Contact Interaction Model Research Articles

First radial excitations of baryons in a contact interaction: Mass spectrum

We compute masses of twenty positive parity first radial excitations of spin-1/2 and spin-3/2 baryons composed of u, d, s, c, and b quarks in a quark-diquark picture within a contact interaction model. These excitations comprise of two elements; one characterized by a zero in the Faddeev amplitude, representing a radial excitation of the quark-diquark system and the other marked by a zero in the diquark’s Bethe-Salpeter amplitude, corresponding to an intrinsic excitation of the diquark correlation. Wherever possible, we compare our results with other models and/or experiment. We verify that the masses obtained through our model conform to the spacing rules for all the baryons studied, whether light or heavy and whether of spin-1/2 or spin-3/2. The computed masses do not just offer a guide to the future experimental searches but also compare well with the existing candidates for the possible radial excitations of some heavy baryons. Published by the American Physical Society 2024

Method of experimental modeling of contact interaction in a worm – worm wheel pair

Method of experimental modeling of contact interaction in a worm – worm wheel pair

Toward extracting the scattering phase shift from integrated correlation functions. II. A relativistic lattice field theory model

In the present work, a relativistic relation that connects the difference of interacting and noninteracting integrated two-particle correlation functions in finite volume to infinite volume scattering phase shift through an integral is derived. We show that the difference of integrated finite volume correlation functions converges rapidly to its infinite volume limit as the size of the periodic box is increased. The fast convergence of our proposed formalism is illustrated by analytic solutions of a contact interaction model, the perturbation theory calculation, and also the Monte Carlo simulation of a complex ϕ4 lattice field theory model. Published by the American Physical Society 2024

Modeling the wear of the "diamond-containing mineral ceramics — ceramics" friction pair

Based on the solution of the contact mechanics problem, a model of wear of the "diamond-containing mineral ceramics — ceramics" friction pair is constructed, in which diamond grains in the ceramic matrix are represented as spherical segments of the same radius. The law of distribution of diamond grains in a ceramic matrix is power law. The dependences of grinding productivity and wear rate of diamond-containing tools on the physical and mechanical properties of contacting materials, roughness parameters of friction surfaces and loading conditions are obtained. Keywords:abrasive diamond tools, mineral ceramics, ceramics, contact interaction model, productivity, grinding, wear onvk@mail.ru, alnikbltov@rambler.ru, vnvkv@yandex.ru

Modeling of Electrostatic and Contact Interaction between Low-Velocity Lunar Dust and Spacecraft

The accumulation of highly adhesive dust on spacecraft presents a serious issue to hinder long-term extravehicular activity and the establishment of a permanent station on lunar surface. In contrast to the immediate physical damage caused by hypervelocity (>1.0 km/s) impacts, this adhesion observed at low-velocity (0.01 to 100 m/s) collisions can more unobtrusively and mortally degenerate the performance of equipment. This paper proposes a theoretical model aimed at comprehensively analyzing the dynamics of adhesion and escape phenomena occurring during low-velocity impacts between charged dust particles and spacecrafts enveloped by a plasma sheath. The electrostatic force is modeled using the image multipole method, and contact force is calculated based on the adhesive–elastic–plastic theory. The results reveal that the implementation of a dielectric coating possessing both low permittivity and low interface energy can substantially reduce energy dissipation during collisions. However, the ultimate adhesion on the surface or escape from the sheath for low-velocity charged dust is dominated by the long-range electrostatic interaction rather than short-range contact interaction. Positively charged particles of smaller sizes demonstrate a greater propensity for surface adhesion in comparison to negatively charged particles of larger sizes. Counterintuitively, without additional dust removal techniques, modifying the properties of the dielectric coating does not effectively reduce the accumulation of dust, which can be merely accomplished by decreasing the spacecraft’s potential. The model presented in this study serves as a crucial step toward understanding the mechanism of lunar dust pollution.

Modeling of contact interaction of crack banks based on finite element schemes

The problems of modeling the formation and propagation of cracks are relevant in a variety of applied fields: dynamics and strength of machines and mechanisms, mechanics of structural materials and structures, etc. When describing the fracture process, in addition to the fracture criteria, it is also important to correctly take into account changes in the rheology of the destroyed material, including the contact interaction between the surfaces of the cracks and fragments formed. This paper proposes a technique for calculating the stress-strain state of cracked bodies taking into account the contact interaction of crack banks in the normal direction. The technique is based on the transformation of a finite element grid with the introduction of double nodes, as well as an iterative algorithm for determining the contact zones of the crack banks. An example of calculating deformations of a shaft with a crack under the action of body weight at different angular positions of the shaft is given.

Modeling of Contact Interaction of Two-Layer Bodies Taking into Account Adhesion and Rheological Properties of Coating or Substrate Materials

Modeling of Contact Interaction of Two-Layer Bodies Taking into Account Adhesion and Rheological Properties of Coating or Substrate Materials

Robust features of a QCD phase diagram through a contact interaction model for quarks: a view from the effective potential

Robust features of a QCD phase diagram through a contact interaction model for quarks: a view from the effective potential

Uncertainty propagation in discrete element models using PDEM

The Discrete Element Method (DEM) for the analysis of cohesive granular materials, such as concrete, requires the use of contact interaction models with several parameters. Despite the existence of a number of approaches to estimate these parameters, uncertainty in their values is inevitable. This uncertainty propagates across the system, giving rise to uncertainty in the measured response. It is important to estimate this uncertainty and to check and control dispersion in the results in order to improve the predictive ability of the DEM model. This usually requires running a very large number of simulations to effectively sample the space of random parameters and thereby obtain the probability density function (PDF) of the response. Such an approach is not feasible for DEM-based simulations on account of the inordinate computational cost. The present paper provides an alternate approach based on the Probability Density Evolution Method (PDEM). PDEM, which requires fewer sampling points, is employed for the fast and efficient generation of the PDF. The approach is demonstrated through a DEM model developed for the slump test, widely used to determine the workability of fresh concrete. The simulation results are analysed using PDEM, enabling the PDF of the measured response to be determined from the results of a limited number of trials. Moreover, the dispersion in the DEM results is found to be low, with a relatively small coefficient of variation, thereby attesting to the predictive ability of the DEM model.

Simulation model of contact interaction during surface strengthening of steel parts

In the processes of surface strengthening of steel parts, the stress-strain state is decisive for explaining the physical processes of strengthening, forming the dimensions of the contact area. Analytical dependences of contact parameters are quite approximate. In this work, based on the Ansys software complex, a simulated model of the contact of a truncated torus with a cylinder is proposed, which demonstrates the kinetics of the process of pressing a hard alloy tool into a steel workpiece - a cylinder. The experiment was conducted for 4 seconds in order to determine the maximum level of stresses, the distribution of stresses and the amount of residual stresses after removing the load. The clamping force was applied mainly in the zone of elastic deformations. The results showed an uneven stress distribution with a maximum in the center of the contact spot of 1082 MPa. After changing the load direction, small residual deformations at the level of 0.00311 μm were observed in the center of the contact patch. This indicates a violation of the elastic region on a small contact area, which does not affect the general nature of the stress distribution and can be removed during the finishing process. The results of simulation of the stressed state are used for the correlation with the observed structural changes of the material during the action of thermal and power stresses. The stress peak was formed at a distance of 200 μm, which contributes to the formation of maximum values of microhardness at this depth.

QCD phase diagram in the presence of electric and magnetic fields

In this contribution, We revisit the effect of electric eE and magnetic field eB and on the critical temperature T χ,C c of the chiral symmetry breaking/restoration and confinement/deconfinement phase transition in the QCD Phase diagram. In this context, we use the symmetrypreserving vector-vector contact interaction model of quarks, in the Schwinger-Dyson equations framework and in the proper time regularization scheme. We also describe the phenomenon of inverse electric catalysis in the pure electric case, magnetic catalysis (and inverse magnetic catalysis) in the pure magnetic case and inverse electromagnetic catalysis in the presence of both electric and magnetic background fields.

Properties of Pseudoscalar Mesons in a Contact Interaction Model

Properties of Pseudoscalar Mesons in a Contact Interaction Model

Physical implications of the extrapolation and statistical bootstrap of nucleon structure function ratios F2nF2p for mirror nuclei He3 and H3

A nuclear physics example of statistical bootstrap is used on the MARATHON nucleon structure function ratio data in the quark momentum fraction regions ${x}_{B}\ensuremath{\rightarrow}0$ and ${x}_{B}\ensuremath{\rightarrow}1$. The extrapolated ${F}_{2}$ ratio as quark momentum fraction ${x}_{B}\ensuremath{\rightarrow}1$ is $\frac{{F}_{2}^{n}}{{F}_{2}^{p}}\ensuremath{\rightarrow}0.4\ifmmode\pm\else\textpm\fi{}0.05$ and this value is compared to theoretical predictions. The extrapolated ratio when ${x}_{B}\ensuremath{\rightarrow}0$ favors the simple model of isospin symmetry with the complete dominance of sea quarks at low momentum fraction. At high-${x}_{B}$, the proton quark distribution function ratio $d/u$ is derived from the ${F}_{2}$ ratio and found to be $d/u\ensuremath{\rightarrow}1/6$. Our extrapolated values for both the $\frac{{F}_{2}^{n}}{{F}_{2}^{p}}$ ratio and the $d/u$ parton distribution function ratio are within uncertainties of perturbative QCD values from quark counting, helicity conservation arguments, and a Dyson-Schwinger equation with a contact interaction model. In addition, it is possible to match the statistical bootstrap value to theoretical predictions by allowing two compatible models to act simultaneously in the nucleon wave function. One such example is nucleon wave functions composed of a linear combination of a quark-diquark state and a three-valence quark correlated state with coefficients that combine to give the extrapolated ${F}_{2}$ ratio at ${x}_{B}=1$.

Contact interaction model of liquid and solid phases

The work implements the approach formulated by B.V. Deryagin, which states for replacing the Coulomb and molecular (dispersion) forces with a system of tensions obtained on the basis of the mechanics of continuum equations using an incompressible liquid model. Interphasal activity modeling is considered from the standpoint of the equilibrium equations of mechanics of continuum using an incompressible liquid model and representing the interfacial tension tensor as a combination of spherical and deviatoric components. Analytical expressions are obtained for the components of the tension tensor depending on the wetting conditions of a solid surface with a liquid. Intermolecular interaction is determined by the value of the internal pressure of the liquid, which is variable over the interfacial layer thickness. The anisotropy of the interfacial tension tensor in the liquid-solid interfacial layer is expressed by the representation of the spherical and deviatoric components combination, which provides the equilibrium conditions for the interfacial layer. The authors propose to consider the adhesive contact as an external force effect of a solid surface on the volume phase of a liquid, leading to the formation of an interfacial tension tensor with components that are variable over the layer thickness. The authors established the nonlinear nature of the interfacial pressure distribution over the layer thickness, due to the difference in interfacial pressures in the liquid and solid phases in the direct contact zone. It is shown that the surface phenomena specificity is due to the deformation of the liquid volume in the interfacial layer, which leads to a change in intermolecular distances in different directions, which occurs with any kind of force acting on the volume phase of the liquid. The law of intermolecular forces distribution of a liquid depending on the distance is established based on the study results of a sitting drop. Expressions are obtained for determining the long-range interaction radius of liquid molecules and the thickness of the liquid-solid interfacial layer, which give a result that fits into the known estimates of the values of these quantities.

Symmetry preserving contact interaction treatment of the kaon

A symmetry preserving regularization procedure for dealing with the contact interaction model is proposed in this work. This regularization procedure follows a series of consistency conditions that are necessary to maintain gauge symmetry. Under this regularization, proofs for the preservation of the Ward-Takahashi identities are given and the loop integrals in the contact interaction model are systematically computed. As an application example, the kaon electromagnetic form factor and ${K}_{l3}$ transition form factor are computed, and self-consistent results are obtained. Since the proposed regularization properly handles the divergence, one is freed from the inconsistencies caused by the regularization and can concentrate more on the physical discussion.

Фрикційний розігрів системи штамп-пружна півплощина при ковзанні вздовж твірної

Friction heating of system punch-elastic half plane when sliding along creative line is considered. Model of so-called “third body”, i.e., thin near-surface and intermediate layers, the physical and mechanical properties of which differ from those of the interacting bodies, and by the microgeometry of their surfaces in the contact zone, used for mathematical description of contact. The method of determination of thermal contact conductance in mathematical modelling of contact interaction with considering friction and hear generation by “third body” is presented. Using of modified conditions of heat contact in mathematical model of contact thermoelasticity, taking into account of friction and heat generation is proposed. The solution of the problem of thermoelasticity for a half-plane is obtained by means of the Fourier integral transformation. Heat conductivity problem for the punch is solved by method of straight lines. The system obtained of dual integral equations is reduced to the system of linear algebraic equations by means of points collocation method. Formulas for thermal fields, heat fluxes and contact stresses are proposed. In order to obtain the unknown contact area, the iterative scheme based on a control of a sign of normal stresses in the immediate contact interaction zones is used. Method of moving line of separation of boundary conditions is proposed.

FINITE ELEMENT MODEL FOR ANALYSIS OF CHARACTERISTICS OF SHROUDED ROTOR BLADE VIBRATIONS

The paper presents the approaches to FE modelling of blade airfoil, contact between the shrouds and operational damage. The regularities are established concerning the influence of the finite element type, finite element mesh and model of contact interaction on the spectrum of natural frequencies of blade assemblies. The use of the developed computational models is substantiated to determine the forced vibration characteristics of the selected objects of investigation. Based on the performed numerical experiments it was substantiated of finite element model selection for analysis of characteristics of shrouded rotor blade vibrations.

NEW PHYSICAL FACTORS IN CONTACT INTERACTION OF ELASTIC BODIES OVER CLOSELY MATCHED SURFACES

The paper contains generalization and development of approaches, models and research methods for contact interaction of complex shaped bodies. In the case of contact along the surfaces of a close shape there are a number of problems. Firstly, analytical methods are not universally applied. Secondly, with a small gap between the surfaces of the contacting bodies the contribution of the deformation of the intermediate and surface layers to the balance of displacements becomes substantial. Thirdly, the application of traditional numerical methods also sharply increases the contribution of errors in contact surface shape approximation. All these factors bring on the need to develop new approaches, models and methods for the analysis of contact interaction of complex shaped bodies. For this purpose, the apparatus of the theory of variational inequalities is applied to deliver Kalker’s variational principle. In addition, a new principle for deriving multiple models of contact interaction of complex shaped bodies has been developed. It consists in gradually increasing the number of physical factors that are taken into account when building these models. This makes it possible to form a sequence of varied parametric models by taking into account new factors while naturally avoiding conflict situations. Furthermore it ensures inheritance in the sequence of models of different levels. The proposed improved approaches, models and methods are illustrated by the case study of the contact interaction of bodies with the intermediate layers located between them. Keywords: contact interaction, complex shaped body, finite element method, boundary element method, Kalker’s variational principle, variational inequalities

CONTACT INTERACTION OF SIMILAR SHAPE BODIES AT SMALL DISTURBANCE OF INITIAL GAP DISTRIBUTION

In this work, on the development of previous research, a model of contact interaction of similar shape bodies is built. Contact in the system "punch - stamped material - matrix" is considered. A gap is set between the material to be stamped and the matrix, which varies in circular coordinate. The regularities of the change of contact pressure and contact areas with variation of the law of distribution of the initial gap are determined. The influence of the load level on these parameters is also determined. In particular, the analysis of the influence of the number of waves in the distribution of the initial gap in the circular direction on the nature of the distribution of contact areas and contact pressure. It is established that at low level of loads significant non-uniformity of the contact pressure distribution along the circular coordinate is realized. In the future, with increasing load levels, this unevenness decreases. The distribution of contact pressure tends to the case of contact with nominally coincident surfaces of the matrix and the material to be stamped, i.e. at zero gap. Thus, an analytical-numerical method for studying the contact interaction of closely shaped bodies with low perturbation of the initial gap distribution has been developed. Regularities of influence of constructive and technological parameters on contact interaction of these bodies on an example of elements of stamp equipment are also established. Keywords: contact interaction; stress-strain state; elements of stamps; contact area; contact pressure

Pion scalar, vector, and tensor form factors from a contact interaction

The pion scalar, vector and tensor form factors are calculated within a symmetry-preserving contact interaction model (CI) of quantum chromodynamics (QCD), encompassed within a Dyson-Schwinger and Bethe-Salpeter equations approach. In addition to the traditional rainbow-ladder truncation, a modified interaction kernel for the Bethe-Salpeter equation is adopted. The implemented kernel preserves the vector and axial-vector Ward-Takahashi identities, while also providing additional freedom. Consequently, new tensor structures are generated in the corresponding interaction vertices, shifting the location of the mass poles appearing in the quark-photon and quark tensor vertex and yielding a notorious improvement in the final results. Despite the simplicity of the CI, the computed form factors and radii are compatible with recent lattice QCD simulations.