COMPUTATIONAL-EXPERIMENTAL STUDY OF CONTACT INTERACTION OF BODIES WITH NEARLY FORM SURFACES

In many constructions, their elements are in contact with nominally matching (congruent) surfaces. In reality, this contact is disturbed due to deviations in the shape of these surfaces from the nominal. To study the effect of this perturbation on the distribution of contact pressure, the analysis of the stress-strain state of the body system of punched sheet-die is carried out. The middle element of this system deviates from the nominally flat shape. This causes a change in the contact pressure distribution. The proportionality between the clamping force and the level of contact pressure is also lost. The reliability and accuracy of the results obtained by numerical calculation have been experimentally confirmed. Keywords: stress-strain state; contact pressure; contact interaction; method of variational inequalities; Kalker variational principle; finite element method

CONTACT INTERACTION OF A TORSION SHAFT WITH A SPLINED BUSH IN ELASTICALLY PLASTIC DEFORMATIONS

Torsion shafts are the main elastic element of the suspension systems of a large number of vehicles. To simulate their reaction to the action of torque, the stress-strain state is analyzed taking into account the contact interaction with the spline sleeve. The features of the distribution of contact pressure between these bodies are established. The nature of stress concentration in the splined hollows of the shaft head is determined. Models and research methods have been developed that make it possible to develop recommendations for design decisions in the design of vehicle suspension systems. The factors are determined that ensure the strength of the torsion shaft at the values of its head diameters close to the diameters of the torsion shaft stem. In the case under consideration, this factor is firstly strength of the torsion shaft head. In particular, it was found that during manufacturing operations there are significant plastic deformations and contact loads in the heads of torsion shafts. This factor is decisive in substantiating the design parameters of torsion shafts. Keywords: torsion shaft; contact interaction; stress-strain state; elastically plastic deformation; suspension system

NUMERCNAL ANALYSIS OF CONTACT INTERACTION OF BODIES WITH NEARLY FORM SURFACES

Contact interaction of structural elements has been studied in the case of nominally close (nearly matching) surfaces. A non uniform gap is present between the contacting parts. Contact pressure and contact spot depend on the shape of this gap. Correspondingly so does the stress-strain state of the contacting bodies too. Since the problem is essentially nonlinear, the contact pressure distribution and the contact zones change with the growing loads. The solution is qualitatively different to the case of perfectly matching bodies. For the latter case, the contact pressure is linearly proportional to the load and the contact zone is predefined. Hence for the real structures for which the deviation from the nominal shape is unavoidable the impact of these inaccuracies on the contact pressure distribution and the stress-strain state need to be taken into account. This problem is addressed in the paper by example of elements of stamping dies. Keywords: element of stamping dies, stress-strain state, contact pressure, contact interaction, variational inequalities, Kalker’s variational principle, finite element method, boundary element method

THEORETICAL AND EXPERIMENTAL JUSTIFICATION OF DISCREETLY CONTINUAL STRENG-THENING METHODS BASED ON ANALYSIS OF CONTACT INTERACTION OF MILITARY AND CIVILIAN VEHICLES ELEMENTS

The paper describes studies of breakthrough methods effectiveness for sharply increasing the resource of highly loaded military and civilian vehicles elements based on methods of their discreetly continual strengthening. These methods, unlike traditional ones, combine the advantages of discrete and continual strengthening methods and lack their main disadvantages. The analysis of contact interaction of representative structures of contacting bodies at the microlevel is carried out. They consist of fragments of contacting parts, one of which is strengthened continually, and the other part is strengthened discretely. At contact interaction at the microlevel, on the one hand, the effects of the nanоlevel are manifested, and on the other hand, the effects of the macrolevel are manifested too. Nanoeffects are the redistribution of contact forces between bodies: from smooth ones they turn into an archipelago of hilly elevations. Macroeffects are to adapt the shape of the contact parts to the distribution of contact forces, smoothing their overall unevenness. As a result, the overall effect of strengthening is achieved, increasing the strength, load capacity and resource of military and civilian vehicles elements. A breakthrough is being achieved in improving the performance of military and civilian vehicles, which corresponds to or exceeds the world level for similar products. Keywords: discrete strengthening; continual strengthening; discreetly continual strengthening; contact interaction; military and civilian vehicles

SUBSTANTIATION OF DESIGN DECISIONS OF ELEMENTS OF MILITARY OBJECTS IN CONDITIONS OF CONTACT AND PLASTIC DEFORMATION

New design solutions, technologies and materials are required to improve tactical and technical characteristics of military equipment. Often this implies operation in such conditions as contact interaction and elasto-plastic deformations of materials. New models and research methods are developed for better utilization of modern materials and improved performance of military equipment. They account directly for complex physical and structural nonlinearities. The properties of conventional and novel materials are determined both in bulk and on surfaces at microstructural level. This will enable physically adequate and mathematically correct analysis of stress-strain state. The new advanced design solutions will emerge through the objective-driven search by means of parametric modeling. The project will extend traditional local problem statements with newly developed variational principles that account for structural and physical nonlinearity and are suitable for parameterization. This will create the basis for fundamental analysis of torsion bar suspensions, hydrovolumetric and gear drives and other crucial components of combat vehicles, engineering solutions for domestic manufacturers of military equipment that will bring their tactical and technical characteristics to highest modern standards. Keywords: contact interaction; stress-strain state; intermediate layer; contact pressure; contact area; plastic deformation

A solvable contact potential based on a nuclear model

We extend previous works on the study of a particle subject to a three-dimensional spherical singular potential including a $$\delta $$ δ –$$\delta '$$ δ ′ contact interaction. In this case, to have a more realistic model, we add a Coulombic term to a finite well and a radial $$\delta $$ δ –$$\delta '$$ δ ′ contact interaction just at the edge of the well, which is where the surface of the nucleus would be. We first prove that the we are able to define the contact potential by matching conditions for the radial function, fixing a self-adjoint extension of the non-singular Hamiltonian. With these matching conditions, we are able to find analytic solutions of the wave function and focus the analysis on the bound state structure characterizing and computing the number of bound states. For this approximation for a mean-field Woods–Saxon model, the Coulombic term enables us to complete the previous study for neutrons analyzing the proton energy levels in some doubly magic nuclei. In particular, we find the appropriate $$\delta '$$ δ ′ contribution fitting the available data for the neutron- and proton-level schemes of the nuclei $${}^{{208}}$$ 208 Pb, $${}^{{40}}$$ 40 Ca, and $${}^{{16}}$$ 16 O.

A multiphysics model of processes in electromagnets and actuators of vacuum switching devices taking into ac-count contact interaction of structural elements

The purpose of the work is to improve mathematical models and algorithms of computer modeling of multiphysics processes in electromagnets and actuators of vacuum switching devices by taking into account the contact interaction of structural elements when changing their stress-strain state. In the design of modern vacuum circuit breakers and contactors, there is a significant use of electromagnetic actuators based on high-coercive hard magnetic rare earth composite materials NdFeB and SmCo. The most promising for use as drives of circuit breakers and contactors are polarized electromagnets based on the use of these high-coercive permanent magnets. However, the existing serial designs of electromagnets and actuators need to be significantly improved in order to increase reliability and service life, reduce weight and cost, further reduce energy consumption, improve the manufacturability of the mass production process. Computer simulation is proposed to be performed by the Finite Element Method in 2D formulation using commercial software products and/or software created directly for these investigations. One of the priority areas for improving mathematical models and algorithms for computer modeling of processes in the mechanical circuit of vacuum switching devices of medium and high voltage is to take into account the contact interaction of the structural elements of the devices under consideration. The next step, thanks to the use of an advanced mathematical model, is to perform a set of computational research and based on the obtained numerical results to develop recommendations aimed at creating designs of electromagnets and actuators that would meet world standards and be competitive in the world market.

Modeling metal removal from workpiece surface during centrifugal rotation processing

The modeling and analysis the removal of metal process in centrifugal rotational processing of workpiece in abrasive medium are considered in this article. The single contact interaction process between abrasive particle and the workpiece surface is researched through three-dimensional modeling taking into account dry coefficient of friction. The contact interaction problem is solved through Ansys software and Archard code programmed to analyze the data. The removal of metal from the workpiece surface is researched when changing the technological parameters: friction coefficient, machining time, speed. The dependences between metal removal from the workpiece surface and technological parameters are constructed, from which reasonable parameters can be selected when machining the workpiece, allowing to achieve high accuracy. Experimental results have been confirmed by simulation results. Through this research, essential and important data sheets will be provided for actual production and testing activities. Consequently, time and money are saved in achieving the desired surface quality.