Discrete and Continual Strengthening of Contacting Structural Elements: Conception, Mathematical and Numerical Modeling

Abstract

The paper proposes a variant of discrete and continual strengthening of contacting elements of machine-building structures. One of the parts is strengthened discretely, and its counterpart is strengthened continually. The resulting pair combines positive qualities of two different types of strengthening methods. Investigations on stressed-deformed state of the treated fragments provides a basis for conclusion about high efficiency of the proposed combined strengthening method. While applying the method mechanisms of negative feedback between the stages “loading – contact interaction – friction – wear” are involved unlike with conventional versions of strengthening technologies. In this way, positive integral effect results from an application of the developed strengthening technology. This effect is significantly higher than the sum of effects obtained owing to application of every strengthening technology. In this case a favorable distribution of contact pressures between contacting bodies has been ensured. This, in its turn, leads to a decrease in wear that prevents a sharp increase in loads acting between bodies. Thus stabilization of the investigated processes occur. The papers considers stress-strain state of a representative fragment of the investigated system in order to demonstrate positive effects arising from the contact of strengthened bodies. Results of the calculations indicate validity of forecast assumptions. Indeed, the strengthened zones can bear high loads. However, due to high tribo-mechanical properties of the material in the hardened zones, friction and wear in them are much lower than for a base material. Due to this, all positive components of the total effect are formed. This effect is supported by the fact that a counterpart is processed continually. In particular, metals from aluminum-type materials are coated with a thin layer of oxides by forming them in a strong electric field of a special medium. Formed solid phases of oxides serve as a structural basis for formation of surface layers. In combination with discretely strengthened surfaces of counterparts the formed pair acquires high strength, antifriction and anti-wear properties.

Conceptual Foundations of Discrete-Continuous Strengthening of Engine and Turbo-Expander Components

“…Важливо зазначити, що у багатьох випадках поліпшуються тільки певні із значущих службових характеристик, а інші -або залишаються на тому ж рівні, або ж -погіршуються [1]. Тому із метою усунення цього протиріччя був розроблений метод дискретноконтинуального зміцнення деталей машин [1,14,15]. Якраз його застосування дає потенційну можливість уникнути ситуації із конфліктом протиборчих тенденцій при зміцненні деталей конструкцій.…”

Substantiating promising technical solutions for turbo- expander power plants based on the research into working processes and states

“…The method of discrete strengthening is also promising [18]. The combination of these methods is even more promising [27].…”

“…As a result of strengthening, a thin layer of coating or coatings is created on the surface of structural elements [27]. The properties of the materials of these layers differ sharply from the properties of the main material [28,29].…”

“…A layer of aluminum oxide (corundum) is applied to the aluminum part by means of micro-arc oxidation. Archipelagos of discrete strengthening zones indented into the base material are applied to the cast iron part by electrospark alloying [18,27].…”

A semi-analytical method for analys of contact interaction between structural elements along aligned surfaces

“…Specifically, this is the impact of bolted joints [30,31], the presence of a linear or nonlinear intermediate layer between contacting bodies [32][33][34], etc. Furthermore, several papers [35][36][37] consider the special properties of thin-walled structures or the reinforced surface layers in machine parts affecting their strength and rigidity. At the same time, classical approaches, described in works [38][39][40], regarding the models of continuum mechanics, a finite element method and the minimization methods, form the basis only for a general variational statement of the problems on analyzing the contact interaction.…”