mechanical behavior of bone.

Investigation the effect of heat treatment on brass defect measurement using Eddy Current Testing

Eddy current technology has been used as a non-destructive method of measuring material properties for many years. Most applications of the eddy current technique lie in locating surface or subsurface flaws and evaluating material characteristics. This paper investigated the effect of heated brass material on material conductivity and defect measurement using eddy current testing (ECT). The ECT signal is compared and analyses in order study the effect of annealing on electrical properties of brass material. Brass block sample is designed and artificial defect with depth of 0.5mm 1.00mm and 2.00mm fabricated using Electrical discharge machining (EDM) machine. Industrial standard ECT set is used inspect the conductivity depth of defect brass sample before and after annealing process. Different frequency of ECT coil excitation are applied in order to determine the suitable ECT inspection frequency on brass material. The experimental results show the heat treatment decrease the conductivity of brass material. Due the changes of electrical properties on heated brass, the measurement of depth defect affected the value of amplitude ECT signal. Where the heated brass material reduced 10% IACS signal.

Effect of different preconditioning protocols on the viscoelastic inflation response of the posterior sclera

Preconditioning by repeated cyclic loads is routinely used in ex vivo mechanical testing of soft biological tissues. The goal of preconditioning is to achieve a steady and repeatable mechanical response and to measure material properties that are representative of the in vivo condition. Preconditioning protocols vary across studies, and their effect on the viscoelastic response of tested soft tissue is typically not reported or analyzed. We propose a methodology to systematically analyze the preconditioning process with application to inflation testing. We investigated the effect of preconditioning on the viscoelastic inflation response of tree shrew posterior sclera using two preconditioning protocols: (i) continuous cyclic loading-unloading without rest and (ii) cyclic loading-unloading with 15-min rest between cycles. Posterior scleral surface strain was measured using three-dimensional Digital Image Correlation (3D-DIC). We used five variables of characterizing features of the stress-strain loop curve to compare the two preconditioning protocols. Our results showed protocol-dependent differences in the tissue response during preconditioning and at the preconditioned state. Incorporating a resting time between preconditioning cycles significantly decreased the number of cycles (10.5 ± 2.9 cycles vs. 3.1 ± 0.5 cycles, p < 0.001) but increased the total time (15.8 ± 4.4 min vs. 51.2 ± 8.3 min, p < 0.001) needed to reach preconditioned state. At the preconditioned state, 2 of 5 characteristic variables differed significantly between protocols: hysteresis loop area (difference=0.023 kJ/m3, p = 0.0020) and elastic modulus at high IOPs (difference=24.0 MPa, p = 0.0238). Our results suggest that the analysis of the preconditioning process is an essential part of inflation experiments and a prerequisite to properly characterize the tissue viscoelastic response. Furthermore, material properties obtained at the preconditioned state can be impacted by the resting time used during preconditioning and may not be directly compared across studies if the resting time varies by 15 min between studies. Statement of significanceAlthough applying a preconditioning protocol by repeated cyclic loads is common practice in ex vivo mechanical characterization of soft tissues, the tissue response is typically not reported or analyzed, and the protocol’s potential effect on the response remains unclear. This is partially caused by lack of a standardized methodology to precondition soft tissues. We present the first systematic analysis of two representative preconditioning protocols used during inflation testing in ocular biomechanics. Our results show protocol-dependent differences in the viscoelastic response during the preconditioning process and at the preconditioned state. Consequently, the analysis of the preconditioning response represents an essential part of mechanical testing and a prerequisite to properly characterize the tissue viscoelastic response. The effect of preconditioning on the preconditioned state response must be considered when comparing results across studies with different preconditioning protocols.

Failure analysis of automobile engine pump shaft bearing

The shaft bearing is the key component of water pump and its fatigue failure results in the abnormal operation of the system. However, the failure mechanisms of bearing are still unclear. In this paper, the failure analysis on the engine water pump shaft bearing was carried out by using the measurement of material composition and properties, observation of macro and micro morphologies, and theoretical analysis of fatigue failure. The wear behavior and failure mechanisms were clarified, and the prevention measures was further proposed. The bearing failure reflected from the fracture of bearing cage and serious wear of roller and mandrel. The wear behavior of the mandrel originated from the surface fatigue, and the failure was attributed to the large radial deflection load. Further, the decreased weight of impeller and shaft connector and the increased bearing thickness were recommended to improve the bearing operation.

Review of Recent Microwave Planar Resonator-Based Sensors: Techniques of Complex Permittivity Extraction, Applications, Open Challenges and Future Research Directions.

Recent developments in the field of microwave planar sensors have led to a renewed interest in industrial, chemical, biological and medical applications that are capable of performing real-time and non-invasive measurement of material properties. Among the plausible advantages of microwave planar sensors is that they have a compact size, a low cost and the ease of fabrication and integration compared to prevailing sensors. However, some of their main drawbacks can be considered that restrict their usage and limit the range of applications such as their sensitivity and selectivity. The development of high-sensitivity microwave planar sensors is required for highly accurate complex permittivity measurements to monitor the small variations among different material samples. Therefore, the purpose of this paper is to review recent research on the development of microwave planar sensors and further challenges of their sensitivity and selectivity. Furthermore, the techniques of the complex permittivity extraction (real and imaginary parts) are discussed based on the different approaches of mathematical models. The outcomes of this review may facilitate improvements of and an alternative solution for the enhancement of microwave planar sensors’ normalized sensitivity for material characterization, especially in biochemical and beverage industry applications.

Measurement of Local Material Properties and Failure Analysis of Resistance Spot Welds of Advanced High-Strength Steel Sheets

afety evaluation of resistance spot welds necessitates the accurate measurement of local constitutive properties. This study employed miniature mechanical tests to investigate the deformation and failure behaviors of nugget, heat affected zone (HAZ), and corona bond of resistance spot welded JSC980YL steel. A novel mini-peel test was developed to enable local fracture in HAZ for numerical inverse calibration of constitutive parameters. The fracture constants of weld zones calibrated using Cockcroft-Latham ductile failure criterion were incorporated in finite element models to predict the failure modes of spot welds in tensile-shear and cross-tension coupon tests. The result indicates that the ultimate tensile strengths of the nugget and the corona bond were 37.6% higher and 5.8 % lower, respectively, than that of the base material. The nugget and HAZ exhibited ductile fracture, whereas the corona bond was brittle fracture with only 1.2% elongation. In the coupon tests, the increase of nugget diameter slowed down the damage accumulation rate in the nugget and accelerated that in the HAZ, resulting in the transition of failure mode from interfacial to pullout. The failure load of corona bond in coupon tests increased with the increase of nugget diameter while its contribution to the peak load decreased.

Thermal diffusivity measurement of microscale slabs by rear-surface detection thermoreflectance technique

A new approach to measure the cross-plane thermal diffusivity of a microscale slab sample, which can be fabricated by the focused ion beam and attached to a substrate, is proposed. An intensity-modulated pump laser is applied to heat the front surface of the sample uniformly, and the thermoreflectance signal is observed at the rear surface to evaluate thermal wave transport in the material. The thermal diffusivity can be obtained by fitting the phase lags of the experimental data with a theoretical model. The model was developed for the sample with thin-film coatings and heat transfer to the substrate. Although the absorbed heat can cause a significant DC temperature increase in the microscale sample, a thin-film coating with high thermal conductivity can effectively reduce the DC temperature increase within low thermal conductivity samples. To validate the method, we conducted measurements of a fused silica sample of 2.16 µm thickness, coated with 95 nm Ti film on the front surface and 120 nm Au film on the rear surface. The measured thermal diffusivity is in good agreement with the literature value. The uncertainty analysis shows that the measurement uncertainty is within 6%. This proposed approach, designed for microscale samples, offers a unique option for thermal property measurements of special materials, such as irradiated nuclear fuel or other irradiated materials, to enable microscale property determination while minimizing sample radioactivity.

Welding intensity assessment of pyroclastic units based on engineering quality requirements

Changes to physical and mechanical properties of pyroclastic flow deposits occur during welding process, resulting from overburden pressure and temperature. A great deal of research has been carried out to identify which physical parameters can enable quantification of the degree of welding within pyroclastic deposits. Material properties, such as density, porosity, hardness, abrasion, and compressive and flexural strength, are critical in assessing the suitability of natural stone as a building material, but they have not been sufficiently integrated. Therefore, an attempt has been made to develop a welding classification which integrates measurements of material properties with petrographic and textural observations. The proposed classification covers physical, index, and strength parameters for pyroclastic flow deposits. The most important aspect of this investigation has been the quantification of material parameters and definition of a welding classification applicable to a wide range of ignimbrites, from nonwelded to densely welded, that are used as natural building stone. This welding classification is proposed to ensure a consistent approach in characterizing key aspects of welded facies in pyroclastic deposits and in the identification of natural stone reserves.

A 1-D Model for the Millimeter-Wave Absorption and Heating of Dielectric Materials in Power Beaming Applications

A heat exchanger, based on a millimeter-wave absorbing ceramic composite, is under development. This article describes a 1-D finite-difference model that is used in the design of the heat exchanger. The purpose of this model is to offer a design tool that can rapidly estimate the overall performance of the heat exchanger. This fast model allows for absorber performance to be evaluated over a wide parameter space as opposed to 3-D finite-difference time-domain methods, which provide accurate results but require substantially more computational resources. The model enables quick calculations by approximating the electric field such that the simulation runs on the slower thermal dynamics time scale without having to resolve the faster electromagnetic time scale. Example calculations were performed to illustrate the performance of a realistic absorber. These calculations used experimentally measured material properties for a molybdenum-loaded aluminum nitride (AlN:Mo) ceramic composite. Simulation results show dielectric tiles reaching equilibrium temperature in around 20 s and the samples absorbing up to 70% of the power from the millimeter-wave beam. Parameter studies over Mo loading percentage and boundary condition temperatures highlight the complexity of this coupled system. An AlN:Mo composite with 3% Mo (by volume) exhibits uniform power absorption across multiple boundary condition temperatures and suggests robustness to variety of possible experimental testing conditions.

Measurement of local material properties and failure analysis of resistance spot welds of advanced high-strength steel sheets

Safety evaluation of resistance spot welds necessitates the accurate measurement of local constitutive properties. This study employed miniature mechanical tests to investigate the deformation and failure behaviors of nugget, heat affected zone (HAZ), and corona bond of resistance spot welded JSC980YL steel. A novel mini-peel test was developed to enable local fracture in HAZ for numerical inverse calibration of constitutive parameters. The fracture constants of weld zones calibrated using Cockcroft-Latham ductile failure criterion were incorporated in finite element models to predict the failure modes of spot welds in tensile-shear and cross-tension coupon tests. The result indicates that the ultimate tensile strengths of the nugget and the corona bond were 37.6% higher and 5.8% lower, respectively, than that of the base material. The nugget and HAZ exhibited ductile fracture, whereas the corona bond was brittle fracture with only 1.2% elongation. In the coupon tests, the increase of nugget diameter slowed down the damage accumulation rate in the nugget and accelerated that in the HAZ, resulting in the transition of failure mode from interfacial to pullout. The failure load of corona bond in coupon tests increased with the increase of nugget diameter while its contribution to the peak load decreased.