Radius Deviation Research Articles

Effect of geometric defects on the mechanical properties of additive manufactured Ti6Al4V lattice structures

Lattice structures realized by additive manufacturing (AM) have the great potential for a broad range of engineering applications. However, the lattice structures are involved in geometric defects. This paper focuses the effect of geometric defects on the mechanical properties of Ti6Al4V lattice structures manufactured by laser powder bed fusion (L-PBF), three cell topologies, i.e., body centered cubic with vertical struts (BCCZ), face centered cubic with vertical struts (FCCZ), and face and body centered cubic with vertical struts (FBCCZ) were studied. X-ray computed tomography was used to extract the shape and the distribution of process-induced geometric defects of these three kinds of samples. Probability density distributions of geometric defects in each layer were also established to analyze the effect of the printing sequence on geometric defects. Then these distributions of geometric defects were inputted into Abaqus to build the modified statistical models to study the effect of geometric defects on mechanical properties. It is shown that the deviation of the cross-section radius exhibits normal distribution and the deviation of the center axis offset exhibits logarithmic distribution. And the middle layer of the sample has a better manufacturing precision. The modified statistical model can predict the mechanical properties within an error of 5 %. The strut thickness deviation had a more significant effect on the mechanical properties than the strut waviness.

Impact of Toolpath Pitch Distance on Cutting Tool Nose Radius Deviation and Surface Quality of AISI D3 Steel Using Precision Measurement Techniques.

The selection of the right tool path trajectory and the corresponding machining parameters for end milling is a challenge in mold and die industries. Subsequently, the selection of appropriate tool path parameters can reduce overall machining time, improve the surface finish of the workpiece, extend tool life, reduce overall cost, and improve productivity. This work aims to establish the performance of end milling process parameters and the impact of trochoidal toolpath parameters on the surface finish of AISI D3 steel. It especially focuses on the effect of the tool tip nose radius deviation on the surface quality using precision measurement techniques. The experimental design was carried out in a systematic manner using a face-centered central composite design (FCCD) within the framework of response surface methodology (RSM). Twenty different experiment trials were conducted by changing the independent variables, such as cutting speed, feed rate, and trochoidal pitch distance. The main effects and the interactions of these parameters were determined using analysis of variance (ANOVA). The optimal conditions were identified using a multiple objective optimization method based on desirability function analysis (DFA). The developed empirical models showed statistical significance with the best process parameters, which include a feed rate of 0.05 m/tooth, a trochoidal pitch distance of 1.8 mm, and a cutting speed of 78 m/min. Further, as the trochoidal pitch distance increased, variations in the tool tip cutting edge were observed on the machined surface due to peeling off of the coating layer. The flaws on the tool tip, which alter the edge micro-geometry after machining, resulted in up to 33.83% variation in the initial nose radius. Deviations of 4.25% and 5.31% were noted between actual and predicted values of surface roughness and the nose radius, respectively.

Uncertainty Quantification of Compressor Performance Affected by Data-Driven Blade Geometric Deviations

AbstractAccurate uncertainty quantification of compressor performance arising from blade geometric deviations is conducive to blade optimization design, blade error verification, etc. In order to investigate the impact of actual blade geometric deviations on compressor performance, this study initially conducted measurements of geometric deviations on three sections of 100 blades. Then, the probability density distributions of various geometric deviations were obtained through kernel density estimation. Subsequently, combining data-driven nonintrusive polynomial chaos with Halton sequence, the distribution of sampling points and the construction approach of the response model were determined. Based on the parameterization of a subsonic rotor geometric model, blade samples with different geometric features were generated. Utilizing numerical simulation results of the aerodynamic performance of each sample, the impact of blade geometric deviations on compressor performance was quantified, and sensitivity analysis was conducted using Sobol' index. It was observed that the total pressure ratio was most sensitive to the stagger angle deviation at 50% blade height, while the sensitivity of the isentropic efficiency to each geometric deviation varied with operating conditions. Then, the flow field was divided into five regions based on different flow loss mechanisms, and a viscous loss coefficient was introduced to quantify the flow losses in each region. It was found that various geometric deviations at 50% span section, as well as leading edge radius deviation and stagger angle deviation at 95% span section, have a significant impact on the flow field losses.

Guided Growth With Minifragment Plates for Angular Deformities in the Distal Radius in Skeletally Immature Patients. Preliminary Results.

Growth modulation allows correction of progressive ulnar deviation of the distal radius in skeletally immature patients, which may occur as a consequence of various pathologies. The aim of this study is to evaluate the radiographic results and complication rate in a series of patients treated with minifragment plates. The medical records of 12 patients who underwent guided growth with a minifragment plate on the radial aspect of the distal radius as a consequence of angular deformities in the distal radius were retrospectively reviewed. Demographic data, radiographic changes, and complication rate were analyzed. A total of 14 wrists and forearms were evaluated. The mean age at which surgery was performed was 10.5 years (interquartile range: 9.0 to 11.3). The average time between placement and removal of the material was 28.7 months (SD: 8,89). In each case, a general improvement of the radiographic parameters was obtained. There were 3 postoperative complications, but only 1 of them required reintervention (broken metaphyseal screw). Hemiepiphysiodesis using a minifragment plate is a treatment that respects the surgical anatomy and offers an alternative surgical option for angular deformities of the distal radius in children. Level IV.

Расчет радиуса влияния пластовой дегазационной скважины

In order to increase productivity and increase the load on the clearing face of coal mines, artificial reduction of methane content of the developed layers, which is carried out by wells drilled through the formation. The purpose of the study is to develop a methodology for calculating the radius of influence of degassing formation wells, using which you can manage the effectiveness of these wells, changing the period of degassing by comparing the calculated and actual data. The main parameter for degassing by parallel formation wells is the radius, relative to the axis of the well, from which the methane is extracted. For each particular layer of the Karaganda basin, the distance between the wells is chosen experimentally, taking into account its thickness, permeability and gas content. Determination of the last two factors is complicated, and often in practice there is a deviation of the actual radius of influence from the calculated one, and this factor determines the efficiency of degassing. The developed methodology allows to make effective decisions on the timing of degassing by formation wells on the basis of a comparative analysis of the actual well flow rate with the calculated one, to achieve the standard methane concentrations in the planned production areas. The peculiarity of this methodology is that the decisions made are based on actual flow rate data, which are difficult to determine reliably.

Characteristics of velocity, bubble's radius, and pressure in liquid and gas bubble mixture

The study focuses on the formation of gas bubbles, a crucial phenomenon that significantly impacts the hydrodynamics in liquid–gas reactors. This phenomenon has been observed in industrial engineering, leading to the development of model equations that describe the velocity of a liquid–gas mixture, pressure, and deviation in the gas bubble's initial radius. Kudryashov–Sinelshchikov (KS) established coupled equations (CEs) to describe the dynamics of the liquid–gas mixture. Here, the study aims to investigate the behavior of velocity, deviation in the bubble radius, and pressures by deriving exact solutions of the KSCEs and representing them graphically. The findings show that the velocity can take negative or positive values, representing interfacial velocity or superficial velocity for both liquid and gas, respectively. The pressure may also be negative or positive, corresponding to the shrinking or stretchering of the liquid surface, respectively. The dynamics of the velocity and the deviation in the bubble radius exhibit similar qualitative behavior, while the pressure shows a variant behavior. The dominant parameters are found to be the gas bubble's initial radius and the polytropic exponent. The stability of the steady-state solution is also analyzed. This study contributes to the existing literature by examining the CEs, which have not been studied until now.

Analyzing the dimensional errors in wire electric discharge machining of squeeze casted Al2024/Al2O3/W composite using cryogenic treated electrodes

Distinctive attributes of hybrid aluminum matrix composites enhance their industrial applications; however, reinforcement particulates complicate their machining, specifically when intricate profiles with high precision are involved due to their intended applications. This study investigates the dimensional accuracy of squeeze casted Al2024/Al2O3/W hybrid composite during wire electric discharge machining. A cone-shaped convoluted profile has been opted for machining to address the industrial needs, therefore, dimensional deviation in length, vertex angle and curvature radius of specimens have been assessed. The influence of cryogenic treatment of wire electrodes has been analyzed to control dimensional deviation in machining. Besides this, the influence of four machining variables including pulse duration, wire feed rate, wire runoff speed and wire tension on the dimensions deviations has also been investigated. The findings indicate that the pulse duration and wire tension notably influence the length error and curvature radius error. Additionally, the pulse duration and wire feed rate have been found to significantly impact the vertex angle error. The non-treated wire creates more significant craters and macro voids on the machined surface due to uneven sparking. In contrast, due to its enhanced electrical properties, the cryogenic-treated wire exhibits a comparatively refined microstructure on the machined surface, displaying fewer micro-voids and shallow craters. Comparative analysis shows that cryogenically treated wire offers 65.5 %, 35.3 % and 33.4 % reduction in length error, vertex angle error and curvature radius error than non-treated wire. The findings of this study can be helpful for the manufacturing industry for precision machining of intricate geometries.

A Corneal Biomechanical Study Measured with a Scheimpflug Dynamic Analyser in Soft Contact Lens Wearers.

The aim of this study was to evaluate the biomechanical changes in the cornea after wearing soft contact lenses (CLs) in healthy myopic patients measured with a Corvis ST® (CST, Oculus Optikgeräte GmbH, Wetzlar, Germany) analyser. This prospective, cross-sectional, single-centre study was performed on twenty-two Caucasian patients aged between 19 and 24 years (20.64 ± 1.21 years) range. Five device-specific biomechanical parameters, the central corneal thickness (CCT), and biomechanically corrected intraocular pressure (bIOP) were measured prior to fitting and one month after CL wear. Differences between the means of the deflection amplitude ratio (DA Ratio) and the standard deviation of the DA Ratio (SD DA Ratio) pre- and post-CL wear were found to be significant (p value = 0.002 in both cases). Significant differences were found between pre- and post-CL wear values in CCT (p value = 0.013). For all other biomechanical measures, no significant differences were observed before and after treatment. A significant association was found between changes in bIOP and classification according to changes in Int. Radius (p value = 0.047) and SSI (p value = 0.026) standard deviations. The corneal biomechanical indices provided by CST demonstrate that the fitting of soft CLs is a safe optical compensation method for the stability of corneal stiffness. No significant differences were found pre- and post-CL wear in the assessment of bIOP.

Charge radius relations derived from the nuclear masses for two neighboring isotopes

In this paper, we get the nuclear mass-density parameter of known mass and known charge radius by using the AME2020 nuclear mass database and the CR2013 nuclear charge radius database. For the nuclei with [Formula: see text], we obtained an empirical formula of the constant parameter equal to 0 for the difference of nuclear mass-density parameter between two neighboring isotope. That is, the nuclear mass-density parameter of the two neighboring isotopes was equal. By using this empirical formula combined with AME2020 and CR2013 databases, the calculated value of 625 nuclear charge radii was obtained. The root-mean-square deviation (RMSD) of nuclear charge radius that we have successfully obtained is [Formula: see text][Formula: see text]fm. In addition, one of the corrections is the neutron factor. This correction is the key improvement which reduces the RMSD to 0.0077[Formula: see text]fm. Considering the neutron shell effect, the different shell ranges were divided into two categories for correction, and the RMSD was reduced to 0.0056[Formula: see text]fm. Based on the revised empirical formula combined with the AME2020 database, the calculated and predicted values of nuclear charge radius were obtained with high accuracy. Some of these predictions are also very consistent with experimental values measured in recent years. In addition, we use BP neural network to study the difference of nuclear mass-density parameter on the basis of two categories. The RMSDs obtained are 0.0028[Formula: see text]fm and 0.0038[Formula: see text]fm, respectively. It can be seen that such a division has a certain degree of reliability and feasibility. These results show that the new relation proposed in this paper has simplicity and reliability, which can be compared with other local nuclear charge radius relations.

Synthesis and microstructure of (Ce0.2Zr0.2La0.2Sm0.2Nd0.2)O2-δ high-entropy oxides characterized by fluorite structure

In this work, single-phase (Ce0.2Zr0.2La0.2Sm0.2Nd0.2)O2-δ high-entropy fluorite oxides (HEFOs) were successfully prepared by conventional solid-phase reaction method and crystal structure and microstructure were studied in-depth. Single-phase (Ce0.2Zr0.2La0.2Sm0.2Nd0.2)O2-δ is formed at 1600 °C for 12 h, and five cationic elements are uniformly distributed without any segregation at the micrometer and nanometer scales. And the XRD patterns with Rietveld refinement reveal the formation of single-phase fluorite structure of (Ce0.2Zr0.2La0.2Sm0.2Nd0.2)O2-δ. The SAED patterns on the [0 1‾ 1] band axes are similar to the diffraction patterns of face-centered cubic fluorite structure, and the standard deviation of the cation radius (coordination VIII) distribution of the specimens is 0.1277, which is again identified as forming a single-phase fluorite structure. The bulk specimens are solid compacts free of obvious cracks with randomly distribution porosity at a rare level, and the powder specimens are irregular fragmented shapes with an average particles size of 5.41 μm. The average cation radius and interplanar spacings becomes larger compared with standard fluorite structure of CeO2 due to the cation radius of La3+, Sm3+ and Nd3+ are larger than that of Ce4+, leading to an increase in lattice parameters of the HEFOs. In addition, the concentration of Ce3+ in the Ce cation is only 8.1 %, and the δ-value is calculated to be 0.3081 based on the content of all cations per mole of the substance, which indicates that the composition of the prepared specimen is (Ce0.2Zr0.2La0.2Sm0.2Nd0.2)O1.6919.

Design of Single-Mode Single-Polarization Large-Mode-Area Multicore Fibers.

In laser science and industry, considerable effort is directed toward designing fibers for fiber laser and fiber amplifier applications, each of which offers a particular advantage over the others. Evanescently coupled multicore fibers, however, have been studied less extensively due to the relatively small mode area in the single-mode regime. Here, by proposing a new structure with stress-applying parts in a 37-core fiber and optimizing this structure through a comprehensive framework, we present 21 solutions characterized by large-mode-area and high beam quality in the single-mode, single-polarization regime. Different fiber designs are optimal for different output parameters. In one design, the mode area can significantly increase to above 880 μm2, which is comparable with that of photonic-crystal fibers. Moreover, besides the single-mode operation, the beam quality factor (M2 factor) of the fundamental mode is considered an output parameter in the bent state and is improved up to 1.05 in another design. A comprehensive tolerance analysis is then performed to assess the performance of the designs under deviations from normal conditions. Moreover, in spite of the shifts in the loss of modes, the proposed high beam quality LMA fibers maintain single-polarization, single-mode operation across a wide range of core pitches, bending orientation angles, and bending radius deviations. Our results highlight the potential of multicore fibers for the efficient operation of fiber lasers and amplifiers.

Theory for highly stressed thick-walled elastic spheres and their vibration without small strain approximations

This paper considers how the radii and vibration of an elastic thick-walled sphere is affected by high stresses imposed by high external pressures or by high internal pressures. For simplicity, the sphere consists of idealized Hookean material allowing unlimited compression or expansion. The sphere is filled by material with an isotropic pressure that generally differs from the pressure on the outer surface of the sphere. The analysis includes large strain nonlinear curvature effects where, unlike linear elasticity theory, the difference in radial and tangential strains is not small compared to those strains. Despite the sphere’s robustness, destructive physical consequences are predicted for nonzero Poisson coefficients where, for instance, a high-pressure tank inner stresses make the inner radius approach the less stressed outer radius. This would be avoided if the Poisson coefficient changed with large strains and approached zero. To model the effect of high stresses and strains on breathing mode vibration, an effective spring constant is derived from quadratic radius deviations of the system potential energy from equilibrium. Insights from analysis avoiding linear elasticity approximations may be applicable to improved understanding of deep-sea marine creature survival, improved underwater vessel design for large depths, and safer containers of fluids at high pressures.

Evaluation of the roundness quality of galvanized steel plate due to variations in cutting speed and nozzle diameter during the laser cutting

Generally, laser cutting processes aim to cut materials with high accuracy, as well as precise and near-perfect sizes and results. The purpose of this study is to evaluate the roundness quality of the holes cut by laser cutting on galvanised steel plates; two variations are given, such as cutting speed and nozzle diameter.The type of laser used is a fibre laser. The material used is galvanized steel with a thickness of 3 mm with dimensions of 200 mm in length and 200 mm in width. A round profile is good if the distance between the points of the geometric shape is the same distance from the centre point.The measurement results show that the smallest radius deviation is with an average value of 20.08 mm at a nozzle diameter of 2.5 mm and a cutting speed of 3 m/min, close to the initial radius value of 20.00 mm.During the laser cutting process, The best roundness quality is the combination of a nozzle diameter of 2.5 mm and a cutting speed of 3 m/min with a small deviation (the index deviation is 0.4%). At the same time, the biggest deviation in this experiment is the combination of parameters with a nozzle diameter of 3 mm and a cutting speed of 4 m/min (the maximum deviation value is 1%).The use of the proposed nozzle diameter and cutting speed approach is an important requirement for industrial applications with laser cutting to get the right product for its intended use.This article presents different nozzle diameters and cutting speeds to reveal the roundness quality due to these variations, where the roundness quality will be adapted for a particular application.

Optical Imaging Deformation Inspection and Quality Level Determination of Multifocal Glasses.

Multifocal glasses are a new type of lens that can fit both nearsighted and farsighted vision on the same lens. This property allows the glass to have various curvatures in distinct regions within the glass during the grinding process. However, when the curvature varies irregularly, the glass is prone to optical deformation during imaging. Most of the previous studies on imaging deformation focus on the deformation correction of optical lenses. Consequently, this research uses an automatic deformation defect detection system for multifocal glasses to replace professional assessors. To quantify the grade of deformation of curved multifocal glasses, we first digitally imaged a pattern of concentric circles through a test glass to generate an imaged image of the glass. Second, we preprocess the image to enhance the clarity of the concentric circles' appearance. A centroid-radius model is used to represent the form variation properties of every circle in the processed image. Third, the deviation of the centroid radius for detecting deformation defects is found by a slight deviation control scheme, and we gain a difference image indicating the detected deformed regions after comparing it with the norm pattern. Fourth, based on the deformation measure and occurrence location of multifocal glasses, we build fuzzy membership functions and inference regulations to quantify the deformation's severity. Finally, a mixed model incorporating a network-based fuzzy inference and a genetic algorithm is applied to determine a quality grade for the deformation severity of detected defects. Testing outcomes show that the proposed methods attain a 94% accuracy rate of the quality levels for deformation severity, an 81% recall rate of deformation defects, and an 11% false positive rate for multifocal glass detection. This research contributes solutions to the problems of imaging deformation inspection and provides computer-aided systems for determining quality levels that meet the demands of inspection and quality control.

Study on the aerodynamic performance of inlet pipe different bending radius of ram air system

In this paper, the bending radius deviation of the intake duct is studied. The computational fluid dynamics (CFD) method is used to evaluate the performance of the inlet by the coupling calculation of the internal and external flow of aircraft. Firstly, the CFD method is used to calculate the theoretical numerical model. The results show that when the pipeline flow is constant and the pipeline R/D decreases, such as from 1.84 to 1.3, the total pressure recovery decreases, especially when the pipeline R/D is less than 1.5, the total pressure recovery decreases rapidly. At the same time, the drag force of the pipeline does not change much, and the flow field of the inlet pipeline is analyzed to analyze the internal reasons for the total pressure recovery and flow rate change with R/D, which has important guiding significance for the application of batch production in future.

Complete topographic measurement of the monolithic multi-surface workpiece on a cylindrical cavity

Monolithic multi-surfaces workpieces (MMSWs) are widely used in aerospace, advanced optics, and other fields. The complete topographic measurement of each sub-surface in MMSWs requires high measurement flexibility and strong space constraints since each sub-surface is located in an inner cylindrical cavity. This paper proposes a complete topographic measuring method for MMSWs based on a four-axis measuring system with a rotating single-point probe. Several basic geometric parameters of the measuring system are identified in the calibration. The mapping relation between the theoretical surface equations and measuring system coordinates is established by searching for reference points. The measurement scanning paths with different orientations are designed for each sub-surface. The iterative measurement and optimization are adopted to compensate for the measurement errors from the coupling of the probe and the four-axis measuring system. A standard sphere is measured, and the deviation of the fitting radius is below 0.5 μm. Besides, a freeform four-mirror optical system is selected as the experimental study case, where the complete topographic measurement of each sub-surface is completed on an ultra-precision machine tool. The form error and the standard deviation of each sub-surface can reach the micron level.

Nucleus density based new relationship of nuclear charge radius

In this paper we predict and evaluate the value of the nuclear charge radius by analyzing the relationship between nuclear mass and nuclear charge radius.We obtain 884 nuclei (<i>Z</i>, <i>N</i> ≥ 8) with known mass and known charge radii by combining AME2020 database with CR2013 database, and calculate the mass densities <inline-formula><tex-math id="M3">\begin{document}$ \rho_\text{m} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20230126_M3.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20230126_M3.png"/></alternatives></inline-formula> of the 884 nuclei. We aim to obtain an empirical formula of one constant which is useful in describing and predicting nuclear charge radius. With the empirical formula and the AME2020 database, the root-mean-square deviation (RMSD) of the nuclear charge radius of <inline-formula><tex-math id="M5">\begin{document}$ \sigma = 0.093 $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20230126_M5.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20230126_M5.png"/></alternatives></inline-formula> fm is successfully obtained.Considering the influence of neutron numbers on <inline-formula><tex-math id="M6">\begin{document}$\rho_{\rm{m}}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20230126_M6.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20230126_M6.png"/></alternatives></inline-formula>, we use the neutron factor <inline-formula><tex-math id="M7">\begin{document}${1}/{N} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20230126_M7.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20230126_M7.png"/></alternatives></inline-formula> to correct the empirical formula, and the RMSD is reduced to <i>σ</i> = 0.047 fm (the accuracy is increased by about 50%). The second correction is shell effect of neutrons. The results show that the RMSD of nuclear charge radius is reduced to 0.034 fm based on shell effect of neutrons. We use the empirical formula with corrections to predict the nuclear charge radius (1573 nuclear charge radius with <i>Z</i>, <i>N</i> ≥ 8) which is difficult to measure experimentally. The difference between our predicted values based on AME2020 database and the experimental values measured in recent years is in the allowable range of deviation. The result shows that the new relation for nuclear charge radius is simple and reliable. In addition, the RMSD of the calculation value for 791 nuclei is reduced to σ = 0.032 fm after we have removed some nuclei with special shell effect and isotope chains. These results show that the new relation proposed in this paper can be comparable to <inline-formula><tex-math id="M8">\begin{document}$ A^{1/3} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20230126_M8.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20230126_M8.png"/></alternatives></inline-formula> and <inline-formula><tex-math id="M9">\begin{document}$ Z^{1/3} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20230126_M9.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20230126_M9.png"/></alternatives></inline-formula> formulas with corrections.Moreover, we study the 884 and 791 nuclear mass densities by using L-M neural network method to build description and prediction models. Comparing with CR2013, the RMSDs of nuclear charge radius are <i>σ</i> = 0.018 fm and <i>σ</i> = 0.014 fm, respectively. The RMSDs are reduced by about 50% compared with that from the empirical formula with corrections, and the predicted values are closer to the experimental values measured in recent years.

Optical spectrum detection of synthetic microsphere resonator using a nanofiber.

We demonstrate optical spectrum detection of a synthetic silica microsphere (SSM) resonator with whispering gallery modes fabricated by chemical methods using an optical nanofiber to touch the SSM. Critical coupling, under coupling and over coupling are obtained by controlling the nanofiber radius. The SSM radius deviation, 0.51 nm, can be obtained through multiple measurements when the nanofiber touches the SSM equatorial planes randomly. The scheme opens a new avenue for accurate sample characterization and sample tracking for microparticle detection.

Surface deformation errors and self-adaptive compensation for microstructured surface generation of titanium alloys

In diamond servo cutting (DSC) of microstructured surfaces, the oscillated cutting motion inevitably cause non-uniform surface deformation errors. Although static and dynamic geometric errors for DSC have been studied, few studies focus on the prediction and compensation strategies of the surface deformation errors for microstructured surface generation. This study proposes an microstructured surface generation model of titanium alloys by considering the dynamic cutting forces, material microstructure evolution, thermal-mechanical coupling effect and subsurface stress-strain distribution. Harmonic microstructured surfaces are fabricated to characterize the non-uniform surface deformation errors as well as to validate the proposed model. The results show that the proposed model can accurately simulate the variation of surface plastic and elastic deformation errors as a function of undeformed chip thickness and cutting direction. Compared with the downslope cutting direction, the machined surface in upslope direction is subjected to greater plastic strain and plastic deformation errors even at the same depth of cut, due to cutting direction effect. To compensate surface deformation errors, a cooperative servo cutting (CSC) strategy is proposed by incorporating a self-adaptive fast tool servo into conventional servo cutting. The instantaneous compensation motion of CSC is jointly determined by the curvature radius deviation, instantaneous cutting depth and cutting direction. The experimental results show that CSC can make the error distribution more uniform, and greatly decrease the peak-to-valley surface deformation errors from 1.29 to 0.24 μm for different microstructured surfaces.

Effect of variable capsule size distribution for unstructured packed bed encapsulated phase change material system

Packed bed encapsulated phase change material (PCM) energy storage systems have considerable potential for energy storage applications involved in renewable energy systems. In this paper, a 3D unstructured packed bed system consisting of spherical encapsulated phase change material with varying sizes of spheres is modelled. The main novelty of the work is that the geometry of the capsules and the flow between the capsules are resolved, even with unequal capsule sizes arranged in an irregular manner. The size of the spheres is varied by changing the radius of the spheres following specified normal distribution curves. Then, by changing the mean and standard deviation values, different size distributions of spheres are generated which are arranged in unstructured packed bed form. The model incorporates the flow of heat transfer fluid (HTF) through the gaps between the capsules, the heat transfer in both the HTF and the PCM capsules, the melting of PCM in each capsule, and the natural convection in the melted PCM. Based on the simulations, important parameters such as the melting time and energy storage rates are compared for different size distributions. It is found that for a normal distribution of capsule radius, increasing the mean radius by 2 times while keeping the standard deviation constant increases the melting rate considerably with an increase in melting time by 29.4%. The effect of standard deviation of radius was found to be significantly less as compared to that of the mean radius.