Force Model Research Articles

Modeling of Cutting Mechanics Analysis of Diamond Core Bits

Diamond core bits are essential tools for coring operations in deep formations during oil and gas drilling projects. By establishing a cutting mechanics calculation model for diamond core bits, this study investigates the changes in bit load and torque under the influence of key factors such as bit cutting structure, rock strength, and diamond distribution density. This research is significant for optimizing bit structure, enhancing coring drilling efficiency, and prolonging bit lifespan. This paper conducts modeling analysis of the cutting element loads for various shaped diamond particles, including rectangular, triangular, cylindrical, and spherical shapes. Based on this, a cutting mechanics calculation model for axial and tangential forces of granular spherical diamonds is established using the fundamental principles of elastoplastic mechanics. Consequently, a set of methods for calculating and analyzing the working loads of diamond core bits is developed. The findings of this paper provide a theoretical basis for studying the rock-breaking mechanism of diamond core bits, evaluating drilling efficiency, and optimizing tooth arrangement structures.

Exploring the potential of Desert Rose fibers (Adenium obesum) for the remediation of oil-contaminated sites

This work proposes the use of Fibers from the pod of Desert Rose, Adenium obesum (DRF), as an alternative for oil removal in spill scenarios and cleaning of contaminated bird feathers. The sorption capacity of biomass was evaluated through kinetics tests, which were adjusted using the Fractal Linear Driving Force (FL-LDF) model. Additionally, capture stability tests were performed to determine the oil retention capacity of the material. Furthermore, the DRF were tested in the cleaning of bird feathers, and the fibers were characterized using Optical Microscopy (OM), SEM, FTIR and TGA. The DRF demonstrated sorption efficiency, with approximately 13.01 ± 1.87 g/g, 14.59 ± 0.58 g/g and 49.12 ± 2.43 g/g, for diesel oils, 20 W50 mineral oil and petroleum, respectively. It was found that these results were achieved by combining the viscosity with the functional groups identified on the material surface, which strongly contributed to the sorption capacity. The sorption kinetics indicated a fast rate in the first minute of testing for diesel oils and 20 W50. The material was still stable, managing to retain 65 %, 83 % and 78 % and removing from the feathers a total of 82 %, 71 % and 81 % of diesel oils, 20 W50 and petroleum. The biomass presented a hollow cylindrical structure, with the presence of grooves and roughness in some regions of its surface with a thin wall, demonstrating to be an efficient and competitive oil sorbent.

Digital dynamic modeling and topology optimized design of shell face mills

This paper presents digital modeling of shell face mills in milling cylinder heads. The cutter's structural dynamics and its mode shapes are predicted using a Finite Element system. The geometries of the cutter body and inserts are imported from their Computer Aided Design (CAD) models. The insert edge is discretized into small segments to model its varying normal rake and inclination angles, which affect the cutting mechanics. The cutter is dynamically assembled with the target machine tool spindle using the receptance coupling method. A general dynamic cutting force model, which considers the varying edge geometry and inserts’ run-outs, is developed and used to predict cutting forces and chatter stability diagrams. The proposed model is experimentally verified to demonstrate the feasibility of the systematic application of physics-based digital design and analysis of tools for the mass machining of specific parts. The cutter body shape is optimized to increase the stiffness of the bending mode shape that caused chatter via topology optimization, which led to five-fold increase in the absolute stable depth of cut.

Promoting Sustainable Mobility: A Walkability Analysis for School Zone Safety

Promoting sustainable mobility and planning walkable school zones is a pressing priority, as it involves the movement of Vulnerable Road Users (VRUs), such as children aged 5–19, along with adult companions, parents, and school staff or faculty. If these children have a safe walking experience today, they will grow up to become ambassadors of sustainable mobility. In this study, several school zone areas were considered in the capital city of India, Delhi. To conduct a comprehensive walkability analysis, three distinct methods were employed: a stakeholder survey, an evaluation of existing walkable corridors, and a microscopic simulation using the Social Force Model (SFM). The limited focus on school zone safety issues in developing nations presents a case for studying the specific concerns of the school zone pedestrians, aiming to assess the magnitude of the problem, provide design centric solutions, and pick an efficient solution for implementation. The results highlight the parameters influencing pedestrian safety in school zones and their effect on pedestrian attributes. This research work can be replicated for school zone safety assessments across the world. This study will benefit the policymakers, urban planners, local government agencies, and traffic management professionals by assisting them in evaluating the walkability of school zones and promoting sustainable mobility choices.

Pedestrian safety behavior modeling method in human-vehicle-intelligence shared road space

In the context of the development of autonomous vehicles sharing road resources with traditional traffic participants in the future, modeling the safe behavior of pedestrians in the shared road space between people, vehicles and intelligence is crucial for the simulation development and reliability and safety testing of autonomous vehicles. To meet this demand, the safe movement behavior of pedestrians is first analyzed, and on this basis, the traditional pedestrian social force model is improved to construct a momentum model for the interactive movement of pedestrians with other pedestrians, traditional vehicles and autonomous vehicles in the shared road space; then, the safety parameters of the model are calibrated using a data set of human-vehicle interactive movement and a genetic algorithm, and a typical shared road space scenario is built to verify the effectiveness of the model. The simulation results show that the model can simulate the real safe movement behavior of pedestrians, and has better simulation effects when used in tasks such as human-vehicle-intelligence shared road space simulation.

Decomposition and Growth Pathways for Ammonium Nitrate Clusters and Nanoparticles.

Understanding the formation and decomposition mechanisms of aerosolized ammonium nitrate species will lead to improvements in modeling the thermodynamics and kinetics of aerosol haze formation. Studying the sputtered mass spectra of cation and anion ammonium nitrate clusters can provide insights as to which growth and evaporation pathways are favored in the earliest stages of nucleation and thereby guide the development and use of accurate models for intermolecular forces for these systems. Simulated annealing Monte Carlo optimization followed by density functional theory optimizations can be used reliably to predict minimum-energy structures and interaction energies for the cation and anion clusters observed in mass spectra as well as for neutral nanoparticles. A combination of translational and rotational mag-walking and sawtooth simulated annealing methods was used to find optimum structures of the various heterogeneous clusters identifiable in the mass spectra. Following these optimizations with ωB97X-D3 density functional theory calculations made it possible to rationalize the pattern of peaks in the mass spectra through computation of the binding energies of clusters involved in various growth and dissociation pathways. Testing these calculations against CCSD(T) and MP2 predictions of the structures and binding energies for small clusters demonstrates the accuracy of the chosen model chemistry. For the first time, the peaks corresponding with all detectable species in both the positive and negative ion mass spectra of ammonium nitrate are identified with their corresponding structures. Thermodynamic control of particle growth and decomposition of ions due to loss of ammonia or nitric acid molecules is indicated. Structures and interaction energies for larger (NH4NO3)n nanoparticles are also presented, including the prediction of new particle morphologies with trigonal pyramidal character.

Nucleation of multi-species crystals: methane cleatrate hydrates, a playground for classical force models

Nucleation and growth of methane clathrate hydrates is an exceptional playground to study crystallisation of multi-component, host-guest crystallites when one of the species forming the crystal, the guest, has a higher concentration in the solid than in the liquid phase. This adds problems related to the transport of the low concentration species, here methane. A key aspect in the modelling of clathrates is the water model employed in the simulation. In previous articles, we compared an all-atom force model, TIP4P/Ewald, with a coarse grain one, which is highly appreciated for its computational efficiency. Here, we perform a complementary analysis considering three all-atoms water models: TIP4P/Ewald, TIP4P/ice and TIP5P. A key difference between these models is that the former predicts a much lower freezing temperature. Intuitively, one expects that to lower freezing temperatures of water correspond to lower water/methane–methane gas–clathrate coexistence ones, which determines the degree of supercooling and the degree of supersaturation. Hence, in the simulation conditions, 250 K (500 atm, and fixed methane molar fraction), one expects computational samples made of TIP4P-ice and TIP5P, with a similar freezing temperature ( T f ∼ 273 K), to be more supersaturated with respect to the case of TIP4P-Ew ( T f ∼ 245 K), and crystallisation to be faster. Surprisingly, we find that while the nucleation rate is consistent with this prediction, growth rate with TIP4P-ice and TIP5P is much slower than with TIP4P-Ew. The latter was attributed to the slower reorientation of water molecules in strong supercooled conditions, resulting in a lower growth rate. This suggests that the freezing temperature is not a suitable parameter to evaluate the adequacy of a water model.

Gap tolerance and molten pool destabilization mechanism in oscillating laser-arc hybrid welding of aluminum alloys

Oscillating laser-arc hybrid welding (O-LAHW) offers significant advantages in enhancing efficiency and mechanical properties. However, in actual production, gap fluctuations can cause instability, limiting its application in large-scale structure manufacturing. In this study, we explored the impact of gap fluctuation on the destabilization of the molten pool in aluminum alloy O-LAHW and identified the maximum gap tolerance for various conditions. High-speed photography revealed that the oscillating molten pool undergoes a transitional state of periodic collapse before complete instability, a behavior distinct from that of a non-oscillating molten pool. We also analyzed the variations in weld geometry prior to destabilization and developed a global force model of the molten pool to identify key geometrical parameters and related driving forces contributing to destabilization. The results show that maintaining a surface tension ratio of over 55 % at the root of the molten pool is crucial for its stability. Additionally, the effects of oscillatory behavior and gap variations on the laser-substrate interaction were explored, revealing the physical mechanisms behind the changes in key geometrical parameters of the melt pool cross-section. The centrifugal effect generated by high-frequency oscillation is identified as a crucial mechanism for extending the duration of periodic collapse compared to non-oscillating molten pools. By discussing the interactions between energy absorption, molten pool shape, and molten pool forces, the study reveals the evolution process of weld destabilization and explains the differences in gap tolerance between oscillating and non-oscillating laser-arc hybrid welding, providing a reference for improving weld stability.

A crystal plasticity phase-field model for microstructure sensitive fatigue crack growth in a superalloy

In this work, a dislocation density-based crystal plasticity phase-field model (CP-PFM) is developed to simulate fatigue crack growth in nickel-based superalloys. Through normalization validation, the plastic dissipation work and crystallographic work are shown to be consistent with the fatigue indicator factors (FIPs), cumulative equivalent plastic strain and cumulative shear strain, and the two energies are computed as the main driving forces of the phase field. Both driving force models are able to obtain fatigue crack growth in close approximation to the experimental rate. However, the model with crystallographic work as the main driving force obtains crack growth paths that are in better agreement with electron backscattering pattern (EBSD) observations, which is attributed to its greater ability to characterize the microstructural susceptibility of fatigue crack growth. Specifically, the model is able to capture the tendency of cracks to crack along the close-packed planes and the hindering effect of grains with large misorientation angles on fatigue crack growth, which together contribute to the curved morphology of fatigue cracks. The combination of large grains or grains with small misorientation angles favors persistent slip band (PSB) formation and leads to softening of the crack tip, which results in lower fatigue crack growth rates.

Simulation of Crowd Evacuation under Attack Considering Emotion Spreading

Abstract In recent years, attacks against crowded places such as campuses and theaters have frequently and negatively impacted social security and stability. In such an event, the crowd will be subjected to higher psychological stress, and their emotion will spread to others rapidly. This paper establishes the Attack-Evacuation Evacuation Simulation Model (AEES-SFM) based on the social force model to consider emotion spreading under attack. In this model, (1)Attack-Escape Derive Force was considered for the interaction between attackers and evacuees and (2) emotion spreading among the evacuees was considered to modify the value of psychological forces. To validate the simulation, several experiments were carried out in a university in China. Comparing the simulation and experimental results, it is found that the simulation results are similar to the experimental results when considering emotion spreading. Therefore, the AEES-SFM proved to be effective. By comparing the results of the evacuation simulation without emotion spread, the emotion spread model reduces the evacuation time and the number of casualties by about 30%, which is closer to the real experimental results. And the results are still applicable in the case of a 40-person evacuation. This paper provides theoretical support and practical guidance for campus response to violent attacks.

Static Model of the Underwater Soft Bending Actuator Based on the Elliptic Integral Function

Underwater soft manipulators are increasingly used for grasping underwater organisms and cultural relics due to their compliance and ability to protect delicate objects. Unlike rigid manipulators, these soft manipulators feature underwater soft bending actuators that deform under external forces, making their shape and output force challenging to predict. Consequently, classical beam theory is no longer applicable. To address these issues, this article models the underwater soft bending actuator as a cantilever beam and establishes its shape and output force using elliptic integral functions. Additionally, this article proposes a method for determining the unknown parameters of the driver shape and output force model using optimization techniques and introduces a solution process based on the particle swarm optimization framework. Given the role of tensile and bending stiffness in the actuator’s performance, this paper employs a parameter identification method based on length and bending angle information. Tests demonstrate that the proposed method effectively estimates the deformation and output force of the underwater soft bending actuators, confirming its accuracy.

Study on seismic performance and restoring force model of framed CFST column-composite box beam joints

Quasi-static tests are conducted on framed concrete-filled steel tubular (CFST) column-composite box beam joints to study the deformation characteristics and restoring force performance under seismic loads. The joints' seismic performance is evaluated. This study shows that the joints with three different connection forms (single-limbed diagonal brace, cross brace, and diaphragm) in the core area have good bearing and energy dissipation capacities. As a result, the joints exhibit excellent seismic performance. The theoretical and fitting analyses of test results reveal the stiffness degradation law for this type of joint. Additionally, a fixed-point directional degradation trilinear restoring force model is established and compared with the test results. The research results indicate that the proposed restoring force model accurately predicts the nonlinear recovery behavior of the joint under seismic loads. This model is in good agreement with the hysteretic curve of the test, providing a theoretical basis for the seismic design and performance evaluation of the joint and for the seismic design and toughness optimization of a structure.

Nonperturbative RG for the weak interaction corrections to the magnetic moment

We analyze, by rigorous renormalization group methods, a Fermi model for weak forces with a single family of leptons, one massless and the other with mass m=Me−β, with M the gauge boson mass, a quartic nonlocal interaction with coupling λ2, and a momentum cutoff Λ. The magnetic moment is written as a series in λ2, with n-th coefficients bounded by Cn(m2M2)β2n(Λ2M2)(1+0+)(n−1) if C is a constant; this implies convergence and provides nonperturbative bounds on the higher order contributions. The fact that the magnetic moment is associated with a dimensionally irrelevant quantity requires the implementation of cancellations in the multiscale analysis. Published by the American Physical Society 2024

Experiment and restoring force model study of precast shear walls with new rabbet-unbonded horizontal connection

The 'rabbet-unbonded horizontal connection' (RUHC) is a new connection form of precast shear wall. This study conducted a low-cycle repeated loading test on three RUHC walls to investigate the hysteretic performance of the walls with the 'axial compression ratio' and 'unbonded level' as the main variables and the results showed that the above two parameters remarkably affected the seismic performance of RUHC walls. Based on the analysis of test skeleton and hysteresis curve characteristic, the influence of parameters such as axial compression ratio and unbonded level on the load and displacement during the loading process was analyzed. The theoretical values of yield, peak and limit points were calculated, and the skeleton curve model was proposed. Moreover, the unloading stiffness formula was proposed by the non-linear relation of dimensionless parameters and Matlab software fitting, and the hysteresis rule model was established. Finally, a three-fold-linear restoring force model of RUHC walls composed of the theoretical skeleton curve and hysteresis rule was established and verified. This model provides an effective prediction for the hysteresis characteristics and a theoretical basis for conducting elastic-plastic analysis of RUHC structures.

Relationship between tension and vertical vibration of roll system of twenty-high rolling mill

Abnormal vibration of the roll system seriously affects the quality of the rolled product and even the occurrence of strip breakage. There are many reasons for roll system vibration, such as roll damage, roll bearing failure, and fluctuations in rolling parameters. Especially for 20-roll high-precision ultra-thin strip mills, a key condition for strip rolling is to apply substantial inlet and outlet tension, with the impact of tension fluctuation increasing as the strip becomes thinner. In this paper, firstly, a dynamic rolling force model that accounts for tension fluctuations and vertical vibrations is established. Subsequently, a vertical vibration dynamics equation for the roll system of the twenty-high rolling mill was established. Then the rolling force model was substituted into the dynamics equation to investigate the relationship between tension fluctuations and roll system vibrations. The results indicate that: (1) Tension fluctuations can cause vibrations in the roll system. With the same fluctuation amplitude, the amplitude of the roller system vibration caused by the inlet tension can reach 10 times the amplitude of the roller system vibration caused by the outlet tension; (2) The vibration amplitude is affected by both the tension magnitude and the fluctuations amplitude and it is mainly influenced by the tension fluctuation when the tension magnitude changes are not significant; (3) Fluctuations in inlet and outlet tension will reduce the damping term and stiffness term, respectively, which increases the main resonance amplitude. Finally, the effectiveness of the model is verified by the experiment. The average inaccuracy between the simulated and measured vibration amplitudes is 13 %.

Stability analysis of multi-leaf oil-lubricated foil bearings with back springs based on nonlinear oil film force model

Stability analysis of multi-leaf oil-lubricated foil bearings with back springs based on nonlinear oil film force model

Chatter stability analysis for non-circular high-speed grinding process with dynamic force modelling

To avoid instability and resulting chatter during the non-circular grinding process, it is necessary to elucidate the potential occurrence of periodic chatter behavior when high-speed grinding loses stability and to define the stability boundary of the grinding system. Building upon an analysis of the geometric kinematic characteristics of non-circular profiled components, a dynamic grinding force model for non-circular high-speed grinding was derived by considering both the delay effect and the elastic yielding mechanism between the grinding wheel and workpiece. Then, A multi-factor coupled dynamic model of non-circular grinding was established. By employing a multi-scale approach, bifurcation analysis and classification of the instability process in the grinding system were conducted, using a typical non-circular profiled shaft component, such as a camshaft, for theoretical analysis and experimental validation. The research determined the stability boundary of the high-speed grinding process for non-circular profile components, validated the possibility of the existence of a conditionally stable chatter region in the non-circular high-speed grinding process, and identified differences in grinding chatter characteristics among different segments of the cam profile, with a greater propensity for chatter at the juncture of the cam fall and base circle.

Hydrodynamic force coefficients for spherical triangle shell fragments: Dependence on the aspect ratio and flatness

Euler–Lagrange simulations of particle-laden flow require hydrodynamic models of drag and lift forces for individual particles. Our goal is to develop models that can prescribe these forces for arbitrarily orientated shell objects. Here, we use computational fluid dynamics simulations of steady bottom-boundary layer flow over a series of spherical triangle shell fragments to calculate the hydrodynamic forces. The simulations explicitly resolve the wall boundary layers using grid resolution on the order of y+=1 at the shell fragment surface and use the SST k-omega turbulence closure model. These fragments cover a range of aspect ratio and flatness characteristics. The shell fragments are generated as triangular selections of a spherical shell with azimuthal and longitudinal angles proscribed based on elongation and flatness parameters (varying between 1 to 5, and 0.02 to 0.2 respectively), while characteristic length of the fragment is held constant to define the overall fragment size. Fragment orientations are considered with independently varying pitch, roll, and yaw each ranging from 0 to 180 degrees. The numerical estimates for the forces from all simulations were used to develop robust parameterizations of the drag and lift as a function of aspect ratio and flatness characteristics, as well as orientation of the shell fragments.

Kinesin-5/Cut7 C-terminal tail phosphorylation is essential for microtubule sliding force and bipolar mitotic spindle assembly

Kinesin-5 motors play an essential role during mitotic spindle assembly in many organisms1,2,3,4,5,6,7,8,9,10,11: they crosslink antiparallel spindle microtubules, step toward plus ends, and slide the microtubules apart.12,13,14,15,16,17 This activity separates the spindle poles and chromosomes. Kinesin-5s are not only plus-end-directed but can walk or be carried toward MT minus ends,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34 where they show enhanced localization.3,5,7,27,29,32 The kinesin-5 C-terminal tail interacts with and regulates the motor, affecting structure, motility, and sliding force of purified kinesin-535,36,37 along with motility and spindle assembly in cells.27,38,39 The tail contains phosphorylation sites, particularly in the conserved BimC box.6,7,40,41,42,43,44 Nine mitotic tail phosphorylation sites were identified in the kinesin-5 motor of the fission yeast Schizosaccharomyces pombe,45,46,47,48 suggesting that multi-site phosphorylation may regulate kinesin-5s. Here, we show that mutating all nine sites to either alanine or glutamate causes temperature-sensitive lethality due to a failure of bipolar spindle assembly. We characterize kinesin-5 localization and sliding force in the spindle based on Cut7-dependent microtubule minus-end protrusions in cells lacking kinesin-14 motors.39,49,50,51,52 Imaging and computational modeling show that Cut7p simultaneously moves toward the minus ends of protrusion MTs and the plus ends of spindle midzone MTs. Phosphorylation mutants show dramatic decreases in protrusions and sliding force. Comparison to a model of force to create protrusions suggests that tail truncation and phosphorylation mutants decrease Cut7p sliding force similarly to tail-truncated human Eg5.36 Our results show that C-terminal tail phosphorylation is required for kinesin-5/Cut7 sliding force and bipolar spindle assembly in fission yeast.

Elucidating the dynamics of carbamazepine uptake using date pit-derived activated carbon: A comprehensive kinetic and thermodynamic analysis

Water contamination with pharmaceuticals such as Carbamazepine (CBZ) presents a significant environmental challenge. This study investigates the use of activated carbon derived from waste date pits (DPAC) for the removal of CBZ from water. The impact of several parameters such as pH, temperature, CBZ concentration, and flow rate on the adsorption were assessed. The generated DPAC demonstrated a specific surface area of 309 m2/g, a pore volume of 0.264 cm³/g, and the pores are mainly distributed at 1.86, 2.73, and 3.43 nm. The Langmuir, Freundlich, Sips, and Toth isotherms were used to fit the experimental data, and the results indicate the occurrence of monolayer adsorption and heterogeneous surface conditions. The Linear Driving Force model was used for kinetic analysis, showing improved fit at higher concentrations. Thermodynamic analyses revealed the process to be endothermic, spontaneous, and entropically driven. The DPAC achieved an adsorption capacity of 14.89 mg/g and maintained 94 % effectiveness after the first regeneration cycle and 70 % after four cycles. This study highlights the potential of DPAC as a sustainable adsorbent for advanced water purification.