Hole Diameter Research Articles

On the parametric assessment of fatigue disparities

Efficiently merging fatigue datasets from diverse sources has proven to be a strategic approach for enhancing the reliability of fatigue assessment and design within industry, while concurrently streamlining costs and time. Statistical parametric analysis is an approach that can be applied to fatigue datasets to determine whether the datasets can be deemed statistically significant (different) or statistically insignificant (similar). This paper systematically employed statistical parametric test-statistic hypotheses to assess significance. To validate this approach the paper used as a case study, fatigue data sets generated from varied notched specimens with hole diameters ranging from 0 mm to 3 mm, in addition to data from the literature. In particular, gross stresses were utilized to ensure that the only means to identify differences in the fatigue datasets was through statistical analysis. This approach was observed to work well for geometries with differences in notch geometry as small as 1 mm and was able to identify notch insensitivity in cast iron. Thus, this method can be used to differentiate fatigue datasets based on statistical parameters rather than other physical parameters.

Technology of flame‑induction heating of ferrous metal shavings in hot briquetting installations

As a result of the study of flame‑induction heating of steel and cast iron shavings, optimal heating modes, dimensions of the furnace and the ratio of the sizes of its components (gas‑flame and induction heaters) were established, which served as the basis for the development of a new heating technology, which ensures minimization of dimensions in comparison with known analogues, increasing the productivity and efficiency of the furnace. It has been established that at the stage of evaporation and removal of water vapor and light oil fractions from the chips in the temperature range of 100–550 °C until the optimal oil concentration of 1.5–3.0 % is achieved, among all known methods of muffle heating, gas‑flame heating is the most economical and productive heating, and subsequently, when heating a dehydrated porous mass of metal with a density of 1100–1700 kg/m3 to 850 °C – induction heating in an atmosphere of products of thermal sublimation and destruction of coolant. It is advisable to carry out induction heating with a current frequency of 2.0–2.4 kHz with a ratio of the lengths of the gas‑flame and induction heating zones of 2.0–2.5 and the dimensions of the inductor (height to hole diameter) of 3.7–4.0. The degree of oxidation of hot‑pressed briquettes corresponds to the initial oxygen content in the chips: for steel – 1.3–1.7 %, for cast iron – 0.46–0.47 %. The data obtained made it possible to develop a technology for flame‑induction heating of ferrous metal shavings, as well as the design of a small‑sized furnace with a specific productivity of 6500–9500 kg/m2·h and an efficiency of 40–45 %.

Design and experiment of impeller seed guide device for rice internal suction hole direct seeding device

Multi-grain hole-forming sowing and uniform hole spacing are important agronomic requirements for precise hole-direct seeding of rice.This paper designs a kind of impeller type seed guiding device. The main structural parameters of the impeller seed guide device were analyzed by constructing the kinematics model of the rice seed in the impeller seed guide process. The experiment analysis were carried out with the long-grain rice variety Chuangliangyou 4418 as the seeding object. The optimal structural parameter combination of seeding-guiding device was determined as inner impeller radius 56 mm, blade offset angle 11° and seeding angle 36°. On this basis, the seeding performance test of different seed guiding devices of internal suction seed-metering device was carried out by using rice seeds with different external dimensions. The test results show that the impeller has better cavitation and hole spacing uniformity than the seed guide tube. The average hole diameter is not higher than 21.7 mm, the qualified rate of hole diameter is not lower than 96.1%, and the coefficient of variation of hole spacing is not higher than 10.1%. Compared with the seed guide tube, which is increased by 32%, 16% and 34% respectively, and the average hole distance is about 200 mm in theory.

Web crippling behaviour of high-strength aluminium alloy channel-shaped members with strengthened web holes: Numerical study and new design rules

This study presents a detailed numerical investigation of 7075-T6 and AA-6086 high-resistance aluminium alloy channel-shaped members with strengthened web holes in web crippling. A nonlinear finite element (FE) model was developed and validated against the test results reported by the authors and other researchers. The material properties of 7075-T6 and AA-6086 high-resistance aluminium alloy were also obtained from the literature. Utilising this validated model, an extensive parametric study including 1296 models was carried out. This study examined both cases with clamped and unclamped flanges, and the variables were web thickness, bearing lengths, diameter of web holes, stiffener lengths, internal corner radii, and grades of aluminium alloys. Given the absence of existing standards for calculating the web load-bearing resistance of such members with strengthened web holes, the numerical results obtained from the parametric study were used to develop new design formulas with new coefficients through regression analysis. The design strengths calculated by the proposed design formulas were then compared against the FE results. Finally, a reliability analysis was also performed, demonstrating that the proposed design formulas can accurately predict the web load-bearing resistance for these members.

Comparative analysis of high index core micro structured optical fibers (HIMSOF) and hollow core band gap fibers (HCBGF) performance efficiency in fiber communication system

Abstract This paper has clarified comparative analysis of high index core micro structured optical fibers (HIMSOF) and hollow core band gap fibers (HCBGF) performance efficiency in the fiber communication system. Total fiber dispersion is clarified versus distance between holes in µm at the employment of 850 nm, 1,300 nm and 1,550 nm wavelength transmission. Besides, the total fiber dispersion is also demonstrated against the hole diameter in µm at the employment of 850 nm, 1,300 nm and 1,550 nm wavelength transmission. The total fiber confinement loss is studied and illustrated against the distance between holes in µm at the employment of various wavelength band transmission. Total fiber losses are demonstrated in relation to the distance between holes in µm at the employment of 850 nm, 1,300 nm and 1,550 nm wavelength transmission.

Investigation on the Influence of Film Cooling Structure on the Flow and Heat Transfer Characteristics of Axisymmetric Plug Nozzle

Some numerical simulations were used to study the effects of blowing ratio (0.25–0.5), hole diameters(0.65~1 mm), and hole inclination angle (30~60°) of the film cooling structure on the cooling and aerodynamic characteristics of the axisymmetric plug nozzle under the condition of transonic. The results showed that the bow shocks appear near the film holes on the plug wall in the supersonic region, which cause the wall cooling effectiveness of the plug to decrease. Compared with the baseline plug, the blowing ratio ranged from 0.25 to 0.5, the wall average temperature of the rear plug decreased by 34.4~48.1%, the thrust coefficient and total pressure recovery coefficient decreased by 0.31~0.61% and 0.52~0.93%, respectively. When the perforated percentage is constant, the wall cooling effectiveness increases with the decrease of the hole diameters. The increase in the inclination angle of the film holes lead to the decrease in cooling effectiveness and aerodynamic performance. This is because the penetration ability of the cooling air to the mainstream is enhanced, and the obstruction to the mainstream boundary layer is increased, resulting in the increase of bow shock intensity near the film holes in the supersonic region.

Enhanced solar energy utilization of thermal energy storage tanks with phase change material and baffle incorporating holes

In response to the pressing need for more efficient thermal energy storage solutions, this study investigates the strategic implementation of baffles in phase change material (PCM) tanks to enhance thermal performance. PCM offers a promising solution for efficient thermal energy storage (TES); however, ensuring uniform temperature distribution inside the tanks remains challenging. Horizontal baffles with holes of varying diameters were introduced in Tanks 02, 03, and 04, while an inclined baffle with holes was used in Tank 05. The Tank 06 benefitted from an inclined baffle with holes of different diameters. A comprehensive analysis of all Tanks was evaluated by assessing PCM and water heat flux, PCM and water static enthalpy, Richardson number, velocity vectors, temperature, and liquid fraction contours. The results demonstrated that significant improvements were achieved with the addition of baffles. Tank 01, without a baffle, exhibited a melting time of 2860 s. However, the introduction of baffles resulted in reduced melting times for Tanks 02 to 06: 2360 s (17.48 %), 2350 s (17.83 %), 2400 s (16.08 %), 2320 s (18.88 %), and 2240 s (21.67 %), respectively; which led to enhance TES efficiency, and a quicker energy storage process. The study also includes a comprehensive economic analysis, evaluating the total cost (Ctotal) and performance-economic ratio (Pc). Tank 06 shows superior economic performance, with a Pc value of 0.26 despite a slightly higher cost than Tank 01 by $2 USD. These findings highlight the baffle design’s effectiveness in achieving better heat transfer and uniform temperature distribution within PCM tanks, making them more efficient for TES applications.

Experimental and numerical investigation of the effects of porous bleed systems on a model scramjet inlet under high backpressure conditions

In this study, we conducted experimental and numerical investigations to assess the effects of backpressure and configurations of porous bleeds on a scramjet inlet's performance at Mach 5. Experiments in a high-enthalpy wind tunnel, using a backpressure controller and a porous bleed with 1 mm holes and 10 mm lateral spacing, were paired with Reynolds-averaged Navier-Stokes simulations to explore the mitigation of flow separation and the prevention of inlet unstart under various backpressure conditions. The simulations provided insights into how backpressure levels and porous bleed geometries impact internal flow structures, as well as the critical backpressure ratio at which inlet unstart occurs. Additional simulations varied the bleed system's hole diameter and spacing, identifying configurations that optimize aerodynamic performance by enhancing total pressure recovery and Mach number at the isolator exit, while reducing bleed mass flow rates. The study also quantified the impact of these configurations on engine thrust, determining that certain bleed system designs significantly improve thrust by efficiently suppressing the interaction between the core flow and corner recirculation zones. This study examined the internal three-dimensional flow structure characteristics under high back pressure and provided insights into porous bleed configuration capable of efficiently suppressing inlet unstart.

Deformation mechanism of glass microlenses and microlens arrays in contactless hot embossing

AbstractContactless hot embossing has been demonstrated to possess the potential for cost‐effective production and precise mounting concepts in fabricating glass microlenses and microlens arrays due to the reduced difficulty of mold fabrication and the possibility of obtaining self‐aligned assemblies. This study aims to provide experimental evidence for understanding the forming mechanism of glass microlenses and microlens arrays in the contactless hot embossing process. The effects of process parameters, diameter and position of the micro‐holes, hole diameter, and pitch of the micro‐hole array mold on the filling deformation of glass in contactless hot embossing were comprehensively investigated. It is found that placing the micro‐hole farther away from the mold center renders decrease in both filling height and tip curvature but increase in the eccentricity of the embossed glass microlens. As a result, the formed glass microlens array shows a nonuniform distribution of filling height and tip curvature. Furthermore, reducing the pitch of micro‐hole array mold can significantly improve the uniformity of formed microlens array. Based on these experimental results, the forming mechanism of microlenses and microlens arrays in contactless hot embossing process is summarized. Finally, a glass microlens array with decent uniformity in the center area was hot embossed by using a SiC micro‐hole array mold.

Observation of Gap Phenomena and Development Processing Technology for ECDM of Sapphire

The main purpose of this study was to develop observation techniques and processing technology for the electrochemical discharge machining (ECDM) of sapphire wafers. To measure the effect of gas-film thickness, discharge-spark conditions, and droplet sliding frequency on machining quality and efficiency in ECDM, this research utilized high-speed cameras to observe the gas film thickness and formation of the gas film during ECDM. Additionally, this study observed the machining-gap phenomena during ECDM. The formation mechanism and machining characteristics of the gas film were understood through experiments. The machining parameters included the liquid level, working voltage, rotation speed, and duty factor. This study analyzed and discussed the effect of each machining parameter on the gas-film thickness, current, electrode consumption, and droplet sliding frequency. Moreover, this study aimed to obtain optimized machining parameters to overcome the difficulty of machining sapphire. The experimental results indicated that utilizing a high-speed camera to capture the phenomena between electrodes during electrochemical discharge could effectively observe the gas-film thickness and the coverage of the gas film. A higher bubble coalescence rate enhanced the machining capability and reduced the lateral discharge. Therefore, this study could obtain better machining-hole depths through observation and analysis to improve gas-film stability and machining capability. This study demonstrated that a liquid level of 700 µm, a working voltage of 48 V, a duty factor of 50%, and a tool electrode rotational speed of 200 rpm could achieve a hole depth of 86.7 µm and a hole diameter of 129.5 µm.

Assessment of Coarse Soil’s Stability Towards Internal Erosion Case of Biskra’s Dam Soil

Abstract Internal erosion is a phenomenon that occurs in soils constituting hydraulic structures under the influence of internal flow. This erosion occurs because of pipe erosion which becomes widespread, leading in some cases to the rupture of the structure. Soils susceptible to piping, generally have particle size instability. This study aims to provide an empirical understanding of the initiation and development of erosion in coarse soil obtained near Biskra’s dam in Algeria. To assess the soil’s dispersiveness chemical analyses such as SAR and PS were conducted, as well as the particle size criteria were verified. The soil was examined in-depth using a double hydrometer test along with Crumb tests. A Hole Erosion Test (HET) device is developed to investigate the effect of certain parameters, such as the compaction degree and the hole diameter on internal erosion’s onset and progression. The results have shown the instability of the soil toward internal erosion given the considerably eroded particles. furthermore, an inverse relationship between the eroded particles mass and the degree of compaction and the initial hole’s diameter is observed.

Research on Extrusion Forming Process of Micro Internal Thread for Nickel-plated Aluminum Alloy Parts

Abstract With the development of electronic products in the direction of miniaturization and lightweight, the specifications of thread gradually become minor, and the high-precision forming of micro threads has become an urgent problem to be solved. In this paper, the extrusion forming process of the micro internal thread was mainly studied on the nickel-plated aluminum alloy parts. The process route suitable for the internal thread forming on electroplated parts was designed, and the key parameters of thread bottom hole diameter and thread tapping speed were determined by experiment. Aiming at the typical problem of internal thread blocked by a broken tap, a thread repair method based on laser ablation was proposed and the laser processing parameters were optimized. Eventually, the manufacturing of M1 micro internal thread on nickel-plated aluminum alloy parts was successfully realized.

Enhancing CO2 Injection Efficiency: Rock-Breaking Characteristics of Particle Jet Impact in Bottom Hole

Storing CO2 in oil and gas reservoirs offers a dual benefit: it reduces atmospheric CO2 concentration while simultaneously enhancing oil displacement efficiency and increasing crude oil production. This is achieved by injecting CO2 into producing oil and gas wells. Employing particle jet technology at the bottom of CO2 injection wells significantly expands the bottom hole diameter, thereby improving CO2 injection efficiency and storage safety. To further investigate the rock-breaking characteristics and efficiency, a finite element model for particle jet rock breaking is established by utilizing the smoothed particle hydrodynamics (SPH) method. Specifically, this new model considers the high temperature and confining pressure conditions present at the bottom hole. The dynamic response and fracturing effects of rock subjected to a particle jet are also revealed. The results indicate that particle jet impact rebound significantly influences the size of the impact crater, with the maximum first principal stress primarily concentrated on the crater’s surface. The impact creates a “v”-shaped crater on the rock surface, with both depth and volume increasing proportionally to jet inlet velocity and particle diameter. However, beyond a key particle concentration of 3%, the increase in depth and volume becomes less pronounced. Confining pressure is found to hinder particle impact rock-breaking efficiency, while high temperatures contribute to larger impact depths and breaking volumes. This research can provide theoretical support and parameter guidance for the practical application of particle impact technology in enhancing CO2 injection efficiency at the bottom hole.

Axial and bending behavior of GFRP bar‐reinforced hollow‐core polypropylene fiber concrete columns

AbstractThis study reported the axial (concentric and eccentric) and bending (four‐point bending) loadings behavior of glass fiber‐reinforced polymer (GFRP) bar‐reinforced hollow‐core polypropylene fiber concrete (HC‐GFRP‐PFC) columns. The confinement effect of HC‐GFRP‐PFC columns with different center‐to‐center (c/c) spacing of GFRP spirals was also investigated. Twelve hollow‐core circular specimens with an outer diameter of 214 mm and an inner (circular hole) diameter of 56 mm were experimentally investigated. Four reference specimens were cast with nonfibrous (normal) concrete, whereas the remaining eight specimens were cast with polypropylene fiber (0.15% by volume of concrete) concrete. It was found that, with a similar ratio of reinforcement, the HC‐GFRP‐PFC specimens gained 2%–4% higher maximum load (PMaximum) and 9%–19% higher ductility (μ) than the GFRP bar‐reinforced hollow‐core nonfibrous concrete (HC‐GFRP‐NFC) specimens under concentric axial loading and four‐point bending. The HC‐GFRP‐PFC specimens with a 30 mm c/c spacing of the GFRP spiral gained 6%–36% higher PMaximum and 4%–59% higher μ than the HC‐GFRP‐PFC specimens with a 60 mm c/c spacing of the GFRP spirals under different loading conditions.

Residual stress determination by blind hole drilling and local displacement mapping in aluminium alloy aerospace components

The determination of residual stresses by combining blind hole drilling and optical interferometric measurement of relief deformation is re-visited to evaluate its applicability to aerospace structures. The experimental methodology involves drilling a deep blind hole and evaluating the hole diameter increments in the principal strain directions using electronic speckle-pattern interferometry (ESPI). This is followed by the determination of the principal residual stress components via the solution of the inverse correlation problem. The study presents the pathway to overcoming one of the primary obstacles in residual stress determination, namely, the optimization of the measurement and interpretation procedures to obtain reliable results. It can be concluded from the analysis of the problem that the formulae connecting the raw experimental data and to the sought residual stress component values lead to a well-posed inverse problem. This makes it possible to obtain estimations of the measurement uncertainty. High density fringe patterns from ESPI provide a rapid and reliable method for residual stress determination, as illustrated using examples of approximately 160 MPa stresses in irregular zones of thick-walled structures.

Visible Light-Illuminated Gold Nanohole Arrays With Tunable On-Chip Plasmonic Sensing Properties

Since the discovery of the extraordinary optical transmission phenomenon, nanohole arrays have attracted much attention and been widely applied in sensing. However, their typical fabrication process, utilizing photolithographic top-down manufacturing technologies, has intrinsic drawbacks including the high costs, time consumption, small footprint, and low throughput. This study presented a low-cost, high-throughput, and scalable method for fabricating centimeter-scale (1×2 cm2) nanohole arrays using the improved nanosphere lithography. The large-scale close-packed polystyrene monolayers obtained by the hemispherical-depression-assisted self-assembly method were employed as colloidal masks for the nanosphere lithography, and the nanohole diameter was tuned from 233 nm to 346 nm with a fixed period of 420 nm via plasma etching. The optical properties and sensing performance of the nanohole arrays were investigated, and two transmission dips were observed due to the resonant coupling of plasmonic modes. Both dips were found to be sensitive to the surrounding environment, and the maximum bulk refractive index sensitivity was up to 162.1 nm/RIU with a 233 nm hole diameter. This study offered a promising approach for fabricating large-scale highly ordered nanohole arrays with various periods and nanohole diameters that could be used for the development of low-cost and high-throughput on-chip plasmonic sensors.

The Effect of The Throat Length and The Hole Diameter in Throat Portion of The Venturi Nozzle on Aeration Efficiency

The Effect of The Throat Length and The Hole Diameter in Throat Portion of The Venturi Nozzle on Aeration Efficiency

Shaking a container full of perfect liquid; a tractable case, a torus shell, exhibits a virtual wall

Manipulation (‘shaking’) of a rigid container filled with incompressible liquid starting from stationary generally results in some displacement, or mixing, of the liquid within it. If the liquid also has zero viscosity, a ‘perfect’ or ‘Euler’ liquid, Kelvin’s theorems dramatically simplify the flow analysis. Response is instantaneous; stop the container and all liquid motion stops. In fact an arbitrary manipulation can be considered as alternating infinitesimal translations and rotations of the container. Relative to the container, the liquid is stationary during every translation. Infinitesimal rotations (an infinitesimal vector along the rotation axis) resolve into three orthogonal components in the container frame. Each generates its own infinitesimal liquid displacement vector field. Their combined consequences are usually obscure. Rather than a volume flow, a surface flow in 3D is considerably easier, the liquid slipping freely in a shell, sandwiched between two nested closed surfaces with constant infinitesimal gap. The closedness avoids extra boundaries. The two dimensionality admits a scalar streamfunction determined by the container angular velocity vector. Manipulation of the container angular velocity at will, usually leads to an infinitely rich variety of area preserving re-configurations of the liquid. In particular, any chosen point of the liquid can be moved, in the shell container frame, to any other chosen point. However, for a torus (shell) with a small enough hole (diameter < 0.195 torus diameter), there exists a virtual wall, a hypothetical axial cylinder intersecting the torus. No matter how the torus is manipulated, liquid inside the cylinder stays inside; outside stays outside. The analysis, solving for the streamfunction, is based on the relative vorticity, and the conformal mapping of a torus to a (periodic) rectangle, which lead to a fairly simple convolution integral formula for the flow.

A novel Zende’s-TOPSIS method towards estimation of measurement uncertainty in hole diameters

The ‘Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS)’ is one of the best methods for ‘Multi-Criteria Decision-Making’ and ‘Multi-Objective Optimization’. The traditional TOPSIS method determines the best alternative under fixed conditions. However, it cannot determine the best upper limit and lowest limit values. This work explains the detailed methodology of the newly developed Zende’s-TOPSIS method which was used to estimate the measurement uncertainty in hole diameters. Four identical holes and one center hole in an industrial component were measured to investigate measurement uncertainty. According to the experimental results, Zende’s-TOPSIS method performed better than the traditional TOPSIS method. The percentage improvement in the Zende’s-TOPSIS method over the traditional TOPSIS method ranges from 0.0209% to 0.3053%. Using Zende’s-TOPSIS method, the percentage maximum measurement uncertainty for four identical holes varies from 0.8067% to 1.0222%, whereas for the center hole, it varies from 0.5261% to 0.5576%. Similarly, the percentage minimum measurement uncertainty for four identical holes varies from 0.3839% to 0.6406%, whereas for the center hole, it varies from 0.4014% to 0.4041%. The proposed method is also capable of estimating the machined tolerances of the component, which ranges from 18.0772 mm to 18.1708 mm for four identical holes and 49.2215 mm to 49.2572 mm for the center hole. The proposed method can solve various ‘Multi-Objective Optimization’ problems.

Damage and Fragmentation of Rock Under Multi-Long-Hole Blasting with Large Empty Holes

The technique of multi-long-hole blasting with large empty holes has been used in practice to break rock mass. However, the damage mechanism of rock mass surrounded by empty holes and boreholes under this type of blasting has not yet been well-understood and identified, which may lead to inappropriate design of the configurations of empty holes for multi-long-hole blasting. The present study investigates the damage modes and mechanism of rock mass under multi-long-hole blasting with large empty holes by conducting a field test and numerical simulations. The results show that multi-long-hole blasting with empty holes mainly causes compressive damage of rock mass around boreholes, reflected tensile damage near empty holes and ground surface, bending-induced tensile damage between empty holes and boreholes, shear damage along the side tangents and bottom of empty holes and boreholes, and tensile damage along the connection of boreholes caused by the superposition of stress waves. In addition, parametric studies are conducted to examine the effects of depths and diameters of empty holes and the spacing between boreholes and empty holes on the damage and fragmentation of rock mass under blast loads. It is found that the flexural stiffness and confined levels of rock mass can be greatly influenced by the variation of configurations of empty holes, which thus induces different damage and fragmentation under multi-long-hole blasting. Analytical formulas for the evaluation of shear and bending-induced damage of rock mass under multi-long-hole blasting are finally proposed to provide references for the design of empty holes in multi-long-hole blasting.