MULTI-CRITERIA ANALYSIS OF CONTACT INTERACTION OF DISCRETE-CONTINUALLY STRENGTHENED PARTS

This paper considers the influence of material properties on the contact interaction of strengthened structural parts. Discrete-continual strengthening technology is used to process these parts. Contacting parts are made of different materials. On the one side there is an aluminum alloy part. A microscopic layer of oxide ceramics is grown on its surface. On the other side there is a cast iron or steel part with an archipelago of strengthened material spots introduced by the electric spark method on the surface. Hence, the first part is processed continually, and the second one is processed discretely. The influence of material properties in the strengthening zones on the contact interaction of such parts is studied. Recommendations regarding the choice of materials and technological modes of discrete-continual strengthening have been developed. In particular, it was established that the character of contact pressure distribution and Mises stresses significantly depends on the combination of the moduli of the oxide ceramic layer on the aluminum part and the discrete strengthening zone on the cast iron part. At the same time, with the growth of the elasticity modulus of the material of discrete strengthening zones, a qualitative change in these distributions occurs. The contact pressure in the central part of the contact area first acquires a minimum and then a maximum. At the same time, the influence of the elastic modulus of the oxide ceramic layer on the aluminum part is less pronounced. The relative level of contact pressure and von Mises stresses varies in the studied range of variation of the modulus of elasticity of materials of continual and discrete strengthening zones in a fairly wide corridor. Therefore, it is possible to control the level of controlled values. And therefore there is an opportunity to justify the choice of one or another material, as well as constructive and technological solutions when creating certain structure elements. Not only the level of contact pressure and von Mises stresses is important for rationalizing technical solutions of new machine components. Contact interaction determines the loads distribution between structural elements, which in a certain way directly affects their stress-strain state and strength. Also, a series of processes and states are launched in addition: friction, wear, bearing capacity. They depend on the distribution of contact forces. So, from a physical point of view, a “multi-physical” process is implemented, and from a technical point of view, this is a “multi-criteria” process. As a result, a number of competing requirements and limitations arise at each of the stages, which should be taken into account when justifying rational technical solutions for new products, in particular, internal combustion engines.