Key Engineering Materials Vol. 743

Abstract: Computer simulation of the stretch forming process of the with different anisotropy of properties in the software package PAM-STAMP 2G was implemented in the work. The design of the multivariate experiment was made to analyze the effect of the anisotropy of the mechanical properties over the final polythickness of the skin after stretch forming. The regression analysis of the results was implemented after simulation, besides a mathematical model of polythickness dependence on the anisotropy of the properties was formulated. The optimal combination of Lankford coefficients, ultimate strength, yield strength and uniform elongation that minimizes polythickness of the finished skin was established.

Abstract: Applications of the new algorithm for the calculation of stress-strain state of multicomponent isotropic bodies are given in the article. The algorithm is based on the derivation of expressions for iterated effective modules obtained by converting the Voigt-Reuss modules. The comparison of exact solution with the solutions based on new characteristics obtained for the problem of loading a round sandwich plate is given as the example.

Abstract: The formulation of a new mathematical model of deformed viscoelastic composite is shown in the work. The method of constructing a model is based on commonality problems of determining the effective modules of inhomogeneous elastic composites and viscoelastic bodies, which demonstrate the dependence of the mechanical properties from the duration of load action. Mathematical model of hybrid efficient modules has been constructed on the superposition of expressions for known effective modules of Voigt and Reuss, Hashin and Shtrikman. The new model summarizes the properties of classical approximate approaches. We have shown that the calculations of stress-strain state with the help of new effective characteristics provide a more accurate prediction in comparison with known models.

Abstract: New 3D metrology and new possibilities of modern measuring equipment allows observing in more details the process of metal surface layer deformation by rough surface of roll. The article covers the question of the change in the void volume of steel sheet rough layer at different section levels of rough layer by roll with different surface roughness.

Abstract: In this research work, we consider the problem of sensor selection for the system controlling full penetration mode in electron beam welding. For this, we have investigated four signals from the backside of the workpiece: electron current in root plasma, ion current in root plasma, through-thickness electron current and penetrating bremsstrahlung X-ray. After having done the research we have estimated the advisability of two signals: one for cases if requirements for control precision are high and the other for other cases.

Abstract: This article deals with the aspects of mathematical description and honing process optimization to obtain high-precision apertures in workpieces. It studies how parameters of a model affect the changes in pressure of honing stones. It offers an algorithm for uninterrupted control of the honing process. The process model reliably describes the workpiece processing in sufficiently wide field and can be used for operation of CNC machine CC743.

Abstract: In this study, the weldability of thick dissimilar steels to a thin-wall pipe using the electron beam welding has been investigated. In addition, weld quality evaluation in as-welded condition has been conducted. For this purpose, micro and macro examination of the welds has been carried out.

Abstract: This work researches a smoothing process of original micro-profile and hardening process of AISI 304 steel surface layer material while performing rotary burnishing of the flat surface ring area. The paper establishes the interrelation between the number of indenter impacts and elementary volume of the material with a roughness and microhardness of the surface layer. The minimum roughness Ra=30 … 45 nanometers and the maximum microhardness of 425 … 475 HV0.25 is reached with the feed rate of 0.05 mm/rev and impact multiplicity of 70 … 100.

Abstract: The present paper presents the results of an analysis of the functioning principles of contemporary CAD systems and of their capabilities for modern process modelling. Requirements to process modelling software have been set forth. Physical processes during cutting of metals have been considered. The selection of Delphi programming environment has been substantiated. An interface, an algorithm and a program code for part machining modelling software has been developed for an all-purpose thread-cutting lathe with 3D graph involvement in OpenGL. A description of the software work and its specifications have been provided. Ways have been defined for further improvement and development of the developed software, as well as its promising application fields.

Abstract: This paper analyses the results of experimental research of contact stresses distribution over an artificial flank wear-land and temperature distribution in a cutting wedge in a free orthogonal turning of the disk made from titanium alloy (Ti-6Al-2Mo-2Cr) by a cutter with a sharp-cornered edge and with a rounded cutting edge. The investigation was carried out by the method of “split cutter” (sectional tool) and method of variable length of an artificial flank wear land. Experiments with variable feed rate and cutting speed show that in titanium alloy machining with a sharp-cornered cutting edge, the highest normal contact stress over the flank land (σ_{h max} = 3400…2200 MPa) is observed immediately at the cutting edge, and the curve has a horizontal region with a length of 0.2…0.6 mm. At larger distance from the cutting edge, the value of normal contact stress is dramatically reduced to 1100…500 MPa. The character of normal contact stresses for a rounded cutting edge is different: it is uniform and its value is approximately 2 times smaller as compared to machining with sharp-cornered cutting edge. In author’s opinion it is connected with generation of a seizure zone in chip formation region and explains working capacity of very worn-out cutting tools in machining titanium alloys. The results of experimental research of temperature distribution in the cutting tool wedge show that temperature reaches 1000 °С at essential wear over the flank surface. Such high value of temperature on the contact surface causes softening of work material, and explains the small value of tangential contact stresses (τ_h = 800…200 MPa) and reduction of normal contact stresses σ_h far from the cutting edge for a sharp-cornered cutting edge.