Cone Angle Research Articles

Impacts of Transition Piece Designs on the Resilience of Large Offshore Wind Turbines Subject to Combined Earthquake, Wind and Wave Loads and Soil‐Structure Interaction

ABSTRACTThe urgent global drive to mitigate greenhouse gas emissions has significantly boosted renewable energy production, notably expanding offshore wind energy across the globe. With the technological evolution enabling higher‐capacity turbines on larger foundations, these installations are increasingly situated in earthquake‐prone areas, underscoring the critical need to ensure their seismic resilience as they become a pivotal component of the global energy infrastructure. This study scrutinises the dynamic behaviour of a 15 MW offshore wind turbine (OWT) under concurrent earthquake, wind and wave loads, focusing on the performance of the ultra‐high‐strength cementitious grout that bonds the monopile to the transition piece. Employing LS DYNA for numerical simulations, we explored the seismic responses of four OWT designs with diverse transition piece cone angles, incorporating nonlinear soil springs to model soil‐structure interactions (SSIs) and conducting a site response analysis (SRA) to account for local site effects on ground motion amplification. Our findings reveal that transition pieces with larger cone angles exhibit substantially enhanced stress distribution and resistance to grout damage, evidenced by decreased ovalisation in the coned sections of the transition piece and monopile, and improved bending flexibility. The observed disparities in damage across different cone angles highlight shortcomings in current design guidelines pertaining to the prediction of grout stresses in conical transition piece designs, with the current code‐specified calculations predicting higher stresses for transition piece designs with larger cone angles. This study also highlights the code's limitations when accounting for grout damage induced by stress concentrations in the grouted connections under seismic dynamic loading conditions. The results of the study demonstrate the need for refinement of these guidelines to improve the seismic robustness of OWTs, thereby contributing to the resilience of renewable energy infrastructure against earthquake‐induced disruptions.

Nanochannel geometry-depended behaviors on ion selectivity for salinity gradient energy harvesting

Nanofluidic osmotic energy, which can be directly converted into electricity, is considered a clean and sustainable energy that effectively utilizes salinity gradients. The rational construction of nanochannel is of great significance to ion transport and osmotic energy conversion, but there is currently little attention paid to naturally formed rough and irregular channels. In this study, a model that considers the effects of nanochannel cone angle and waveform surface on interface reaction coupling was established for osmotic energy conversion. The results indicate that cone angle and waveform have a significant effect on osmotic energy conversion. It is found that the reduction of cone angle and the addition of waveform will improve ion selectivity and increase energy conversion efficiency, and ion rectification effect of corrugated cylindrical channel is the most obvious. Meanwhile, enlarging waveform dimensions leads to a significant overlap of electric double layer, resulting in a growth in cation transference number and selectivity, thereby enhancing the system's energy conversion efficiency, which can reach 49.62%. At low concentration ratios, the waveform dimensions are inversely proportional to the maximum output power, whereas at high concentration ratios, increasing the waveform dimensions and applying the waveform at channel entrance can efficiently improve the maximum output power.

Effect of single and multiple acoustic frequencies on the atomization of a spray

A comprehensive investigation on the behavior of methanol and diesel sprays when subjected to single and multiple-frequency acoustic fields is provided. For all acoustic frequencies, the cone angle and penetration length rise while the Sauter mean diameter (SMD) reduces, indicating an atomization improvement in an acoustic field. Furthermore, the rise in cone angle/penetration length and decline in SMD are observed to be higher at lower frequencies, showing a significant enhancement in the atomization compared to the higher frequencies. Particle image velocimetry is employed to understand the spray dynamics in single/multiple frequency acoustic fields. The velocity vectors show a higher magnitude at lower frequencies compared to the higher ones, indicating the presence of higher acoustic streaming at lower frequencies. The presence of an acoustic source at the bottom of the sprays shows the formation of strong recirculation zones in the sprays, enhancing the mixing due to higher air entrainment because of intense streaming. The streaming is significant at lower frequencies compared to the higher ones. Furthermore, the data predicted using the Rosin–Rammler distribution model show good agreement with the measured one. Empirical relations are developed for the cone angle/penetration length/SMD. The smaller drops' number in the spray is determined to quantify the acoustic frequency's influence on the atomization. The presence of many smaller drops in acoustics is observed, and the number increases at lower and combined acoustic frequencies. Thus, the study unequivocally demonstrates that the presence of low/combined acoustic frequencies is essential for achieving an atomization enhancement.

Experimental study on the spray characteristics of high-pressure liquid ammonia under different ambient conditions

As a promising carbon-free fuel, ammonia is expected to be widely applied in internal combustion engines. However, the physical properties of ammonia are quite different from those of conventional fuels, which leads to different spray characteristics. In this paper, the ammonia spray under injection pressure as high as 80 MPa was visualized by the diffused back-illumination imaging method, and the liquid ammonia spray characteristics under different ambient pressures and ambient temperatures were analyzed. The liquid spray penetration length, cone angle and tip velocity calculated from the spray images provide a reference database for numerical simulation. The results show that the development characteristics of liquid ammonia spray are significantly different under flare flash boiling, transitional flash boiling and non-flash boiling conditions. Flash boiling (especially flare flash boiling) inhibits the initial liquid spray penetration. The spray tip velocity increases first and then gradually decreases under flash boiling conditions. Ammonia spray has obvious radial expansion at the initial stage of flare flash boiling and the spray contour under flare flash boiling conditions is noticeably distorted, forming an obvious dilute region. With the increase of ambient pressure, the intensity of flash boiling reduces, the dilute region gradually disappears, and the distortion of the spray contour gradually weakens. Under non-flash boiling conditions, ammonia spray presents a dense and regular shape; there is no spray acceleration but a sharp decrease in spray tip velocity at the initial stage, and then the spray penetrates forward at a similar velocity. The spray penetration velocity decreases significantly with the increase of ambient pressure. The increase in ambient temperature accelerates the vaporization of ammonia spray. The liquid spray penetration length decreases and maintains with only slight fluctuations during the injection process as the ambient temperature increases from 300 K to 600 K because the vaporization rate and penetration velocity reach a balance.

ARTEMIS Observations of Lunar Crustal Field‐Solar Wind Interaction and Impact on Reflected Plasma Under Weak Radial IMF

AbstractMagnetic anomalies or crustal fields are frequently observed close to the lunar surface, yet their interaction with the ambient plasma is not fully understood. Utilizing data from the Acceleration, Reconnection, Turbulence and Electrodynamics of Moon's Interaction with the Sun (ARTEMIS) spacecraft, we perform case studies of such interactions under radial, weak interplanetary magnetic field. Our analysis shows that while the lunar crustal field direction did not directly affect the velocity and density of reflected ions, it locally increased their pitch angles, favoring growth of ultralow‐frequency waves. Additionally, we find that while the solar wind ions were demagnetized, retaining a nearly constant velocity, the magnetized electrons acquired significant perpendicular drift velocity due to the crustal field, resulting in a Hall current. This current altered the field strength near the lunar surface. The calculated loss cone angles of electrons reflected by the near‐surface field estimated from the Hall current are consistent with observations, suggesting that the crustal field was dominated by the Hall magnetic field. Our study advances our understanding of how lunar crustal fields interact with the solar wind and modify the nearby reflected plasma.

Revisiting Metal Dihalide Complexes with Phosphine Ligands: Isostructurality, Steric Effects, Anagostic Interactions, Crystal Voids, and Energetic Calculations

AbstractThe crystal structures of seven metal dihalide complexes with triphenylphosphine (PPh₃) and two with tribenzylphosphine (PBz₃) have been reanalyzed. The studied complexes include [FeCl₂(PPh₃)₂], [CoCl₂(PPh₃)₂], [CoBr₂(PPh₃)₂], [NiCl₂(PPh₃)₂], [NiBr₂(PPh₃)₂], [NiI₂(PPh₃)₂], [ZnCl₂(PPh₃)₂], [NiCl₂(PBz₃)₂], and [NiBr₂(PBz₃)₂]. A detailed geometric analysis revealed high isostructurality among several pairs. Ligand steric effects were assessed using cone angles and percentage surface coverage. Crystal packing is stabilized by weak C─H⋯π and C─H⋯X (X = Cl, Br, and I) interactions. Notably, [NiCl₂(PBz₃)₂] and [NiBr₂(PBz₃)₂] feature rare intramolecular C─H⋯Ni anagostic interactions. Reduced density gradient (RDG) and noncovalent interaction (NCI) plots confirmed weakly attractive C─H⋯π contacts in all complexes. Void‐volume analysis assessed the mechanical strength of the crystals, while pixel energy and energy frameworks clarified structural stability and dominant interactions. Density Functional Theory (DFT) calculations, along with QTAIM/NCIplot and NBO analyses, as well as electron density (ED) versus electrostatic potential (ESP) plots, were performed to better understand the C─H···Ni interactions and distinguish between agostic and anagostic interactions.

Insights Into the Uranium Phosphine Bonds in [UCp3(PR3)]: A Combined Molecular Orbital, QTAIM and EDA‐NOCV Study

A series of ten uranium(III) complexes with cyclopentadienyl and monodentate phosphine ligands [UCp3(PR3)] with R = Me, Et, nPr, iPr, tBu, Ph, Cy, F and CF3 was investigated using density functional theory calculations. The ligand dissociation energies were calculated, as well as bonding analysis of the uranium‐phosphorus bond performed, using molecular orbitals, bond orders, quantum theory of atom in molecules (QTAIM) analysis and energy decomposition analysis with natural orbitals for chemical valence (EDA‐NOCV). It was found that the bond orders correlate well with the U‐P bond lengths and phosphine cone angles, indicating a large influence of phosphine sterics on the bond properties. All bonding analyses show partial covalent character of the U‐P bond, which is most pronounced for PF3 and least for PtBu3. π‐Backbonding was found for the most π‐acidic phosphine ligands. No good correlation was found between the ligand dissociation energies and bond metrics.

Parameter Optimization of Spiral Step Cleaning Device for Ratooning Rice Based on Computational Fluid Dynamics-Discrete Element Method Coupling

Ratooning rice plants have a high moisture content and strong adhesion during harvesting. Traditional cleaning devices are prone to clogging when processing ratooning rice, resulting in a series of problems such as high grain loss rate and high grain impurity rate. In response to the above issues, this article adopts the CFD-DEM coupling method to design a spiral step cleaning device. A detailed analysis was conducted on the influence of the cone angle and thickness of the spiral-stepped skeletons on the flow state, and flow velocity and pressure distribution cloud maps were obtained under different structural parameters. The vortex morphology under different thicknesses of the spiral-stepped skeletons was compared, and the structural parameters of the device were determined. The motion trajectory and distribution of impurity particles under different inlet flow velocities were analyzed using data superposition, and the appropriate inlet flow velocity range was determined. A test bench was built, and a three-factor quadratic regression orthogonal rotation combination experiment was conducted with fan speed, feeding rate, and device inclination angle as experimental factors. The results of the bench test show that the performance index reaches its optimum when the device inclination angle, fan speed, and feeding rate are 2.47°, 2906 r/min, and 4.0 kg/s, respectively. At this time, the grain impurity rate, grain loss rate, and sieve clogging rate are 2.21%, 2.15%, and 3.5%, respectively. Compared to those of traditional cleaning equipment, these value are reduced by 44.5%, 39.6%, and 83.9%, respectively. This study can provide ideas for the design of ratooning rice cleaning devices.

Scalar-flat Kähler metrics with varying cone angle singularities along a divisor

Using an ansatz due to LeBrun we construct complete scalar-flat Kähler metrics with a prescribed varying conical singularity along a divisor.

Optimization flutter response of laminated smart nanocomposite truncated conical shell under supersonic aerodynamic pressure using hybrid IGWO-DQHFEM

Given the wide application of conical shells in the aerospace and aircraft industry, there comes a need for dynamic analysis and optimum design of these structures against supersonic aerodynamic forces, which induce a phenomenon called flutter. As the key contribution of this paper, a new method has been developed and applied to optimize the dynamic and flutter control of truncated conical shells under supersonic aerodynamic loads. Here, a truncated conical shell with a layered configuration is considered for the optimization of supersonic aerodynamic conditions with smart control, shape, and size optimum design, wherein every layer is reinforced with carbon nanotubes (CNTs). Moreover, a conical shell is considered with piezoelectric properties to smartly control the aerodynamic behavior of the structure, so by applying voltage, it will be possible to control flutter or critical aerodynamic pressure and frequency. The objective of the optimization model is defined based on aerodynamic pressure and frequency of conical shells. Mathematical modeling of the structure with high accuracy is carried out to optimize the model. The supersonic aerodynamic force is considered employing piston theory, where seven variables are used through a high-order shear deformation theory. In the new numerical method, the differential quadrature hierarchical finite element method (DQHFM) is used for the solution of the coupled electro- dynamic equations of the structure and computing the frequency of the structure along with the flutter or critical aerodynamic pressure. The optimization model obtained by the DQHFM method is applied to search the optimum conditions using an Improved Grey Wolf Optimization (IGWO) method. In IGWO, the local search condition is proposed based on the optimum positions and statistical properties of agents in previous positions. Finally, the optimum size, shape, and smart control parameters of the structure such as the length and radius of the cone, cone apex angle, external voltage, CNTs volume fraction, number of layers, and airflow angle are drawn out and discussed by IGWO and DQHFM. The results show that by increasing the cone angle from 30 o to 60 o, the optimum voltage that has to be applied decreases. On the other hand, an optimal radius stabilizes at around 1 m and the optimum volume fraction of the CNTs is 10 %.

Short-range azimuth measurement method based on a single-pulse laser beam expanding mechanism.

Aimed at addressing the problem of azimuth measurement of a short-range target with a pulsed laser, a new, to our knowledge, azimuth measurement method based on a single-pulse laser beam expanding mechanism is proposed based on the research of the pulse laser dynamic/static azimuth detection method. The echo power equation of single-pulse laser beam expanding short-range detection is derived theoretically. Combined with the spatial geometric distribution of the optical path and the normalized sum-difference angle measurement algorithm of the four-quadrant detector, a single-pulse laser short-range azimuth angle calculation model is established. Monte Carlo theoretical simulation and laboratory static measurement experiments are carried out. The influence mechanism of laser emission power, beam expanding reflection cone angle, and target projection size on the probability distribution of azimuth measurement is studied. The results show that with the increase of transmission power and target projection size, the half-width of azimuth measurement distribution decreases, the peak value increases, and the detection accuracy improves. With the increase of the cone angle of the reflected light, the half-width of the azimuth measurement distribution increases, the peak value decreases, and the detection accuracy decreases. As the spot is far away from the coordinate center, it will lead to an increase in the half-width of the azimuth measurement probability distribution, a decrease in the peak value, and a decrease in the detection accuracy.

Research on passive adaptive wall-climbing cleaning and inspection robot of marine cylindrical steel structure based on conical magnetic adsorption wheel

The marine growth cleaning and structural defect detection of steel structures of offshore underwater facilities are essential parts of the inspection and maintenance of offshore platforms. However, a majority part of underwater structures of offshore facilities, such as offshore wind turbines, Jacket platforms, Jack-up platforms, etc., are cylindrical structures. Compared with the planar structures, cylindrical structures have large curvature, and less supporting area, and therefore put forward higher requirements for the performance of the attached surface working robot. This paper proposes a wall-climbing cleaning robot that can move freely on the wall of cylindrical steel structures and passively adapt to cylindrical structures with various curvatures and diameters. According to the structural characteristics of the robot, a static failure model is established to analyze the different instability forms of the robot and the minimum critical magnetic adsorption force is determined. To ensure the minimum mass and the maximum magnetic adsorption force of the conical magnetic adsorption wheelsets, the effects of air gap and cone angle on the performance of the conical magnetic adsorption wheelsets were analyzed parametrically, and the optimal structural size was obtained. Finally, the mobility and capability of the robot on the surface of the different diameter cylindrical structures has been validated through prototype experiments.

Energy-absorbing performance of multi-segmented conical tubes with different connections

Thin-walled tubes are widely used in vehicle engineering due to their exceptional energy absorption capabilities. This study presents a series of multi-segment tapered tubes (MSTs) characterized by varying connection angles and segment counts. The MSTs are designed by establishing different connection angles (α) between adjacent tapered segments. A finite element (FE) model was developed to simulate axial impact loading, which was subsequently validated using the simplified super-folded element (SSFE) theory. The crashworthiness of MSTs with varying connection angles was analyzed. The following conclusions were drawn: (1) When α exceeds 10°, an increase in α leads to a gradual decline in the energy absorption efficiency of the MSTs, resulting in a “descending” load-displacement curve; (2) MSTs with α less than 0° exhibit a greater tendency to buckle under load and demonstrate a more rapid response to external forces; (3) Compared to corrugated straight tubes, the configuration featuring α = −30° and +30°, consisting of three segments and a cone angle of 7.5° (designated as MST3-7.5), significantly enhances specific energy absorption (SEA) and reduces the initial peak crushing force (IPCF).

Parameter Optimization Method for Centrifugal Feed Disc Discharging Based on Numerical Simulation and Response Surface

In this study, a centrifugal feeding disc device is proposed. To investigate the influence of the process parameters on the discharging efficiency and the lifting of the discharging efficiency, the centrifugal feeding disc device was dynamically simulated based on the discrete element method (DEM), and the simulation results were experimentally verified. Based on the quadratic regression orthogonal test method, a significant lossless regression model of process parameters and discharging efficiency was established, and the response surface of the interaction of process parameters was obtained. The results indicated that the order of influence of the process parameters on the discharging speed of the centrifugal feeding disc was as follows: outer turntable speed > inner turntable speed > inner turntable tilt angle > conical turntable angle. The interaction of the conical turntable angle and the inner turntable tilt angle had the greatest influence on the centrifugal feed disc discharge efficiency. The response surface method (RSM) was used to optimize the process parameters, and the optimal combination of process parameters included an outer turntable speed of 135 r/min, an inner turntable speed of 64 r/min, an inner turntable tilt angle of 7°, and a conical angle of 15°. The discharged efficiency of the optimized centrifugal feeding disc device was increased by 31.9%.

High-Pressure Behaviors of Hydrogen Bonds in Fluorine-Doped Brucite.

Brucite, Mg(OH)2 (P3̅m1, Z = 1), is a prototype material for studying hydrogen bonds in solid hydroxides. In this study, substitutional effects of fluorine (F) on the hydrogen-bonding geometries of hydrogenated and deuterated brucite were investigated under ambient conditions and at high pressure using combined experimental methods of neutron powder diffraction, Raman spectroscopy, and infrared (IR) spectroscopy. Under ambient conditions, neutron powder diffraction results showed that F substitution decreased the donor-acceptor distance and increased the hydroxyl covalent bond lengths of both hydrogenated and deuterated brucite, strengthening the hydrogen bond. Red shifts of the hydroxyl stretching modes also indicated an elongation of d(O-H) and d(O-D). High-pressure neutron diffraction experiments were performed on Mg(OH)1.81F0.19 and Mg(OD)1.74F0.26 up to 7.04 and 10.02 GPa, respectively. For both samples, changes in the hydrogen-bonding geometries did not indicate hydrogen-bond strengthening under high pressure. Compared with Mg(OD)2, the doping of F suppressed the increase of the hydroxyl covalent bond length, the hydrogen-bond angle, and the cone angle, inhibiting pressure-induced hydrogen-bond strengthening. High-pressure Raman and IR absorption spectroscopic measurements on Mg(OD)2 and Mg(OD)1.79F0.21 up to 9.7 and 13.7 GPa confirmed that F substitution restrains pressure-induced hydroxyl elongation.

Charged atomization characteristics and influencing factors analysis of aviation kerosene/ethanol blended fuel

ABSTRACT In this study, an experimental apparatus for charged atomization was established to explore the charged atomization modes of blended aviation kerosene/ethanol fuels and the corresponding evolution of atomization modes for E0 (100% aviation kerosene), E10 (10% ethanol + 90% aviation kerosene), E30 (30% ethanol + 70% aviation kerosene), and E50 (50% ethanol + 50% aviation kerosene) blends with varying applied voltages. Furthermore, the influence of the ethanol blending ratio, electrode separation distance, fuel flow rate, nozzle diameter, and other influencing factors on the charged atomization characteristics was investigated. Experimental results within the 0 to 10 kV voltage range revealed that as the voltage increased, the E0 fuel transitioned from droplet formation to spindle shape without exhibiting atomization, while the E10, E30, and E50 fuels displayed a sequential progression of atomization modes including droplet, micro-droplet, pulsed-jet, cone-jet, deflected-jet, and multi-jet configurations. As the ethanol blending ratio increases, the critical voltage required for the transition to atomization mode decreases, while the atomization cone angle gradually increases. The average atomization cone angles are 38.98°, 49.97°, and 66.83° for E10, E30, and E50, respectively. When the nozzle diameter is reduced from 1.05 mm to 0.3 mm, the charged atomization cone angle does not change significantly. With increasing fuel flow, the critical voltage for the atomization mode transition increases progressively, and the charged atomization cone angle also increases. The average atomization cone angles are 65.80°, 88.45°, 93.04°, 103.63°, and 110.97°, respectively.

An MPC-DCM Control Method for a Forward-Bending Biped Robot Based on Force and Moment Control

For a forward-bending biped robot with 10 degrees of freedom on its legs, a new control framework of MPC-DCM based on force and moment is proposed in this paper. Specifically, the Diverging Component of Motion (DCM) is a stability criterion for biped robots based on linear inverted pendulum, and Model Predictive Control (MPC) is an optimization solution strategy using rolling optimization. In this paper, DCM theory is applied to the state transition matrix of the system, combined with simplified rigid body dynamics, the mathematical description of the biped robot system is established, the classical MPC method is used to optimize the control input, and DCM constraints are added to the constraints of MPC, making the real-time DCM approximate to a straight line in the walking single gait. At the same time, the linear angle and friction cone constraints are considered to enhance the stability of the robot during walking. In this paper, MATLAB/Simulink is used to simulate the robot. Under the control of this algorithm, the robot can reach a walking speed of 0.75 m/s and has a certain anti-disturbance ability and ground adaptability. In this paper, the Model-H16 robot is used to deploy the physical algorithm, and the linear walking and obstacle walking of the physical robot are realized.

Global magnetic field properties in the solar wind interaction of Mercury from MESSENGER measurements

The space environment of Mercury is shaped by its proximity to the Sun and by the relatively weak planetary magnetic field, presenting a unique regime of plasmas and shock conditions. We present the global magnetic properties in Mercury's space environment based on more than 4 years of MESSENGER Magnetometer data. We used 20 Hz magnetic field data to examine the magnetic strength, the field configurations, and the fluctuations. We considered both compressional and transverse modes, with frequencies from 5 mHz to 10 Hz, which cover typical ultra-low frequency waves at Mercury. We identified regions of the solar wind, the magnetosheath, and the magnetosphere during over 4\,000 MESSENGER orbits. The solar wind and magnetosheath data were analysed in the solar wind interplanetary magnetic field (IMF) coordinate system, and the magnetosphere data were analysed in the aberrated Mercury solar magnetospheric coordinate system. Each data point was relocated into normalised space using averaged magnetopause and bow-shock models. The magnetic environments for a quasi-parallel and quasi-perpendicular IMF were compared. Under the typical Parker-spiral IMF, the magnetic environment of Mercury features strong fluctuations that are dominated by the transverse mode and stem from interactions at the bow shock and the magnetopause. When they are subjected to a quasi-perpendicular IMF, the magnetic fluctuations diminish, and the magnetic field strength becomes highly compressed throughout the bow shock, magnetosheath, and magnetosphere. Unlike Earth, Mercury exhibits weaker dawn-dusk asymmetries in magnetic field strength and lacks substantial magnetosheath-generated sources of magnetic fluctuations. The magnetic field draping pattern associated with the IMF cone angle at Mercury also differs from that at Earth. Our comparative analysis highlights the critical role of the solar wind Mach number, the radial IMF component, and the system scale size in shaping planetary space environments.

Circular Spline Tooth Longitudinal Modification Design and Contact Analysis for Harmonic Drives with Short Flexspline

Harmonic drives (HDs) with short flexspline (FS) always suffer from small meshing areas and severe stress concentration caused by large cone angles when a short FS is assembled and loaded. To address this issue, a tooth longitudinal modification method for the circular spline (CS) with a double circular arc common-tangent tooth profile (DCTP) is proposed. Using neutral layer and envelope conjugation theories, a mathematical model of the conventional straight CS tooth was developed. A shaping cutter for this tooth profile was then designed through coordinate transformation and meshing principles. The proposed longitudinal modification for the CS was achieved by adjusting the cutter’s trajectory. A precise finite element model of the HD was developed, revealing that tooth longitudinal modification can reduce the maximum contact pressure by 69.6% and significantly increase the contact area for HDs with short FS. This work provides valuable technical references for improving the contact state of HDs with short FS.

Numerical investigation on the influence of cutting parameters on rock breakage using a conical pick

To comprehensively understand the effects of roadheader cutting parameters on rock breakage, this paper conducts a numerical investigation of rock vertical indentation tests using a conical pick, utilizing the discrete element method (DEM). Three crucial cutting parameters, including cone angle, attack angle, and cutting depth, are analyzed as independent variables to elucidate their impact on rock breakage characteristics, such as peak cutting force and specific energy. The research results indicate that the ultimate failure of rock is primarily caused by the accumulation of microcracks from each local fracture, predominantly governed by tensile failure. As the cone angle increases, both the peak cutting force and specific energy exhibit a monotonic upward trend, while the maximum stress at the tip of the conical pick shows a fluctuating pattern. To achieve a balance between cost effectiveness and efficient rock breakage, an optimal cone angle range of 55° to 100° is recommended. The peak cutting force and specific energy decease exponentially as the attack angle increases, with an optimal range of 70° to 90°. Under continuous cutting conditions with a fixed total length of 60 mm, the average peak cutting force increases with cutting depth, while the average specific energy initially decreases and then increases, identifying an optimal cutting depth of 20 mm. These findings have significant engineering implications for optimizing the cutting parameters of roadheader to enhance the efficiency of mechanized excavation.