Circular Rods Research Articles

Mechanism and application of drill pipe bending induced borehole collapse in soft coal seam drilling

AbstractGas extraction drilling is a necessary measure for managing gas hazards. For soft coal seams where gas extraction drilling holes are prone to collapse, it is believed that drill rod disturbance is the main cause of hole collapse. This study proposes a research approach to reduce wall stress by optimizing the drill rod structure. Through theoretical analysis, numerical simulation, and industrial tests, a stress model for the drill rod inside the hole was established, and a wall stress equation was derived. The effects of various parameters on wall stress were analyzed. The study suggests optimizing the drill rod structure to reduce the disturbance‐induced wall stress. SolidWorks was used for drilling stress simulation, and a four‐winged concave groove drill rod was developed. After strength verification, comparative industrial tests were conducted. The research results show that as the line density increases, the wall stress of the drilling hole increases. As the length of the suspended section increases, the wall stress initially decreases and then increases. With increasing drilling thrust, wall stress increases linearly, and the growth rate is greater with a larger diameter difference between the drill hole and the drill rod. Numerical simulation results indicate that the critical point maximum stress at the hole entrance, the critical point maximum stress at the hole bottom, and the average stress at the bottom section of the four‐winged concave groove drill rod with a concavity of 5 are significantly reduced compared to those of circular and grooved drill rods. Industrial test results show that using the four‐winged concave groove drill rod significantly reduces the extent of hole collapse. This study provides a reference for addressing the issue of hole collapse in gas extraction drilling for soft coal seams.

Advanced techniques for analyzing solitary waves in circular rods: a sensitivity visualization study

Advanced techniques for analyzing solitary waves in circular rods: a sensitivity visualization study

Evaluation of microstructure and mechanical properties of Al1050/Al2O3/Gr composite processed by forming operation ECAP

Abstract Enhancement of microstructure and mechanical features of the hybrid aluminum matrix composite (HAMC) prepared by the stir-casting process (SCP) is quite significant for failure prevention during the service. In this work, the circular rod of hybrid aluminum matrix composite reinforced with particles of alumina (Al2O3) 50 μm, and graphite (Gr) 40–100 µm fabricated by SCP was adopted. This Al1050/Al2O3/Gr composite was subjected to severe plastic deformation using equal channel angular pressing (ECAP) at room temperature to show the impact of this process on the microstructure and mechanical features of the fabricated composite. Grain refinement, strength, and hardness were evaluated at different forming passes (1P, 3P, and 5P) with two channel angles (die angles) of 120° and 135°. The results revealed that the number of ECAP cycles has a significant effect on the refinement of the grain size. The fifth pass of ECAP (5P ECAP) with a die angle of 120° gave more refinement of the grains in the range of 36–75 nm compared to other passes. On the other hand, the strength and hardness relatively augment until 5P ECAP with increasing the cycle number at two die angles of 120° and 135°. The ultrafine grain can reduce the voids of the aluminum matrix then the hardness is enhanced.

Investigation of rogue wave and dynamic solitary wave propagations of the $$\mathbf{M}$$-fractional (1 + 1)-dimensional longitudinal wave equation in a magnetic-electro-elastic circular rod

Investigation of rogue wave and dynamic solitary wave propagations of the $$\mathbf{M}$$-fractional (1 + 1)-dimensional longitudinal wave equation in a magnetic-electro-elastic circular rod

Bifurcation analysis and solitary wave solution of fractional longitudinal wave equation in magneto-electro-elastic (MEE) circular rod

In this study, we investigate the longitudinal wave equation (LWE) with the M−fractional derivative, which describes the propagation of longitudinal waves along a rod while incorporating interactions between mechanical, electrical, and magnetic fields within the material. Initially, we apply bifurcation analysis to examine the critical points or phase portraits where the system transitions to new behaviors, such as stability shifts or the emergence of chaos, and observe the mechanism of static soliton formation through a saddle-node bifurcation. Subsequently, we utilize a modified simple equation (MSE) technique to find solitary wave solutions. Depending on the relationships between free parameters, the solutions are expressed as hyperbolic, trigonometric, and exponential functions. The numerical form of the obtained solutions reveals complex phenomena, including dark and bright bell waves, kink periodic lump waves, kink periodic waves, periodic lump waves, interaction waves between kink and periodic waves, linked lump waves, and interactions of periodic and lump waves. Additionally, we compare our results with previously published work, demonstrating that the discussed methods are valuable tools for providing distinct, accurate soliton solutions relevant to nonlinear science and technology applications.

Extending the operational range of Francis turbines: A case study of a 200 MW prototype

Francis turbines are now widely used to support the integration of renewable and intermittent energy sources such as solar and wind power. Consequently, these turbines often operate away from their best efficiency point (BEP). Such operations cause detrimental pressure fluctuations in the runner and draft tube, leading to early fatigue failures. To address these harmful flow conditions and extend the operating range of Francis turbines, a mitigation system was developed and tested on a large-scale, high-head 200 MW Francis turbine. The system consists of four circular rods placed in the draft tube with variable radial protrusion lengths, adjustable using linear actuators. Pressure, accelerometer, and vibration sensors installed on the turbine allowed quantification of the rod system performance. The results demonstrate the system’s capability to reduce pressure pulsations by up to 80 % in terms of maximum pressure amplitude and 100 % in terms of fatigue cycle in both low and high-frequency ranges, up to ten times the runner frequency, based on pressure analysis. The optimal rod protrusion ranges from 5 to 20 % of the runner outlet diameter function of the operating load. The impact of the rods’ protrusion on the turbine structure appears negligible from the accelerometer measurements performed on the draft tube and spiral casing. The hydraulic efficiency is reduced by up to 1 %. These findings are significant across a wide range of part-load operations, from 40 % to 60 % load, indicating the potential to extend the operational range of existing Francis turbines. The research presented here is a novel attempt to enhance the existing Francis turbines with a new degree of freedom using protruding rods.

Experimental investigation on retrofitting effects of circular steel rod damper systems on non-seismic detailed reinforced concrete frames

Existing non-seismically detailed low-rise reinforced concrete (RC) buildings are vulnerable to seismic attacks due to their insufficient seismic details including the spacing of transverse reinforcements and splice length at column critical regions. In order to mitigate those deficiencies, various retrofit strategies using externally-bonded reinforcing materials and adding external braced frames have been suggested, and adopted on the construction fields. Although various retrofit methods have been verified their retrofitting effects, there have been architectural concerns and difficulties in providing appropriate connections between supplemental structural systems and existing RC frames. One of the methods applying supplemental energy dissipating devices, this study introduces an externally retrofit method using circular steel rod dampers (CSRDs) which are installed between the existing RC frame and the external sub-frame. The existing RC frame have relatively long natural period and large displacement demand while the external sub-frame has short natural period and small displacement demand. Such relative displacement between two frames is a main mechanism acting the CSRDs. When the interaction of two frames occurs in the CSRD due to the seismic load, the load-transfer mechanism ensures stable hysteretic behaviors of the CSRD even during extreme earthquakes. To verify retrofitting effects of CSRD systems on non-seismically detailed RC frames, this study carried out component-level tests of CSRD systems and their hysteretic characteristics are investigated, especially in terms of their fatigue resistance. Then, full-scale cyclic tests are carried out with non-seismic detailed RC frames with and without CSRD systems in order to confirm the effectiveness of the introduced external retrofit method.

Effects of different loading on the bifurcation of annular elastic rods: Theory vs. experiments

The bifurcation problem of a circular Euler–Bernoulli rod subject to a uniform radial force distribution is investigated under three distinct loading conditions: (i.) hydrostatic pressure, (ii.) centrally-directed, and (iii.) dead load. Previous studies on this apparently ‘familiar’ structural problem have yielded controversial results, necessitating a comprehensive clarification. This study shows that results previously labelled as ‘correct’ or ‘wrong’ simply refer to different external constraints, whose presence becomes necessary only for the two latter loads, (ii.) and (iii.). Moreover, the paper presents the first experimental realization of a circular rod subjected to centrally-directed loads. The experimental findings align with the theoretical predictions and show the exploitation of a new type of load acting on a continuous structural element. The feasibility of this load is demonstrated through the use of inextensible cables and opens the way to applications in flexible robotics when cables are used for actuation.

Elastic wave spin and unidirectional routing in thin rod systems

The unusual topology of elastic waves in continuum systems has been recently uncovered. Prominently, the spin of Rayleigh-Lamb waves has been experimentally observed and used to achieve the unidirectional wave propagation. In this work, the elastic wave spin in thin rod systems is theoretically predicted and experimentally observed, for all the three basic wave modes, i.e., the zero-order flexural, longitudinal and torsional modes. By elaborately building up the subwavelength chiral sources, the spin-momentum locking has been achieved for these three modes within broad frequency range. Interestingly and surprisingly, the spin-momentum locking occurs for flexural and longitudinal modes in both circular and non-circular thin rods; the spin-momentum locking for torsional modes only exits in non-circular thin rods, due to the warping effect in non-circular cross-section rods. Our results open up the door for elastic wave spin in thin rod systems, and provide general tips for the research on basic modes in diverse thin rods, based on either the continuum media or the artificial metamaterials in future.

Heat transfer inside annular passages: A comparison of non-circular and fully circular passages using eco-friendly graphene nanofluid

This research investigates the thermal performance of an annular passage using eco-friendly nanofluids as substitutes for conventional working fluids. Specifically, the study focuses on the utilization of covalently functionalized Graphene Nanoplatelets (GNPs) dispersed in an aqueous medium, with Gallic acid as the functionalizing agent. Nanofluids were synthesized at different weight concentrations (0.1 wt%, 0.05 wt%, and 0.025 wt%) and exhibited an excellent long-term colloidal stability for 39 days, with a relative concentration of 94.4% at 0.025 wt%. Thermophysical property evaluations revealed significant enhancements of 18.25% and 8.23% in thermal conductivity and viscosity, respectively at 0.1 wt%. The nanofluids exhibited average enhancements of convection heat transfer coefficient evaluations indicating improved thermal performance for GaGNPs/DW nanofluids, with the highest average enhancement of approximately 12.11% achieved at 0.1 wt%. To investigate the impact of different annular geometries, a numerical study (CFD) was conducted. Various inner rod shapes, including circular, rectangular, square, triangular, and pentagonal, were considered. The pentagonal cross-section exhibited the highest average increase in convection heat transfer coefficient at 13.9%, followed by rectangular and triangular shapes. In a numerical case study with different thermal boundary conditions, the circular inner rod shape demonstrated the highest thermal performance at 0.1 wt%.

Exploring soliton solutions and interesting wave-form patterns of the (1 + 1)-dimensional longitudinal wave equation in a magnetic-electro-elastic circular rod

Exploring soliton solutions and interesting wave-form patterns of the (1 + 1)-dimensional longitudinal wave equation in a magnetic-electro-elastic circular rod

Machinability of waste bamboo powder ash reinforced 7075-T651/B4C Hybrid composite in computer numerical control lathe

Metal Matrix Composites (MMC) are novelly prepared with the reinforcement of different wood ash in the matrix material to achieve desired properties. Utilizing the waste material for reinforcement may reduce the material cost. Usually, fly ash from thermal power plants has become a popular reinforcement material for MMC through stir casting and employing in friction stir processing. This research is motivated by using ash of waste bamboo powder (AWBP). The waste of bamboo pieces was collected from the furniture industry. They have been gathered, prepared to ash and used as reinforcement of 4 wt%, 8 wt%, and 10 wt% in stir casting of aluminium alloy 7075-T651 and that was optimized as 8 %. The objective of this research is CNC turning type machinability of AA7075-T651/ B4C/AWBP hybrid Composites. The details of the reinforcement are 2 wt% B4C and 8 wt% AWBP. The effects of such reinforcement in AA7075-T651/ B4C/AWBP hybrid composite have improved the friction and wear behaviours, such as high wear resistance and low wear rate. The composite was cased as circular rods. The CNC turning type machinability was investigated in the CNC turning centre. The cutting speed varied from 1000 rpm to 3500 rpm, the feed rate varied from 100 mm per hour to 200 mm per hour. The Al2O3 nanoparticles concentration on cutting fluids varied from 0.25 wt% to 1 wt%. The response surface methodology was used to optimize the parameters. A mathematical model was developed to predict the responses.

THz plane wave scattering by azimuthally periodic array of conformal graphene patches on circular dielectric rod

THz plane wave scattering by azimuthally periodic array of conformal graphene patches on circular dielectric rod

Pipe to annular flow conversion: Numerical study

Large Eddy Simulation (LES) of turbulent flow at the entrance to an annular pipe section has been performed. The flow over a single circular rod, coaxially immersed in a circular pipe is considered. The Reynolds number, based on mean velocity and hydraulic diameter of the annular section, is ReDh=40530. The study aims to gain insights into the turbulence characteristics of the primary and secondary separation bubbles, developing on a side surface of the rod. Key findings include tiny toroidal vortices in the primary bubble's front, forming a vortex train with intermittently shed vortex structures. Large-scale helical stripes have been reproduced at the entrance to the annular section. Tilting of the axially-oriented streaks was observed close to the rod surface. It resulted in a slight anisotropy of the normal Reynolds stresses. The LES data could refine classic Reynolds-averaged Navier-Stokes-based turbulence models.

Dynamic study of new soliton solutions of time-fractional longitudinal wave equation using an analytical approach

In this study, the modified exponential approach is used to investigate the fractional order longitudinal wave equation in a magneto-elastic circular rod, which represents the nonlinear interplay between dispersion and longitudinal wave velocity depending on the rod’s material and geometry. The time-fractional order is used in the standpoint of conformable derivative. Comprehensive and descriptive waveform solutions, including kink-shaped, bell-shaped, and bright bell-shaped solitons, are obtained. The produced soliton solutions are advanced, unique, developed, and crucial. To demonstrate the physical appearance of the obtained solutions, 2D, 3D, and contour graphs of some of the obtained solutions are plotted. The extracted solutions demonstrate the physical significance of the model and express the pressure and electrostatic potential for the longitudinal wave equation and can be used to elucidate more complicated nonlinear models of classical and fractional order. The obtained results are helpful in finding the amplitude of tsunami waves which is of great interest to researchers in the field of ocean engineering. If a tsunami extends across a large area, it becomes a manifestation of solitons. The comparison of the obtained solutions is also given in the form of remarks 1 and 2 which shows the novelty of our work.

Integrability and Dynamic Behavior of a Piezoelectro-Magnetic Circular Rod

The present work strives to explore some qualitative analysis for the governing equation describing the dynamic response of a piezoelectro-magnetic circular rod. As a result of the integrability study of the governed equation, which furnishes valuable insights into its structure, solutions, and applications in various fields, we apply the well-known Ablowitz–Ramani–Segur (ARS) algorithm to prove the non-integrability of the governed equation in a Painlevé sense. The qualitative theory for planar integrable systems is applied to study the bifurcation of the solutions based on the values of rod material properties. Some new solutions for the governing equation are presented and they are categorized into solitary and double periodic functions. We display a 3D representation of the solutions in addition to investigating the influence of wave velocity on the obtained solution for the particular material of the rod.

Bifurcations of an elastic disc coated with an elastic inextensible rod

An analytical solution is derived for the bifurcations of an elastic disc that is constrained on the boundary with an isoperimetric Cosserat coating. The latter is treated as an elastic circular rod, either perfectly or partially bonded (with a slip interface in the latter case) and is subjected to three different types of uniformly distributed radial loads (including hydrostatic pressure). The proposed solution technique employs complex potentials to treat the disc’s interior and incremental Lagrangian equations to describe the prestressed elastic rod modelling the coating. The bifurcations of the disc occur with modes characterized by different circumferential wavenumbers, ranging between ovalization and high-order waviness, as a function of the ratio between the elastic stiffness of the disc and the bending stiffness of its coating. The presented results find applications in various fields, such as coated fibres, mechanical rollers, and the growth and morphogenesis of plants and fruits.

Tunable THz Leaky-Wave Radiation from Periodic Chains of Graphene-Coated Circular Rods

Tunable THz Leaky-Wave Radiation from Periodic Chains of Graphene-Coated Circular Rods

Investigation of Bifurcation Analysis and Soliton Solutions to the Longitudinal Wave Equation in a Magneto-Electro-Elastic Circular Rod

Investigation of Bifurcation Analysis and Soliton Solutions to the Longitudinal Wave Equation in a Magneto-Electro-Elastic Circular Rod

Pressure sensor based on two-dimensional photonic crystal ring resonator

This paper proposes a novel pressure sensor utilizing a two-dimensional photonic crystal (2DPC) based on a ring resonator design. The sensor consists of a square ring resonator that is connected to two photonic crystal waveguides. The photonic crystal is comprised of a square lattice of circular Silicon dielectric rods with air serving as a background. The proposed sensor operates within a pressure range of 0 to 6 GPa, corresponding to a wavelength range of 1554 nm to 1569 nm. The band structures and transmission characteristics of the proposed sensor are studied using the plane wave expansion (PWE) and finite-difference time-domain (FDTD) methods. The normalized transmission spectra of the sensor are observed by varying parameters such as the refractive index, radius, lattice constant, and pressure value, resulting in corresponding wavelength shifts. The proposed sensor design offers a compact size, a wide dynamic range of 6 GPa pressure, and a high sensitivity of 3 nm/GPa. These properties make it highly suitable for a range of applications such as high-pressure or stress-sensing, medical applications, and long pipeline strain monitoring.